New GSP axles @ Rock Auto...

mcenter · Post by **mcenter** » Tue Aug 07, 2007 11:21 am

The axles are fairly easy to install. The hardest part is getting them to "pop" out of the transaxle. I am sure the FSM has good instructions, and I am sure I didn't follow them. I whacked them with a hammer and punch. The GSP axles are great. But, I still had a vibration. Come to find out, I had a badly bent rim. I would have thought the guy at the tire shop would have noticed when I had them balanced.

Typrus · Post by **Typrus** » Tue Aug 07, 2007 12:17 pm

Not typically. The issue you had was what is caled "Road Force" and the average balancer will not detect it. It is caused by distortions in the rim or soft/hard spots in the sidewall.
The best balancers have a big roller on them that applies pressure and feels the kickback or road force. BAse on this, you will run feelers along the rim to find its highest point of deflection, where it provides the most road force. You then will break the bead of the tire and line up the tire and rim so that they will counteract each other (the machine tells you where to line up) and that will hopefully make it unnoticable.

>.<

keith · Post by **keith** » Tue Aug 07, 2007 6:07 pm

If a rim is bent, you will feel it, no road force balancer is going to help.

takza · Post by **takza** » Wed Aug 08, 2007 3:39 am

You can hammer minor rim dents out...but steel is real tough. I've also straightened minor lip bends in alum...need to use a block of shaped wood for this....oak.

keith · Post by **keith** » Wed Aug 08, 2007 5:00 am

Dents in the rim are not the cause of vibrations. Vibrations are caused when the plane of the lug holes is not perpendicular to the wheel rim. You can have a "bent rim" without a visible dent in the lip, and you can have a lip with a major bend in the lip and not be a "bent rim".

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takza · Post by **takza** » Thu Aug 09, 2007 4:04 am

True. It's where the tire rides on the rim that counts. But bent lips are ugly.

Typrus · Post by **Typrus** » Thu Aug 09, 2007 10:25 am

Whatever you want to think. I've seen a road force balancer be able to tell, on a few seperate occasions, enough of a soft/hard spot in the sidewall to match up with the rim damage and bring the "vibration" to a stop. And its really the suspension being flung upwards as either a hard spot in the sidewall causes a rise, or a soft spot causes a fall then rise as it returns to the normal wall.

If you have steelies, most bends are fixable. On alloy rims, not so much. I'm just going off of what I've been taught in a professional environment, what I've seen with my own eyes, and experienced myself from the drivers seat.

You know, it could be true that if its been so badly bent that its just fully out of balance (kind of ovular) that nothing can be done. But I've never seen that (doesn't mean it can't happen)
But what I have seen is where thats a little bit of a flat spot in the round. This will create a road force issue, not a balnce issue. The tire/wheel assembly might balance perfectly, but have a nasty vibe at certain speeds, not because of a balance issue, but because of the low spot. What a road force balancer will do is not only balance it, but tell you where the stiff and soft spots are in the tire's sidewall, and also were the highs and lows are in the rim. It will then tell you if it is possible to rotate the tire to match a certain spot with a certain spot on the rim to eliminate the issue. If it is, it will line them up with a witness on the machine and you chalk mark them, go and break the bead, line then up, re-fill to recommended PSI (sidewall PSI), then check the RF again. It should be much lower, and far less perceptable, assuming the values on the rim and the tire match up.