Titan LSD - Warranty claim

[Wrightpayne]

I hate splinters - very painful.

sorry to have taken the post off track!

Ian

[Shortshift]

"I don't buy the poor Belleville spring design argument, (but perhaps the machining to size is not ideal) and there appears (I stand to be corrected) no failures of them in sintered plate units."

Sorry to say David (and sorry in many ways!) that is exactly the mode of failure in my diff.  My Seven is a 2012 R500D with zero preload showing at 7,000 miles, BMW diff with Titan unit and sintered plates that look as good as new - probably because the Belleville's failed (fortunately, without depositing shrapnel around the place) which likely means the plates been having a very easy time.

But I agree that some perspective is needed here.  Although, at around £2k all up for me to get it sorted, it's a bit of a struggle to smile too much about it!

James

[GulfSeven]

#24 that's good to hear.

As a new club member with a new 310R I was starting to get concerned...

[ScottR400D]

#28. You've a good chance of the Titan lasting a while with 150bhp but you need to keep an eye on it. 

#26 Chris, don't knock it until you've tried it!!

#24 David, as such an advocate of the Titan assembly perhaps you'd be interested in my fully rebuilt, unused assembly? All new bearings, seals, everything Including sintered plates! 1/2 CC list price to you. 

[7 wonders of the world]

Hi David,

I think you've been lucky so far,

If you measure the permitted travel in the pack you will see that this allows the bellevilles to be compressed to 100% - there desgined working range is circa 20-80% in this type of application, taking them to 100% increases the tensile load on the outer circumference which is why you see them fracture, once one spring does the remaining spring suffers an even harder life as its working travel will increase, when both got the end user get the heavy knocking as the pack impacts the casing in a totally unrestricted manner under throttle on / throttle off conditions. 

I'm not sure what your meaning about getting a harder life in a light car.... I assume your again referring to the bellevilles..?

I understand your point in so much that a lighter preload will permit more movement within the pack, however again this dosen't hold true as the Titan comes set at 40ft/lb where as other run there's at half or even less than that figure will no ill effects.

As for the clutches, these get an easier life as they will only be subjected to maximum torque when there is sufficient tyre to road adhesion, in a heavy car this is much more likely and will therefore be more frequent, in a 7 wheelspin is always possible, therefore at the point where adhesion is broken the torque the LSD is required to transmit falls away dramatically.

Whilst there will be owners will no ill effects, or possibly haven't checked theres yet, it is fair to warn others or potential new owners as being hit with a repair bill in excess of a grand will not be well recieved, especially when many owners save long and hard to enjoy 7 ownership.

 

 

[David_Long]

Without wanting to be rude, I think you've been selective with some data that fits your argument. I can just as easily quote info that suggest taking them to flat is normal. In fact most of my experience with these types of springs is that they do compress to flat in many applications. But out of curiosity, I will check the height to thickness ratio on an old spring and report back.

From Belleville Website . . .

 

 

 

Shown above are some examples of different cone height to thickness ratios, and up to a ratio of 1.5 the disc springs may safely be taken to ‘flat’ or stacked in columns. 

 

As the compressed disc spring nears its ‘flattened’ condition, the reducing cone angle results in the movement of bearing point toward the centre, thus effectively shortening the ‘lever’ length and ‘stiffening’ the spring.

 

So I don't buy the argument that 100% deflection is bad - the 75% simply refers to the linear section of the spring's characteristics - beyond that the forces increase rapidly and it's less useful as a spring (as you would expect when squashed flat). 

EDIT to say my measurements of the Titan Belliville spring ratio is 1 (2mm thick/defelts 2mm), so acording to the graph, is an ideal spec for 'flat' operation.

[7 wonders of the world]

Not been selective at all David,

As I said in certain applications......

My information came from Belleville directly I exchaned a few emails with their tech guys as they were carrying out deflection simulations for me as I looked for alternate weight springs.

You didn't clarity what you meant about them working harder in light cars...?

 

[aerobod - near CYYC]

I don't know if there have been subtle design changes in the Titan LSD at various points, but My 2012 era unit has concave relief areas that the main clutch pack Belleville washers are located in, with my measurements from recent disassembly of my carbon plated unit with 33,000km on it indicating the maximum Belleville deflection can only be up to about 75% and the preload has the starting deflection at about 25%. Basically deflection ranges for the washers is in the ideal range in my diff. My Belleville washers for the clutch packs were in good shape, the clutch pack wear after thousands of km of hard track use and spirited road driving (5 sets of tyres in 33,000km) was the factor that determined rebuild need, with sintered plates now in place.

One of the smaller Belleville washers that preloads the side gears was cracked (there is no deflection relief in the thrust washers for it), but they were eliminated in the rebuild kit with thicker thrust washers with oil flow cut outs in them.

[7 wonders of the world]

James,

Thats interesting, and a good point re design tweaks.

