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Discussion Starter #1
I installed a T-5 tranny in my 68 coupe (302, 8inch rear, originally a 3-SPD) last summer and was going to use the original driveshaft but to get it in I had to really wrestle with it and once installed there was very little room between the tail shaft and slip yolk. After posting some pics here I was advised it was best to shorten the driveshaft as you need at least an inch of free play. Fast forward to today... I'm in the middle of reupholstering my seats and was under the car taking the bolts out when I noticed there seems to be a lot of room between the tail shaft and the slip yolk. Looking at the pics attached, there's about 1 and 3/4 inches between the flat metal part of the tail shaft and the flat part go the yolk. I think what happened was when I took the initial measurement I must have had the car lifted and the wheels hanging... thus no load on the rear suspension. So my question now, is the driveshaft too short? I've read multiple sources that state the 1 inch of space starts from the black rear seal, not the base of the tail shaft where the ruler in my pic is. If that's the case, I think I'm okay as there's about an inch of room. If not... well then yeah I'm like 3/4 to an inch too short. Is that a big deal? I haven't noticed any crazy vibrations yet but I really don't want to trash the new Tranny by continuing to drive it and messing up the bearings. Thanks
 

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It is a little short but if you have the yoke where the spines are cut deep it shouldn’t be a problem. If your splines were cut short then it may be an issue but given you’ve been driving it I would say let er rip. I can’t remember which yoke has the spines cut further but you would be able to tell by looking at it and of course you can make a drive shaft longer.
 

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Yes, you are a little short. The 1" is from the tail shaft not the end of the black seal. You only needed about 1/4"removed. The real reason for the 1" of shaft showing is simply for ease of installing the driveline. If you can get it installed then in reality you have enough play. The driveline moves very little as the suspension travels up and down.
 

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Whoever advised you to cut it was incorrect, the original length in your photo, if the rear axle was not supporting the weight of the car, was perfect.
 

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Discussion Starter #5
Ah man...

Thanks for the replies. Knowing myself the next time I drive it on the highway and feel a slight vibration I'm going to jump and assume it's because of the driveshaft. I know there's not really a universal driveshaft length that works across all T-5 conversions, but is there a somewhat agreed upon length? 50-51 inches? Just trying to calculate some numbers. Thanks
 

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Ah man...

Thanks for the replies. Knowing myself the next time I drive it on the highway and feel a slight vibration I'm going to jump and assume it's because of the driveshaft. I know there's not really a universal driveshaft length that works across all T-5 conversions, but is there a somewhat agreed upon length? 50-51 inches? Just trying to calculate some numbers. Thanks
When I did my swap 10 years ago, I used this....https://www.dennysdriveshaft.com/how_to_measure.html
 

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Although the consensus is that it may be too short, it is still engaged quite a bit if your yoke is splined its full length like many are. Drive it and see how is works out. It may be fine. You may be able to move your engine and trans back a bit to improve things.

I converted to a T5z years ago and moved the engine forward as much as I could and never had the driveshaft shortened. About 1/4" of yoke was exposed with weight on the car. Never had a problem, but was going to shorten it someday. The rear end started leaking from the pinion yoke a while back and I removed the yoke and found it had a groove in it from rubbing on the seal for years. Bought a shorter yoke and installed it and it solved 2 problems as now I have about 1" of front yoke exposed. I could move the engine back now if I want to reduce the amount of exposed yoke.
 
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