Thread: Gearboxes for Dummies ???

Originally Posted by Lotz-A-Landies

Hi Guys

I am considering myself quite ignorant about the terminology used for some of the transmissions in the coil sprung Land Rover products and want some advice

1. The LT95 is the transmission used in the original range rover? What is it's Hi and low ratios?
2. The LT95 was also used in the Isuzu Series 3 Stage 1 but with a higher hi ratio of 0.95:1. - Is the low ratio the same and what is it?
3. My 1985 model Phase II Range Rover had a 3 speed automatic. Is this a Torqueflyte 727 + LT230 transfer box?
4. Graeme Cooper has changed the transmission in my '85 to a ZF 4 speed auto and Borg Warner viscous coupling transfer box. What is this called?
5. What is an LT77?
6. Have I heard the term LT85 and what is it?
7. What is a 380?

Now for the main question. A friend has offered me a 5 speed manual box from a Series 1, 4 door Disco.

1. What would that be?
2. Is it a reliable box (for use in an S2B Forward Control project)?
3. Can I lock 4wd in this transmission?
4. What are the final ratios in 1st and 5th in both high and low ratio?

Should I be looking for a particular engine/gearbox/transfer box combination to use in the project vehicle which will be regularly towing a series 1 on car trailer long distances? (it will mostlikely be running on LPG)

Any info would be appreciated.

Regards
Diana

I can't answer all of them, but can try some!

1. I think high is about 1:1, low, I believe, is the same on all LT95, 3.321

2. I believe it is 3.321 - certainly the 110 has the same low ratio for V8 & Isuzu although the V8 is 1.336 (High same as Stage 1.

3. No idea

4. No idea

5. I think it is the first Landrover five speed box.

6. I think Second Landrover five speed box, actually made by Santana. Replaced the LT95 in the 110 Isuzu, but is not regarded as being quite as rugged.

7. Current (more or less) Landrover manual gearbox, fitted to Disco 1 (?) & 2 and Defender. Came in various versions, some of the early ones with issues.


Main questions :-

1. See above - I think it will be a 380 plus 230 transfer

2. Yes, but some boxes have issues - Disco experts should be able to tell you better than me.

3. Yes. All disco 1 have centre diff lock, some Disco 2 don't.

4. Can't help.

Best I can do, but my info can be corrected by those who know more - I've started the ball rolling.

John

This may help

http://www.csse.monash.edu.au/~lloyd...Rover/GearBox/

http://www.expeditionlandrover.info/gearboxes.htm

Duane

I.m not an expert either but every little bit helps The 85 Phase 11 would have been a Chrysler 3 speed hydraulic Torqueflyte auto with an LT 230 as you suggest Strong auto, cheap (relatively ) to work on but built for a big torquey motor and a bit power sapping on a 3.5
The LT 77 was the first rover 5 speed and the manual version of yoir 85 Rangie would have had this box. It is easy to identify by the long gearlever unlike the remote mount on Discos.(which had the R380 originally)
The Lt 85 is the Santana box, 5 speed and was fitted to the later Isuzu powered Countys. It is generally considered to be a good strong box hence being fitted to the Isuzu motor .They are expensive to work on but good and sound.( Also a long lever layout)
Now, I have to get off this computor and get out to the shed !
Ian

Originally Posted by djam1

This may help
http://www.expeditionlandrover.info/gearboxes.htm

Duane

Duane

All that is very interesting and brings up another question. I am not currently planning to change the 4.7:1 ENV diffs on the Forward Control because it will run 9.00 R16 tyres (255 100 R16 for those who don't speak crossply) So the final drive for highway speed is important.

Looking at the data, the early Range Rover LT230 (which I am assuming is actually the phase II introduced in 1984 (1985 model)) has a 1:1 transfer box ratio.

Will this be the box on my LT230/Torqueflyte 727?

And can I fit that early LT230 transfer box to a newer R380 or LT77 gearbox or should I avoid either of those and which one?

(I have another '85 model RR sitting in the shed on the farm for use as spares)

Diana

Diana
This is probably heading beyond the realms of my expertise but what engine are you running as this will have an impact on this discussion.
I know ENV were a good diff but the front end was not designed for full time 4x4 (more the unijoints than the diff)
I understand that the many ratios on the high speed side of the LT95 will be possibly the most configurable here.
I would suspect that with the characteristics of a 2B you would not wanting to be cruising at more than 90-100 kmh
My manuals state that my stage 1 has a high ratio of 1.336:1
Quite frankly I dont think you would want to go too much higher than this but once again this is dependent upon the torque characteristics of the engine.
There are many more out there more knowledgeable than I.
Just remember winding a 2B up to even 80 km/h with 2 tonne behind it will take more than the standard brakes to stop.
I have a stage 1 with standard gearing with a good engine running on LPG I think it would do the job perfectly but the Stage 1 has 3.54:1 diff ratios quite a bit higher than yours.

Because the 3 speed auto does not have an overdrive top gear, the high ratio in the LT230 is higher geared (lower numeric ratio) than in LT230's behind other gearboxes. See suffix 26D in the list below.

From Dave Ashcrofts web site:

List of Serial numbers and corresponding Ratios
All stock LT 230's have a low ratio of 3.321, the following list refers to the high range ratio.


