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OK to shim driveshaft?


dibo
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So I took the engine, 5 speed and related parts from a donor car to put into my 75. I'm pretty much done with everything, but I'm running into problems with the 5 speed driveshaft from the donor... it's about 1/8-1/4" too short (and yes, the diff is already as far forward as possible).

My questions:

1) Is it safe to shim the driveshaft at all?

2) If yes, where is the best place to shim it (trans-to-shaft or shaft-to-diff)?

Initially I was thinking about shimming between the diff and the driveshaft(the washer-type shims from mcmaster-car), but it looks like the driveshaft flange keys into the diff flange and I have to think that contact patch carries most of the rotational force (as opposed to the diff to driveshaft nuts/bolts that hold it together).

That said, I was also thinking about fabbing a piece of metal (at the right thickness) that would be the exact shape of either the trans output flange or the driveshaft-to-trans flange (I would do this in CAD, then cut it on a CAD plasma table), and that would sit in-between one of these flanges and the guibo... my thought here is that it shouldn't alter the contact patch between the guibo and the flange, but would just be sandwiched in-between to give me my extra depth.

Any thoughts on whether either of these practices are safe? I'd love to hear some first-hand experiences on whether this is ok or not. I really don't want to spend the cash on getting the shaft lengthened (the one I have is practically brand new), but if it's that or suffer a catastrophe, then I'll fork up the cash.

Thanks!

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If you shim the front (where I would, if you need that little)

just make sure that the pilot nose rides securely on the transmission

stub.

Then you'll be fine.

It should be ok.

If it's 1/8".... well... If I couldn't make that up in the motor mounts,

I might be tempted to stretch the guibo a little and see how it went.

That thing is pretty tough.

I had a shaft that was about that much too long, and it

never had any trouble with guibos... and I tracked it frequently.

jus' sayin'

t

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Thanks for the feedback guys... I think I'm going to try the driveshaft-guibo spacer... see how that goes. There's enough distortion in the disc as it rotates that I'm not really comfortable going as is... just needed a sanity check that the approach mentioned wasn't faulty in some way.

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If you have a spacer made I think it would have to only be three holes. You want to line up with the driveshaft flange or the trans flange. If you make a spacer that bolts to all six bolts it will lock up the guibo from flexing.

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If you shim the front (where I would, if you need that little)

just make sure that the pilot nose rides securely on the transmission

stub.

Then you'll be fine.

It should be ok.

If it's 1/8".... well... If I couldn't make that up in the motor mounts,

I might be tempted to stretch the guibo a little and see how it went.

That thing is pretty tough.

I agree.

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