well at Anglesey yesterday the bloomin diff gave up the ghost after only 45 mins of driving. not happy at all but I suppose these things happen. Has anyone experienced any problems with these? are there any other options out there that maybe more reliable?

any help would be great

Never known a genuine Quaife QDF7ZR sealed chain drive unit fail.

Are you sure it is a Quaife unit?

Perhaps you have a failed CV joint?

Is it the one with the reversing mechanism? or the plain QDF7ZR?

the diff is the qdf725r unit, im removing it in the next week or so and phil peacock is going to sort it, must admit im not too impressed with it as its not had hardly any work or stress

What has failed with it? QDF7ZR is pretty bombproof... has the torque biasing failed? lost drive? or is the problem with the carrier/chain/tensioners? (which won't be Quaife)

James

Would be handy to know what exactly has failed!

thats exactly what I thought which is why im suprised its failed, ive not removed it yet but basically you can put it into gear and the whole diff unit just rotates with the chain but the input drive shafts stay perfectly stationary. really strange, I was a bit reluctant to speak to quaife direct so spoke to a few friends in the trade and got in contact with phil, he has been dealing with quaife for 30 odd years and is well know amongth the motorsport trade for his excellence in transmissions.

I will try and get a vid of whats going on this weekend, once removed I will also upload a ruck of photo's. Hopefully it might just be something simple, but what ever it is it put a stop to my track action 40mins in at anglesey lol I was not a happy bunny. But did spend the rest of the afternoon entertained by a mates 400+bhp evo hooning around the coastal

[Edited on 2/9/14 by Autoflock Motorsport]

Given the construction of the ATB diff it would have to be pretty catastrophic to produce no drive! You'd have to completely strip both output shaft splines or completely destroy all the helical gears - even then you'd think the debris would jam up the diff

Could it be the sprocket bolts that have sheared? Most impressive if it is the diff, pics would be interesting!

quote:

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Originally posted by Autoflock Motorsport
thats exactly what I thought which is why im suprised its failed, ive not removed it yet but basically you can put it into gear and the whole diff unit just rotates with the chain but the input drive shafts stay perfectly stationary.
[Edited on 2/9/14 by Autoflock Motorsport]

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Cloudy - Jim, thank you very much for your comments, I shall defo try and whip the diff off over the weekend and report back with pics!!!

Fingers crossed it will be an easy fix.

jim have you any pics of how you fixed yours?

Hi

No pics as such - but I'll have a go as describing what you should find:-

Your diff, will be held between a pair of mounting blocks.
Each block will have a large bearing in it, which the output's from the diff fit into.

You'll then have a pair of driveshafts on which there will be a joint of some discription at each end.

If you remove the driveshaft(s) (or just undo the diff end if there's enough room to swing it out of the way) you'll be faced with the diff to driveshaft joint.

The small shaft (it's about 4 - 5 inch long) will be slide fit into the diff outputs and the joint (might be a retainer on the joint side, isn't normally one on the diff side)
So now remove the joint and pull the shaft out
If it comes out looking like the picture you Googled earlier then it's the other side that's busted
If it's in Two bits - you've found your problem.

But I would check the other side anyway!

Almost certainly the part in question will be off a Mini (Classic sort) as that's what these diffs evolved from.

Post a pic of the knackered bit and we'll certainly be able to identify it between the folk on here
HTH

thank you very much jim, very useful information there. I shall report back shortly :-)

Driveshafts can just go directly into this diff - the QDF7ZR will take a fiesta driveshaft directly (it's based on a fiesta/escort fitment diff) (unless you have lobro flanges)

James

quote:

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Originally posted by cloudy
Driveshafts can just go directly into this diff - the QDF7ZR will take a fiesta driveshaft directly (it's based on a fiesta/escort fitment diff) (unless you have lobro flanges)

James

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This is the inboard side on a fiesta shaft - no need for adapters, CV + splines are one unit - much lighter that way

quote:

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Originally posted by cloudy
This is the inboard side on a fiesta shaft - no need for adapters, CV + splines are one unit - much lighter that way

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You would almost certainly need new lengths making up ...

If your diff is relatively new they have a lifetime warranty from Quaife - call them if you have your receipt.

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Originally posted by Nick Skidmore
If your diff is relatively new they have a lifetime warranty from Quaife - call them if you have your receipt.

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Which car?

quote:

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This is the inboard side on a fiesta shaft - no need for adapters, CV + splines are one unit - much lighter that way

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quote:

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Originally posted by Nick Skidmore
Which car?

