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.

^^ 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]

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.

quote:

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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.

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quote:

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Originally posted by mcerd1

quote:

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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.

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^^ 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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