bi22le
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| posted on 17/5/21 at 02:57 PM |
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7.5" push in shaft to LSD conversion
I did a track day at the weekend at Oulton Park and it was very wet.
My car was terrible. Very low levels of traction out of corners. As soon as I put any power down. Once it dried up it became the M4 slaying monster it
normally is.
So, I have a 7.5" non-LSD. Push in shaft. Is that an easy conversion as most seem to have bolt on shafts. I won't be doing it myself and
would consider just buying a whole diff. I don't want to change half shafts or move from the 4.27 that I currently have.
I'll do a full write up with pics (if pic uploads work) later.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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mcerd1
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| posted on 17/5/21 at 04:59 PM |
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^^ what kind of LSD do you want to use ?
The ford viscous one is the one that only comes with bolt-on stubs (unequal length ones)
if you want to use that with your existing hubs you can make hybrid driveshafts (if your push-in ones are the same size shaft at least)
or I've seen at least one person who modified / made custom push-in shafts to match the internal sizes of the Ford LSD stubs
either way its not a guarantied drop in fit 
the other way to make a bolt-on diff work is to change the whole rear end setup to bolt-on (which means either rear disc brakes or even more mods to
retain the drums if you have them)
you'd probably have a few more choices with a 7" diff - but for most of the s/h ford 7.5" diffs you'll come across will likely
be Sierra Cossie 2wd or the Granada 24v Cossie (bot had 3.64 ratio 7.5" LSD's) or maybe a few late model XR4x4's too
or if your going for one of the aftermarket LSD I think some of these are made for push-in shafts in 7.5" (I know quaife used to, but I
don't see it listed without bolt-on flanges just now - you could ask though)
aftermarket LSD's may be better suited/tuned to a lightweight car anyway - just a not that cheap 
but as most of the tin-top applications for 7.5" LSD's are the cossie's mentioned above that all had eitehr 100mm or 108mm bolt-on
shafts you'll need to be careful that the it matches your driveshaft sizes...
[Edited on 17/5/2021 by mcerd1]
[Edited on 17/5/2021 by mcerd1]
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bi22le
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| posted on 17/5/21 at 08:58 PM |
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I have a 7" in the garage to but it is 3.92 and the 4.27 is so much better for track. That's the only reason I have the 7.5", I
don't have that much power.
I have rear discs already, the half shafts are custom so I could just get some more made but that's more monies.
I was thinking aftermarket as I have read that the ford Cossie LSD is not right for a 500kg car. I was expecting to get either just the LSD and pay
for fitment or a whole diff and drop it in.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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mcerd1
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| posted on 18/5/21 at 04:51 PM |
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quote:
Originally posted by bi22le
I have rear discs already, the half shafts are custom so I could just get some more made but that's more monies.
^^ if you have the
bolt-on CV's at the hub end it would just be a simple swap back to the std. shafts at least (and pick the diff version with matching CV sizes -
sierra cossie=108mm / granada cossie=100mm)
if you want to stay with the push-in setup then you'll need to know the diameter of the stubs going into the diff and the spline count (and
maybe length too) - that should be enough to confirm any new diff you pick should fit your current shafts
I honestly don't know all the pros and cons of the various aftermarket LSD's - but searching around now it looks like:
Quaife 7.5" ATB's are only being offered with bolt-on flanges right now
3J's NXG ones do a 7.5" without flanges but its not clear if it would suit the equal length stubs or not
Titan don't seem to have a 7.5" version at all
Gripper do offer a 7.5" unit to suit equal length (or a different one to suit unequal)
https://gripperlsd.com/product/ford-sierra-7-5/
https://www.burtonpower.com/parts-by-fitment-type/parts-by-car-model-ford/ford-sierra.html?product_area=Transmission%2C+Clutch%2C+Wheels&product_g
roup=Differential+LSDs+%26+ATBs
[Edited on 18/5/2021 by mcerd1]
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bi22le
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| posted on 19/5/21 at 08:08 PM |
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quote:
Originally posted by mcerd1
quote:
Originally posted by bi22le
I have rear discs already, the half shafts are custom so I could just get some more made but that's more monies.
^^ if you have the
bolt-on CV's at the hub end it would just be a simple swap back to the std. shafts at least (and pick the diff version with matching CV sizes -
sierra cossie=108mm / granada cossie=100mm)
if you want to stay with the push-in setup then you'll need to know the diameter of the stubs going into the diff and the spline count (and
maybe length too) - that should be enough to confirm any new diff you pick should fit your current shafts
I honestly don't know all the pros and cons of the various aftermarket LSD's - but searching around now it looks like:
Quaife 7.5" ATB's are only being offered with bolt-on flanges right now
3J's NXG ones do a 7.5" without flanges but its not clear if it would suit the equal length stubs or not
Titan don't seem to have a 7.5" version at all
Gripper do offer a 7.5" unit to suit equal length (or a different one to suit unequal)
https://gripperlsd.com/product/ford-sierra-7-5/
https://www.burtonpower.com/parts-by-fitment-type/parts-by-car-model-ford/ford-sierra.html?product_area=Transmission%2C+Clutch%2C+Wheels&product_g
roup=Differential+LSDs+%26+ATBs
[Edited on 18/5/2021 by mcerd1]
Thanks for hunting around and getting that info for me. I just ignored more of them as the were not push in and wondered if I can just change the half
shaft connection anyway ( I don't know how the diffs are constructed).
It sounds like I can just get some bolt on shafts though as I have rear discs so they should go straight on (assuming length is correct). Time to go
shopping.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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