LT95 Overdrive

[kaa45]

Anyone tried an overdrive fitted to the LT95. Will the Isuzu kill it?

[101RRS]

Yes of course the Isuzu will kill it - you had better give it too me.

I saw that you bought the o/d that I was procrastinating over:mad:.

If I had known the market better it would have been mine but I decided to hold off:(.

I hope it all goes well for you:). Let me know what sort of nick it turns out to be in when you get it.

Grumble, grumble, grumble.

Cheers

Garry

(and yes I am still in the market for one)

[kaa45]

Sorry Garry,
But I have been looking for over a year. I'd prefer a 5sp box but don't have the coin at the moment. I'll put your name on it. When I'm done it's yours.
Looking at 12-18 months (if it's suitable).
Danny

[JDNSW]

I do not have personal experience but I was advised years ago not to bother - the Isuzu will kill it.

John

[Blknight.aus]

yep the suzi will eat any bolt on overdrive you stick on the lt95 via the PTO housing Especially if you try to tow with it or climb with it set to overdrive.

IF you really want more top end. source some 3.1:1 or better CWP sets and then put in the lower speed tcase gears but you still lose out on low range crawl speed. Which isnt a problem if your only doing it for a formed track runner or beach work but is going to hurt you if you go for niggly offroad work.

[101RRS]

Sorry Garry,
But I have been looking for over a year. I'd prefer a 5sp box but don't have the coin at the moment. I'll put your name on it. When I'm done it's yours.
Looking at 12-18 months (if it's suitable).
Danny

"yep the suzi will eat any bolt on overdrive you stick on the lt95 via the PTO housing Especially if you try to tow with it or climb with it set to overdrive".

"the Isuzu will kill it."

Those $$$$ I paid to the other guys on the forum seem to be working out:twisted:

Garry

[EchiDna]

LT85 with 35's = same effect :)

oh wait... that's what I've got B)

[Bush65]

I fitted a fairy od to the lt95 in my old rangie. It was a big disappointment - lot of whine and they aren't very durable behind a 3.5 v8.

[kaa45]

any good news? :(

[rovercare]

They're hard to source spares for:D

Oh, sorry, you wanted "good" news:angel:b

[isuzurover]

The cheapest way to get taller gearing is fit larger tyres. 255/85-16s should fit with only a slight cut and shut to the exhaust. 35's need more work.

Swapping diff ratios gets expensive. Especially for a salisbury.

I assume you already have 0.996:1 T-case high range already?



IF you really want more top end. source some 3.1:1 or better CWP sets and then put in the lower speed tcase gears

??? AFAIK the tallest ratio available for the Sals/D60 is 3.54:1. The SD1 has rover diffs in 3.08:1 and 2.8:1, but that is no help if you can't get a matching rear.

[justinc]

The cheapest way to get taller gearing is fit larger tyres. 255/85-16s should fit with only a slight cut and shut to the exhaust. 35's need more work.

Swapping diff ratios gets expensive. Especially for a salisbury.

I assume you already have 0.996:1 T-case high range already?



??? AFAIK the tallest ratio available for the Sals/D60 is 3.54:1. The SD1 has rover diffs in 3.08:1 and 2.8:1, but that is no help if you can't get a matching rear.

Hi Ben, The Sd1 has 'salisbury' type rear ends dont they? with a watts link or similar like the XE falcon? actually Looks a bit like the XE falcon borg warner diff from memory...

Hmmm, Memory:wheelchair:

Anyway, the overdrive will self destruct in 10 seconds behind the Isuzu, I have thought about using a Laycock type unit from a Volvo 740 Turbo 'box. These are similar to the GKN overdrives for defender LT230's, but a little smaller.:( I was only going to use mine when cruising on the flat, but then, with all that torque and towing a camper, I might just want to USE it....:twisted: And I can see THAT destructing too. Just face it. The Isuzu with a turbo on it will destroy most LR boxes except a TRLT95, so we just have to run 33" tyres minimum and stay under 130km/hr:twisted:


JC

[isuzurover]

Hi Ben, The Sd1 has 'salisbury' type rear ends dont they? with a watts link or similar like the XE falcon? actually Looks a bit like the XE falcon borg warner diff from memory...

