SRF Posted July 8, 2012 Share Posted July 8, 2012 The downside of having a non overdrive Vitesse as everyone knows is the high revs at cruising speed. Can anyone tell me whether changing to a 3.63 diff would make much difference. Also it is a long time since I rebuilt a diff, my Haynes manual has no information. Has anyone any experience of a rebuild and any advice, especially how to set the pre load. Link to comment Share on other sites More sharing options...
James Posted July 8, 2012 Share Posted July 8, 2012 Check out the tool on my website to find cruising speed etcDetails in my signature. Link to comment Share on other sites More sharing options...
Nick Jones Posted July 8, 2012 Share Posted July 8, 2012 3.63 is an improvement but not a huge difference. 3.27 gives relaxed cruising but makes 1st/2nd a bit high. Overdrive or 5 speed is the best solution if you are planning lots of open road use but will require some investment. I have a tall 5th (0.78) and 3.63 which gives 70 mph at 3000 rpm - car would still pull a higher gear.Nick Link to comment Share on other sites More sharing options...
SRF Posted July 8, 2012 Author Share Posted July 8, 2012 Cheers both, from your site James it's about 5mph. Which differential has a 3.27 Nick. I don't intend doing a lot of open road driving and certainly no motorway stuff I am not going down the O/D or 5 speed route. My mates Spartan has 1500 Spit running gear and he rarely uses his O/D. Link to comment Share on other sites More sharing options...
Richard B Posted July 8, 2012 Share Posted July 8, 2012 4874 wrote:Which differential has a 3.27Non-O/D GT6's Popular with people fitting 2500 engines in small chassis cars. okay, ok and overdrive GT6's in Switzerland for some reason. :P Link to comment Share on other sites More sharing options...
Mark Hammond Posted July 8, 2012 Share Posted July 8, 2012 So what benefits (if any) would be there in fitting a 3.27 diff to my otherwise standard in every respect Herald 1200? The speed through the gears and top speed all looks great but i imagine that it would take forever to get there.....Mark Link to comment Share on other sites More sharing options...
Nick Jones Posted July 8, 2012 Share Posted July 8, 2012 SRF,Seems like you might as well stick with the 3.89 then. If it's quiet just leave it be......Mark,I doubt a standard 1200 would pull a 3.27 diff - I think it would end up slower than standard in all respects. A long time ago I had J type OD on a 1200 Herald, modified with a high compression SAH head, twin carbs and 4-2-1, still running the standard 4.11 diff and that was ok, though you'd have to knock it out of OD for even quite gentle inclines. 3.89 or even 3.63 might be worth a try though....Nick Link to comment Share on other sites More sharing options...
davecymru Posted July 8, 2012 Share Posted July 8, 2012 After doing a lot of reading and phoning around I recently changed my 4.11 for a 3.63 and despite what the numbers say, there is a quite nice noticeable difference. Everything i read and everyone i talked to (without exception) advised me that while the 3.27 would give even more relaxed cruising, it is a weaker diff and they are also a rarer on the 2nd hand marketI've now done just under a thousand miles with the 3.63 and it's lovely and there is a noticeable difference over the old diff with my 4 speed box and 2L engine. The car cruises at 70 on the motorway just fine and with the 2L engine i've got plenty of power to overtake, although in the Sammio it's quite scary at on the motorway no matter what speed I'm doing :)Based on everything i've read/heard I'd say if you don't have quite the money/time for a complete overdrive swap at the moment then the 3.63 is the quickest way to get a bit more of a relaxed cruise. But that's just my 2p and even though I'm more than happy with what i've done i will admit that at some point i will also be considering swapping to an overdrive gearbox as well to make cruising even nicer. Link to comment Share on other sites More sharing options...
SRF Posted July 10, 2012 Author Share Posted July 10, 2012 I have decided to upgrade my diff. Is there any way I can tell which diff I have at present. I have looked at James web site but for some reason mcafee won,t let me go there again. I am considering a 3.63 because the 3.27 are hard to find. Can anyone tell which models had the 3.63 please. Link to comment Share on other sites More sharing options...
Nick Jones Posted July 10, 2012 Share Posted July 10, 2012 1500 Spitfire was the only small chassis Triumph that had them. The same internals were used in Dolly 1850 manual (poss 1500 auto?) but that means rebuilding a diff.............. so the 1500 Spit is the one - rear casing only has 4 holes for the spring studs but can be swapped with the one from your existing 3.89Nick Link to comment Share on other sites More sharing options...
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