BMW/Titan LSD Viability

[aerobod - near CYYC]

I thought the spacer for the gearbox was to eliminate contact between the Mazda box and chassis under certain conditions, that caused driveline noise to be transmitted into the chassis?

After one trackday and a fair distance on the road with my rebuilt Titan LSD using the sintered plates as opposed to the carbon ones, it is totally quiet, no banging or clattering anywhere in it's operation. I have 9 trackdays scheduled this summer, so hopefully that gives it a good workout to see if it stays in good health.

[ChrisC]

I haven't been able to edit the video of the noise it stopped on my car (yet), but will post when I can.   All I can say is my 420R build was predicted to have diff noise, due to the synter plates, and it did.   However it was embarrassing bad, especially in reverse.  The car was seen by CC during PBC, and again in videos highlighting the problem.  All suspected to be due to the diff, ok fair enough.  I had tried the RRT special oil, it improved most on the sound but not the clonking.   I had discovered the spacer and had specifically asked CC if it would help, the answer can back as no.  But for £3.75 plus some postage it thought I would give it a try.   It resolved 90% of my noise problems.  I now only get diff noise, when I expect diff noise, and no more embarrassing clonking while reversing.  So this must mean the clonking noise wasn't diff, and was caused by gearbox chassis contact. 

[ScottR400D]

Ah, OK, so it stops the box hitting the chassis. That will help. 

[ChrisC]

I am guessing its the only thing it could have been. 

[ScottR400D]

Yes, it's likely. I think I'm conflating two separate issues. 

[ScottR400D]

Chris, did you go back to CC with your findings after they'd told you the plate wasn't the answer? 

[ScottR400D]

Chris, did you go back to CC with your findings after they'd told you the plate wasn't the answer? 

[john hooper]

The spacer is simply a 3mm thick strip of ally 75mm long by 21mm wide with 2 x 13mm holes in it.

If you have got any scrap ally lying about it is cheaper and quicker to make your own. 

[ChrisC]

Yes - I did, and they are aware of the impact it had on my car. 

[Lazzer]

I know it's in this thread somewhere but for the life of me...

Could some kind soul advise what torque the Diff filler plug should be set to please? BMW, 22mm Gold Plug. 

Many thanks

[ScottR400D]

I'm not sure it's been mentioned. I just nip it up. 

[Geoff Brown]

ScottR400D #446 - You need to be more aware !! 

Received an answer from Graham M 9th November 2020 but only after contacting CC to hasten. You can view the 'potted' answer at #304,page 30, dated 14th November 2020. 

Basically - Yes CC confirm there is a problem ! Yes they made an error not publishing Titan servicing requirements as they did not foresee the problem coming. Yes CC is committed to finding a solution (one of the solutions with existing carbon plates is for CC to fall on it's sword, publicly acknowledge the cock up, offer a sintered plate retro fit & pay up which in the long run is highly unlikely). 

The letter is carefully worded with no expression of blame, guilt or contrition. But what do you expect ?

 

 

[Lazzer]

Thanks Scott.

Should also add thanks to you, Geoff et al for all the advice on this thread.

Went through the whole saga with a R300D at 3000 Miles after testing, disbelief, retest, acceptance and a trip to SPC..

[Geoff Brown]

Lazzer - #463 

Not to contradict what ScottR400D has stated but it should be a reasonably heavy handed nip up as the aluminium sealing ring does not grip that well.

I am sure you understand what a heavy handed nip is.....

A word of warning about the Gold plug fit. If one has an early diff back plate where the fill plug is canted at about sixty degrees facing down then without modification the de Dion will strike the top edge of the plug flats.

This will require careful 'engineering terrorism' on the top edge of the plug. As I have an early but bolt modified back plate I had to file down the two top flats to half thickness with a shallow cut, slightly removing the tops of two points. This just gives enough material to safely apply a spanner.

I eventually took two bites at the job even though I settled the weight of the car on the de Dion to check & had SWMBO bouncing up & down in the drivers seat (no, not what you think!).

A test drive over a known reasonably bumpy route is the only way to find out if the two items (plug & tube) miss each other. The nice shiny witness mark against the powder coating stands out in stark relief ! 

[ScottR400D]

#462 Thanks Geoff. You're right but sometimes I think I'm too old to spend much time searching for anything........

As you say, nothing unexpected there. Still no acknowledgment of the plate and washer failures being a major issue (?) and I guess it's easy to offer replacements for carbon plates when the majority of them have, by now, been replaced.

Oh well, I'm glad I don't need to hold my breath, I get the feeling it would be a long hold.........

Final word, Not much of a 'heavy hand' needed on the mag plug with a typical 26mm spanner if the size of mine is anything to go by!!