Hmmm, Memory:wheelchair:

JC - you are probably right - I know very little about rover cars, only that a few models have landie diffs - I thought the SD1 was one of them... Must have been wrong.

[Blknight.aus]

??? AFAIK the tallest ratio available for the Sals/D60 is 3.54:1. The SD1 has rover diffs in 3.08:1 and 2.8:1, but that is no help if you can't get a matching rear.


I didnt say stick with rover diffs....

about the quickest ratio I know of in a diff is about 2.6:1 but its not all that tough. and I wouldnt put one in...

that said Im not into speed and Id be going the other way running 4.7:1 and just taking my sweet time since my plan to liver forever is thus far right on track I reckon I can afford to slow down.

[kaa45]

So, has anyone actually tried putting an overdrive behind an Isuzu. Or are these only opinions. (well informed opinions I believe) :angel:

[C H T]

If I might offer my two bobs worth: try an overdrive behind an Isuzu and see how it goes. I have heard a lot of theories about the longevity or otherwise of various Landrover transmissions behind Isuzus eg an R380 won't last the distance - yet when I speak to people who are driving vehicles with the various transmissions fitted I find out that they have not had significant problems. So try an overdrive - in good condition - drive with a bit of mechanical sympathy and we might all be surprised at how long it lasts.

MyR380 seems to handling a 4BD1T without any problems (over 20000ks now - heaving towing - long distance fully loaded) - the torque rating of the box is significantly above the torque output of the engine.

Christopher

[Blknight.aus]

FWIW

the thing that lets the suzi eat a gearbox is its torque impulse at or near idle especially if loaded up and "chugging"

the rapid acceleration and deceleration of the shafts makes the helical cut gears change thrust loadings significantly which is sort of the equivelent of using a jack hammer on your bearings over time. If Ive still got them the piccy's of the dead box from brian hejlms county (lt85) provide a perfect illustration of this. I cut the front off of the fubar input shaft to make a clutch alignment tool but he might still have the bits and be able to take some more pics of exactly what turns to swarf behind the isuzu.

a short term solution to the problem is to up the idle speed of the suzi. of course a pure square cut box would be my long term solution, no thrust loading of the shafts then. (just woefull tooth contact to worry about)

[kaa45]

The way i drive, it (the overdrive) would only be engaged in 4th gear at highway speed to reduce rpm and noise. Be nice to have a conversation without yelling. :wheelchair:

[Blknight.aus]

not quite...

those bolt in overdrives are always engaged, they replace the input gear that slides onto the output shaft of the gearbox if the bolt in overdrive has a catclysmic failure unless youve still got your origingal drive gear (and the OD hasnt taken out what I call the idler gearset) you aint going nowhere.

they usually whine and howl like a banshee before they let go so you do get a wrnaing.

[C H T]

FWIW

the thing that lets the suzi eat a gearbox is its torque impulse at or near idle especially if loaded up and "chugging"

the rapid acceleration and deceleration of the shafts makes the helical cut gears change thrust loadings significantly which is sort of the equivelent of using a jack hammer on your bearings over time. If Ive still got them the piccy's of the dead box from brian hejlms county (lt85) provide a perfect illustration of this. I cut the front off of the fubar input shaft to make a clutch alignment tool but he might still have the bits and be able to take some more pics of exactly what turns to swarf behind the isuzu.

a short term solution to the problem is to up the idle speed of the suzi. of course a pure square cut box would be my long term solution, no thrust loading of the shafts then. (just woefull tooth contact to worry about)


Dave

Thanks for your comments - it seems to that the major issue is allowing the engine revs to drop down too far - easy to do given the way the Isuzu pulls at low revs - keep the revs up a bit say above 1500 in the intermediate gears, and above 18-1900 in fifth and gearbox life should be reasonable

Christopher

[Blknight.aus]

just a thought. Brians gearbox is repairable with a new front bearing, lay and input shaft. have you tried asking him about his....

IMHO the lt85 should be stronger than an lt95 with an overdrive.

[kaa45]

just a thought. Brians gearbox is repairable with a new front bearing, lay and input shaft. have you tried asking him about his....

IMHO the lt85 should be stronger than an lt95 with an overdrive.