12D = 1.667 LT 230R
13D = 1.410 LT 230R
14D = 1.003 LT 230R
15D = 1.192 LT 230R
20D = 1.667 (2.5 N/A 110)
22D = 1.410 (all 4Cyl 90/110 bar above)
25D = 1.410 (V8 110 LT 85)
26D = 1.003 (RR Classic 3 speed auto)
27D = 1.192 (early RR Classic)
28D = 1.222 (RR and Disco I)
29D = 1.192 (V8 90 LT 85)
32D = 1.222
34D = 1.410 (2.0 Disco I)
36D = 1.211
38D = 1.211
40D = 1.211 (NAS/Japan 90&Disco)
41D = 1.211 (Disco II, diff lock stud)
42D = 1.211 (Disco II, diff lock stud)
43D = 1.410 (90/110 TD5)
57D = 1.410 (90/110 TD5)
61D = 1.211
62D = 1.211
68D = 1.211
69D = 1.211
70D = 1.211 (Disco II, no diff lock)

When British Leyland owned Rover, their gearboxes were prefixed with LT for Leyland Transmission. The numeric value corresponds with the centre distance of the gears in mm, eg LT95, LT85, LT77 and LT230.

The LT85 was designed and manufactured by Santana, for Leyland.

Leyland no longer owned Rover when the R380 was designed as a replacement for the LT77 (which was based on an old Jaguar 4 speed gearbox). The R is for Rover and 380 is the torque rating in Nm.

With the LT230:
LT230R uses roller bearings for the intermediate gears.
LT230T has taper roller bearings (later than LT230R)
LT230Q has Quiet gears (newer discos)

LT77 are the weakest gearbox, although early R380 (suffix J) break mainshafts because of a design flaw. Suffix K and L are much stronger.

The Borg Warner transfer case uses a chain instead of gears. The viscous coupling is easier for Range Rover drivers to drive because they don't have to remember to lock the centre diff . With age the, viscous coupling tends to fail and not let the diff work.

Originally Posted by djam1

Diana
This is probably heading beyond the realms of my expertise but what engine are you running as this will have an impact on this discussion.
I know ENV were a good diff but the front end was not designed for full time 4x4 (more the unijoints than the diff)
I understand that the many ratios on the high speed side of the LT95 will be possibly the most configurable here.
I would suspect that with the characteristics of a 2B you would not wanting to be cruising at more than 90-100 kmh
My manuals state that my stage 1 has a high ratio of 1.336:1
Quite frankly I dont think you would want to go too much higher than this but once again this is dependent upon the torque characteristics of the engine.
There are many more out there more knowledgeable than I.
Just remember winding a 2B up to even 80 km/h with 2 tonne behind it will take more than the standard brakes to stop.
I have a stage 1 with standard gearing with a good engine running on LPG I think it would do the job perfectly but the Stage 1 has 3.54:1 diff ratios quite a bit higher than yours.

I agree with djam - on ratios - the LT95 has the advantage of a number of different ratios. My guess is that running 900 tyres and 4.7 diffs you will want the lower ratio - the 2b, particularly loaded, is going to be heavy, and you probably won't be driving it all that fast - it is high, and so is the load bed, although at least it has a wider track than the 2a FC.

John

Originally Posted by djam1

Diana
This is probably heading beyond the realms of my expertise but what engine are you running as this will have an impact on this discussion.
I know ENV were a good diff but the front end was not designed for full time 4x4 (more the unijoints than the diff)...

...Quite frankly I dont think you would want to go too much higher than this but once again this is dependent upon the torque characteristics of the engine. ...

... I have a stage 1 with standard gearing with a good engine running on LPG I think it would do the job perfectly but the Stage 1 has 3.54:1 diff ratios quite a bit higher than yours.

All of this discussion is why I am here.

Just a bit of information.

The 1970's Ford F100's, with a 351 Cleveland V8 had the same size drum brakes as the S2B.

Years ago on my S2a (Suffix G 109" 253 V8) I used the same booster and dual line master cylinder as used on the Ford F100/351 V8 and the brake specialist who set up the balance etc suggested that it was the first Land Rover he had driven that had excellent brakes. We plan to do similar on this beast.

Regarding the ENV, yes I have heard the stories about the poor quality of the unis in the front of the S2B swivels and their not being designed to run in constant 4wd. DO NOT WORRY - I have in my study at this very moment a pair of Mal Story's Maxidrive specials - these are designed to mate the ENV diff to stage 1 V8 swivels and CV joints. These should be up to the requirements of constant 4wd.

Regarding travelling with 2 ton behind the beastie. Yes I see your point - however having travelled the Hume Highway many times overnight, I also don't want to be on a highway travelling at S2B 80 KPH when a B Triple or even just one of the current B Doubles comes up behind me at 120KMH. The ability to maintain a road speed of 95 - 110 KMH will be just fine and what we are aiming at.

The engine / transmission combination is a D1 V8 unit. The engine is actually a 4.6 and am assuming R380/LT230.

If the gearing is too tall there is an option to drop down to 8.25 R16 tyres which are a very cheap readily available size, whereas for 9.00 R16 I am limited to for a mainly on-road pattern Michelin XZY at over $500 each or the regular off road Michellin XZL at a similar price.

Handling/suspension we are considering hybridising the current leaf springs, with reduced leaves and coil helper springs, at least on the front. Suspension is far from finalised at the moment.

So the current power train consideration is: use the LT230 from my '85 it would be a final drive of 3.431:1 while; the Disco LT230 am assuming 4.193:1 which may be more appropriate.

Am I heading in the right direction????

Diana