1966 T5 Vibration Issue

[2+2GT]

I have been involved in a number of T5 swaps, and in every case, we were able to use the existing driveshaft and slip yoke.

Have you re-checked the driveshaft? The slightest dent or twist will cause problems. New driveshafts can had quite reasonably- Certainly it would cost little more for a new one than to buy and modify a used one.

 

[v8only]

Good thread!

I've just put a t5 in my drivetrain, but haven't yet driven it really.

you need to eliminate the trans as being the problem.

FYI, it's not the bushing in the tailshaft that would cause a vibration, it's the mainshaft in the trans.

I'm not sure what to tell you shy of pulling the t5 and measuring the mainshaft on bench with a dial indicator. While I've rebuilt 10-15 t5's and haven't come across a bent mainshaft yet, it does happen, and if that's the problem you'll be chasing your tail forever.

If you can get a known good t5, you may want to try that

 

[phutch11]

Do I just measure the runout of the output shaft? I can easily do that with the tranny in the car.

I put the car back up on blocks and am now waiting on it to settle. Quick and dirty measurements last night showed that the pinion angle is now too great - I.e. 8 degrees up.

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[jikelly]

I had an issue with my pinion angle too. I cleared up a bit of the anoying vibration by putting the appropratly angled shims under my rear end.

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[phutch11]

Got the angles lined back up with the shims and the vibe is still there - but again more muted than before.

I'm going to re-torque the pinion nut to make sure the bearing preload is still correct.

Maybe that'll help it.

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[DK832]

Late to the thread, sorry.
When it comes to moving the natural resonance frequencies of the driveline you can also look at the tranny mount. I had a vibration issue at highway speed and nothing I did made it go away until I swapped the PU mount to a rubber one. It's easy to swap and cheap to try.

 

[phutch11]

Already got a new rubber tranny mount.

Thanks for the suggestion though.

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[Edster]

I had a 64 Falcon I converted from 6-8. The engine, tranny and rear end all came from different vehicles. I wound up shimming up the rear end. All I used were some 1/16th inch pieces of aluminum sheet. I think it was two per side and that fixed my harmonics. None whatsoever and it was good 'til 125mph after that I don't know as I was too scared to try and go any faster as the car was all over the road (stock 6 cyl suspension). The crazy things we do when we're young

 

[Glen's 1965 5.0]

I would suspect a bent mainshaft (output shaft) The T5 should be torn down to properly check the runout off of one of the journals (I use the speedo one since that is the thinest area and the most common area for a bend)