Then I have to source a new bellhousing, not a common item

[isuzurover]

If I might offer my two bobs worth: try an overdrive behind an Isuzu and see how it goes. I have heard a lot of theories about the longevity or otherwise of various Landrover transmissions behind Isuzus eg an R380 won't last the distance - yet when I speak to people who are driving vehicles with the various transmissions fitted I find out that they have not had significant problems. So try an overdrive - in good condition - drive with a bit of mechanical sympathy and we might all be surprised at how long it lasts.

MyR380 seems to handling a 4BD1T without any problems (over 20000ks now - heaving towing - long distance fully loaded) - the torque rating of the box is significantly above the torque output of the engine.

Christopher

Good point - might be worth starting a database of what has worked and what hasn't. A lot seems to be down to how gently you drive it.

Off the top of my head:
Justin C (4BD1T/RR) - 2 ZFs Destroyed
Sam/Def90 (4BD1T/90) - LT77S holding up fine, engine and box now belongs to DaveS.
Chuck(not on forum - 4BD1T/RR) - LT77 (ex VM) and about 6 R380s destroyed
CHT (4BD1(T?)/110?) - R380, holding up fine
Me (4BD1/county) - LT85 - rebuild at 240k km by Mal Story. Now 340k km and holding up fine.

According to Dave Ashcroft, the late model R380s are as strong or stronger than an LT85.

[Bigbjorn]

FWIW

the thing that lets the suzi eat a gearbox is its torque impulse at or near idle especially if loaded up and "chugging"

the rapid acceleration and deceleration of the shafts makes the helical cut gears change thrust loadings significantly which is sort of the equivelent of using a jack hammer on your bearings over time. If Ive still got them the piccy's of the dead box from brian hejlms county (lt85) provide a perfect illustration of this. I cut the front off of the fubar input shaft to make a clutch alignment tool but he might still have the bits and be able to take some more pics of exactly what turns to swarf behind the isuzu.

a short term solution to the problem is to up the idle speed of the suzi. of course a pure square cut box would be my long term solution, no thrust loading of the shafts then. (just woefull tooth contact to worry about)

I still have the box, untouched since returned. I have sold the trasfer off it though.

Straight cut, or correctly, spur gears would make so much noise you would not hear the 4BD1. Generally speaking spur gears are stronger (subject to material and other design criteria) and run cooler not having the sliding friction of helical gears. Long time ago I cut a few gearbox internals including cluster gears on milling machines. These were for vintage/veteran restorations where usable replacement gears were no longer to be found and cost therefore was no longer a factor. Milling gears using involute cutters and dividing head is a slow and high labour cost task.

[Larns]

MyR380 seems to handling a 4BD1T without any problems (over 20000ks now - heaving towing - long distance fully loaded) - the torque rating of the box is significantly above the torque output of the engine.
Christopher

Ya reckon?:D

Check the spec's for the N/A and turboed, I think you'd be suprised.
There is a reason they kill R380's, and it ain't just because there ugly!
My first R380 suffered a snaped mainshaft, did that idleing off from the lights.

On the overdrives, Dave is spot on, the thing is in constant mesh. You break the OD you get " no drive for you", have personal expearience here, very embaressing in traffic let me tell you

Good luck though

:twobeers:

[isuzurover]

Ya reckon?:D

Check the spec's for the N/A and turboed, I think you'd be suprised.
There is a reason they kill R380's, and it ain't just because there ugly!
My first R380 suffered a snaped mainshaft, did that idleing off from the lights.

On the overdrives, Dave is spot on, the thing is in constant mesh. You break the OD you get " no drive for you", have personal expearience here, very embaressing in traffic let me tell you

Good luck though

:twobeers:

4BD1 is about 250Nm, 4BD1T is about 320Nm in standard spec. Probably wouldn't be hard to get one to produce more than 380Nm though.

So haow many boxes of what type have you broken Larns???

[rar110]

Is there an adaptor out there to match a lt95 bell housing to a R380?

The lt95 gearing is ok but the noise is louder than the motor. Lower highway revs would be better.

[Bush65]

I still have the box, untouched since returned. I have sold the trasfer off it though.

