Lowering front end lift help with vibration?

[peterson1604]

I just ordered a set of cheap alignment shims off Amazon and started with a 1/8 shim on each side of the bearing and then increased it by 1/64" until it stopped vibrating at 5/16". I also swapped out the stock bolts for longer stainless grade 8 bolts and lock washers to compensate for the shims and to prevent the bolts from rusting or backing out.

I'd like to do this tonight but the parts store doesn't have any shims in stock, go figure. Do you have the Amazon link on the shims you ordered as well as the bolts? I'd like to order them. Also, while a bit more work because you have to fully remove the bolts and support the driveshaft, could you just use washers instead of shims?

Thanks,
Scott

Sponsored

 

[Porpoise Hork]

This is the shim kit I used. As for the longer bolts, I just pulled one out took the wife's car and went up to to the local hardware store to find one the same thread pitch only longer and a pair of lock washers to go with the longer bolts when I realized I needed longer ones.

You can use washers in a pinch to test it but the downside is they may not be a standard thickness and you'd need to measure them. Also you will need to loosen the bolts a fair bit and let the drive shaft hang from one, pull the other out to install the washers then get it started and repeat on the other side. If you use the alignment shins you would only need to loosen the bolts enough so the shim will slid in place with the bolt in-between the notches of the shim. Once you have the shims installed just torque everything down and take it for a test drive. Then repeat as needed until you find the sweet spot. The stock bolts are long enough to handle up to just about 3/8" but anything thicker and you will need longer bolts.

 

[peterson1604]

This is the shim kit I used. As for the longer bolts, I just pulled one out took the wife's car and went up to to the local hardware store to find one the same thread pitch only longer and a pair of lock washers to go with the longer bolts when I realized I needed longer ones.

You can use washers in a pinch to test it but the downside is they may not be a standard thickness and you'd need to measure them. Also you will need to loosen the bolts a fair bit and let the drive shaft hang from one, pull the other out to install the washers then get it started and repeat on the other side. If you use the alignment shins you would only need to loosen the bolts enough so the shim will slid in place with the bolt in-between the notches of the shim. Once you have the shims installed just torque everything down and take it for a test drive. Then repeat as needed until you find the sweet spot. The stock bolts are long enough to handle up to just about 3/8" but anything thicker and you will need longer bolts.

So I've started the process and am now at 1/2 inch and it's improving. I get a very mild vibration at 55 to 60 and at 75 it starts to get annoying but much better than it was. I'll keep going with 1/16 increments and hopefully hit the sweet spot soon. I see yours was good at 5/16 an inch. Did you have a lift on yours or larger tires? I'm thinking with my 2 inch lift and 255/75R17 tires it may be why it's taking more shim height.

I appreciate yours and @P. A. Schilke help and advice.

 

[the5Gmartian]

I have the same lift with 265/70/R17s and I had the exact same issue. Almost positive it is a tire balancing issue and I wouldn’t mess with Ford Performance lift myself. Take it to a different shop and have them balance your tires, some are harder to balance or the tire itself may have an issue. Lowering it and seeing an improvement sounds like a placebo effect to me more than anything, but thats just my opinion. Hope you can get it ironed out ??

 

[CashSeeAO]

Yep, dealer actually road balanced the tires.

Before putting too much effort in lowering the front, add shims, etc., I would rotate the tires and see if you can detect a difference in the vibration. If so, the culprit is likely the tires. I know you said the tires were road force balanced. However with defective tires, road force balance can only do so much. Good luck.

 

[Porpoise Hork]

So I've started the process and am now at 1/2 inch and it's improving. I get a very mild vibration at 55 to 60 and at 75 it starts to get annoying but much better than it was. I'll keep going with 1/16 increments and hopefully hit the sweet spot soon. I see yours was good at 5/16 an inch. Did you have a lift on yours or larger tires? I'm thinking with my 2 inch lift and 255/75R17 tires it may be why it's taking more shim height.

I appreciate yours and @P. A. Schilke help and advice.

I have a 2.5" leveling kit on the front and stock 265/60R 18's on it.

If you're not getting any vibration from a stop but only at 55-60+ then I would hold off on adding any more shims for now. As @the5Gmartian and @CashSeeAO suggested take a closer look at the tire / balance. At the speeds you reported that's typical for a balance issue. Other possible causes is an out of round or bent rim, or improperly applied balance weights. More times than I can count have I seen people working the tire balancer put the weights in the wrong place and not perform the final spin test to zero it out. It'll ride smoothly at first but usually will quickly come out of balance within 500-1K miles. Or they don't pay attention and counter balance the rim by putting weights opposite of each other. Again causing the same problem of the tire going out of balance too quickly.

To identify which tire it is do a front/rear rotation on one side only and test drive it. If no change is seen repeat with the other side. When the out of balance/round tire is moved to the front the shake in the seat will stop and you will feel it in the steering wheel. If this happens take it in for a re-balance and have them also inspect the rims and tires to ensure the rims are true and none of the tires have a high spot in them.

Sponsored