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-   -   These aren't my kinda vibes (https://forums.vintage-mustang.com/vintage-mustang-forum/1148862-these-arent-my-kinda-vibes.html)

Rowdy 12-02-2018 01:05 AM

These aren't my kinda vibes
 
I've been chasing driveline vibration for a while now!

Lowered the motor with RM mounts. Shimmed the trans up and added lowering blocks in the back. We're now within 1/4 of a degree driveline angle wise. It has a freshly balanced driveshaft with new spicer u joints. New yoke and trans mount when I put the T5 in.

I don't see anything making contact that isn't supposed to.

Rear wheels were straightened and rebalanced.

Rear end was rebuilt last december. However, when we changed the yoke on the pinion to accept the larger u joint this past week, it was noticed that the pinion support bearing had walked forward. Tapped it back into place and replaced the star clip. Didn't look like there was any damage. Didn't think to check it with a dial gauge for roundness.

The driveline angle sorting got rid of a bunch of vibes, but I still have one from about 60mph onward. It annoys me enough that I don't want to take the car on to the highway.

I'm in to see IWE about the rear end issue on wednesday, but I'm guessing that may not be the cause.

Anyone with any thoughts?

zray 12-02-2018 01:59 AM

were the RM mounts and T-5 put in at the same time ?

does the vibration intensify if you are in 4th instead of 5th at the same speed ?

have the axles been replaced and / or checked to see if they are bent ?


Z

dobrostang 12-02-2018 09:24 AM

55 to 60 MPH is classic bad tire resonant mode try swapping fronts to back etc... Good luck

Rowdy 12-02-2018 12:55 PM

Quote:

Originally Posted by zray (Post 10069714)
were the RM mounts and T-5 put in at the same time ?

does the vibration intensify if you are in 4th instead of 5th at the same speed ?

have the axles been replaced and / or checked to see if they are bent ?


Z

The RM mounts were installed after to get the pinion angles right and help clear the TCP monte carlo bar (AC compressor)

Vibration is the same in 4th or 5th. Clutch in or clutch out at those speeds.

I believe they checked everything in the rear end, but they were the original axles.

Rowdy 12-02-2018 12:57 PM

Quote:

Originally Posted by dobrostang (Post 10069790)
55 to 60 MPH is classic bad tire resonant mode try swapping fronts to back etc... Good luck

Dobro, that was one of my first thoughts too. The rear wheels were taken to a wheel shop and straightened and everything been balanced. I've swapped front to back too without any luck.

Grabber Blu 12-02-2018 04:21 PM

Check that pinion flange that it has no play. Technically you just can't replace the pinion flange and establish correct bearing preload unless you have a solid spacer. But if you have the more common collapsible spacer you only guesstimating. The collapsible spacer is a one time use.

The solid spacer torque is 175 ft lb, some guy's use 124-150 ft lbs for reusing a collapsible spacer. I would be willing to bet you have play in that pinion flange

Woodchuck 12-02-2018 05:07 PM

Take the car to a shop that does "on the car" balancing and have the rears done.

Rowdy 12-02-2018 05:33 PM

Quote:

Originally Posted by Grabber Blu (Post 10069978)
Check that pinion flange that it has no play. Technically you just can't replace the pinion flange and establish correct bearing preload unless you have a solid spacer. But if you have the more common collapsible spacer you only guesstimating. The collapsible spacer is a one time use.

The solid spacer torque is 175 ft lb, some guy's use 124-150 ft lbs for reusing a collapsible spacer. I would be willing to bet you have play in that pinion flange

You may be right. I'm curious as to why the pinion bearing had walked.

It now also sounds like the limited slip is doing funny things.

Rowdy 12-02-2018 05:35 PM

Quote:

Originally Posted by Woodchuck (Post 10069998)
Take the car to a shop that does "on the car" balancing and have the rears done.

The rear wheels were taken to Greens automotive that exclusively does wheel straightening and repairs and they're now straight as an arrow and well balanced.

Woodchuck 12-02-2018 05:37 PM

Quote:

Originally Posted by Rowdy (Post 10070010)
The rear wheels were taken to Greens automotive that exclusively does wheel straightening and repairs and they're now straight as an arrow and well balanced.

Trust me.

Rowdy 12-02-2018 05:57 PM

I've thought about replacing the wheels and tires completely...

Woodchuck 12-02-2018 06:06 PM

Quote:

Originally Posted by Rowdy (Post 10070032)
I've thought about replacing the wheels and tires completely...

And if the problem is a brake drum or an axle flange your problem STILL won't be resolved...

Nailbender 12-02-2018 06:53 PM

1 Attachment(s)
I was unable to solve 65mph up vibration until I put on new tires and rims even though I had the old combo checked and balanced. Given the power that you are making, a serious wheel and tire upgrade is way past due! Might want to throw a few Moser axles in as well for good measure.

Grabber Blu 12-02-2018 07:10 PM

Quote:

Originally Posted by Rowdy (Post 10070008)
You may be right. I'm curious as to why the pinion bearing had walked.

It now also sounds like the limited slip is doing funny things.

Could be the pinion is loose, if so you'll ruin that gear set in a hurry. Do you know if you have a solid pinion spacer?

kenash 12-02-2018 07:29 PM

Quote:

Originally Posted by dobrostang (Post 10069790)
55 to 60 MPH is classic bad tire resonant mode try swapping fronts to back etc... Good luck

I "like" this for the reason, it's quite possible the rim, in a addition to the tire, is at fault too.


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