Straight cut, or correctly, spur gears would make so much noise you would not hear the 4BD1. Generally speaking spur gears are stronger (subject to material and other design criteria) and run cooler not having the sliding friction of helical gears. Long time ago I cut a few gearbox internals including cluster gears on milling machines. These were for vintage/veteran restorations where usable replacement gears were no longer to be found and cost therefore was no longer a factor. Milling gears using involute cutters and dividing head is a slow and high labour cost task.
Given same number of teeth, same size (diametral pitch or module) teeth, same addendum modification factor, same material and heat treatment, helical gears have a considerably higher rating than spur gears.

As mating teeth move in and out of mesh, the point of contact changes. The further out toward the tip, the greater the stress created in the root fillet of that tooth (the load is applied on a longer lever). But, when the contact is near the tip, another tooth is coming in to mesh and the load is shared - this load sharing is much more effective for helical gears. So the helical gear can have higher tangential load for the same allowable stress in the root fillet.

[Bigbjorn]

Theory vs. practice raises its ugly head again and again in engineering problems. Spur gears last better and longer in rough use. Helical gears are quieter hence their use in road going vehicles particularly passenger carrying vehicles.

[JDNSW]

Actually, the discussion about tooth type is fairly academic, since tooth failure in gearboxes is relatively rare compared to broken shafts and failed bearings, not to mention worn splines, disintegrated synchro assemblies and various other failure mechanisms.

Same thing applies to the discussion about hypoid vs. spiral differentials - although here tooth failure is probably more common, my impression is that again, other failure modes still predominate - certainly in my experience.

John

[Larns]

I've only destroyed one box, the first R380 I through into my car. I think your prob right with those numbers on the tourque figures from factory, even if I think they are a little conservative.
I only say that because I've witnessed a 4BD1T stall a mobile engine dyno that was rated to 400Nm. Did it a couple of times to make sure it wasn't a fluke, very impressive.
In the dynos defence, I think the pump had been tweeked, but it was otherwise a stock standard 4BD1t with the non-gated garrett.
I think with a decent turbo/intercooler with the pump tweeked you'd be looking at around the 450-500Nm mark.
Just remember they move the army's 6x6 GMV fleet along alright and they can weigh in excess of 6.5 Tonne
I would have thought that the N/A engine would have had better figures though.

:twobeers:

[d@rk51d3]

The way i drive, it (the overdrive) would only be engaged in 4th gear at highway speed to reduce rpm and noise. Be nice to have a conversation without yelling. :wheelchair:

Picked one up recently for $100 :cool:, and fitted it for use on a recent trip to Darwin.

Found out pretty quickly that towing, or even driving with a load was useless, noise reduction was minimal, and was even noisier as the oil level slowly dropped over the course of the journey. (yet another reason to replace my TC seals;))

[Blknight.aus]

Just remember they move the army's 6x6 GMV fleet along alright and they can weigh in excess of 6.5 Tonne

:twobeers:


no they dont, they cant... the GVM of the vehicle isnt that high....:coplight:

no-one would ever overload a landrover........:angel::wasntme:

the PB ive seen was 9.3T which upset me somewhat as I had to re rig the crane twice to lift the bloody thing.

the first was easy, just add one more line to the block but nooooo still ran past 110% on the winch and that had run me out of sheaves so I had to put that sheeve block back on the crane and rig up the next one.

[C H T]

Ya reckon?:D

Check the spec's for the N/A and turboed, I think you'd be suprised.
There is a reason they kill R380's, and it ain't just because there ugly!
My first R380 suffered a snaped mainshaft, did that idleing off from the lights.

On the overdrives, Dave is spot on, the thing is in constant mesh. You break the OD you get " no drive for you", have personal expearience here, very embaressing in traffic let me tell you

Good luck though

:twobeers:

FWIW

4BD1T torque figures from manual 320nm (236 ft lbs) @1800 rpm early engine
or 314 (230 ft lbs) @ 2200 rpm late engine. Turn the wick up a bit and you probably add 10-15% to these figures - 271 lbs ft (368 nm). The R380 is rated for 380 nm (279 ft lbs input torque).

I have heard of early R380s breaking main shafts - stree riser on the main shaft is the cause of the problem. My R380 is a very late one with big layshaft bearings.

Thanks though Larns for your input

Christopher

[C H T]

Good point - might be worth starting a database of what has worked and what hasn't. A lot seems to be down to how gently you drive it.

