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Wheel balance problem?

85 Jimmy

85 Jimmy

Sheepdog
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I just put 37" Baja T/A's on my Blazer with 24 bolt hmmwv wheels and PVC inserts. When I'm driving under 45 mph everything is fine, as soon as I get around 50 mph I start to get some vibes. I'm balancing my tires with airsoft bb's.

Before I put these tires on I had some bald Baja claws on H2 wheels that were balanced with airsoft bb's and they seemed fine, but I don't know how fast I ever got them going. I didn't recalibrate my speedo until now.

The only other thing I've changed is I pushed my front axle about 2" forward.
I'm also running drive flanges instead of locking hubs, could it be the front driveshaft vibing?

Should I throw some more bb's in and see what happens?
 
Those wheels and inserts are HEAVY. You will need to add a bunch more bb's.

I would pull the flanges and see if the vibe goes away first though. That's the easiest check.
 
Yeah I would pull the flanges or the front driveshaft first and to the checks like that.

How much weight is in each tire? Do you use centering washers on the wheels? Do you feel any "loping" or bouncing at lower speed to indicate something is out of round? Is the vibration or shaking constant or does it come and go periodically?

I have messed with my 8-bolt wheels a lot to get the outer ring centered enough to be true. It took a lot of messing with the Oz radials before I could get up to freeway speeds. You can learn a lot by raising one wheel and spinning it by hand with some fixed object near it. This can tell you whether it is out of round or off true by any significant amount. If not - congratulations - you get the easy way out by just adding beads. If so - then you know where to work.
 
I just had this conversation when I met Andy at Trailworthy Fab yesterday. I was getting a spare 12 bolt wheel and Baja to go with my set. I was going to have him put in 2000-2500 airsoft BB's from the start. This is what I have in mine now. I am smooth to 50 then vibration at 55-60 which gets better at 65.

He said the proper way to balance these setups takes some time but is as follows:

Check wheel balance for the wheel alone on a bubble balancer. Find and mark the heavy side.

If possible set up tire only on bubble balancer to find the heavy side. At least this way you can put heavy side of wheel opposite the heavy side of tire to minimize the out of balance from the start. This is tough to do. I was going to cut a piece of plywood to fit on the bead, balance the piece of wood to take care of inaccuracies when I cut it out and then set the tire on the wood, centered on the bead.

Assemble heavy spots opposite each other and balance again. At this point if you are still out of balance you start adding weight by setting it on the outer edge of the tire. Once it balances you weigh the weight and then know how much BB weight to add to the tire.

If you can't do just the tire you can put the assembly on the balancer and by trial and error disassemble and rotate the tire on the wheel to see if it improves. When best go back to setting the weight on the outer edge of the tire to determine how much BB weight to add inside.

Takes some time but supposed to be worth it in the long run. He said that he has been able to balance some sets with no weight and some take as much as a pound.

Also, I just grooved mine using a similar pattern to what he does and he said that grooving can throw the balance off if the cuts aren't equal. This makes sense as I estimate that I grooved off 2 lbs of weight for the set of tires based on the pile in the dust pan when I swept up.
 
Last edited:
Blue85 said:
Yeah I would pull the flanges or the front driveshaft first and to the checks like that.

How much weight is in each tire? Do you use centering washers on the wheels? Do you feel any "loping" or bouncing at lower speed to indicate something is out of round? Is the vibration or shaking constant or does it come and go periodically?

I have messed with my 8-bolt wheels a lot to get the outer ring centered enough to be true. It took a lot of messing with the Oz radials before I could get up to freeway speeds. You can learn a lot by raising one wheel and spinning it by hand with some fixed object near it. This can tell you whether it is out of round or off true by any significant amount. If not - congratulations - you get the easy way out by just adding beads. If so - then you know where to work.
Click to expand...

I have about 200g (1000 .20g bb's) of bb's in each wheel. I have almost that much more to put in each one, but may go get another big thing of bb's, split it 4 ways, and add that to what I already have ready to go in. I think it's safe to say that if you put too much airsoft bb's in it won't negatively affect the balance.

I don't have any centering washers. When I was in the Navy and replaced tires on the old 8 bolt and 12 bolt wheels none of them had centering washers, nor did we put any on them, and we'd run them on hmmwv's up to around 60-65 mph with no problem. Hell, we wouldn't even rebalance them when we were done.

Everything feels really good at lower speeds, no loping or anything. I guess I could lift the truck so the tires are off the ground and check for lateral runout (these tires were stored stacked on a pallet for a long period of time), but I don't think a radial would be affected by that like a bias ply would. Maybe the rim its self has too much runout?

I only got it up to around 50 mph for a short period of time and didn't get going much faster, but the vibe didn't gradually get noticeable to me, it just all of a sudden was there. I don't know if it'll go away if I get going any faster.
 
Are you running dually axles or recentered wheels? It's possible for the centering to go wrong, but TWF claims that they test all wheels for runout now. 7oz is not a ton of weight, so I wouldn't hesitate to add more. I think I ran 12 or 14 in my radials. I have 26 in the TSLs now, but there is probably no hope for them.

