Thread: Diff Lockers

Having now finished uni exams, I've had a bit more time to research this. I'm wondering if anybody can confirm what I've found out, make sure I'm thinking along the right track here. Exams do funny things to my brain.

I see there was indeed a change in the Rover diffs, imperial to metric about 1983. Given my vehicle is from the 60's, I'll assume it's an imperial one, but I'll check shortly to see if this is indeed correct. Judging by the welded patch on the back of one of the casings (not to mention the dents in the gearbox cross member and engine sump!), they've taken some beatings and may have been replaced at some stage. The previous owner also said he broke a half shaft in the rear axle a few years ago and was able to source a new one no problems from the local LR dealership. Maybe it's already been changed to 24 spline... I'll check.

Anyway, what I seem to have discovered is that I can run a 4.7 ratio ring and pinion with a 3.54 centre with this adapter from Ashcroft: Ashcroft Transmissions - 4.7 Spacer ring

Assuming I do have the imperial casing, I'll also need to run a set of bearing spacers, also produced by Ashcroft. Ashcroft Transmissions - Imperial Bearing Sleeves

Now, the problem I'm seeing is that I'll have 24 spline diffs with 10 spline shafts (we'll assume). I must admit a lack of knowledge now, as I haven't pulled the front axle and swivel apart... I'm guessing that all the bits and pieces in there are also 10 spline, and won't play nice with the new diff centre. Is this an easy problem to get around, can I just install a later swivel kit which will have 24 spline halfshafts, or is this going to get complicated quickly? I see from another thread on here that this could be a problem which will require custom drive shafts to be made up.

Originally Posted by Lotz-A-Landies

{snipped for relevance}

Are they a 24 spline replacement for the Series LR 4.7:1 diff hemisphere?

If it is the second option, then getting Barry (HiTough) to broach a couple of series halfshafts with 24 splines at the diff end won't be a problem.

Is there another way around this which I have not yet stumbled upon yet? For the rear diff I figured you would be able to fit a 24 spline drive flange from something like a Defender, but I see they've been changed to 5 bolt rather than the Series 6 bolt design. I'm yet to find anything which is 24 spline with 6 bolts...

Alternatively, are there any 10 spline lockers available? That seems like it would solve a huge amount of pain for me right now! Mind you, according to ROAM Offroad, they recommend swapping to 24 spline gear right through.

Any advice pointing me in the right direction would be greatly appreciated!

Cheers,

Martin

If you have a 109" with a rover diff and intend to use it in anger offroad you will need to upgrade it.

Personally I would probably go for the toyota diff centre conversion.

I'm not entirely sure anger is the right word for what I'm planning. My plan is to use the vehicle as a camper/tourer with much better off road credentials than your average camper van. It certainly would be used as a 4wd, but I'm not looking for a comp truck, nor do I intend to stick it in big holes just to see if I can get stuck. The reason I'm thinking of installing diff lockers is to allow me to get that little bit further without stressing the vehicle as much.

I will have a look at the toyota conversion though, sounds interesting.

Arthur has just dropped around, apparently my diffs are pretty bad and need a fair bit of work. This didn't come as much of a surprise...

If you have a SII or SIIa 109", the quickest, easiest and stringest option is to fit a Salisbury rear end out of a 109" SIII. You can get Detroit/Maxidrive/Aschroft etc centres for these. They are already 24spline.

Then you are left with the decision about your front diffs, given that they have uni joint half-shaft swivels you are basically locked into the 10 spline Rover style. A lot of the movement in the Rover diffs are the accumulation of wear in the crown-wheel and pinion, inside the hemisphere and mostly wear on the splines of the half-shafts.

There are plenty of good second-hand 4.7:1 Rover diffs out there, a rear Rover can be fitted to the front etc. So a bit of trial and error looking for a good diff can save a lot of money buying new bits and re-building a diff. It may be possible to get both assemblies off the one SIII vehicle. This will give you the more reliable 16mm studs that don't pull out of the hubs like can happen with the SIIa style. SIII 109 front halfshafts are stronger than SIIa front halfshafts, they are only 10 spline at the diff end but 24 spline at the hub end.