Off the top of my head:
Justin C (4BD1T/RR) - 2 ZFs Destroyed
Sam/Def90 (4BD1T/90) - LT77S holding up fine, engine and box now belongs to DaveS.
Chuck(not on forum - 4BD1T/RR) - LT77 (ex VM) and about 6 R380s destroyed
CHT (4BD1(T?)/110?) - R380, holding up fine
Me (4BD1/county) - LT85 - rebuild at 240k km by Mal Story. Now 340k km and holding up fine.

According to Dave Ashcroft, the late model R380s are as strong or stronger than an LT85.

Isuzurover

Great idea - it would be helpful to idnetifiy which suffix box has been used eg mine is a late box with the big layshaft bearings. The boys at KLR have R380s behind turbo Isuzus apparently without any problems. add to the list a 4BD!T Rangie that I thought about buying - LT77S with big miles and no problems - how about starting a thread on the subject?

Christopher

[Bigbjorn]

Actually, the discussion about tooth type is fairly academic, since tooth failure in gearboxes is relatively rare compared to broken shafts and failed bearings, not to mention worn splines, disintegrated synchro assemblies and various other failure mechanisms.

Same thing applies to the discussion about hypoid vs. spiral differentials - although here tooth failure is probably more common, my impression is that again, other failure modes still predominate - certainly in my experience.

John

Dead right, JD. Tooth failure in automotive transmissions is nowadays rarely seen except in the now uncommon unsynchronised gearsets with sliding gears. Nowadays, with constant mesh gearing in even non-synchro boxes (Road Rangers, Spicers etc.) you hardly ever see a damaged gear with a tooth or three missing. The dog clutches and synchros now take the hammering.

[isuzurover]

Theory vs. practice raises its ugly head again and again in engineering problems. Spur gears last better and longer in rough use. Helical gears are quieter hence their use in road going vehicles particularly passenger carrying vehicles.

Not in LR boxes - I have pulled plenty of IIA boxes apart where 1st gear is stuffed (worn/pitted/broken), but the rest of the gears are like new.

[Larns]

9.3T!!!!


That's impressive, can't say Ive ever weighed one that heavy.

Bet the turbo whistled on that one!

[JDNSW]

Not in LR boxes - I have pulled plenty of IIA boxes apart where 1st gear is stuffed (worn/pitted/broken), but the rest of the gears are like new.

The reason S1/2/2a boxes tend to have stuffed first gear is the same reason that the first gear is a spur gear - unlike all the others (except reverse, which uses the same gear) - is that first and reverse are not constant mesh - they are sliding in and out of mesh. You cannot do this with helical gears, which is why they are straight or spur gears. And the reason they are stuffed is that subject to mishandling, they can have very high loads imposed on the leading edge of a single tooth as they are engaged. (in a constant mesh gear set, the shock load is taken directly by the leading edge of all the dogs at the same time, and the shock is transferred to the entire tooth on the constant mesh gear, not just the leading edge.

The difference is nothing to do with the fact that one is spur and the other helical - it is to do with whether the gears are constant mesh or not.

John

[Blknight.aus]

9.3T!!!!


That's impressive, can't say Ive ever weighed one that heavy.

Bet the turbo whistled on that one!

she blew a few tyres too.

[Bush65]

Theory vs. practice raises its ugly head again and again in engineering problems. Spur gears last better and longer in rough use. Helical gears are quieter hence their use in road going vehicles particularly passenger carrying vehicles.
We will have to agree to disagree.

The trend for many years has been to build smaller gearboxes that transmit increased power and torque. You will not find any large manufacturer of gearboxes today that use spur gears.

In a previous life I worked for the manufacturer of the largest gears in Australia - the largest in my time weighed 200 tonnes. They have since installed larger gear cutters.

We also designed and manufactured the largest sugar mills in the world, which were driven by multiple large kW steam turbines. Helical gears were used for the transmitted power. Smaller sugar mills use long addendum spur gears to connect the crushing rolls together, but this is because the rolls wear and the operating centre distance between rolls has to be reduced (the large mills have separate cardan shafts to each roll instead of gears).