[Shortshift]

Adding to #463:

Replying to Geoff's comments about modifying the Gold plug so that it fits to the early style of BMW diff rear cover plate that angles the fill-hole and places the bolt head very close (too close) to the dedion.  This is indeed the case but the necessary mods are easy to carry out:
 

Chamfered bolt head:

 

And installed on the car (chamfered bolt head clearance to dedion etc):

James

[Mrp]

I don't think it will be a problem on newer cars as the rear cover has a recess for the plug (gold plug not fitted yet)

 

[Geoff Brown]

Shortshift #466 - More or less as I described (but could not be arsed to remove to photograph after the second attempt !)  

My 'cuts' to the two flats were more parallel leaving just under half thickness but I did turn down the two points slightly. I think 'adjustment' is individual as fits & clearances will differ slightly from car to car. 

 

[Jonathan Kay]

[GulfSeven]

With nearly 500 posts this topic is a bit overwhelming for new readers. Could somebody summarise the current consensus by answering these questions please?

1. Is there an issue with the Sigma-engined cars as well as the higher-powered Duratec-engined cars?
2. Is there an issue with the newer sintered plate diffs as well as the older carbon plate diffs?
3. Is there any preventative maintenance that can be done beyond the standard yearly diff oil level check without resorting to a full rebuild every 10,000 road miles as Titan recommend?
4. How much does a full rebuild cost anyway? It looks like the rebuild kit alone is £300 for a sintered plate BMW diff.

Thanks.

[ScottR400D]

#470

In my experience and opinion:

Is there an issue with the Sigma-engined cars as well as the higher-powered Duratec-engined cars?

Not as far as I know. Several mates have 135/150hp cars with 15/20k miles without issue. The torque of the more powerful cars plays a big part. 

Is there an issue with the newer sintered plate diffs as well as the older carbon plate diffs?

The sintered plates might last longer than the carbon but they're noisier and clunkier. They all wear quicker than they should with higher power cars. So, yes. 

Is there any preventative maintenance that can be done beyond the standard yearly diff oil level check without resorting to a full rebuild every 10,000 road miles as Titan recommend?

No. For higher powered cars the Titan just isn't up to it. 10,000 miles is very optimistic. 

How much does a full rebuild cost anyway?

£550 to £950 depending on what's replaced. More if you have to pay someone to remove and refit the unit in the car. 

[GulfSeven]

Thanks Scott.

[Geoff Brown]

I agree with ScottR400D summary. But I would suggest that the sintered plate variety may have 'longevity' but IMO it is all down to the TITAN unit itself. Built on a budget & not man for the job. Especially where higher torque output engines are concerned. 

BUT what makes it worse for those with a carbon plated TITAN is that Caterham did not publish recommended service intervals. From what I understand CC have still not publicised any guidance so those with sintered plates will eventually fall in to the expense trap ?

Preventative maintenance guidelines here: BMW Differential Titan limited slip unit - how to check & protect while in service. | Lotus Seven Club (lotus7.club)

[ScottR400D]

I'm not sure the sintered plates give the unit overall much chance of a longer life. They may not wear as fast in themselves but the Bellevilles still fail. 

Some of the reported failures, judging by their age, would have had sintered plates. 

[Neil Allen]

I have a 310S SV with a BMW / Titan LSD.

It is five years old and has done nigh on 35,000 miles.

I don't do any track days.

I do very little motorway driving.

I do like gently enthusiastic B Road driving. The car drives nicely and I'm sure the diff is doing good work when the bends are tight.

I also really enjoy exploring single track roads. This often requires driving half the car on a very slippery muddy verge when meeting occasional oncoming traffic. Sometimes mud, snow or ice on steep inclines can be quite a challenge but the diff really helps.

Yet the much maligned BMW / Titan LSD has always got me to my destination. 

But a few weeks ago on my home from South Wales there was a loud bang just behind my back. It sounded bad. 

Thank goodness there was a lay-by ahead. I stopped and did some pointless looking and prodding. I plucked up courage to drive back and forth in the lay-by. There were bad noises from what I assumed was the diff, but only on the over run. I tried some more enthusiastic driving in my lay-by and it seemed that if I avoided the over run as much as possible it looked like it was ok-ish. 

I managed drive home to Buckinghamshire that evening and to Caterham Crawley the next day.

Caterham Crawley had a reconditioned diff in stock. Rebuilt by "Road & Race" it says on my invoice.

After only a couple of days I collected my car. The "new" diff is much quieter. The helpful chaps a Caterham tell me that this is down to using thicker oil in the diff ("LS90 GL5 RRT LSD OIL" is what appears on the invoice.)