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Spitfire Replace GT6 diff with Spit diff?

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Flinkly

Jedi Trainee
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hey guys,

sent my gt6 diff in to have the seals replaced and the whole thing cleaned up nice only to find out i'm missing teeth (in the diff). I do have a very early spit diff which is probably a 4.11, and could probably get my hands on a late spit diff, but are they swappable with a gt6 diff, and can they handle the 6 cylinder power and torque? thanks for the enlightenment, and i wish there weren't so many suprises in rebuilding a car.

-Jon
 
My understanding is the diffs are the same. The main difference is in the gearing: non-O/D GT6 diffs are geared lower. My Spit6 (GT6 engine in a Spit chassis) currently has a 3.27 GT6 diff in it (installed by the previous owner when the last diff didn't hold on to its output flanges... However the trans <span style="font-style: italic">does</span> have o/d... so highway cruising is pretty nice.

Depending on what I end up doing with the car, I will probably swap in a lower ratio diff eventually for better response off the line.
 
Reports are that the best differential ratio for a GT6 with overdrive is 3.63, but the 3.63 diff was supplied apparently only on late home market Spitfires.

Nick Jones has supplied instructions for how to construct a 3.63 diff from more easily available parts:

https://www.geocities.com/rotoflex/gt6-mod.htm#_construct_363_diff

I have read a report from only one person who's said he put a 4.11 in his GT6. I doubt it's the best way to go.
 
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