Hub vs Lug Centric Wheel fit

[NAPA 68]

I have searched the archives for vibration. I did see one post that spoke of wheel fitment issues (thus causing a vibration) for certain wheels. Here is the problem I am trying to solve. On my 67 Nova, I have GM steel wheels that I have checked for being bent, runout, etc. These appear to be fine. I am on my second set of tires (Bridgstones.......not just cheap tires) and have had everything Road Force balanced. I am still getting a fair vibration in the front end from 70mph on up. Due to the fact I switched to a rack and pinion last year only made the problem more apparent. Worse yet, it is inconsistent. sometimes it is worse that others. That leads me to the wheel is moving around on the rotor. The car does have a disc conversion of unknown origin (on the car when I bought it)

My question is, how tight should the wheel fit the hub of the rotor? When I first purchased the car, it had some aftermarket ralley wheels that I not recall having an issue like this. Buying another set of wheels is no problem. I would just like to diagnose the problem rather than shoot parts at it.

Thanks,

Tim

[Track Junky]

To answer your question, IMO, the wheel should fit the hub pretty well. You dont want the wheel to rely on the lugs alone. You say you have already checked the wheels for balance, or have had them balanced.

Couple questions for you......do your alignment specs match what the rack-n-pinion manufacturer suggested? Sometimes they suggest a slight amount of toe in.

How new is the rack-n-pinion? When rack-n-pinion kits for our cars first came out not everybody used splined shafts to tie into the knuckles and or u-joint connections. I would check and see if the rack unit isn't loosening up somewhere.

Are you tightening the wheel lugs with a torque wrench and/or checking to see if your lugs are backing off?

[NAPA 68]

Originally Posted by Track Junky

To answer your question, IMO, the wheel should fit the hub pretty well. You dont want the wheel to rely on the lugs alone. You say you have already checked the wheels for balance, or have had them balanced.

Couple questions for you......do your alignment specs match what the rack-n-pinion manufacturer suggested? Sometimes they suggest a slight amount of toe in.

How new is the rack-n-pinion? When rack-n-pinion kits for our cars first came out not everybody used splined shafts to tie into the knuckles and or u-joint connections. I would check and see if the rack unit isn't loosening up somewhere.

Are you tightening the wheel lugs with a torque wrench and/or checking to see if your lugs are backing off?

I cannot answer the alignment question. I will say the fellow who aligned it is very familiar with aftermarket racks. The rack is 2 years old although it is a reman unit (Cardone) I myself am happy with the play (or lack thereof).

The steering shaft is splined on both the rack and the steering column (Ididit). The lugs have been torqued with a torque wrench and are not losing torque. I will add though an improvement in the shake this morning when loosening the wheels and SLOWLY sneaking up on torque.

[ccracin]

Check to make sure the lug is not bottoming out on the rotor hub before it clamps the wheel in the counter sink. I have seen this issue with steel wheels before. The countersink in the lug hole is not formed properly allowing the taper on the lug to pass through the wheel and bottom on the hub. This allows it to maintain torque, but not clamp the wheel properly. I also agree with TJ that the center hole in the wheel should fit the hub snug. Good Luck.

[NAPA 68]

Just a follow up. the wheel ws not fitting the hub as tight as mentioned nor did it match a 67 Corvette I am working on currently. The lugs were not bottoming out on the hub (but I do see what you mean).

Does a difference of .035 between the wheel and hub sound alarming to any of you?

Thanks,

Tim

[TheJDMan]

Have you checked to see if the rotors are out of balance? You mentioned that the brakes were from an unknown source. You might also try Dyna Beads inside the tires which will dynamically balance the wheels as you drive.

http://www.innovativebalancing.com/index.php

I have been running these for years and they work great. Plus you don't have to worry about periodic rebalancing and you don't have weights stuck on the wheels.