nathanD Posted October 4, 2004 Share Posted October 4, 2004 Hello everyone finally at long last i have just picked up my SEiW kit from westfield and cant wait to start the build im planning to use a vauxhall 2.0 16v some time ago i bought a LSD from a fellow westfield owner i told him on what i was planning and he assurred me the diff i bought would fit. But i have a horrible feeling that it wont the diff came from a XR4X4 and the bolt hole flanges are 7 inches long can anyone tell me if this will fit, i can allways get the part number if it will help cheers Nathan Quote Link to comment Share on other sites More sharing options...
adhawkins Posted October 4, 2004 Share Posted October 4, 2004 Sounds right to me. My diff came from an XR4x4. Andy Quote Link to comment Share on other sites More sharing options...
Terry Everall Posted October 4, 2004 Share Posted October 4, 2004 It will fit but what ratio is it? 3.92 is best Quote Link to comment Share on other sites More sharing options...
adhawkins Posted October 4, 2004 Share Posted October 4, 2004 3.92 is best Assuming a Type 9. Doesn't it give an unusable first gear on an MT75? Mine is a 3.62 (on an MT75). Andy Quote Link to comment Share on other sites More sharing options...
nathanD Posted October 4, 2004 Author Share Posted October 4, 2004 im not sure of the ratio all i do know that its a limited slip is there any way i can tell could i tell from the part numbers i think i have to use a type 9 with the vauxhall engine Quote Link to comment Share on other sites More sharing options...
adhawkins Posted October 4, 2004 Share Posted October 4, 2004 On mine, there was a metal tag attached to the diff, with a load of information on it. I think the ratio was on there. You can tell from the part number too I think. Post it here, and I'm sure someone will be able to help. Andy Quote Link to comment Share on other sites More sharing options...
KerryS Posted October 4, 2004 Share Posted October 4, 2004 My complete kit collected recently has a diff with 3.92:1 painted on it and I believe the box is the MT75 bolted to the drive end of the Zetec. I too thought the diff was a Sierra one. I have just been out to the garage to look at the diff - it has mounting lug centres of about 192mm, just over 7.5 inches Kerry S Quote Link to comment Share on other sites More sharing options...
adhawkins Posted October 4, 2004 Share Posted October 4, 2004 My complete kit collected recently has a diff with 3.92:1 painted on it and I believe the box is the MT75 bolted to the drive end of the Zetec. From what I've read on here, you'll end up with a very short 1st gear... Andy Quote Link to comment Share on other sites More sharing options...
KerryS Posted October 5, 2004 Share Posted October 5, 2004 Andy Mmmm..that's what I thought. I presume it's the same spec as the one I drove at the factory but I cannot recall how "short" or "long" first gear was, except it accelerated like nothing I'd ever been in before, which tends to suggest it is "short". I was told there was a 20 mph limit within the industrial estate, ha! Kerry S Quote Link to comment Share on other sites More sharing options...
Mike H Posted October 5, 2004 Share Posted October 5, 2004 A round up on diffs: Sierra diffs can be 7" or 7.5" across the top mount. A 7" diff will need a spacer to make up the difference. Newer diffs seem to use 2 bolts on the top mount rather than a single double ended rod that goes all the way through. No tag on the diff means you've got to rotate the input and count the turns on the output to see what ratio it is. If you take the back off the diff to see the condition of the crown wheel then you will find the ratio written on the edge of it. Just clean up the edges of the case and cover and reseal with silicon when you put it back together. Most XR4x4 that I've seen were 3.62:1. Zetec with MT75 and 3.92 or 4.09 diff IMO will give a short first gear unless you can go to 7500rpm. Diffs from Sierras with rear disk brakes always have bolt on drive shafts (AFAIK). A push in shaft diff can be converted to bolt on very easily. If you are after a higher ratio (lower number) then you will want a diff from a diesel car but these usually have drum rear brakes and are therefore use push in shafts. HTH Mike Quote Link to comment Share on other sites More sharing options...
Blatman Posted October 5, 2004 Share Posted October 5, 2004 3.9 diffs will render both MT75 and Type 9 first gears as good as useless.... well not quite, but it ain't good... Quote Link to comment Share on other sites More sharing options...
Matt Seabrook Posted October 5, 2004 Share Posted October 5, 2004 With a Type 9 box and a 3.62 first gear at 7000 rpm you will be doing 36mph with a 3.92 diff you will be doing 33mph (195/50x15) tyres. To be honest I had a 3.62 diff in my car with an MT75 gearbox and then changed it to a 3.92. First gear with either diff was over to quick and going for a 3.92 did not make that much difference IMHO. It did help with the higher gears though and as I did not build my car to be a touring machine the 3.92 diff suited me better. I think you would be hard pushed to tell 3mph difference in first. If you are talking going from 36 to 46mhp in first than that’s a different matter. I fitted a BGH gearbox which took the car to 47mph in 1st and that helped a lot but 3mph was nothing to write home about Quote Link to comment Share on other sites More sharing options...
Blatman Posted October 5, 2004 Share Posted October 5, 2004 Well, quite. Either way, 1st is over all too quickly, and it's a *big* drop from 1st to 2nd, which is what I failed to say... Quote Link to comment Share on other sites More sharing options...
Matt Seabrook Posted October 5, 2004 Share Posted October 5, 2004 Yep close ratio box is the answer just dont think that you should right off the 3.92 diff as both 3.63 and 3.92 are over far to fast in a Westy with a standared box Quote Link to comment Share on other sites More sharing options...
stu999 Posted October 5, 2004 Share Posted October 5, 2004 Or just dont bother with first gear at all for a fast start with a 3.6/3.9 and a standard type 9... Of course, this is fine with a VX, but Zetecs may struggle Quote Link to comment Share on other sites More sharing options...
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