More recently I have been involved with the design of grinding mills. We produced gear driven mills with installed power of 4.6 MegaWatt. For larger mills over 7 MegaWatt, gears were not used , instead wraparound motors were more practical. The gearwheels for the 4.6 MW drives were too large for manufacture in Australia, but the pinions were made here. No one in their right mind would have contemplated using spur gears.

Current gear rating theory is incredibly complex. Practice has validated the theory over many years. There is no possible way that spur gears can be designed as small as helical gears for the same rating.

[rovercare]

MegaWatts:eek:, that's a fuggin big mill:eek::eek::eek:

[Blknight.aus]

when you start working with herringbone gears and get the gear to cut them someone come and talk to me Im dreaming of rebuilding the R380 with a full compliment of herringbones and then replacing the syncros with dogs.

[JDNSW]

We will have to agree to disagree.

The trend for many years has been to build smaller gearboxes that transmit increased power and torque. You will not find any large manufacturer of gearboxes today that use spur gears.
..............
Current gear rating theory is incredibly complex. Practice has validated the theory over many years. There is no possible way that spur gears can be designed as small as helical gears for the same rating.

The advantage of spur gears over helical gears is two fold - because they do not have significant sliding contact, they are a lot less demanding as far as lubrication goes (and stand running without oil better) and they do not impose side thrust, with all the implications that has for case and bearing design. This does not mean they last better and longer in rough use, unless you include poor design and poor lubrication in "rough use", which of course, you can.

As Dave points out, much better than helical gears are herringbone gears - all the advantages of helical gears without the side thrust. Only problem is making them. An interesting side point here - how many of you know that the double chevron used by Citroen as a logo comes from herringbone gears? Andre Citroen built up an engineering business during WW1 making herringbone gears for various bits of machinery, and then branched out into car manufacture after peace broke out. Some of the early cars had herringbone gears (including crown wheel and pinions - I have seen one!), but market realities soon put a stop to that.

John

[Bigbjorn]

Some of the early cars had herringbone gears (including crown wheel and pinions - I have seen one!), but market realities soon put a stop to that.

John
AEC trucks & buses own double reduction differentials had herringbone gears into the 1970's well after their "merger" with Leyland.

[JDNSW]

AEC trucks & buses own double reduction differentials had herringbone gears into the 1970's well after their "merger" with Leyland.

Yes, but they were not selling cars in the low cost end of the market like Citroen were in the 1920s. Actually, as you point out some people have used herringbone gears, and it is obviously possible to make them, so it is surprising that they are not more widely used, particularly with the emphasis on weight saving these days - if you do not have to cater to the end thrust of helical gears you can save a significant amount of weight on both the case and bearings, particularly where a lot of power is being transmitted.

John

[Dougal]

4BD1 is about 250Nm, 4BD1T is about 320Nm in standard spec. Probably wouldn't be hard to get one to produce more than 380Nm though.

Currently knocking out over 500Nm:twisted:

I just had my worst tank of fuel in a long time. I ran out (about 75L) at 600km.
This was all urban work, shifting house with a trailer in tow and lighting up tyres at each intersection.:D

Fuel gauge was on holiday, fuel light came on and it coughed to a stop 200m later.

[Bush65]

The disadvantage of herring bone gears is that most gear cutters (except Sunderland) require space in the centre of the V for cutter runout.

High performance gears must be cut to a very high accuracy (profile and pitch). Gear grinding machines are required obtain the accuracy. The allowable tolerances for the higher accuracy grades use in gear rating are smaller than the average machine shop will achieve machining common parts like shafts.

The gear cutter/grinder has to compensate for the change in tooth profile as the tooth flexes and as the pinion bends and twists under load.

The increased face width of herring bone gears lead to greater deflection of the pinion.

The grinding mills I mentioned in the previous post have arrays of infra red sensors than measure the temperature across the width of the gear teeth close to the mesh. Here we are looking for changes in the tooth load distribution because of deflection.

If anyone is near Orange (NSW), Cadia gold mine run public tours. If you have a chance to look at the grinding mills, they are impressive machines - particularly the SAG (semi autogenous grinding) mill, with the wrap around motor.

Grinding mills rotate in plain bearings (white metal or aluminium) and only have a lower bearing shell. They typically use 4 by 500 tonne jacking cylinders to lift one end of the mill for bearing maintenance.

