About to s**t-can putting an LSD in the S!
Discussion
On the verge of giving up on this one. I'm used to pulling TVRs apart and putting them back together on a daily basis, but the world of Sierra differentials is too painful!
So, originally I decided to replace the 7.5" 3.64 ratio open diff with an LSD, while I was doing the body off. Managed to find a decent 7.5" LSD with the same 3.64 ratio from a Sierra Cosworth (a 3dr one, it turns out). I then pay to have it refurbed.
Fit the diff, before realising it has the 108mm output flanges, and the S uses 100mm types. Bugger. No matter, I'll put 108mm CV joints on one end of each driveshaft, so run 100mm one end and 108mm the other. Don't fit - different splines on the shaft! Bugger again.
Think about converting entire rear end to 108mm, but they won't fit in the trailing arms (and it's expensive). Bugger again.
Think I'm only a winner when someone suggests changing the output flanges over from the old diff. Pull old diff apart, remove output flanges in minutes. Even think I'm onto a winner when I realise I can remove the output flanges of the Cossie diff while it's still sat in the chassis. Result! Then crumble into a heap of self-pity and torture when I realise (and immediately kick myself for not thinking it through previously) that the LSD output flanges have deeper shafts than non-LSD, meaning they aren't interchangable.
Try to find Granada 24v diff (that's the one I really needed, same as fitted to V8S) but with no luck. Try to find Granada 24v output flanges. No luck.
Currently in comms with GKN to see if they can do a custom driveshaft or CV joint with 108mm outer and 25 splines. Not holding out much hope of it being cheap, or even possible.
Very close to thinking screw it - no LSD for me. But I was so excited about it!
So, originally I decided to replace the 7.5" 3.64 ratio open diff with an LSD, while I was doing the body off. Managed to find a decent 7.5" LSD with the same 3.64 ratio from a Sierra Cosworth (a 3dr one, it turns out). I then pay to have it refurbed.
Fit the diff, before realising it has the 108mm output flanges, and the S uses 100mm types. Bugger. No matter, I'll put 108mm CV joints on one end of each driveshaft, so run 100mm one end and 108mm the other. Don't fit - different splines on the shaft! Bugger again.
Think about converting entire rear end to 108mm, but they won't fit in the trailing arms (and it's expensive). Bugger again.
Think I'm only a winner when someone suggests changing the output flanges over from the old diff. Pull old diff apart, remove output flanges in minutes. Even think I'm onto a winner when I realise I can remove the output flanges of the Cossie diff while it's still sat in the chassis. Result! Then crumble into a heap of self-pity and torture when I realise (and immediately kick myself for not thinking it through previously) that the LSD output flanges have deeper shafts than non-LSD, meaning they aren't interchangable.
Try to find Granada 24v diff (that's the one I really needed, same as fitted to V8S) but with no luck. Try to find Granada 24v output flanges. No luck.
Currently in comms with GKN to see if they can do a custom driveshaft or CV joint with 108mm outer and 25 splines. Not holding out much hope of it being cheap, or even possible.
Very close to thinking screw it - no LSD for me. But I was so excited about it!
Ceejay73 said:
Think the 7" has been fitted to an S by somebody on here but can't remember who. Can't see it being too difficult and don't think there is a great difference in reliability/strength between the two sizes.
ETA: It's TopGearTVR what done it recently.
Another edit: He may have a goosed 7.5" diff with 100mm flanges for sale too.
I'll try and get him on FB, cheers!ETA: It's TopGearTVR what done it recently.
Another edit: He may have a goosed 7.5" diff with 100mm flanges for sale too.
Edited by Ceejay73 on Friday 15th August 11:40
Edited by Ceejay73 on Friday 15th August 11:42
The 7" diff isn't any weaker.....truth be told I'm not sure why they made so many different bloody types! But to fit a 7 means shims & washers etc. Can't be dealing with all that.
magpies said:
I may be wrong but try mailing Alan Whitaker - I think he fitted larger drive shafts and 'opened' out the trailing arm to suit - looked an easy cut and weld job
You probably could, but they've only just been refurbed so I'm reluctant to muck around, plus it would mean getting new shafts made.LSD back on - custom driveshafts being made at Berrisford. 28splines one end, 25 the other. That way I get to keep the proper 3.64 ratio in the diff, but have the Cosworth LSD with it. I'd already refurbed it, so didn't want to give up on it!
Means for future work I can still just buy standard CV joints and not have to worry about having them custom made. I {i]nearly[/i] found some 108mm CV joints with a 25spline, but gave up eventually. It was the prop coupling on the front differential on a Jeep Grand Cherokee if anyone decides to pick up the ball, but I'm not convinced they're the answer. They're £100 a pop too, so too much just to try out for me!
Means for future work I can still just buy standard CV joints and not have to worry about having them custom made. I {i]nearly[/i] found some 108mm CV joints with a 25spline, but gave up eventually. It was the prop coupling on the front differential on a Jeep Grand Cherokee if anyone decides to pick up the ball, but I'm not convinced they're the answer. They're £100 a pop too, so too much just to try out for me!
I wondered if the Jeep's joint would have been suitable anyway, due to the angles it's designed to work at like you say. They're £100 a pop (on eBay, not main stealer), so I'd be £200 down for something that may or may not work. And if it did let go, it'd likely make a mess.
Chased the Porsche one up and found there were some cataloguing errors, and couldn't actually find a 25sp 108mm joint. There's a lot of talk from Porsche owners about using 108mm joints on the 930 over the 100mm, but they change the shafts too, so if beefs up the drivetrain in general.
Chased the Porsche one up and found there were some cataloguing errors, and couldn't actually find a 25sp 108mm joint. There's a lot of talk from Porsche owners about using 108mm joints on the 930 over the 100mm, but they change the shafts too, so if beefs up the drivetrain in general.
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