tomo Posted January 8, 2002 Posted January 8, 2002 I need to choose a diff ratio for a new build and am trying to decide between a 3.62 from a 4X4 which I assume will be LSD and a 3.97 non LSD. I have a BGH close ratio box. The car will mainly be used on the road. I'm still negotiating track day use. I'm getting mixed feedback about the benefit of LSD and one boardroom thread I've read implies that the LSD bit wears off over time. Any thoughts or advice would be most welcome. Tomo Quote
Blatman Posted January 8, 2002 Posted January 8, 2002 I've read the same thing about the Sierra 4x4 diffs. Phil Stewart (of Road and Race Transmission fame) said to me over Christmas dinner that the viscous Sierra diff should never wear out in a Se7enesque vehicle.......... If the 'box has a "long" first gear (ie 2.39 or 2.04) I would steer clear of the anything below 3.9 for the diff, and I would spend the extra on having a non lsd converted. My favourite would be a Quaiffe ATB rather than a plate type. Others will disagree though, for various reasons. My answer is the ATB is a fit and forget solution, whereras the plate type will need "fettling" from time to time. Quote
Nick M Posted January 8, 2002 Posted January 8, 2002 The ATB is not quite a fit and forget job in the Sierra diff casing !! I know of one or two people who have had all sorts of fun and games changing output flanges, getting the inside of the case "fettled", etc. Phil charges between £75 and £100 to convert a 3.62 LSD to a 3.9 (not 3.97 by the way) ratio one - you supply the bits, he supplies the know-how !! I'm going to use the Sierra one to begin with and see how it goes. I'm running (or at least will be running) a 2.48 first gear with a 3.9 diff ratio. Quote
tomo Posted January 9, 2002 Author Posted January 9, 2002 Thanks for the response chaps. Can you give me contact details and location for this Phil Stewart. Many thanks Tomo Quote
Blatman Posted January 9, 2002 Posted January 9, 2002 Phil Stewart, Road and Race Transmissions, 01959 525105 Quote
tomo Posted January 16, 2002 Author Posted January 16, 2002 Blatman, Great recommendation. Got 2 diffs at the weekend, one 3.92 and one LSD, phoned Phil on Monday, dropped off the diffs Tuesday am, picked up one reconditioned 3.92 LSD Tuesday pm. Fantastic service. Quote
Mike H Posted January 16, 2002 Posted January 16, 2002 If the 'box has a "long" first gear (ie 2.39 or 2.04) I would steer clear of the anything below 3.9 for the diff, and I would spend the extra on having a non lsd converted. Sorry for being stupid, but why would you avoid anything below a 3.9? Is it because of you particular engine characteristics? Or is it because of the type of driving you mainly do? Or both? thanks Mike Quote
Nick M Posted January 16, 2002 Posted January 16, 2002 In practical terms, having a high first gear ration (2.39, or 2.04) coupled with a high diff ratio (3.62) means pootling around town is a *real* pain in the A*** as you're constantly slipping the clutch and trying to keep the thing moving. It can also generally make the car over-geared so that it stifles the bottom end performance - you'd be constantly dropping down a gear to accelerate quickly. Even with a 2.48 first gear I am getting my diff converted to a 3.9 LSD so it doesn't bog down, but that's largely due to the fact that my engine won't have the same level of torque as, for example, a 2.0 VX. Quote
Rascal Posted January 22, 2002 Posted January 22, 2002 For what it's worth...... The diff's ratios out of 2.8/2.9 XR4x4 and a 2.0 XR4x4 are 3.62 and 3.9 respectively. Both are LSD. The 3.9 version can be picked up cheaply from a couple of XR breakers in Essex. Quote
Nick M Posted January 22, 2002 Posted January 22, 2002 The 3.9 diff is as rare as rocking horse droppings !! Can you let me have contact details for this place in Essex please !!! Is one of them in Southend ?? Quote
Rascal Posted January 22, 2002 Posted January 22, 2002 I picked up a mint 2.9 diff from Barry at XR4i spares 01375 672641, http://www.xr4ispares.co.uk/ - 15mins from Laindon about 2 months ago, he had a couple of 3.9 LSD he said he couldn't give away. As an indication I paid £100 for the diff with a guarrentee. The other place is XR4x4 Sierra spares Tel: 01702 433233 or mobile 07752647696 in Southend. They're usually breaking cars. Also a good place to look is the XROC site, http://www.xroc.net/forums/index.php - everyone there is after 3.62 diffs so you may pick up a bargain. P.S. Barry's site isn't the best around but he's an honest guy. Quote
windy Posted January 23, 2002 Posted January 23, 2002 The 3.9 CWP should fit to the LSD unit on the 3.6 diff. A std diff can be obtained for peanuts so is a good source for a donor CWP. I had no problems getting hold of LSD diffs from my local scrappy - maybe I was lucky. Your viscous diff will be OK for road use and occasional track days - for competition use no - I got through 2 viscous units before spending my money wisely on an ATB which Phil Stewart built for me. Regards Windy Quote
Rascal Posted January 31, 2002 Posted January 31, 2002 If anyone's looking for a 3.9 LSD http://www.xroc.net/forums/showthread.php?s=&threadid=8804 Quote
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