Overdrive??

[Leigh 110]

Has anyone got opinions on overdrives????
Roamer??? Do I need to sacrifice pto winch???
Any advise appreciated???
Vehicle-1988 perentie 110GS Winch-"48264"
Thanks Leigh

[isuzutoo-eh]

If you search around a bit you'll find a few threads about LT95 overdrives and how they don't survive behind an Isuzu.

[Homestar]

Yep, they struggle to survive behind a stock V8...

Roamerdrive don't make one for the LT95 but say they are working on one, but I don't think they are any closer than they were a year ago. I emailed them about it, but never got a response.

[DeeJay]

Only the 6wd would not be able to take a overdrive if ever one is manufactured as it will tack on to the rear of the LT95 Where as the PTO for the winch comes out the underneath.

[Bearman]

Has anyone got opinions on overdrives????
Roamer??? Do I need to sacrifice pto winch???
Any advise appreciated???
Vehicle-1988 perentie 110GS Winch-"48264"
Thanks Leigh

G'day Leigh, Some bad news mate, If your Perentie has a winch fitted as the above suggests, you cannot fit an overdrive to it even it you wanted to. Reason is as you hint, the winch PTO drive is from the gear on the rear of the mainshaft (in the transfer case). It is a special gear with teeth on it to drive the chain for the PTO. When you fit an overdrive you remove this gear and replace it with the overdrive gear. So you can either have a winch or an overdrive, but not both. I would stick with the winch personally but if you decide you want an overdrive I am certainly interested in buying the winch and PTO assembly from you.

[123rover50]

If you search around a bit you'll find a few threads about LT95 overdrives and how they don't survive behind an Isuzu.

I bought mine new and its been behind the 4BD1/ Lt95 since the 80,s.
Now turbo,d but is still going strong.
Synchro when changing down is dodgy now but I just double d clutch.
I dont have it in OD when working hard and slip it out going up hills.
Touch Wood:p

Didiman

[Barefoot Dave]

Didiman, there is a lot to be said for mechanical sympathy ;-)

[101RRS]

I bought mine new and its been behind the 4BD1/ Lt95 since the 80,s.

I dont have it in OD when working hard and slip it out going up hills.
Touch Wood:pDidiman

Yes there have a few people who have had the overdrive survive behind an Isuzu but the majority have the opposite experience. To me it is clear that the overdrive is living on the edge and driving style depends on whether it lives or dies.

Garry

[mark2]

At 100 km/h, an Isuzu powered 110 with the standard transfer gearing of 0.996 and 31" tyres is only turning 2370 rpm in 4th gear. This is quite tall - 4th in these things is similar to 5th in most vehicles. IMHO, a n/a vehicle does not need an o/d and would struggle.

[Mammalalien]

Has anyone got opinions on overdrives????
Roamer??? Do I need to sacrifice pto winch???
Any advise appreciated???
Vehicle-1988 perentie 110GS Winch-"48264"
Thanks Leigh
How about changing the ratio of 4th gear, the transfer case or even at the axels as alternative to an overdrive? Just enough to allow comfortably sitting on 110kph would be ideal for SA.

[JDNSW]

My 110 (same engine, gearing and tyre size as the army 4x4s) has been sitting comfortably on 110 without an overdrive for the last twenty years. As Mark points out, it is not revving all that fast at that speed.

John

[Landy Smurf]

I know next to nothing about this era of land rover. Isnt the lt85 a 5 speed? can it go in to replace the lt95?

[Mammalalien]

My 110 (same engine, gearing and tyre size as the army 4x4s) has been sitting comfortably on 110 without an overdrive for the last twenty years. As Mark points out, it is not revving all that fast at that speed.

John
Hmm, I've seen a few comments about 90-100kph being the maximum comfortable speed for a Perentie. Maybe those were referring to the realities of having a canvas back at those speeds as opposed to gearing?

[Lotz-A-Landies]

How about changing the ratio of 4th gear, the transfer case or even at the axels as alternative to an overdrive? Just enough to allow comfortably sitting on 110kph would be ideal for SA.Not sure what you mean about changing the ratio of 4th gear. In the LT95 4th is direct 1:1 engine to mainshaft and then 1:0.996 on the front/rear output shaft. (No 5th in a LT95)

Changing the diff ratios you would go backwards AFAIK there are no Rover Diff ratios higher than 3.54:1 so your limiting factor is the front diff ratio. Plenty of lower ratios.

[isuzutoo-eh]

I know next to nothing about this era of land rover. Isnt the lt85 a 5 speed? can it go in to replace the lt95?

Yes, but, the Isuzu/LT85 bellhousing is different to the LT95 bellhousing, and since it was only made for the '86-'90ish period, they are somewhat uncommon, less common than LT95 bellhousings it seems.
Also, the LT85 uses the LT230 tranfser, so if the Perentie has a winch or third driven axle then it won't be compatible with the LT230.

[Mammalalien]

Not sure what you mean about changing the ratio of 4th gear. In the LT95 4th is direct 1:1 engine to mainshaft and then 1:0.996 on the front/rear output shaft. (No 5th in a LT95)

Changing the diff ratios you would go backwards AFAIK there are no Rover Diff ratios higher than 3.54:1 so your limiting factor is the front diff ratio. Plenty of lower ratios.
Ah, yes. Thanks for pointing that out. I still have much to learn. :)

Actually I did come across that bit about 4th being direct drive after I posted. If you haven't seen it, there is a great YouTube channel (http://www.youtube.com/user/trailerfitter2/videos) with lots of how-to, tare-downs and useful advice on Landy maintenance.

