BMW/Titan LSD Viability

[ScottR400D]

Yes, David, I think you may be right. Used on track it will spend much of its time locked up and it seems pretty settled that oil is important. Though if it was designed just for that perhaps CC should tell their customers.

I also wonder if they wear OK to some point then ‘fall off a cliff’ and deteriorate rapidly from there on. Maybe at the point that the Bellevilles fail. IIRC most of us with failures have been nearer 7-10k miles, mostly on the road. 

Was it noisy during use? I appreciate that’s less of an issue on track too, with fewer really tight slow turns, but when my carbon plated Titan was rebuilt with sintered plates the noise when manoeuvring was awful. 

I’m still at a loss as to why Titan design it so that the Bellevilles can be absolutely flattened in use. It’s widely known and published that they should operate within 15/75% deflection, not just because they break if overstressed but because they don’t behave predictably outside of that range. 

[David_Long]

It seems Caterham where the only ones to use carbon plates due to the noise the sintered plate make. As my Titan was acquired directly from RR, it was sintered by default.

In terms of the noise, I don't find it too bad, probably a lot quieter than I remember the Quaife ATB that came with the car. It had one of those awful remanufactured Sierra diffs just before the change to BMW.

[7 wonders of the world]

Interesting David, 

Though I'm not sure that "using the LSD as it was intended" is correct, as there are many thousands of road cars covering millions of miles with plate LSD's (many ZF) that don't suffer the kind of wear that owners are experiencing in very light low mileage applications, bearing in mind the weight and preloads used in tintops.

Without a doubt designing a unit (Titan) that permits 100% deflection is a design flaw, so naturally with more road use this will see failure sooner that track cars.

Many of the Ford final drives were built to incorrect specs buy a third party, this is not the fault of the units as when built correctly, and assuming the CWP's are not worn beyond tolerance they are silent. 

Would be interesting if you could measure the plates and compare to a new thickness..?

 

[Geoff Brown]

I have just received a reply from my letter to Graham Macdonald. At least the reply appears to be honest & that the problem is known of & there is a way forward.

In a nut shell:

The carbon plate longevity (or lack of) is awaiting resources to investigate.

Carbon plates were introduced to reduce noise but switched back to sintered plates  'some time ago' when premature wear started to be reported.  Date of change back not specified but could be any where between 2015 to 2018 from info on this thread.

The first reports of premature wear appeared to be few & far between grouped around a particular cycle of car use. 

Though there have been few reports of issues anecdotally there appears to be a wider problem.

Committed to finding a solution.

It is understood that the servicing or life requirements a manufacturer places on an item may differ in a light & lightly used product but it is apparent that the diff servicing requirement needs to be corrected. No time scale mentioned.

With the support of understanding & passionate customers problems such as these can be addressed & improved upon.

 

 

[David_Long]

#304

''Many of the Ford final drives were built to incorrect specs buy a third party, this is not the fault of the units as when built correctly, and assuming the CWP's are not worn beyond tolerance they are silent.''

 

Caterham did use a non Ford crown wheel and pinions (Quaife, I believe) for a period before they changed to the BMW diff. Although these were robust and functional, they were horrendously noisy and lacked the finesse of the quieter Ford tooth profile (which you could write a book about). Mine arrived so poorly assembled that the pinion was literally flopping about before it was even fitted to the car.  

[7 wonders of the world]

OE Ford metallurgy has always been pretty good, didn't know CC had used pattern CWP's late in the Ford final drive life cycle- still no excuse for building them in such a piss poor manner though.....

 

[John Vine]

Re #305:

Caterham did use a non Ford crown wheel and pinions (Quaife, I believe) for a period before they changed to the BMW diff.

That's very interesting.  Do you happen to know the date CC started to use the non-Ford CWP?

JV

[ScottR400D]

#304 It’s good that you got a reply Geoff, though cold comfort to those of us who’ve been stuck with big bills. 

