Thread: vibration from dynamic rims - what speed?

Originally Posted by MLD

Thanks Tombie,

I tried to google a 'finger mount' iro tyres and the results were ambiguous to what maybe your suggested solution. Can you offer more detail or a picture so I know what to look for.

I have been recommended to use balancing beads before i start chasing prop shaft imbalance. They are 35" mud tyres which is part of the problem.

The joys of modification, it invariably creates another problem.

cheers Mark

This is the plate for "finger balancing"


You can see more detail here: Wheel Balancer Pin & Finger Plates

Late last year I bought 6 16/8 -25 dynamic rims. Had really bad vibrations. After the second rebalance it still vibrated, Evan though on there balancer they were fine. Tyre dealer tried to say it was my tyres, I said not likely. Put my fender up on hoist and put in gear and you could see two of the rims were rolling around like they were egg shaped. It seemed like they never punched out the stud holes center, they were a fraction out. They were sent back and replaced and no more vibrations.

Jus09 you are the 2nd story i have heard that the dynamic rims were out of true from the factory. The local tyre reseller won't sell dynamic because he had grief with your complaint with a set that he says he spent hours fiddling around to work out the problem.

I don't think mine is an out-of-true rim. They were vibration free for the first few thousand kms when driven on the road. It was not until I took it off-road that the vibration became really noticeable. That was almost immediately after the rebuild of the suspension thus the enquiry about getting a vibration from not centring the rim on the axle.

Anyhow, balancing beads are going in today. I'll see how that goes before I look for other causes of the vibration. All else excluded I'll strip the rubber off the rim and test the rim balance. If they are out i'll look to replace them.

MLD

I look forward to your report on the beads!

Originally Posted by jus09

Late last year I bought 6 16/8 -25 dynamic rims. Had really bad vibrations. After the second rebalance it still vibrated, Evan though on there balancer they were fine. Tyre dealer tried to say it was my tyres, I said not likely. Put my fender up on hoist and put in gear and you could see two of the rims were rolling around like they were egg shaped. It seemed like they never punched out the stud holes center, they were a fraction out. They were sent back and replaced and no more vibrations.

Yep, on alloys my tyres are perfect. On Dynamic rims one wheel nearly vibrated me off the road at 80-90 kph. Replaced that one but there is another still causing a problem. If you are thinking of getting a set - DON'T DO IT!!!

I think a set of ZU alloys might be on the cards. Should have saved my pennies for decent wheels in the first place.

Now I'm worried - a new sset of Terrafirma steelies ready to go on.


Also for you blokes who say it goes out of whack and you need to get a rebalance for vibrations to disappear - are you actually getting a 'balance and alignment' ? If so that might make sense as
a) Wheel alignment could easily be knocked our of whack from 4wding.
b) Misalignment could cause vibration issues I think.

Hi VladTepes - I don't think it is an alignment problem specifically or in combination with the balance. I ran around on factory disco 1 alloys and 33" tyres for years and never once had vibration problems. I only aligned and balanced when replacing the tyre.

The dynamic rims were fine until I aired down for the first time and since then the vibration has been a problem.

Judo - some feedback on the balancing beads. This is my impression from a trip on the highway from Sydney to the Vic High Country and back over the weekend. The theory may contradict my experiment but this is what i found worked.

First off, the balancing beads are not a one stop solution and don't cure vibration all together. I found that there was no consistent speed at which the vibration set in. Sometimes in the low 90's, sometimes in the low 100's. The vibration was the same experienced by a wheel out of balance. After a half a ton of metres (300 - 500m) the beads would locate and the vibration would settle into an acceptable (by comparison to the out of balance vibration) vibration that was evident and caused a slight shimmer in your hand and arm. If you maintained that speed the beads would find their equilibrium. If you dropped more than 2 km/h or sped up more than 2 km/h the vibration would return until the beads found their equilibrium again. Thus there was a narrow band of balance. There were times when the vibration from a change in speed would be bad and other times the vibration would be minor. When it was minor i just waited for the beads to find their equilibrium. When it was bad I found dropping the speed and then accelerate up to about 2 km/h above your cruise speed then ease off to the cruise speed would settle the beads.

Maintaining a consistent cruise speed on the highway with traffic and hills is difficult. I found myself driving to the dictates of vibration rather than any other influence.

Below about 80km/h there is no vibration.

I don't think the vibration is good for wheel bearings and other suspension components. Even the shimmer after equilibrium can't be healthy. I'll persist with the beads for a while and see if it improves. I might need more beads. The alternative is to return to weights and re-balance periodically or strip the rubber and check the rim balance. There is a limited rim choice for a 16x8 neg 25 rim.

MLD

On the Dynamic Wheels subject. I have a set for my BFG Mud Terrains - They are 7x15's, with 31x10.5" tyres. I have recently done a few thousand k's on them, highway and off road and found them to be good, absolutely no vibrations. In fact I left them on after my last trip as I found my D1 to be smoother with them on than with the Gotti alloys I have with the same size All Terrains. I had got the alloys second hand, (but fitted new tyres) and one of them was a bit damaged/buckled. I took the wheel to Eastern Wheel Works to get rolled and machined, its now spot on - those guys do good work if you have a bad wheel.