BMW/Titan LSD Viability

[ChrisC]

I know this doesn't help, but my diff is exactly the same, I was advised to would be, while I was at the Factory back in 2019.  Its the same as recent YouTube vids of the Caterham 420R demo car, and my cars diff noises where present and heard (you can't miss them) during PBC at Gatwick.   So I can't call TADT, but I know three cars that do.  

The reason I feel Marks car is important is the mileage and use are known.   He can give a clear indication of potential life expectancy increase (or not).  If we had a 2018 car, again with known usage even better. 

My "X" statement is ambiguous because apart from the quoted life of the Titan parts website, we don't know a life expectancy for the sintered plates.  The 10,000 miles quoted by Titan looks achievable, with the carbon plates based on road only and lower power, but its not specific.  Is it best case, worst case, average, Sintered or Carbon????  The text doesn't change based on your selection. 

Moly plates comment comes from a reason to upgrade.   This thread has obviously impacted a large number of owners, who will have choices to make.  Hopefully it gets the information out there to prevent the catastrophic failures we are seeing at the moment, and brings them more in line with scheduled rebuilds.  My hope is the owner (member) gets to make an informed choice.  They can chose the Sintered route, knowing a life expectancy of X years, knowing about the bangs and clonks whenever they try to drive in normal traffic flow.  Or they seek a Moly plate option, I believe SP Component Tracsport has Moly plates (happy to be correct on that one), but there are others for the BMW 168, Drexler for example, not sure what Cusco uses.   

Who knows CC/Titan could be working on such a change, it can't be good having demonstrations cars sounding like a bag of bolts are loose behind your ears.

[ScottR400D]

Yes, the SPC has moly plates but they’re not the only thing that’s better than the Titan, which, I’m told, only uses the high friction sintered plates with a high preload to overcome other shortcomings. 

I’m also told that Titan are well aware of their shortcomings but are quite happy to sell repair kits and CC are of the same mind. Whether they will change if alternatives prove popular, we’ll see. I think that’s a little way off yet. 

But, as you say, knowledge of life expectancy for sintered plate Titans would be useful for owners to make a balanced judgment. I suspect it won’t be too long before we have that info but remember the 10k/12month service recommendations apply whatever plates are in the Titan so maybe the choice is there to be made. 

Certainly for me, especially in hindsight, it’s a no brainer. An extra £1000, maximum, at first lsd ‘service’ time will likely be repaid in 3-4 years or so, ignoring the work saved, and you’ll have a quiet, more effective diff in the meantime. 

[ChrisC]

My last car had a Titan BMW Carbon diff, and I feel dodged a bullet.  but, and its a big BUT the noise difference between the two plates is excessive.  If I had my previous car, and knowing what I know now, at rebuild time,  sintered plates wouldn't be at the top of my list. 

The only saving grace would be increased life expectancy.    

[ScottR400D]

There’s a chance your old car had the earlier carbon plates. According to RRT the current ones don’t last anywhere near as long as the older ones did. 

[ChrisC]

Unfortunately not, it was a 2017 car. 

[R400svn]

Hi what year did they change to the new style carbon plates ?

[ScottR400D]

From what I have been told no one is quite sure. Phil Stewart told me that at some point they just stopped lasting but no one (at least officially) knows what changed or why. I think it was then that the sintered plates were introduced, though they may have been around earlier for race applications and began to be offered for road use at the time of the great carbon plate evolution!

I'm not sure anyone (who would tell us) knows. It's all a bit murky.

[R400svn]

Just checked through my paperwork and the invoice for my diff was dated March 2014 

[ScottR400D]

R400svn. How old is your car? I understood it to be a 420, which weren't launched until 2015, yet your username suggests it's a R400. I know they're the same thing.

Anyway, my R400 kit was delivered in December 14. I assume it had the 'not so good' carbon plates as it's lsd failed at 7750 miles. Yours could be from the same batch. 

[R400svn]

Hi yes the car is 2015 420r but the invoice for both engine and diff used for its registration were from March 2014 

[ScottR400D]

Of course, Jason, I remember now. Good chance our diffs are from a similar age then, if your car was built 2015 from parts a year old and mine was delivered later that same year. I will dig out my paperwork and see if it can find diff details.

 

[CtrMint]

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".    Marriage 

[gulf 1]

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]

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.

 

[Geoff Brown]

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.

    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 wiltshirenorth@lotus7.club

And on Thursday I am picking my diff up from SPC 

 

[aerobod - near CYYC]

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.

[Grant_7]

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]

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]

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 - near CYYC]

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.

[ScottR400D]

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. 

[CtrMint]

My Results ~48ftlb

I've been into the garage this evening and measured mine.  I'll post what I did just in case there's an error.  The results were better than expected.

I jacked the car up on the A frame middle, removed the right hand side / drivers rear wheel.  Lowered the car until the near side was back on the ground without any suspension lift due to the jack.  I left the jack under the A frame and also placed another trolley jack forward off the removed wheel at the end of the floor pan.  This didn't take any load but was there for safety.  I also put chocks under the front wheels.

Measurement was taken in the clockwise direction.  A socket was placed on the hub nut and rotated gradually until the hub rotated, the maximum torque was then read.  I used a SnapOn torque wrench and a Clarke digital adapter.   I took 4 readings with each.

The Snap On measured a peak 53 ftlb, and a min of 51 ftlb, then others at 52.   The Clarke was consistently 46 ftlb. So about 48ftlb considering an average across the two tools.

My 420R has approx 3600 miles, no track days, first road mileage occurred last day Feb 2019.   I've launched it on damp ground may be 3 times, never in the dry.  Pulled hard from 2nd more frequently, but certainly nothing excessive.  I don't usually get beyond 6k rpm.   The car usually runs in free traffic around the TT course.  Speeds can be high over the mountain.  Car has also done the Taffia plus may be 300 motorway miles.

Sound wise, there's quite a knock and noise on and off load, cornering its quite noisy, basically like two friction plates.  Very early on I recorded the diff knock from the cabin.  This was taken Jun 2019, I suspect around 1000 miles 

  As mentioned was told TADT, and the diff was sintered. I Learned to accept the knock.

[ScottR400D]

It’s good that you now have a figure to compare with. I don’t think it’s too surprising that you’ve got a good preload at only 3600 miles. The key thing will be how it goes in the future but at least you can now easily keep an eye on it. 

50lb ft or so, though? That’s a heck of a preload for a light road car, no wonder it clunks and knocks. 

[aerobod - near CYYC]

If the diff is chattering due to high preload, additional friction modifier can be added to smooth the plate movement. Depending on the oil already in place and how much friction modifier it has in it (needs some for proper operation of a clutch LSD), you can add small amounts of modifier at a time, as per instructions from the supplier, until chatter is reduced.

[CtrMint]

I would do a comparison on the 620R as it's only got 900 miles on it and is significantly quieter.  Unfortunately getting the car jacked up is a complete PITA because of the rear silencer.