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Quick one jim

if only one of these small couplings has failed would it still mean thr whole diff unit will simply spin and give no drive to either wheel?

I have not had time to take it apart yet but I am hoping to go on track this weekend, I have one spare coupling so if it is only one at least I can have a blast at the weekend.

quote:

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Originally posted by Autoflock Motorsport
Quick one jim

if only one of these small couplings has failed would it still mean thr whole diff unit will simply spin and give no drive to either wheel?

I have not had time to take it apart yet but I am hoping to go on track this weekend, I have one spare coupling so if it is only one at least I can have a blast at the weekend.

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well small update, massive thanks to Jim for his diagnosis, it was bang on the money. The small input shaft coupling has sheared streaght off, but suprised really as it is very hard steel and has also been case hardened.

Here is a few pics of the broken part and the replacement, im just taking measurements to get some more made up and also making a puller to get the couplings out of the diff













Fingers crossed it should all be sorted by tonight

[Edited on 3/10/14 by Autoflock Motorsport]

Hi Raj

Good stuff - re the broken bits:-

See if the conical drive flange is seperate to the small shaft - it should be - unless it's been tag welded onto it
The small shaft (with the boss in the centre) has splines at both ends, so can be a very tight fit into those flanges.

It can then simply be got from MiniSport (or similar) - "Mini LSD Output shaft Pot Joint Type"

See you at a track sometime

Can you measure the OD of the splines that broke? I'm having the same issue with a diff converted to chain drive that has 25mm OD splines with a portion just after the splines that is 22mm OD

Dave

quote:

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Originally posted by JimSpencer
Hi Raj

Good stuff - re the broken bits:-

See if the conical drive flange is seperate to the small shaft - it should be - unless it's been tag welded onto it
The small shaft (with the boss in the centre) has splines at both ends, so can be a very tight fit into those flanges.

It can then simply be got from MiniSport (or similar) - "Mini LSD Output shaft Pot Joint Type"

See you at a track sometime

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yes these are specials, like averything on this car (raj frowns)

im just redrawing these up now in cad so I can have more made once this is fitted.


Large spline dia - 27.8
Small spline dia (where it failed) - 25.4

these are just rough measurements quickly taken with my vernier so hope this helps.

Just had a puller made up to remove the input shafts easily.

Let me know what you think

well got tit all back together friday night and went to aintree saturday for a track day, did 6 laps and the same thing happened with the other side. NOT IMPRESSED

Ive not removed it yet but im guessing it has sheared off in the same place as the other one, where the spline changes diameter. Anybody got any advice or input on the cause of this??

quote:

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Originally posted by Autoflock Motorsport
well got tit all back together friday night and went to aintree saturday for a track day, did 6 laps and the same thing happened with the other side. NOT IMPRESSED

Ive not removed it yet but im guessing it has sheared off in the same place as the other one, where the spline changes diameter. Anybody got any advice or input on the cause of this??

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Sounds like the output adapters had a defect, as minitici says your particular diff is based on a fiesta, in which the shafts will receive much more abuse!

James

the steel we think is EN32 or 40b which has been tempered and case hardnened. I think its the shape of the splines which may be at fault, where it changes diameter, not too sure which shafts have been used though.

Im not too sure why these input shafts have been made, its a pain in the arse not being able to buy them off the shelf. I have since produced cad drawings to get more made but now the other one has broke I am now thinking to bin the whole setup and start again???

The diff it self also feels like there is slack in it, I can rotate one wheel when jaced up approx 1" either way before the opposite wheel had any omvement, is this normal?

I'm also looking for a chain drive lsd with splines larger than 25mm. Haven't really found anything use able yet

just spoke to the lads at spire, very helpful people, although they run the radical diff they gave me some sound advice about what they run. Im going to have a work with the machine shop about the current design and get another one made with no change in spline diameter. Also looking into the heat treatment side of it as I think it may have had too much making it strong but also brittle. The shock loading of the gear changes and slack between drivetrain components has just been too much for the metal but this is only my speculation.

Spire use the shaftec PJ8N input shaft with the lobo joint and have had no issues, myself and friends have had these shafts taking in excess of 350bhp & 300ft lb of torque pulling a fully trimmed fiesta so the spline diameter would be more than up to the job, which is why I think its a design issue not a power one.

quote:

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Originally posted by dave_424
I'm also looking for a chain drive lsd with splines larger than 25mm. Haven't really found anything use able yet

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