 

David,

You may want you take a look at this, 

https://www.bellevillesprings.com/estimating-fatigue-life/

 

[ScottR400D]

"Belleville washers - 3.80mm uncompressed, 2.00mm fully compressed (material thickness, I didn't want to risk damaging them by compressing to 100%). Effective thickness as described below is 3.40mm, (x2 = 6.8mm)."

So a cone height to thickness ratio of 1.9?

I gleaned that from Aerobod's excellent rebuild article  a few months ago. That also seems to imply significant design changes in the Titan since his car was built in 2012, which may or may not be relevant.

Anyway, I think I'm going to bow out now, I'm not sure we're ever going to reach a consensus and I'm not sure there's more to be gained. 

Good luck to those who choose Titan, and my fully rebuilt unit is still for sale..........

Edited to add, I wrote this before seeing the recent posts, including Aerobod's. 

[David_Long]

#32  Perhaps not directly weigh related but more type of use. But a lighter cars generally means the LSD spend more time in a lightly loaded (preload) state (slipping the plates) rather than in a locked mode that uses tyre slip to provide the differential action (primarily why race cars seems to last better than road cars). The LSD is trying to undo what an open the diff does. So using it in situations that needs an open diff, the LSD is working harder and wearing faster. Under higher loads it's the tyres that wear.  

[David_Long]

#34

My reading of that is that deflection sould not exceed 75% of available (not a maximum of), which it doesn't in the Titan as the preload is conciderabley more than 25% deflection - over 50% in my overhaul. It tells us nothing about where the deflection should take place, just the scale of it. But it does perhaps hit the nail on the head as to why springs fail when preload disapears.

[Wrightpayne]

See, I dont need this level of cerebral engagement with a quaife ATB!

[7 wonders of the world]

But conversly the preload applied to a tintop is 2 or 3 times higher, and they will normally see much much higher milage, whilst not related to the torque capacity, the plate area will naturally increase durability as will the choice of friction material so these are clearly a factor in tihs design. 

 

 

[simon_h]

I guess all this bad mouthing of the Titan has destroyed the saleability of them now? If anyone read the posts on the forums you’d never get one used/rebuilt or new. Obviously the tracsport people are going be happy though. Glad I found a zf when I was looking for one

[7 wonders of the world]

the preload can disaapear, and has for two opposing reasons, excess plate wear or broken springs with plates still in good order when stripped.

[heptagon]

Is this a good time for me to say I'm looking for a Titan LSD? 

seriously..

[Tazio]

My Titan, finally gave up the ghost after 15 years, it's early life spent Sprinting and Hillclimbing, clutches knackered, one Belleville washer cracked. Until then, though noisy, it worked...

[Shortshift]

That would be a Sierra diff with Titan, Alan, yes?  They seem to be noticeably more robust.

James
 

[Tazio]

James,

That's correct, it's a Ford one, regarding the 'debate', I just wanted to add a little balance ...

[Geoff Brown]

Throughout the lengthy chat re Titan v Tracsport v ATB the one thing that comes of it all is that Titan 'failures' are all connected with the BMW but not the Sierra casing.

Any theories on that one?

And as for 'bad mouthing' the Titan it is not the unit to some extent that requires such a riposte but CC for not publishing servicing recommendations & health monitoring for owners.

The swing toward the Tracsport unit is a personal, considered decision based on available evidence. Are those that have done so as wrong as those that stick faithfully to the Titan? Only time & disintegration will tell. 

[aerobod - near CYYC]

Re #44 & #46 - The plates, Belleville washers, thrust washers and shims are all exactly the same in both the BMW and Sierra Titan units, as it is the same rebuild kit for both. The part numbers for the ramp cups are also the same in each unit. The only major variable is the use of the carbon plates in the BMW units for about a 6 year period in the range of 2012 to 2018 with the most troublesome plates more in the second half of that range.

The splines on each are different, which means a difference in the side gears, but the only other factor that could be different is the concave relief at the end of the casing where the Belleville washers locate, that prevent 100% deflection of the washers. Otherwise all other internal dimensions have to be the same for the same rebuild kit and ramp cups to work.

A telling factor on whether the concave relief is present and/or the same in each unit may be the shims used for a given preload, as the relief increases the total internal length of the casing by 0.8mm where the Belleville washer internal diameter locates. My unit required 1mm of shims (2x 0.5mm) to reach 40lb ft of preload with the relief present. Does anyone who has had a rebuild know the shims used for their unit?

[David_Long]

I understood that there were difference with the BMW and Ford kits -  although they are marketed as the same, I thought you have to specify what type at point of order. Certainly kits do seem to vary.

The concave point is interesting in that I thought mine were flat, so that could be a change. But I had no shims to directly change the Belleville spring preload, just one each end to adjust the gear position. But I'll need to think through that to see if it does impact the preload too. It may be worth taking my spare to bits again to check.

Here's a video animation of it put together (just for the making of the video). 

[7 wonders of the world]

James / David

What is the permissble movement of the pack in your units..?

 

[7 wonders of the world]

sorry hadn't finished ut hit the wrong key!

as shimmimg to alter the preload naturally affect this critical dimension so interested what you both had before and after