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Mk 3 GT6 fitted with a 2 litre, OD and 3.27 diff?


Rubce
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Shouldn't be an issue. It will be like a std non-od GT6, but with the addition of OD. 

It means you may need to flick out of OD sometimes, but is very relaxed for motorway. It may not make much difference to economy, unless you have a very light foot (heaven forbid)

The other alternative is to use a 3.63 diff from a spit 1500. Halfway between a 3.89 and 3.27, a lot easy to come by, and stronger.  Andy Cook has this combo (and many other GT6 owners) so do consider it.

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Hi Clive.

Thanks for the quick reply and the suggestion regarding a 3.63

I have a 2.5 litre engine stashed in the garage which will be going into the car at some point in the future. 

Why is the 3.63 considered stronger than the 3.27? Load stresses?

Regards

Bruce

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7 hours ago, Rubce said:

Hi Clive.

Thanks for the quick reply and the suggestion regarding a 3.63

I have a 2.5 litre engine stashed in the garage which will be going into the car at some point in the future. 

Why is the 3.63 considered stronger than the 3.27? Load stresses?

Regards

Bruce

The internals are different. I think there may possibly be a variation within the range of 3.27s, and the dolly 1850 auto was the last, so strongest? you would really need to check with somebody like Peter Cox or Mike Papworth.

I had a 2.5 vitesse, fitted with a 3.27. It used to get through them, after 4 breaking, I fitted a 3.63, and that survived, went into my zetec spitfire, and the next, and now lives in Dirks spitfire (checked before it went to Dirk, all was well, just fresh seals as a matter of course)

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12 hours ago, Rubce said:

Hi All

I am considering fitting a 3.27 diff to our Mk3 GT6 to reduce engine revs. The car has a  2 litre engine, 4 speed box with overdrive.

Can anyone advise from previous experience on this configuration?

Thanks in anticipation

Bruce

Hi Bruce I have this in my 2.5 pi spitfire with a 28% overdrive works really well , I can’t see why in your car why it wouldn’t be similar 

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Hi both my gt6s Inc current mk1 have run this combination,  OK it may not be fastest off the mark, but is v relaxed motorway cruising  and the 2l lump is v capable of pulling this. I  easily keep up with tr6,s and it s as fast as my pi.  Ratio is  25 mph per 1000 rpm in od and 20mph per 1000 in top.  I'm sure thus would have been a more standard fit if more motorways were around and Stanley markland wasn't, hiding in the wings with his pull from 10mph in top gear without hesitation bull!

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  • 5 weeks later...

Hi Bruce,

I have driven my GT6 with J type overdrive and 3.63:1 differential for over 30 years and found it to be the ideal gearing for the car, decent enough engine speed at motorway speeds and nippy enough when pulling away. My GT6 is a non overdrive model and therefore had a 3.27:1 ratio diff, awful gearing for getting away quickly, much better now with the o'd and 3.63.

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On 28/11/2021 at 19:57, docwad said:

Hi both my gt6s Inc current mk1 have run this combination,  OK it may not be fastest off the mark, but is v relaxed motorway cruising  and the 2l lump is v capable of pulling this. I  easily keep up with tr6,s and it s as fast as my pi.  Ratio is  25 mph per 1000 rpm in od and 20mph per 1000 in top.  I'm sure thus would have been a more standard fit if more motorways were around and Stanley markland wasn't, hiding in the wings with his pull from 10mph in top gear without hesitation bull!

Hi Doc

Just to clarify, you have a 3.63 or a 3.27 diff fitted?

Regards

Bruce

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39 minutes ago, Tim Bancroft said:

Hi Bruce,

I have driven my GT6 with J type overdrive and 3.63:1 differential for over 30 years and found it to be the ideal gearing for the car, decent enough engine speed at motorway speeds and nippy enough when pulling away. My GT6 is a non overdrive model and therefore had a 3.27:1 ratio diff, awful gearing for getting away quickly, much better now with the o'd and 3.63.

Hi Tim

Thanks for the advice. Looks like I will on the look out for a good condition 3.63. 

Regards

Bruce

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I have a 3:63 in my Mk1, a few years ago I took 3 or 4 tired diffs to Mike Papworth, he pulled all the good bits and made me up a 3:63 and a 3:27.  Not tried the 3:27 yet bur the 3:63 works well, apart from I cannot find a stock speedo with the correct gearing so the speed indication is well out!

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32 minutes ago, mikeyb said:

I have a 3:63 in my Mk1, a few years ago I took 3 or 4 tired diffs to Mike Papworth, he pulled all the good bits and made me up a 3:63 and a 3:27.  Not tried the 3:27 yet bur the 3:63 works well, apart from I cannot find a stock speedo with the correct gearing so the speed indication is well out!

Like myself....the speedo works but not spot on...so I bought an electronic /digital speedo.......miles/Kms/ max speed pre programmer/tire alarm/ etc etc and that sits on the dash....all for £18.00 Saves the hassle of swapping gauges etc 

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On 29/12/2021 at 10:14, mikeyb said:

I have a 3:63 in my Mk1, a few years ago I took 3 or 4 tired diffs to Mike Papworth, he pulled all the good bits and made me up a 3:63 and a 3:27.  Not tried the 3:27 yet bur the 3:63 works well, apart from I cannot find a stock speedo with the correct gearing so the speed indication is well out!

Can't see the speedo being  problem, they will have banned IC engines before it is on the road again, so you will need to find an electronic one to work with the batteries.

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Not a GT6,but if you are planning on a 2.5 conversion,i have a tuned 2.5 in my Vitesse with a saloon o/d box and 3:27 diff,built by Mike Papworth with a stronger carrier(TR7?),i find it a great combo, too old for No.11 starts but driven enthusiastically.

Steve

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  • 2 weeks later...

Hi,

 With a 2.5EFI, I have had many 3.63 diffs go gender neutral  poof.

Even 3.27 is not numerically low enough for me. Going to fit taller tyres on back to lower RMP cruise speed.
If I want to move quick I switch off OD or change down. Over 70 in 3rd is available.
1st is plenty numerically high enough to smoke tyres with ATB diff & 215's.

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