dpuckett

I have had a vibration or shimmy (kinda hard to distinguish, but I lean more toward a shimmy, as it feels like it is in rythm with a tire, and not the engine) for quite some time now in my 92 D350. Front end has been rebuilt with MOOG or Spicer parts (I have one Spicer ball joint after the MOOG developed slack)- bushings, ball joints, center link, new Bilstein shocks. I had an "alignment" done at an alignment shop in town, but my tires are starting to feather a little, and the steering wheel is cocked about 60deg to the right. Anyway, can an alignment problem casue a shimmy? Or is one of my new MasterCraft tires bad out of the box?

Front wheels are pretty straight- one has about 1/8" lateral runout on the mounting machine; other is completely straight. Rear wheels are good. I do have a D80 axle, and didnt do any alignment to it when I installed it- I just bolted it up and went. Driveshaft has been balanced. Twice.

It starts at anywhere from 45-55mph, and it going pretty good by 60. Starts to smooth out around 70-72, and is smooth by 75, to about 80-82, but comes back around 85 (not that I drive that ALL the time, but I do occasionally shoot to there and back down). It is not consistent- it will be smooth for miles, then it'll get rough for the next few miles, then on again, off again. SPrings appear good, as does the rest of the front end (only slack is a little in the steering box itself.) I am at my wits end trying to chase this down. ANy ideas or help would be appreciated. I'll look again in my FSM for ideas, too.

Daniel

91.5CTDBanks

If it comes and goes at different speeds and at different times I would say it is in the tires. Have you rotated the tires around? How about playing with the air pressure? Good luck.

dpuckett

Update- I jacked each of the front wheels up and set a concrete block in front of the wheel, and placed a piece of flat 12ga steel (~2" wide) on the block, and rotated the tire slowly and let the steel just barely touch the tire. It got to its highest point, and I held it. I had 1/8-3/16in of up fore/aft movement on the right side, and about .050" bobble on the left. I know the right is bad, either the wheel, tire, mounting, or any of the three. The FSM says any more than .043 in is cause to replace tire and/or wheel. It may be time for wheels, too.

DP

leper

Mine does something similar. I am going to install Dyna balancing beads and get rig of the outer wheel weights and see if it helps. At the same time I am going to make sure the wheels were put back on correctly, by using some centering lug nuts.

BearKiller

Tire problems will (usually) exhibit theirselves at comparatively LOW speeds, usually between 35 and 45 MPH.

Before scrapping a tire/wheel, due to your scientific concrete-block findings, break the tire loose from the wheel, and rotate it 180 degrees from where it was (mark the valve-stem as a referrence), then air it up in it's new position.

Of course, you will need remove all the weights, as this negates any balancing that was done.

I will also state this, I have grew up in a tire-store, that is celebrating it's 50th year this year, with more kinds of ways to balance wheels than you can imagine.

With all of this at my disposal, absolutely free of charge, I have not balanced a wheel on any of my personal vehicles in many years.

I have less vibrations and complaints than any of our customers that insist on balancing.

Computer spin balancers are a JOKE at best, and we have three very expensive ones.

If you must balance, a good old, completely mechanical, BUBBLE balancer is the best way to go.

Now, let me get my flame suit on.

leper

Rotating the tire on the wheel is such a simple thing that I don't understand why it isn't common. Especially when you see a wheel with a pound of weight in one spot.

I tend to agree with you about the no weights(sometimes). It doesn't take much to unbalance a tire/wheel combo, so weights can be in the wrong place in a very short time. I tried in vain to get rid of some vibration on my 39.5x16x16 Pitbull Rockers. It rides the best right now, with no weights at all.

I have talked to a bunch of people that run internal balancing. Everything from sweet-n-low to BBs, to water. I believe it will work the best because it is a constantly changing media. A tire will balance differently at 70, than it does at 30. Also, an imperfection in a tire that is only noticed when it has a ton of weight on it, will not show up on a free wheel balancer.

One thing I do know is that if the wheel isn't mounted correctly, centered as the lugs go on, it will create all kinds of problems driving down the road.

justagoodolboy

This was the majority of my problem. For some reason Dodge did not have anything other than that hub stud to get the wheel centered, so you have about an 1/8" of slack for the wheel to get off. I bought some 5/8" beveled lug nuts, run 4 of them up, and then install the flat factory lugs on the other 4 and back the bevels off and put the other 4 factories in their spots.