Over the course of a few videos he opens up and compares the inner workings of LT77 and R380 boxes and even interviews people from Ashcrofts about common causes of failure.

[JDNSW]

Hmm, I've seen a few comments about 90-100kph being the maximum comfortable speed for a Perentie. Maybe those were referring to the realities of having a canvas back at those speeds as opposed to gearing?

I imagine that 110kph in one would be pretty noisy, wind noise, tyre noise, and flapping canvas mainly. Not sure what an overdrive would do about any that! Worth noting that the civilian 110 has a lot more soundproofing than has the Perentie, but even in it, the engine is not obtrusive at 110 - mainly wind and tyre noise.

John

[xxmaxx]

How about changing the ratio of 4th gear, the transfer case or even at the axels as alternative to an overdrive? Just enough to allow comfortably sitting on 110kph would be ideal for SA.
Hi mate... I know this is an old post... but... can you expand on the type of work involved in re-gearing the diff or gear box for a better 4th gear at 100km/h?

[JDNSW]

Hi mate... I know this is an old post... but... can you expand on the type of work involved in re-gearing the diff or gear box for a better 4th gear at 100km/h?

As pointed out - there are no front diffs with a higher ratio, so you would need to get new gears designed and made. Probably cost more than the perentie. Rear diff is possibly simpler, as there are probably more ratios available.

As far as the gearbox goes, changing the ratio of fourth gear to anything other than 1:1 means a different gearbox, which means a different transfer case, as the transfer case is integral in the LT95. Possibly an Isuzu gearbox with an R230 transfer case, but as pointed out this means you can't use the PTOs designed for the LT95.

It should be pointed out that there are overdrives for the LT95, since they were fitted to the Rangerover for years. Whether they stand up to the Isuzu engine may be another matter - there seems to be mixed results on this. And there goes your PTOs again.

Can I suggest the simplest and easiest solution to the not very serious issue of engine rpm is to look at slightly larger diameter tyres.

John

[mark2]

Going the other way,
I would happily swap my 0.996 transfer gears for a set of RFSV 1.113 gears....

[Mammalalien]

Actually, you can't with the LT95. I did some research after posting that and the 4th gear in that box effectively just mates the input and output shafts together so 1:1 is the one and only option.

That being said, I've driven Arternune's (formerly Spudboy's) Perentie with standard gearbox, engine and tyres at 100Km/h over not too long of a distance. It did it quite happily. The biggest problem was the noise of rushing air making it difficult to hold a conversation.

Unless you are going a long, long way, very quickly, I wouldn't worry too much about gearing.

[Lotz-A-Landies]

The biggest problem for the Perentie gearing is getting to 100 KPH, they are no race car off the mark but will plod along all day. Rather than spending money on gearing, you'll get better results spending dollars on a turbocharger conversion on the engine.

KLR at South Windsor, now do it as a routine conversion.

[87County]

I recently travelled to Pucka/Corowa in the Perentie (w/LT95).

Further expanding JDNSW's suggestion above re tyre size, I used 255/85 16 tyres (abt 33") on D1 rims. These raised the gearing quite usefully (even makes the speedo read more normally).

The limiting factors for comfort, as JD points out, are wind, canvas & road noise.

Overall fuel consumption averaged about 10.2 l per 100km.

BTW the Perentie has the after market KLR turbo which enables the larger tyres to be used without fuss. The exhaust modifcations for the turbo included greater clearance on the rear lhs tyre.

It may be of interest to be aware that in practical terms the use of 255/85 16 tyres raises the gearing a little too high on a standard Deefer with 300tdi and R380 (and that's how we happened to have these tyres and wheels "in stock" when the Perentie arrived).

And to forestall any of the usual "you can't do that" nay-sayers around, here's a pic showing that 255/85 16s fit well on the Perentie. They fit without any chassis or hanger rubbing and even in the spare wheel space. :)

https://www.aulro.com/afvb/images/imported/2014/06/1444.jpg (http://s708.photobucket.com/user/87county/media/LRs2005_zpsd5b6efb5.jpg.html)

[mark2]

Actually, you can't with the LT95. I did some research after posting that and the 4th gear in that box effectively just mates the input and output shafts together so 1:1 is the one and only option.

That being said, I've driven Arternune's (formerly Spudboy's) Perentie with standard gearbox, engine and tyres at 100Km/h over not too long of a distance. It did it quite happily. The biggest problem was the noise of rushing air making it difficult to hold a conversation.

Unless you are going a long, long way, very quickly, I wouldn't worry too much about gearing.

The transfer gearing can be swapped and is different on the RFSV models. Any RFSV owners fitting a turbo and wanting to swap for a set of taller gears - let me know....

[303gunner]

Feeling game?


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[Blknight.aus]

overdrive.... behind a 4bd1.

might last as long as a pollies promise.

change the Tcase gearset if you must but dont put in the overdrive esp if you have the OEM winch because that i know of no overdrive supports the use of the chain drive down to the bottom plate.

you could of course go an lt85 with the lt230 for a slightly better choice of gear options but you'd need a custom PTO for the winch.