BMW/Titan LSD Viability

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CtrMint
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On a lighter note, asked the wife if she could make time on Wednesday night to watch the jack as I test the preload.  I explained why I needed to do this.  She cynically replied "is this so you can justify a new diff".   Rofl Marriage Nono

Caterham 420R S3 Lotus Toxic Green,  Caterham 620R S3 Exocet Red. Blog: https://www.caterham7diaries.com
gulf 1
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After following this thread for weeks I think if only doing road work an open diff or ATB is the way to go.
Simon.Rogers
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I think you need to realise there are two distinct issues.

You have the carbon plates disintegrating as one issue which in itself is an easy fix under service.

However it is the preload washer shattering with the loss of all preload that is ongoing and not "fixable".  This will always require the diff out and serviced to resolve.  That could be every year it could be every 6 months or 2 race meetings - who knows.

 

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Geoff Brown
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On the longevity of carbon plated Titans as related many pages back by myself:

 On the road 2013 home built R400D, 220bhp.  Failure symptoms after 7 years/20,000 & an average of one track day per year.

 Arrow Right   Some pages back I volunteered to collate all Titan occurrences whether an early or late car. Only myself & ScottR400D so far. Don't be in denial!   Inform me by PM or [email protected]

And on Thursday I am picking my diff up from SPC Thumb Up

 

aerobod
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210BHP 2012 R400D 8 years of summer use ~20 track days (most with slicks). Amsoil 75w90 for first 5,500km, 2 changes of Redline 75w140 GL5 from there to current 33,500km. Now below 20lbft of preload, but otherwise working fine with no clunking or increase in noise. Will rebuild this winter with sintered plates.

James

Grant_7
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Details of mine as per my post #144 and included video.

And that reminds me, I need to message Steve Perks for an update on when my diff will be ready.

....

Geoff Brown
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Grant7- thanks. Pick my diff up from Steve tomorrow. His turn round is about two weeks but this could be longer in future as he is becoming popular!

aerobod - 21478 miles + track days! You have been lucky expect some debris though ? I ran my diff on Syntrax 75/140 for most of its life. Steve Perks & R&R recommend a good SAE 90 LS oil. So am contemplating Castrol B373. Plus R&R have their own special brew SAE 90. But which oil to use is always open to discussion.

With such longevity but irrespective of frequent oil changes the carbon/oil soup produced could potentially act like fine grinding paste on the bearings & seals. Makes a simple Titan refresh more expensive.

ScottR400D
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Geoff, I think James will be rebuilding himself and presumably will change the bearings after that long. 

He definitely seems to have done unusually well but I would wonder if the diff is genuinely working fine if it’s worn down to that preload. 

I’ll be interested in James’s opinion of the sintered plates compared with the carbon ones he presumably has now. 

 

aerobod
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From my rebuild perspective, I plan to inspect the bearings and CW&P with a magnifying glass to look for pitting or any other damage, but with no increase in noise from diff, it is likely things are fine. This is also supported by the last oil change just over 3,000km ago that showed some darkness to the oil with some expected plate wear, but no solid debris.

The diff is still working fine, as with slicks on and an aggressive clutch drop (last one done about 100km ago), both rear tyres immediately break away together, as they always have done.

The seals are fine with no leaks or seepage, but the side seals have to be replaced anyway as you can't remove the LSD without prying out the seals to remove the large circlips that hold the bearing races in place, they are covered by the seals.

I will keep with a fully synthetic 75w140 oil as opposed to an SAE 90 hypoid oil (assuming non-synthetic, at least the ones available in Canada) as the BMW diffs over the past 20 years have only specified either 75w90 or 75w140 full synthetic oils and Titan specifies 75w140. One problem here is that I need to run in ambients from 0 to 35C, which mean diff oil temps from 0 to 130C. SAE 90 oil is very thick at 0C,  with typical pour point of -15C, the 75w140 Redline oil I use has a pour point of -45C. Also at high temps an SAE 90 oil will have a viscocity of about 16 cSt at 100C, the 75w140 is 27 cSt. The non-multigrade SAE 90 oil viscocity is likely to fall off faster as the temps hit 130C and it will also degrade rapidly if it is not a full synthetic.

James

ScottR400D
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I would think you’re going the right way with oil, James, especially in those temps, though I’m no expert. 

I have used both mineral and synthetic, 75-80/90 and the 75-140 grades. I’ve never noticed any difference in noise or function to be honest.

My original Titan was run on 80/90 mineral as recommended by both Caterham and Titan until relatively recently but I don’t think that was the cause of its early demise because we have people on here who’ve always run the 75/140 synthetic and they’ve fared little better. 

I’ve currently got the RRT 90 in but haven’t been on track yet. Next year when I do I’ll possibly change to a synthetic, in expectation of an increase in temperature. At the moment it never goes above 70c or so.