secretsenor Posted October 25, 2007 Share Posted October 25, 2007 Been a while...GT6 has been going like a train... until....While in sydney I had a bit of a diff catastrope.Diff broke a tooth and spat it our through the back of the casing. Diff still made it the 140km home - but did a lot of complaining.I have found a genuine GT6 diff in Australia - Its described as a reco-ed "327".Apparently its a longer legged highway type of set up?How will this go with the 4 speed + O.Drive?What are the differences in the diffs?Is there any affect on rear track width between the diffs? Link to comment Share on other sites More sharing options...
secretsenor Posted October 25, 2007 Author Share Posted October 25, 2007 OK...I have some changes.Apparently I have the 3.89 which is a more long legged diff.So I am up for a recondition of my existing one.I am also wondering about prices in the UK/USA for a replacement diff as the exchange rate is OK at the moment.While I am looking broadly at options... Does anyone have some details about the conversion to subaru R160 LSD? I hear theres a bloke in NZ that can supply some sort of conversion kit? Any experience here? Link to comment Share on other sites More sharing options...
Deleted User Posted October 25, 2007 Share Posted October 25, 2007 3.27 is a bit weak and will give a very high od-top. It was an original option thoughGood ratio is the 1500 spit or TR7 four speed 3.63 ratioObviously the Tr7 CWP would need building into a GT6 / spitfire diffFor simplicity ( as opposed to a subaru diff) it is pretty strong if built correctly Link to comment Share on other sites More sharing options...
secretsenor Posted October 25, 2007 Author Share Posted October 25, 2007 I am confused... so the 3.27 will giove a higher top speed.I reckon this might be a nice option. lower revs at highway cruising.The engine has plenty of torque. Link to comment Share on other sites More sharing options...
Deleted User Posted October 25, 2007 Share Posted October 25, 2007 If your engine can pull the gear.... basically a 3.27 diff will allow top speed in direct top (circa 120mph? ) and make overdrive just a cruising gear whilst before you would need overdrive to get near that speedits all here........http://www.mintylamb.co.uk/gearspeed/ Link to comment Share on other sites More sharing options...
GT6Steve Posted October 25, 2007 Share Posted October 25, 2007 From my USA perspective I've found the 3.63 with OD to be about perfect for every situation. 3.27 is a good gear without OD but you'll give up the stoplight to stoplight Grand Prix. If you can get a good 3.63 I'd say do it! And no, you're not getting one of mine however weak the dollar gets ;D Steve Link to comment Share on other sites More sharing options...
GT6Steve Posted October 25, 2007 Share Posted October 25, 2007 And for what it's worth, I always say that if you can hear the engine over the diff then keep going! ;D ;D ;D Link to comment Share on other sites More sharing options...
Clive Posted October 25, 2007 Share Posted October 25, 2007 3.27 gives 25mph/100rpm in od top. 3.89 about 20mph, 3.63 22ish.There is a quantum leap between the 3,27 and the 3.89. 3.27 top=3.89 top+od, if that makes sense.The 3.63 is the best option, honest. Got one in my vitesse as I broke 2 or 3 3.27, now no probs. Get one built up!And whatever you do, a recon will not be easy as you need at least a CWP, the carrier may be damaged too, and a case. Thats about all of it really!All the diffs are the same (well, avoiding the early herald/spit ones which have square input flanges). Link to comment Share on other sites More sharing options...
Tim Bancroft Posted October 25, 2007 Share Posted October 25, 2007 I'd do as Andy T suggests and go for a 3.63, this coupled with od gives nice gearing for a GT6 and makes the car well able to match a modern.3.27 is too high, with od you are up into 24mph/1000 ranges. Link to comment Share on other sites More sharing options...
