Vibration

[chris989]

Hello all,

After a complete rebuild, all new moog, timken, bendix, spicer, bla bla bla, i still have a shimmy vibration at 50mph. not in the steering wheel but enough that the passenger seat looks possessed while driving.

I have checked the runout on the hub surface, rim surface, rotors . discount tire just road force balanced my tires and the worst offender is 17#s the others are 11, 9 and 9. COnsidering they are 35s i think that should be ok?

Short of buying new rims and tires, i just do not know where to look. My tires are 315/75/16 on a 7 inch outlaw2 rim. The rims are at the way minimum width for these tires.

Any guesses? Anyone in Boise want to swap rims for 30 minutes in trade for $, beer or burb parts?

Thanks in advance,
Chris

[geezer#99]

How much air pressure you running in those tires.

[franken]

Try rotating front to back.
I'll guess its a 4x4--part time or full? Full, yank the front DS. Either way, you might have the rear checked for balance. Any clunk going from R to D, assuming an auto trans.

A lot of assumptions since you provided zero info.

[mongocanfly]

if you've had the driveshafts out and apart are the yokes lined up right?

[chris989]

The driveshafts are new front and rear (4l80 conversion) with all spicer joints and balanced. It has manual disconnects in the front. 456 w/eaton posi front and rear and a slip joint eliminated kit.

tires have been rotated and do not notice a change.

I have run as low as 35 psi and as high as 65 when towing. no difference.

It had this shimmy before the restore but i thought it would be solved with all of the new parts. The only parts used from before the rebuild are the rims but they spec out OK with the tools i have to check.

I think it could be something like the lug stud bores not being in the center of the rim. When Discount tire balances, they used the center hub bore not the lugs. I might try to make a jig to test out of round while on the truck.

[homemade87]

I had some what the same problem on my bigger rear wheels and tire ( aftermarket wheels ) . They were balanced from the center hub . Never was right . I had a talk with the tire people and they did a balance with the lugs . There was quite a bit of difference in the weight and was much better . I am going to do the front like this as well .

Some wheels are lug centric .

[chris989]

Originally Posted by homemade87

I had some what the same problem on my bigger rear wheels and tire ( aftermarket wheels ) . They were balanced from the center hub . Never was right . I had a talk with the tire people and they did a balance with the lugs . There was quite a bit of difference in the weight and was much better . I am going to do the front like this as well .

Some wheels are lug centric .

discount said there was no lug centric adapter for 8x6.5 but i can't believe that.

I will call around

[andyh1956]

How much lift?
What is your rear driveshaft angle?
If you have over 4 deg of combined angle you may need a CV rear shaft. That will necessitate rotating the rear axle pinion up to match the driveshaft angle.
We had to go CV on our K5 w/ 4" lift.

[homemade87]

Originally Posted by chris989

discount said there was no lug centric adapter for 8x6.5 but i can't believe that.

I will call around

It would be worth a shot if you could fine someone that could . I had them check balance on center hub before the lug balance . 8oz & 6oz weight difference .

[cadillac_al]

I dunno if 315 tires will ever ride right on 7 inch rims. There is a reason that nobody does it. I think there is a good chance that new rims will cure it. That is the answer that nobody ever wants to hear and is usually the last option.

[chris989]

I am running 2 inch of lift, the drivershaft if not the issue.

I am leaning towards the lug centric as Homemade mentioned. It also did this with 33s and no lift.

I will report back this week when i find the adapter.

Chris