Not sure why Dodge did it this way, but 95% of my road vibration problems have been solved this way. Even after my front end rebuild a few weeks ago, I forgot to do this, took it on the 1st testdrive, and still had a shimmy/shake and it hit me. Went back to the shop, centered the wheels with the method above - smooth as glass now.

RickCJ

If they lined your truck and the new tires are wearing funny they probably didn't balance the tires right either!
Get a good alignment and balance!

wannadiesel

Daniel, do you use cone nuts to line up the wheels when you put them on? It sounds like you haven't been doing that. Our wheels are neither hub-centric nor lug-centric. The only way to get them centered on the hub is to run a couple of cone shaped lug nuts on, put on 6 of the flanged nuts, then remove the cone nuts and put on the last two flange nuts. I know it sounds kooky but it's in the owner's manual.

edit - I guess I should have read Jeff's post - he covered it better than I did.

dpuckett

I have been mounting the tires on the hub like specified in the FSM- line up with the conical lug nuts, run the other 6 down and tighten. Remove the 2 cone nuts, and tighten the lug nuts.

I have the DynaBeads in the tires. I am not impressed thus far, but I havent ruled out all other things. So there are no weights to worry about. The shop I got the tires from has a reman balancer (I didnt know that was an option, but hey). They seem to have shifted their focus to money rather than getting it right and good service, in the last year or two. If I were to have them balance the tires, move the tire on the rim, etc, you can bet your behind none of it would be free, and the bill would come to more than a simple rebalance (heck, I even got charged for rebalancing the rear tires MYSELF, and my girlfriend works there). I have a feeling we are going to have some real battles once I start shoeing horses and reset a shoe in 3 weeks cause it fell off due to bad luck or workmanship.

I had a bad wheel bearing a while back (shop turned the rotors, then failed to tell me they didnt clean them out and I needed to ), and replacing that helped, but didnt eliminate it. It seems to be worse now, so I may dig into that.

Once the rain passes, I will go remount the tires on the hubs; may even swap sides. I have a D80 rear, so swapping front to back is not an option at this time.

Thanks for the ideas, guys.

DP

Caver Dave

Well, that may explain why my "vibes" lessened when I put the SS Sims on (had to pull them off as 1 of the outside rear rims is a completely different shape... depth wise from the rest) and returned when I removed them...

Say 5/8" tapered acorns will work?

justagoodolboy

Yep, 5/8" is what the studs were on my truck. I think they are all that size....

BearKiller

If you want to try the slipping the tire on the rim trick, you don't need a tire shop to accomplish it.

Mark the tire at the valve stem.

Let out all the air.

Lay the tire/rim under the rear bumper of the truck, or the frame of a bull-dozer, or anything else heavy.

Set the base of a jack (preferably a HandyMan, but any kind of jack will do) on the sidewall, such that the long edge of the jack is lined up next to the rim of the wheel.

Apply jacking pressure until the tire bead gives.

You may have to do this in two or three spots around the tire.

When one side breaks loose, flip the wheel over and do the other side.

When the beads are loose, simply spin the tire 180* on the wheel and re-inflate.

It took longer to type the instructions than it will take to do this.

Jim Lane

Questions:

So what size conical lug nuts do we need to use 5/8?
Aren’t' out trucks metric?

Can we get by using 2 lugs or is it better with 4?

Also on the rear with a steel rim on the inside will they self align themselves to the hub and then use the conical nuts to align the outside rim?

We have an Owners Manual?
Anyone have that in PDF?

Thanks Jim

wannadiesel

The studs are 5/8" - remember the basic "1st gen" truck has been around since 1972. The only metric on our trucks is the Cummins. The nuts you need are 5/8 - 18.

The manual recommends a pair, and that's what I've been using with good success.

The inner rear relies on the coined holes of the wheels to hold it in alignment with the outer wheel. The idea is that if the outer is lined up right, the inner has to follow it due to the coined holes mating up. With your Alcoas I don't think there's a reliable way to center the inner rears.

Owner's manuals pop up on Ebay pretty regularly.