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Lower gearing


Marc
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Sure you can, using a 2a t-case, you can change the intermediate gear and low gear over to a series 3 t-case and trans. OR simply, bolt the t-case up to the series 3 trans. The lower gear in the 2a t-case is 2.888:1, compaired to the 2.35:1 you have in the series 3 t-case. This then coupled to the series 3 transmission, which has lower gear in first ( maybe second to, going by memory) is going to give you lowered gearing. The idea of changing the gears is simply, but you have to use the correct parts. The early suffix t-case used small bearings/rod for the intermediate gear, but the suffix "B" 2a t-case used large bearings/rod, the same size as is fitted in the series 3 t-case.

So, in short, the answer to your question is, yes.

AND,

if you just wanted to order the correct parts to do the gear changes, here are the parts numbers ===>

521330 Intermediate gear

235438 Low gear

599869 Intermediate gear bearing

521328 Shim

Todd.

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hey - you sure you got that the right way round? I just went and looked at Mark's gear ratio calclator and S3 is 2.89, the lower, s2a being 2.35. hmmm, someone will come along and sort this out out I'm sure. :unsure:

521330 Intermediate gear

235438 Low gear

599869 Intermediate gear bearing

521328 Shim

Todd.

Todd, so these 4 parts are all i would need to get lower low ration in my s3 transfer box?

did quick search on jc, total about £ 70 exc vat.

Edited by 02GF74
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02GF74,

Approx. '66 '67 series 2a t-case suffix "B" is what you want to upgrade the t-case for a series 3. It was this particular t-case that was upgraded or considered as a "HD" in the 2a, that has the same size intermediate gear shaft and bearings. The earlier series 2 & 2a, all use the smaller shaft.

The series 3 t-case, no matter the suffix letter, "A,B,C....." they are ALL 2.35:1

Ja, that's about right on the parts £, I'm going to do the upgrade, just hoping to find something on eBay, during the winter. If not, I'll order new.

Todd.

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Tuko is correct. I did it over the summer. B suffix tbox S3 gearbox. Short of majore transmission changes this is all you've got. On R&P, there's nothing lower than 4.7:1 in a standard rover axle.

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Short of majore transmission changes this is all you've got. On R&P, there's nothing lower than 4.7:1 in a standard rover axle.

The suffix B gears and later model box gives 49:1, which isn't too bad.

As for ring and pinions - if you fit salisbury diffs front and rear (genuine fronts are hard to find...) you can go down to 7.17:1 with Dana 60 ratios!!!

Also, a guy in OZ made a home-made series crawler box from a Fairey OD and a Borg warner 1331 jeep ransfer case. There is a thread on Outerlimits showing how for those with the machining skills.

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Well, if you're willing to go a bit farther than just a R&P change - which you would have to do to get Dana 60 gears in there - why not take the plunge:

10.jpg

Volvo portals will give you 5.99:1 combined axle ratio. This is what I have done, along with the change to a Suffix B box and now have a 1st Low ratio of 64:1 which is a reasonably respectable crawl ratio. The plus side is excellent performance in low range. In high range, 4th is a struggle on any sort of incline and I estimate that 45 - 50 mph is top speed. It's a trade off, but if it's not a daily driver, it's a very good compromise.

Cheers,

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  • 3 weeks later...

I believe Sereis II and IIa transfer casesm suffix A&B have a 2.89:1 low range, IIA suffix C and later (series III etc) have a 2.35:1.

For the Gearbox:

First Gear in IIa Suffix A&B is 3:1

First Gear in IIaSuffix C on is 3.60:1

First Gear in Series III is 3.68:1

I have a 1965 Series IIa that I intend to put an early 1960's suffix B transfer case on- the resulting ratio

3.6*2.89*4.7= 48.9

My stock gearing currently is

3.6*2.35*4.7= 39.72

Your gearing will be slightly different if you start with a series III transmission because I believe the first gear is a slightly lower 3.68:1 instead of 3.6- I could be wrong there though... :o

That should make a decent change though nothing too radical. I think this is the best you can do with swapping stock series parts.

Now if someone could tell me if you could adapt a 1 ton's transfer case so the low range would be 3.27:1

and the high range 1.15:1 instead of the 1 tons 1.53:1- that might be interesting ~55.33:1.

Cheers!

Matt

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Now if someone could tell me if you could adapt a 1 ton's transfer case so the low range would be 3.27:1

and the high range 1.15:1 instead of the 1 tons 1.53:1- that might be interesting ~55.33:1.

Cheers!

Matt

AFAIK the one-ton had a longer gearbox mainshaft to mate with the helical transfer case, so you would need the gearbox as well. There are also no other high range ratios available that I am aware of...

It would probably end up being better to fit an LT230, since they have an equivalent low range, and a choice of high range between 1:1 and 1.6:1?? May as well fit an LT77 or R380 while you are at it.

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AFAIK the one-ton had a longer gearbox mainshaft to mate with the helical transfer case, so you would need the gearbox as well. There are also no other high range ratios available that I am aware of...

It would probably end up being better to fit an LT230, since they have an equivalent low range, and a choice of high range between 1:1 and 1.6:1?? May as well fit an LT77 or R380 while you are at it.

So it appears that the early Series IIa transfer attached to a later transmission would be the easiest way to lower low range gearing the most bang for your buck.

Anything more would require more radical and costly swap LT77, NV4500 :o etc...

Some links that might be of interest:

Novak Gearing Calculators

Rover and other related gear ratios

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So it appears that the early Series IIa transfer attached to a later transmission would be the easiest way to lower low range gearing the most bang for your buck.

It is just as easy to buy the suffix B intermediate and low-range gears and fit them to a later (SIIA or SIII) transfer case. That is what I did - they are available new and don't cost much. Unless you do a rebuild, a whole suffix B t-case would probably be on its last legs now, and a suffix A has a smaller intermediate shaft with associated bearing problems, so would not be a good idea.

With a 2.25 petrol or diesel, the suffix B gears are fine up until 33-34" tyres. Larger than that and you need to look for other options.

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Did the series 11a box change again after '66,'67 or did the 'B' suffix last to the end of series 11a production?

Suffix B finished long before 66/67 - the suffixes continued at to at least E. The changes were mostly minor though. The ones I am aware of:

Suffix A - small intermediate shaft (same as Series 1 T-case)

Suffix B - large intermediate shaft (but retained 2.88:1 low)

Suffix C - changed from 2.88:1 low range to 2.35:1 (this ratio then continued for all SIIA and SIII) - all 2.25 engined land rovers should have the suffix C or later.

Suffix D ?

Suffix E/F - stronger (correctly radiused) intermediate shaft introduced about 1970ish...

Can anyone fill in the blanks???

Edited by isuzurover
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Well, I fitted a S1 transfer to my S3 box and the 2.89 ratio VS 2.35 rings a bell.

This is about 23% lower, only in low range.

The idea of fitting some other gears to the existing case doesnot work I think, because the intermediate shaft is smaller in dia, and the casing has smaller holes in it.

I believe that you cannot have the lower range with the bigger intermediate shaft, because the smaller gear wouldnot fit.

Anyway, the endresult was very good for me, with a 100Hp petrol engine it was reliable for years.

Daan

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I believe that you cannot have the lower range with the bigger intermediate shaft, because the smaller gear wouldnot fit.

Did you read my post above?

Suffix B - large intermediate shaft (but retained 2.88:1 low)

I have a 1968 model (suffix E?) t-case with 2.88:1 suffix B gears fitted, as do lots of other peple I know.

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