New MD drive flanges on the hubs can reduce the play further.

Originally Posted by turkeybrain

I'm not entirely sure anger is the right word for what I'm planning. My plan is to use the vehicle as a camper/tourer with much better off road credentials than your average camper van. It certainly would be used as a 4wd, but I'm not looking for a comp truck, nor do I intend to stick it in big holes just to see if I can get stuck. The reason I'm thinking of installing diff lockers is to allow me to get that little bit further without stressing the vehicle as much.

I will have a look at the toyota conversion though, sounds interesting.

Arthur has just dropped around, apparently my diffs are pretty bad and need a fair bit of work. This didn't come as much of a surprise...

Series 4.7s are the weakest rover CW&P. They are OK for a front application, but in the rear it is not if you will break it but when. If you are planning on touring you will likely be going to (reasonably) remote spots and be (reasonably) heavily loaded. The last thing you want is to need to crawl around underneath removing the tailshaft so you can try and drive home in FWD.

As Diana says, you could upgrade the rear to a sals which is what I did. However the toyota conversion is another good option, which allows you to use (cheap 2nd hand) LSDs or lockers, and retains ground clearance.

Isuzurover, you're correct, I expect to end up in some fairly remote places with a reasonably loaded vehicle. From that perspective the stronger the better.

So, from what I understand from both your posts is that it wouldn't be too difficult to do the rear diff, but I'd end up with a weak point with the 4.7:1 crown wheel and pinion. The front diff is almost impossible to convert to 24 spline? With the weak CW&P, would something like a heavy duty one from Ashcroft eliminate this problem? Ashcroft Transmissions - Heavy Duty 4.75 R & P It does only solve the problem at the back though, the front will still be the original diff, which I'm not hugely keen on.

As for the Toyota vs Salisbury option, the Salisbury would be very easy to fit once I find one, but the Toyota would retain better ground clearance. Hmm, it's a conundrum! Is this basically the type of conversion you're talking about, rather than fitting a full Toyota axle? Toyota differentials

Isuzu, given you've got the Salisbury locker already, why are you suggesting I should consider the Toyota option rather than the Salisbury, and what made you go with the Sals over the Toyota in the first place? Or had you just not heard about it when you did your conversion?

I guess the other question is do I really need lockers at all? Given I have extremely limited off road experience, is it something that I should just ignore now and maybe do later if I decide I want to get a little bit more adventurous? The main reason I'm thinking about this now is because I have to do something about my diffs anyway, so why not upgrade while I'm at it!

Your knowledge and advice is very much appreciated!

-Martin

Hi Martin

Thank you first of all, for showing me all of your treasures and works in progress.

The two diffs in question, will need a thorough inspection to determine whether the housing, crown wheel and pinions are salvageable.
Unfortunately there's a strong possibility due to the amount of fore and aft movement of the pinion, that the wearing surfaces of the crown wheel and pinion have been damaged.

We will hope for the best and have a look when you get a chance to come over to my place and I can also show you what is involved with the fitting of a Salisbury replacement .

Your question about the chassis number I ran through CalVIN.

Clifton Scientific Text Services, the Netherlands

25306190B
253 Model: Land Rover, Series IIA
Body type: Basic
Wheel base: 109in
Engine: petrol
Model years: 1962-1971
Destination: Completely knocked down (CKD), right-hand drive (RHD)
06190 Serial number
B Design: One significant design modification
Suffix used from March 1963 till April 1966
.

Hi Arthur,

It's good to have somebody far more knowledgeable than myself around. Thanks very much for your advice today, it's much appreciated. I look forward to catching up with you again. I'm quite interested in what it would take to fit a Salisbury, given that appears to be a good option for me.

I've dug up a photo of what's under that tarp and put it up for you in the Serenity thread proper.

Cheers,

Martin