Deleted User Posted October 25, 2007 Share Posted October 25, 2007 i have a 3.27 in he spit, not had any trouble with strength so far and its had track days and all manner thrown at it, the main thing it does make the car a bit gutless straight off the line once your moving its not too bad, and doing 90 on the motorway at 3500 revs is ace:D BUT with my new engine ill be going 3.63 or 3.89 as ill be tracking it more and want the acceleration. Link to comment Share on other sites More sharing options...
rotoflex Posted October 25, 2007 Share Posted October 25, 2007 The non-overdrive GT6 came with a 3.27:1 differential; overdrive cars came with a 3.89:1 differential(except for Germany, which got the 3.27 for both OD & non-OD).3.27 give you a higher top speed.3.89 gives brisker acceleration, & banks on OD use for loafing at highway speed.3.63 is legendary as the best diff choice for an OD GT6, but few came to the US (I will be burglarizing GT6steve's garage when I can get time free to drive to the Wild West).The 3.63 is supposed to have been a common fitment for some later UK Spitfires, so maybe you can find one in Australia.http://i66.photobucket.com/albums/h276/rotoflex/caution.jpgLucky you. When my diff went out in the late 70s, it was at 1 a.m. in the middle of nowhere in February, & the car wouldn't move. FYI: A human being walking at a brisk pace has a speed of almost exactly 5 mph, because it took me almost exactly 5 hours to reach the city the sign said was 25 miles away. Keep your differential as happy as it can be, check its oil frequently. Link to comment Share on other sites More sharing options...
secretsenor Posted October 26, 2007 Author Share Posted October 26, 2007 Thanks fellas - that has really helped.Does anyone know where I might find myself a 3.63 in the UK?I wonder if my Aunt, who is visiting the UK, would mind popping it in her luggage on the way home? Link to comment Share on other sites More sharing options...
GT6Steve Posted October 26, 2007 Share Posted October 26, 2007 rotoflex wrote:3.63 is legendary as the best diff choice for an OD GT6, but few came to the US (I will be burglarizing GT6steve's garage when I can get time free to drive to the Wild West).The 3.63 is supposed to have been a common fitment for some later UK Spitfires, so maybe you can find one in Australia.http://i66.photobucket.com/albums/h276/rotoflex/caution.jpg.a bit remarkable how the markets vary. Earlier this year was a thread similar to this where 3.63's were common as muck in the UK but priceless in the US. It's good we've got this forum to exploit the strengths and advantages of all the brethren. Link to comment Share on other sites More sharing options...
Clive Posted October 26, 2007 Share Posted October 26, 2007 get a new/fully recon one if you are paying the postage (or excess luggage!) no point in messing around. Mike papworth is recommended by the racers on the TSSC board, but canleys are a fav of mine. Interestingly I fitted a 3.63 to my 2.5 vitesse, twas a recon one bought at an autojumble, tight and new. Done only 5000 miles, and when I checked it yesterday it has a lot of backlash. Not sure why really. Totally silent though, no problems with the driving. Seem to remember a lot of the originals had fibre washers in which tended to disappear.The last one I had rebuilt (for my sprint engined spit, 15 years ago!) was done with a solid front spacer and kippings copper washers. That was a super diff! Link to comment Share on other sites More sharing options...
Deleted User Posted October 26, 2007 Share Posted October 26, 2007 The 3.63 survives very well in the Dolomite 1500. Same carrier as the (late) Spitfire, it's relatively simple to swap it into one of those. Most if not all 3.63 CW&P's we see in Spitfire diff's these days are knackered, including the last three another trader (known for his reconditioned mechanical units) tried to sell me recently as suitable for recon (in his professional opinion!).All late diff fibre washers break up and disappear (mashed up by the gearset), and should be replaced with copper washers as a matter of course. Link to comment Share on other sites More sharing options...
secretsenor Posted October 26, 2007 Author Share Posted October 26, 2007 Thanks again for the information. Link to comment Share on other sites More sharing options...
99176 Posted October 27, 2007 Share Posted October 27, 2007 3.27 with OD in my GT6 is great and sooo frugal.Perfect for RBRRs and not too tardy at trackdays. Link to comment Share on other sites More sharing options...
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