Drive shaft length
Discussion
I just double checked my measurements and they are all correct from my OE driveshaft -96 GKN Diff. I was also under the impression that there was no difference between GKN and BTR as I can't remember Racing Green asking this when I bought the raceproved ones some years ago.
We have of course assumed they are identical either side, I only have one since the other snapped, I can't remember which side.
If it would help I will attempt to measure the width of the GKN diff this eve.
I reckon you may be OK length wise. As there is a decent amount of allowed play through the CVs. At least I really hope so!
Matt
We have of course assumed they are identical either side, I only have one since the other snapped, I can't remember which side.
If it would help I will attempt to measure the width of the GKN diff this eve.
I reckon you may be OK length wise. As there is a decent amount of allowed play through the CVs. At least I really hope so!
Matt
macdeb said:
Group buy seemed to fade out, so couldn't be arsed to wait.
The OE shafts fitted to my car [BTR diff'] are 22mm shorter. I've was led to believe they are all the same be it BTR/GKN/Griff'/Chimaera, but it may not be the case. Hoping someone may say, 'it's ok to fit as there is room' otherwise I have two unbreakable driveshafts for sale at knockdown price for cars with GKN diff'.
Oh dear. Yes it was suggested somewhere that GKN and BTR were same length.The OE shafts fitted to my car [BTR diff'] are 22mm shorter. I've was led to believe they are all the same be it BTR/GKN/Griff'/Chimaera, but it may not be the case. Hoping someone may say, 'it's ok to fit as there is room' otherwise I have two unbreakable driveshafts for sale at knockdown price for cars with GKN diff'.
22mm is quite a difference. There is a lot of play in the CV joints but maybe 22mm is asking too much. I am sure a GKN owner will 'snap' those up off you Mac. Sorry it seems you were the guinea pig on this one.
Would it be an idea to establish for certain what length the different types are first? I am fairly sure i know someone with a GKN diff, but wouldn't want to point him in your direction just to be cursed later.....
A quick call to any of the TVR parts guys should get the information. Or to anyone who services TVRs.
A quick call to any of the TVR parts guys should get the information. Or to anyone who services TVRs.
I have pictures of both the diffs in my chassis (sort of before and after).
I have taken measurements from these pictures of the width between the output flanges and between the two lower rear body bolt holes as these are a fixed measurement on all the pictures (to take into account the different distances from the camera to the chassis)
When the adjusted measurements of the two diffs are compared I could not see any difference in the width of both.
I know that this is not going to be really accurate but I would have expected to see enough difference to justify drive shaft differences of 22mm as has been suggested and I don't believe the rear suspension changed between models.
I my case I have used the original driveshafts on the new diff. Before fitting the shocks I moved the built up suspension through its full range of movement (which is more than is possible when the shocks are fitted) and the shaft still had sufficient free movement through out the full range of movement.
It has now been on the road for over half a year without any issues, strange knocks or any other strange occurrences when driving.
I have also done a check since (last month) to check everything and it all looks good.
I have taken measurements from these pictures of the width between the output flanges and between the two lower rear body bolt holes as these are a fixed measurement on all the pictures (to take into account the different distances from the camera to the chassis)
When the adjusted measurements of the two diffs are compared I could not see any difference in the width of both.
I know that this is not going to be really accurate but I would have expected to see enough difference to justify drive shaft differences of 22mm as has been suggested and I don't believe the rear suspension changed between models.
I my case I have used the original driveshafts on the new diff. Before fitting the shocks I moved the built up suspension through its full range of movement (which is more than is possible when the shocks are fitted) and the shaft still had sufficient free movement through out the full range of movement.
It has now been on the road for over half a year without any issues, strange knocks or any other strange occurrences when driving.
I have also done a check since (last month) to check everything and it all looks good.
neal1980 said:
QBee said:
Mac, how long ago did you buy them, and was it by mail order? The distance selling regulations allow you time to reject the goods if they are incorrect I believe.