End thrust from helical gears is a simple engineering problem.

[101RRS]

I guess this thread has well and truely been hijacked from issues related to overdrives on the LT95 with a Isuzu diesel to a discussion on different types of gears.

I was hoping for more info on the pros and cons and general discussion of the o/d in the configuration would come out.

Garry

[kaa45]

I guess this thread has well and truely been hijacked from issues related to overdrives on the LT95 with a Isuzu diesel to a discussion on different types of gears.

I was hoping for more info on the pros and cons and general discussion of the o/d in the configuration would come out.

Garry

ME TOO!!!:mad:

[Blknight.aus]

FWIW IMHO .. most of the pertinant cons came out in the first dozen posts or so, to summate

the pros are obviosuly

lower engine revs at cruising speed
lower fuel consumption at cruising speed providing you dont labour it up too much

and the cons are

weakening of the driveline
additional noise when in OD


you drive an isuzu so noise is more than likely something you wont notice.

the weakening of the driveline is 2 fold running the overdrive increases the risk of the torque impulses (not the overall torque they're 2 different things) letting your gearbox lunch its bearings and the potiential of the same thing killing the OD itself when the OD glags thats it no drive for you.

Im about to PM brian to see if he'll post up some pics (or email them to me) if his input shaft bearing and main gear and you will get to see the classic symptoms of torque impulse loading lunching a gearbox bearing.

[kaa45]

Dave,
Your opinion is always valued :D
Danny

[justinc]

FWIW IMHO .. most of the pertinant cons came out in the first dozen posts or so, to summate

the pros are obviosuly

lower engine revs at cruising speed
lower fuel consumption at cruising speed providing you dont labour it up too much

and the cons are

weakening of the driveline
additional noise when in OD


you drive an isuzu so noise is more than likely something you wont notice.

the weakening of the driveline is 2 fold running the overdrive increases the risk of the torque impulses (not the overall torque they're 2 different things) letting your gearbox lunch its bearings and the potiential of the same thing killing the OD itself when the OD glags thats it no drive for you.

Im about to PM brian to see if he'll post up some pics (or email them to me) if his input shaft bearing and main gear and you will get to see the classic symptoms of torque impulse loading lunching a gearbox bearing.

I agree Dave, All the problems of fitting ANY transmission behind an Isuzu, N/A or turboed, stem from the torque pulses of this herculean powerplant.

Have I mentioned that I love this engine??:p

JC

[Blknight.aus]

http://www.aulro.com/afvb/technical-chatter/56461-smashing-gearbox-bearing-7-bigish-off-site-images.html

theres the link to how the damage gets done.

[rovercare]

^^^ that must be due from range changine on the fly:D

[Blknight.aus]

no mate thats from changing engine speeds on the fly.

its the input gear from the gearbox not the intermediate gear dogs in the tcase..

look closely at the first pic of the first post of the linked thread. you might just be able to make out the bell housing as opposed to the handbrake mount in the periphery of the picture...

:p

[rovercare]

:D I thought it was gonna be a link to some blown LT95 Tx gearsets you've posted before, I hadn't looked at the link, My post was obviously a bit premature, should have read the link FIRST, posted later:angel:

Thanks for letting me know what I was looking at though, I was struggling to tell what it was :lol2:

[101RRS]

If the Isuzu engine is so hard on gearboxes how come so many are still happlily running around in front of LT95s in the Army and in Stage 1s and early County's. Surely the failures you highlight are just the odd failures that occur with any box.

Garry

[Blknight.aus]

nope the 95 is the tough box that generally deals well with the suzi But it still does have it occour. And its not like it happens overnight in the other gearboxes I would guess that about 60-70% of all the gearboxes have the problem have it taken care of when thegearbox cops a rebuild for some other reason like a worn output shaft, failed syncros, a precautionary rebuild after the oils been run contaminated for an extended time or if its been run sans oil.

think of it like this. youve pulled the box out and apart wouldnt you replace the bearings at the same time ?

[Dougal]

I'm thinking a heavier flywheel would help mitigate the low rpm torque pulse issue.