Perhaps CC will acknowledge those failures and make reparations.........? 

Just joking! 

[David_Long]

I don't know the date but my car was early 2008 and it wasn't a Ford crown wheel. Discussions with CC staff at the time were somewhat guarded on their part, but the impression i got was that Ford CWP of the correct ratios where in short supply and the casings of other ratios where being fitted with pattern CWPs. So it is possible there was a mix of Ford and non Ford.

[Geoff Brown]

ScottR400D #308 - In a way CC have acknowledged there is a problem though mainly based on anecdotal evidence i.e. contents of this post?

To extract any sort of reparation from CC I think would be exhaustive. For a start CC are not members of any automotive association like the SMMT so that pathway is out. I do not think the AA or RAC would be interested nor Citizens Advice. Individual claims could be hard work especially some years & miles down the road.

As to class action that is a whole different world I would rather not consider.

I suppose in reality we should put this all down to experience & move on. CC know we know & are looking into it but as they have limited resources, allegedly, they may learn from this & find an easy fix. Or simply move on to the next problem.

 

[7 wonders of the world]

CC have some very capable engineers within the team who will be well aware of these and other issues, problem is, as with all companies, politics and bean counters get in the way...

Nice to get a reply from CC though.

[ScottR400D]

Of course. I wouldn’t think of following any of those courses, life’s too short!

But I don’t agree that they don’t have the resources; They’re clearly well aware of the issues and they have at least one solution to hand. 

It’s possibly more of an issue figuring out justification for change without being incriminated by their past, that will challenge resources.   

 

 

[Geoff Brown]

According to the letter CC have limited extra resources to bring to bear on the problem!

Remember some years back the BMW diff output leak saga?
It took time & some pressure for CC to recognise that there was a problem.  At the time it was not at the top of the 'to do' list. The limited resources decided just to adjust the oil content from overspill, 1.1L to a measured 0.8L.  Not exactly a mechanical fix as I suspected some of the OE fit seals were of a poor standard.

The re designing of the prop shaft to accommodate the BMW drive flange would have helped immeasurably canceling out shaft rotation irregularity that always occurs. Again a problem that affected the BMW diff but not the Ford.

Should I dare mention the 620 cooling saga as another episode where 'limited extra resources' come in to play?!

On reflection we, all of us here in this post, have carried out their duty as club members & owners to bring the Titan problem to the fore so as to warn others & to be able to flag up to Caterham however they decide to deal with the problem.

If this was an aerospace problem concerning a critical component - I see the diff as such - then fleets would have been grounded awaiting a well thought out & engineered fix. Yes aviation is incredibly safety orientated & has large resources but in scale CC should approach things the same way.

 

[John Vine]

Re #309:

Thanks, David.  My car is early 2008 as well. Presumably the best way to find out what CWP is fitted is to dismantle the diff and then ask an expert?  I'm not proposing to do that, but when Phil Stewart refurbed the diff in 2014, he made no comment either way on the source of the CWP.

JV

[David_Long]

A little more feedback on my the Titan diff - I ordered some new Belleville springs and bolts from Titan (mainly as a precaution) and I put it back together. As a reminder this is an early 2013 sintered plate version. 

The Titan part is very straight forward engineering, but perhaps the Sierra diff is a little more daunting. Certainly the crown wheel and pinion needs some knowledge to set-up from scratch - but you can just mark it up and put it back together as it was. Out of interest, I went through the Ford procedure (found in their manual) and it returned to the marks as Road and Race had delivered to me. The bearing pre-load is quite large so you really need the tool that engages the castellated bearing carriers.

The BMW diff is an unknown to me, but in the process of doing this, it has become relatively clear that there are few (if any?) carbon plate Titan Sierra diffs out there - although there might be exceptions, the shift to carbon was after Caterham adopted the BMW diff. This explains why the Sierra Ford diffs don't exhibit the same problem, and sintered plates are a route to fixing the issue. These were the original type and have, in my experience, very good durability. 

