BMW/Titan LSD Viability

[Dave Hardcastle]

#318 Bob. I have a 2008 R400 and had the same question a while ago. Turned out mine was fitted with a Quaife ATB.

As to the test shown in #322 no.5, an ATB doesn't lock so I don't believe that can be right. Also, when I did this test, I could turn my wheel by hand, easily.

I do think 50-60ft/lb sounds high. You only have to read through this thread to find that Titan appear to set it to 40ft/lb. The Tracsport recommended in this thread is set to 25ft/lb and, as above, the Quaife doesn't lock.

The way I found out was to write to the club archivist, Martin Phipps, who was able to tell me what my car was delivered with. He just requires the chassis number.

Hope that helps,

Dave

[7 wonders of the world]

60 ft/lb of preload....

you either have an original ZF..... or you left the handbrake on during the test....  

[Geoff Brown]

Not sure about the 25 setting for a Tracsport LS unit. Steve Perks set mine at 45/45 on build.

[ScottR400D]

That’s the ramp angles, Geoff, the preload is 25lb ft. 

[john hooper]

Just checked the diff on my 2017 620s and have no measurable preload at all after 6000 miles and only 2 track days.The diff has been noisy from day one but i was advised that they were all like this ? Car has been routinely serviced by dealer. I have now ordered a new open BMW diff and will have a Tracksport unit fitted by SP Components. I will update blatchat after I swap the diffs over. Im hoping for a big improvement over the Titan rubbish.

 

[Benton]

I thought the 620R and S had Ford diffs?
I haven't examined it closely but  superficially my 2018 620R diff is different from the BMW one I had in the 420R?

[john hooper]

No the 620R uses the Ford diff, the 620S uses the BMW diff.

[simon_h]

620r has a ford diff. I would expect the s to as well. That is unless they have changed the spec recently 

[john hooper]

Mine is a 2017 620S and is definitely a BMW Diff

[simon_h]

Yes, saw your post just after I’d posted. Was told at the time they used the ford diff as it was stronger. Maybe that wasn’t the reason

Sounds like your plan is the right move though 

[Benton]

Thanks for the clarification, hope you get it sorted soon John

[Shortshift]

I think the Ford diff is still used when a sequential transmission is specced  on a new build - so Ford on 620R (Sadev seq) and BMW on 620S (5 speed Mazda man).

James

[CtrMint]

Isn't power a factor in the longevity expectations?  I've seen numerous comments in this thread stating as such.  

[Shortshift]

I guess it is, Mark, but I think its the shock loadings from the sequential that dictate the Ford fitment (or, the other way round, the manual box provides a more benign shock-load case that allows fitment of the BMW diff).  Just guessing at the strategic thinking behind the specifications.

James

 

[7 wonders of the world]

Not power but torque, and as James says a sequential box puts significant shock loads through the driveline.

[ScottR400D]

7W, of course you’re right that it’s the torque that’s central to the issue but in general, if not always, the more powerful engines have most torque. 

On that point, the smaller engined 7s have torque figures around 160/65Nm. The Duratec N/A range from about 190 to 235Nm and the 620 is around 300Nm. 

From my and others experience with the N/A Duratec, I’m amazed that the Titan lasts more than 5 minutes on a 620 regardless of the diff housing or box! 

 

 

[Geoff Brown]

After four weeks of not wearing shoes (a long story) finally got the car out for a test drive post diff refit with SPC LS unit.

Although sunny here in tropical Wiltshire the roads were cold & damp so could only test straight line performance after a cautious start to check all was OK in the back end.

Car feels solid when accelerating in a straight line more so than the previous Titan. With new rear tyres, the road conditions & low temperature of 6c I decided not to push my luck on corners & roundabouts but car felt good. No peculiar noises from diff any more.

Am going to try to get out a few times before I SORN on the 30th November. But otherwise 

[Geoff Brown]

Just browsing - like you do - on the Road & Race web site this very bold statement about the Titan: 

'Titan currently offer a very limited range for only 3 differentials, Ford Sierra 7 Inch, BMW 168 and Ford English. They were designed from the ground up specifically for the Caterham & other ultra lightweight kit cars. Starting from a blank slate they focused on optimising performance for these types of vehicles. This was achieved by thorough real world testing on a variety of circuits to select the best ramp angles and preloads. Preloads are also adjustable to tailor the amount of oversteer to suit a specific handling set-up or driver. The rest of the design was focused on reducing rotating mass, and reducing manufacturing costs. By reducing manufacturing costs they are able to pass on the cost savings to the end user, whilst also incorporating high friction Sintrak clutch plates. These clutch plates are highly durable and last for years of hard use without needing to be replaced. They also have a high coefficient of friction which allows less plates to be used, and for the clutch plates to be smaller. This also contributes to reducing rotating mass. Titan LSDs are used in the factory & kit built Caterhams as they offer the best performance when compared to other competing LSDs.'

If this statement is to be believed whatever happened with the BMW/Titan diff up till about 2018 when CC went oops we have a problem, fit sintered plates?

[ScottR400D]

One of the salient points from that might be “This was achieved by thorough real world testing on a variety of circuits...........”

As has been pointed out, the LSD may well suffer less on circuit where it’s more often than not in a locked condition.  

[Geoff Brown]

The line that attracts my attention is is: 'By reducing manufacturing costs they are able to pass on the cost savings to the end user,' 

Does this mean restricting the design & materials to come within a fixed budget with a sting in the tale after a few years of use?

[Geoff Brown]

Steve Perks sent me a text last night enquiring how the LS unit performed knowing that I would  be back in shoes after four weeks. His timing was impeccable. See #342.

Now that is what I call real customer service. He is content to wait until Spring for a full report.

 

 

[Dave Hardcastle]

Steve Perks also made an unexpected customer follow up call to me to see how my diff felt. It's obviously part of his business practices and to be applauded in this day and age. The usual these days is "we care what you think, please fill out this 30 minute survey for the battery you've just purchased". 

[Tom Scanlan]

I must offer my thanks to Geoff Brown and others on this thread who brought this issue to my attention.

I bought my 2015, 420R in June from Sytner in Oldbury. They took it in as part exchange on a Porsche Spyder and sold it to me with a 6 month warranty. Having under 8000 miles on the clock I wasn't expecting any issues, but having read some of the posts and after carrying out a wheel rotation and  preload test, was concerned  that my diff was suspect. I contacted Road and Race and spoke to Ollie for some advice. He recommended speaking to DPR Motorsport who were happy to deal with the warranty company and manage the repair. The diff was taken to Road and Race who found that all the carbon had fallen off the plates, the Belleville washers were shattered, the bearings were gone and the carbon had attacked the surface of the CWP.

They supplied a complete new diff and DPR put it all back together, using Road and Race's recommended oil. David and Daniel at DPR couldn't have been more helpful and got everything sorted under the warranty, Since collecting the car I have noticed much improved traction and a more predictable rear end, it is actually very quite with no undue noise or vibration.

Very pleased that I was alerted to this while I still had a warranty as this was not a cheap exercise, but hopefully it will be good for a few years now.

 

 

[ScottR400D]

Tom, I hope all goes well for you but bear in mind that the car began with an all new diff and lasted less than 8k miles. 

You may have a different oil but that’s more to do with keeping the noise down with friction modifiers, rather than preventing wear. Keep a regular eye on the preload and maybe fit a magnetic filler plug. 

 

[ScottR400D]

#346/347 I think that’s Steve’s MO! He messages me regularly for feedback and to urge me out on TDs to give the LSD a good workout!