[JDNSW]

nope the 95 is the tough box that generally deals well with the suzi But it still does have it occour. And its not like it happens overnight in the other gearboxes I would guess that about 60-70% of all the gearboxes have the problem have it taken care of when thegearbox cops a rebuild for some other reason like a worn output shaft, failed syncros, a precautionary rebuild after the oils been run contaminated for an extended time or if its been run sans oil.

think of it like this. youve pulled the box out and apart wouldnt you replace the bearings at the same time ?

Interestingly, when my (LT95) gearbox was overhauled about ten years ago (about 200,000km), because it was getting noisy, according to the bloke who did it, the only part that really needed replacing was the input bearing, although it was nowhere near as bad as the one in your pictures. Of course, all bearings and seals were replaced while it was apart.

John

[kaa45]

Would an overdrive even fit an LT95 behind an Isuzu? Aren't the ratios different between the Isuzu and V8 boxes? So an overdrive designed for the V8 LT95 wouldn't really fit an Isuzu LT95?

[JDNSW]

Would an overdrive even fit an LT95 behind an Isuzu? Aren't the ratios different between the Isuzu and V8 boxes? So an overdrive designed for the V8 LT95 wouldn't really fit an Isuzu LT95?

The LT95, in common with other Landrover transfer cases, is designed so that the input gear on the gearbox mainshaft is the same for all ratios, and effectively the overdrive just replaces this gear. So the overdrive fits all LT95s. I am not too sure whether the fitting is the same on the LT230 transfer case, but although the layout is similar it is definitely NOT the same as Series Landrovers.

John

[Lotz-A-Landies]

My apologies to everyone, this is a very late reply and it is also Off-Topic and Off Forum (Isuzu) but is a reply to posts in this thread.
...??? AFAIK the tallest ratio available for the Sals/D60 is 3.54:1. The SD1 has rover diffs in 3.08:1 and 2.8:1, but that is no help if you can't get a matching rear.
Hi Ben, The Sd1 has 'salisbury' type rear ends dont they? with a watts link or similar like the XE falcon? actually Looks a bit like the XE falcon borg warner diff from memory...
Someone is getting their Ps and Ds mixed up.

The Rover SD-1 has a live beam axle, which could in fact be traditional Rover style diffs.

The P6 Rover car had a "De-dion sliding rear end" (independant suspension) with a non-Rover style diff which looked a bit like a Salisbury (and may in fact have been Salisbury).

[justinc]

My apologies to everyone, this is a very late reply and it is also Off-Topic and Off Forum (Isuzu) but is a reply to posts in this thread.
Someone is getting their Ps and Ds mixed up.

The Rover SD-1 has a live beam axle, which could in fact be traditional Rover style diffs.

The P6 Rover car had a "De-dion sliding rear end" (independant suspension) with a non-Rover style diff which looked a bit like a Salisbury (and may in fact have been Salisbury).

G'day Diana,
Your are correct, sort of. The 8HA sals in the Fenders etc is way bigger than the sals TYPE of diff in either SD1 or DeDion equiped P series Rover.(P6B etc)
The SD1 had a sals type of differential, looked like a XE falcon Borgwarner diff withthe watts link attached etc. As far as I remember, the ratios for the P6B V8 auto were 3.07:1, and the Manual 3.36:1 or similar. The SD1 was I think as low as 2.88:1 for the auto,(Trimatic or BW 35/40/65)and around 3.36 for the 5 spd.
The Banjo type Rover diff wasn't fitted to either SD1 or P6 series, but WAS fitted to the V8 and 3000 Coupe P5 series. These were 3.54 ratio and were basically an early RRC diff centre.

JC-on- Holiday...:D

In the ACT at the moment, heading for Dubbo and Sapphire soon!!:)

[Bigbjorn]

I didnt say stick with rover diffs....

about the quickest ratio I know of in a diff is about 2.6:1 but its not all that tough. and I wouldnt put one in...

that said Im not into speed and Id be going the other way running 4.7:1 and just taking my sweet time since my plan to liver forever is thus far right on track I reckon I can afford to slow down.

You can get 2:1 by mating an Albion truck diff. centre from a hub reduction Albion into a Toyota Dyna housing. Not too difficult. Bit of lathe and drill work.

Hot Rodder after market gear suppliers have a terrific range of C&P's for 9" & other Fords, Dana, and GM diffs, from low 2's up to 9's.