[ScottR400D]

David, you may be right and the carbon plates were an effort to reduce the noise which may be made worse by the BMW steel casing and mounting method? Though Phil Stewart did tell me that there were also two sorts of carbon plate and the earlier ones lasted better than later ones.

The sintered plates may be more durable but, for me with a BMW diff at least, the noise and banging/grunting was just not acceptable in what is mainly a road car.

[Geoff Brown]

Irrespective of carbon or sintered plates the Titan service schedule still prevails to a certain extent especially where the BMW unit is concerned.. To deviate from this could court disaster. The only way is to monitor the LS unit health on a frequent basis if one does not want the habitual nause of dropping the diff every 12 to 18 months. Of course dependent on use & mileage. 

The issue with the Titan has always been with the BMW unit & not the Ford. For whatever reason the Titan is best suited to the Ford giving exceptional longevity & serviceability.

CC have admitted that carbon plates were introduced to the Titan in the BMW unit to reduce noise which they realise now was a big mistake.

'Ironically, carbon plates were introduced to reduce noise, but we switched back to sintered plates some time ago (probably 2018 GB) - when reports of premature wear first started to appear, although they seemed few and far between, and also grouped around a particular duty-cycle of the car. I continue to have very few reports of issues but understand anecdotally (Tech Talk ? GB) that it is a wider problem than first understood and am committed to finding a solution.' End quote.

ScottR400D - My  enforced immobility ends 25th November so after re establishing the oil level in the diff I will be out for a test drive in the window of two days weather that appear to be available after that date. 

Will report back - then SORN for three months.

[Bob Shelley]

One of the issues that this thread has thrown up is that it is difficult to establish which LSD internals a car has. Does anyone know how to tell without removing the driveshafts for the "Angus Davidson" test. Are there any stamped codes on the outside of the Ford casing?
My car is a 2008 R400D with 25k miles since new. Does anybody know what type CC were fitting then?

[David_Long]

At that date it should be the Sierra 3.62 Diff with Quaife ATB. If your car 'ticks' as you push it then that will confirm the ATB.

[7 wonders of the world]

On that year it could also be an AP Suretrack too....

[Geoff Brown]

The only hopefully positive way to ascertain what lies inside a diff is to enquire with the CC Archivist who hopefully will find the original factory build or spec sheet for the car.

[ScottR400D]

Bob, if your diff is original I would suggest it’s unlikely to have lasted this long without rebuild if it’s a Titan. Unless it’s very low mileage. 

Did you check the preload, shaft rotation yet? Not that I’m sure a Quaiffe would behave like a plate diff. 

I did find this on line, supposed to be from Quaiffe, for testing if you have an ATB fitted:

1. Lift the drive wheels off the ground
2. With the engine off, put the car in any gear.
3. Rotate the Drivers wheel clockwise. The passenger wheel should rotate counter clockwise.
4. Block or lower the passenger wheel so it cannot turn.
5. Try to rotate the Drivers wheel. It should not turn but about 1 inch in either direction.

[Bob Shelley]

Thanks Scott,

I did the preload test yesterday and got 50-60 lb ft. I'll try the test you suggest and get back. What preload should a torque biasing LSD have?I can't understand why, if the different types of internals are so different, why CC aren't explicit about which types are available and make it an option in the spec of a car.

[ScottR400D]

Someone with more knowledge will hopefully respond Bob. I’m not sure an ATB diff has a preload as such. 

Again, don’t know the answer to the question about CC. 

As far as I am aware they haven’t offered the ATB as standard or an option for many years. All diffs are now open or they have the Titan in them. 

I’m not sure what the situation was back in ‘08, maybe they were developing the options and trying various things?

 

[7 wonders of the world]

no preload on the ATB,

could be more a case ofwhatwas available at the time....