Not So Good Vibrations

[jikelly]

I installed the 2.5 degree pinion wedges I bought this weekend and it seemed to help with the vibration. Now I'm only really feeling it when I'm doing hard acceleration from 3500 up. The vibration on the highway seems to be gone up through 85 anyway. I don't know beyond that because I didn't drive that fast yet.

Do you think I should make some custom motor mounts to drop down my engine so I can tweak that angle a bit?

 

[bnickel]

I installed the 2.5 degree pinion wedges I bought this weekend and it seemed to help with the vibration. Now I'm only really feeling it when I'm doing hard acceleration from 3500 up. The vibration on the highway seems to be gone up through 85 anyway. I don't know beyond that because I didn't drive that fast yet.

Do you think I should make some custom motor mounts to drop down my engine so I can tweak that angle a bit?

either that or cut into those pristine floors and move the tunnel up. personally i would get some TCP or RM motor mounts that will you allow to lower the engine 1" and hopefully change the angles at the trans enough to bring you closer back to specs. i find it odd that the bigger cars have less room in the tunnel than the 69/70 (possibly 67/68 as well) cars. there are tons of guys who have put the tremec in the 69/70 and had acceptable driveline angles, still not ideal mind you but within allowable tolerances.

 

[D.Hearne]

I installed the 2.5 degree pinion wedges I bought this weekend and it seemed to help with the vibration. Now I'm only really feeling it when I'm doing hard acceleration from 3500 up. The vibration on the highway seems to be gone up through 85 anyway. I don't know beyond that because I didn't drive that fast yet.

Do you think I should make some custom motor mounts to drop down my engine so I can tweak that angle a bit?

I've been fighting the same problem on my 77 Comet after the 9" swap. First thing I did was learn the pinion shaft bearings were bad. Changed those. Same vibes. Next replaced the driveshaft with the original off the car ( I had swapped it for a larger shaft I already had,turned out it was a bit out of round) Still got vibes. Next replaced the C-4's tailshaft bushing. It had a bunch of slack. Still had vibes, only now just on decelleration. Just installed an ebay special 02 Stang driveshaft. Still got a very, very slight vibe, but not nearly as bad as it started out with. Ordered the 2.5* pinion angle shims yesterday. Gonna install them when I get from Wyoming later this week.

 

[jikelly]

Hum, well I would think my transmission bearings were fine since I replaced them all when I rebuilt the tranny. 327 or so miles on them now. The rearend bearing, hum, or the driveshaft could both be part of the problem I guess. Do you think I should take my driveshaft to be rebalanced or replace it? how about the rear?

I had new gears installed in the rear approx 6000 miles ago. Aren't cars fun?

 

[D.Hearne]

Did you replace the transmission tailshaft bushing ?(not bearings, but bushing) As far as the driveshaft goes, if you can jack it up off the ground to where you can run the engine with the trans in gear, then watch the shaft, if it's out of round, you'll see that. If your rearend was rebuilt, that probably rules out the pinion bearings. The chunk in mine came from a junkyard 81 Bronco, the only thing I'd checked before using it was the clutches. Wasn't till I was hunting the driveshaft vibes that I realized the pinion bearing were rough.

 

[jikelly]

I guess I was happy with the results after I put in that 2.5 degree shim because I hadn't really worried about the vibration until this week. I got on it and found that in every gear there was a really bad vibration from 4000 RPM up.

BLAGH!!

I think I'm going to stop driving my car till I can figure out what the heck is causing the vibration. I did some searching online and stumbled on people saying that it could also be the clutch, flywheel, or a bad water pump bearing.

Well, I reved the engine up to nearly 5000 RPM with the tranny in nutral and I'm feeling no vibration.

My clutch does slip a bit when I shift into third gear if I'm on the power. Maybe I warped it or something.

So what do you guys suggest?

And is there a place where I can find a set of motor mounts for my 73 stang that will lower the engine as someone suggested?

Something else that could be a part of the issue is my carb. It needs to be replaced because I suspect that it either has a crack in the housing or near the main linkage shaft because the mixture just stays rich. I'm going to pull all my plugs tonight and see how they look.

 

[BarnStang]

Is the trans tunnel completely intact? You can notch out the floor support and not cut the tunnel open. I went back and see it's a 3550, so notching the floor support may not give you enough to solve the problem.
We have been looking at these guys:
ford transmission swaps | tremec | mopar restoration parts | automatic transmission, camaro transmission

We have a customer who wants to use this setup, but have not tried them yet. Not that you want to dump your 3550 and buy another trans...but if leaving the tunnel intact 100% is the goal, this is an option. If it is what they say it is.

I notch all the T-5 conversions, and the Keisler instructions have you notch it too.

I am interested to see if anyone has dropped the motor an inch to solve this, and what compromises ensued as a result. THis seems like a no brainer, but there is almost always a trade off somewhere...

 

[jikelly]

Yeah, I'd like to have that transmission from Keisler, but I just rebuilt this one and unless there is somethign wrong with it I don't even want to take it out of the car.

The 73 mustang transmission tunnel is big enough for the 3550, but the top of the case is right on the tunnel. Seems like I had more clearance with the last engine block. It may be that my engine mounts got tweaked or something, but really that doesn't make much sense. Seems like that would be kinda hard to have happen.

It seems like no one makes a motor mount for the 73 mustang and that's crazy to me.

Could I make new mounts myself?