But thats no good as he requested the length that he got.....Modify all 4 wishbones by 22mm and flair the arches to accomodate the new wheel positions.
QBee said:
Mac, how long ago did you buy them, and was it by mail order? The distance selling regulations allow you time to reject the goods if they are incorrect I believe.
Hi anthony, appreciate the thought [crikey, people will be talking about us again for different reason 
] But I ordered the length as indicated on a diagram provided by Matt who was trying to help in all sincerity and I'm not for one minute going to blame him. But, it appears he has GKN diff' and he measured the shafts from that so I supplied incorrect information to the manufacturer. What I was trying to avoid was having the car off the road whilst waiting for them to be made and delivered but I'm now faced with having it off the road for longer.I'm going to try a 'dry build' with them tomorrow night and see if any clearance difficulties, if not I'll try them, but if there is I'll need to sell on [ideally to someone with a GKN diff' that's in the market for some unbreakable shafts at discount] before I can order some more as that would mean I would've spent £800 for them [£400 a pair] which is no good.
or....
just have one more made but 44mm shorter.
Modify your diff brackets to offset the diff by 22mm.
Sorted. You would still need to modify 2 wishbones 22mm longer and the others 22mm shorter.
This may have an effect on cornering so you could consider detting the car up for oval racing.
Sometimes you have to think out of the box Mac.
Always glad to help. I am an engineer after all.
just have one more made but 44mm shorter.
Modify your diff brackets to offset the diff by 22mm.
Sorted. You would still need to modify 2 wishbones 22mm longer and the others 22mm shorter.
This may have an effect on cornering so you could consider detting the car up for oval racing.
Sometimes you have to think out of the box Mac.
Always glad to help. I am an engineer after all.
Quinny said:
I can't see why they can't be made shorter.... It's only machine time....
11 mm off each end, lengthen the splines and re machine the circlip grooves....just leave the old groove unused..
What I thought [almost] though the start of the splines are the same from middle on both sets so the splines on the new are longer IYSWIM. So I thought machining off 11mm either end and putting a circlip groove in, job done but they're saying not possible. If they were too short I'd understand. 11 mm off each end, lengthen the splines and re machine the circlip grooves....just leave the old groove unused..
Edited by Quinny on Tuesday 22 July 14:32
unless I have it wrong,
which is always possible,
I hate getting old.
maybe thats your answer Mac.
Theres a lot of play available in both CV joints.
Maybe even if they are 22mm longer they will be fine.
Get em fitted. Feel the play, jack the suspension through full travel while checking there is still play.
If OK then go out and put 458 bhp through them. Jobs a good un.
Theres a lot of play available in both CV joints.
Maybe even if they are 22mm longer they will be fine.
Get em fitted. Feel the play, jack the suspension through full travel while checking there is still play.
If OK then go out and put 458 bhp through them. Jobs a good un.
macdeb said:
Group buy seemed to fade out, so couldn't be arsed to wait.
The OE shafts fitted to my car [BTR diff'] are 22mm shorter. I've was led to believe they are all the same be it BTR/GKN/Griff'/Chimaera, but it may not be the case. Hoping someone may say, 'it's ok to fit as there is room' otherwise I have two unbreakable driveshafts for sale at knockdown price for cars with GKN diff'.
I have a gkn diff and just swapped out my original shafts for BTR shafts that came on the 2nd hand hubs I bought (they looked in better condition) and they fitted with no issue? Sorry, couldn't tell you what length either are tho as both are fully assembled shafts. The OE shafts fitted to my car [BTR diff'] are 22mm shorter. I've was led to believe they are all the same be it BTR/GKN/Griff'/Chimaera, but it may not be the case. Hoping someone may say, 'it's ok to fit as there is room' otherwise I have two unbreakable driveshafts for sale at knockdown price for cars with GKN diff'.
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