Diff Differences???

[68Elanplus2]

Hi Folks -

As reported earlier, my diff is shot. Not knowing much about these things, can someone explain what is meant by a 7" vs. 7.5" rear end, and are they interchangeable?

Thanks,

Aaron
Minnesota, U.S.A.

[dcr]

AFAIK 7" is std sierra , 7.5" is 2WD Cosworth ,have swapped between the 2 before without problems as far as mountings go,hth, Dave

Edited by dcr on Saturday 3rd November 08:07

[jamesG20]

My g20 was fitted with a 7.5 xr4x4 diff, it has bolt on drive shafts and is LSD.
The 7" diff will fit the g20 but has push in drive shafts i think. Ginetta didn't fit these as stanadard and i doubt you need one.

[68Elanplus2]

Well - according to paperwork history the Previous Owner had with Peter Merrilees of Ginetta, the standard diff WAS the 7".

The reference to "bolt on" vs "push in" drive shafts. All of the schematics I've seen of the Sierra/Merkur rear ends show CV joint - bolt on shafts. Am I missing something, and do people feel there would be an issue with swapping a 7.5" for the 7"?

Thanks again,

Aaron

[dcr]

Quaife list the 4x4 diff as being 7" (RS Cosworth as 7.5" ) its what the G20 race cars ran originally and didn't cause us any problems even when run all day long, fitted with 100mm pcd flanges.Flanges push in with a snap ring on most aftermarket diffs , on factory viscous diff there is circlip fitted through the inside of the diff. Drum brake sierra had push in shafts , disc brake cars had bolt on cv's. RS 500 Cosworth had 9" diff and i think Scorpio sized 108mm pcd drive flanges. think i have remembered it all ok , been a while! Dave

Edited by dcr on Saturday 3rd November 18:58

[68Elanplus2]

Thanks - I think that helps.

Situation I'm in is either ordering the parts I need to rebuild my original Sierra diff from Ginetta with the crummy exchange rate in effect AND shipping to mid-America, or - buying a used full diff out of the Merkur XR4Ti for around $200 TOTAL...

Decisions, decisions.

Cheers,

Aaron

[dcr]

A quick look on Burtons site which wont be the cheapest gives all bearings £100, seals, crush spacer and crownwheel bolts about £50 and a new CW & pinion (3.62:1)£235. $200 for a used diff seems pretty cheap in comparison !
As long as you have reasonable rubber on the back of the car, the lack of LSD wont hurt in the dry , rear end grip on a G20 is pretty impressive , rear springs and shocks permitting. hth, Dave

[68Elanplus2]

Thank you Sir! I do have some pretty decent rubber back there, and I hope this thing will bolt right up.

I'll keep you all in the loop!

Aaron