I gained a lot of ground by measuring the roundness of the tread surface and then reassembling the wheel to compensate. It's like the outer ring wants to go on a certain way (off center), which isn't visible, and the only way to correct this is to intentionally assemble off center in the opposite direction. Which bolt is tightened first makes a big difference. This let me greatly reduce runout of the ring and the tire. The 24-bolt wheel is another creature altogether (and I expect much better in this respect) but you could look at trends like this to see if you can change the assembly at all for the better.

I got periodic shaking on the freeway. It would get bad and almost completely go away like once a minute. I believe it was either lateral runout or lateral imbalance in the front tires. Since the diameter is never exactly the same, they would slowly come in and out phase, either adding for a resonance or cancelling. Unfortunately adding pellets doesn't fix lateral imbalance. But by getting everything centered as good as possible I was able to drive 65 with no problem. Getting up to 70 or more it was still noticable.
 
Stein said:
I just had this conversation when I met Todd at Trailworthy Fab yesterday. I was getting a spare 12 bolt wheel and Baja to go with my set. I was going to have him put in 2000-2500 airsoft BB's from the start. This is what I have in mine now. I am smooth to 50 then vibration at 55-60 which gets better at 65.

He said the proper way to balance these setups takes some time but is as follows:

Check wheel balance for the wheel alone on a bubble balancer. Find and mark the heavy side.
Click to expand...
This is interesting to hear because when I first got my H1's and everything was shaking, Todd at TWF seemed completely clueless that it was even possible. He didn't have any ideas, but was going down the path of sending me a whole new set of wheels :eek1:. I was able to improve things by tightening stuff up on the truck and eventually used a dial indicator to convince myself the wheels were pretty decent. Most of the issues are with the tires and the difficulty of getting them mounted right. By design, the 8-bolt rim just doesn't center the tire on the rim or the 2 rim pieces together very well.
 
Blue85 said:
Are you running dually axles or recentered wheels? It's possible for the centering to go wrong, but TWF claims that they test all wheels for runout now. 7oz is not a ton of weight, so I wouldn't hesitate to add more. I think I ran 12 or 14 in my radials. I have 26 in the TSLs now, but there is probably no hope for them.

I gained a lot of ground by measuring the roundness of the tread surface and then reassembling the wheel to compensate. It's like the outer ring wants to go on a certain way (off center), which isn't visible, and the only way to correct this is to intentionally assemble off center in the opposite direction. Which bolt is tightened first makes a big difference. This let me greatly reduce runout of the ring and the tire. The 24-bolt wheel is another creature altogether (and I expect much better in this respect) but you could look at trends like this to see if you can change the assembly at all for the better.

I got periodic shaking on the freeway. It would get bad and almost completely go away like once a minute. I believe it was either lateral runout or lateral imbalance in the front tires. Since the diameter is never exactly the same, they would slowly come in and out phase, either adding for a resonance or cancelling. Unfortunately adding pellets doesn't fix lateral imbalance. But by getting everything centered as good as possible I was able to drive 65 with no problem. Getting up to 70 or more it was still noticable.
Click to expand...

I'm running SRW axles and unmodified wheels with 1.5" spacers in the front and 3" spacers in the rear so the rears sit as wide as the front.

In my other sets of wheels and tires I've added way more bb's in them then I did in this set. I just added what I had on hand and was hoping it would be enough.

The outer ring could be off center, but with these 24 bolt wheels it can't be too much. When I tighten down the wheels I try to do it in an even criss cross so they would tighten down even. I also don't tighten them down all the way on the first go around. I tighten themabout halfway then move to the next, after the first go around I get them pretty close to all the way tight, then on my last pass I tighten them all the way. It's alittle bit of a pain with 96 nuts total, but I figure that's the best way to get them as close to centered as I can.

2 of my tires are brand spanking new, still have the tits on the tread. The other 2 are pretty close to new
 
I've never touched 24-bolt wheels, but I can tell you a slow, iterative, even tightening pattern doesn't get 8-bolt wheels centered.

What I've done is put a dial indicator on the wheel (near the bead) in 2 axis to measure the out of round and the lateral runout. I mark it with little pieces of masking tape and a sharpie (numbers are all relative to each other, so exact frame of reference isn't needed). You almost have to do the inside and outside of the wheel to make sure they match. If not, the assembly has to be adjusted. Then I do the same thing with the tire (still mounted). If they aren't out of round in the same direction, then the tire should be rotated on the rim.

You might do some of this and find that everything looks good, but if you're going to break them open to add beads anyway, it's not that much more work.
 
I have updated my post above but I met with Andy not Todd. Sorry for the confusion.
 
Well, I guess I have an update.

I broke the wheels down and added more weight to them. It helped out, but I still had a vibration that started around 50-55 mph and didn't get better.
Then I pulled the drive flanges out and it helped, but, I still have a vibration that starts around 60-65 mph.

Today I checked the runout on the wheel, or how centered up the outer rim is on the main rim. The most runout I had was .050in. I don't know what the exeptable runout is, but .050in isn't that much to me...

Another thing, I ran the numbers with a 700r4, 4.56 gears, and a 37" tire I should be running about 2000rpm at 70mph. When I'm doing about 55mph in my truck I'm at about 2000rpm. I'll have to use my gps next time to confirm speed, but if my speed is correct what would cause this? It is in O/D when this happens, I watch the rpm's fall fall between shifts.
 
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