Rear Alignment Causing This?

[markpj23]

We have just over 27K miles on the coach and the reason I'm shopping new tires is that the driver side duals (GY G670s)have both worn down to flat rubber on all except the outer edge. I am careful to keep them inflated properly (I run 90psi in all rear tires). We were pretty heavy during most of that mileage as we were full-timers.

I would think that if rear alignment were the issue I'd see abnormal wear on the passenger side duals also? Both tag tires are fine. We did have front alignment checked at about 10K and it was dead on.

Will rear alignment show up as abnormal wear on only one side? Seems to me that a straight axle that far out of alignment would scuff all tires and not just those on one side?

Thanks in advance,

[Mike Canter]

Mark, have you weighed your drive axle and tag axle separately on a truck scale and how pressure are you running in the tag axle air bag regulator? It sure sounds like your drive axle has too much weight on it. I have weighed all three of my axles and I have to run my tag axle regulator at 45 psi to get the weights correct. If I run it at the owners manual specified 28 psi then I have too much weight on my drive axle and not enough on my tax axle. You just have to be careful that you don't exceed the max on the steer axle.

[Steve Ownby]

Mark,

Mike is exactly right. You might want to check the ride height also. I agree that if strictly an alignment problem, you would see some odd wear at the other end of the axle. Have you looked closely at the curb side steer tire? Some times you get wear on diagonal corners if alignment or ride height problems.

[markpj23]

Thanks for the replies.

I have not weighed the coach - a must-do for me now. Still don't understand how just the 2 driver side dual wheels would be affected. If I can find a single-wheel scale I'll check weight at each wheel. Since most of my interior cabinets are on the driver's side of the coach, it is logical that when fully loaded those drive wheels would bear the most weight. (Not that we ever went down the road heavy or anything... )

I've not changed the tag axle pressure from its 42 psi factory setting.

I did have some rivering in the right front steer tire and had them swapped side to side at about 15k miles. I assumed it was just these lovely GY tires....

[Mike Canter]

Mark, if it was alignment and the tracking of the MH was off then it would have to be going down the road slightly sideways. This is possible but normally in those situations the drive axle and the tag would show opposite wear on both sides and not just one side (as you stated). Since you have the tag pressure up where it should be then it would be worth verifying the alignment and also weighing the MH because something sure is wrong.

[JohnCamelot]

My driver's side dual showed significant wear at only 14,000 miles. None of the others, except the fronts were beginning to river. I took the coach to a well know alignment shop and they found that the rear driver duals (only) had serious toe out. That meant these tires were drug sideways when driving straight down the road, and wearing fast.

The alignment was kind of expensive ($900) because the rear axle is welded in place and does not have alignment. Frequently, if the Monaco welder is in a hurry, he applies too much heat which causes the rear axle to warp slightly. The alignment shop then has to use heat (usually a welding torch) to pull the rears into alignment. Once complete there was no more excessive wear.

Nevertheless, I had to change all my tires (except tags) which I did at 22,000 miles. Coach rides better now too. On the alignment shop recommendation, I bought Bridgestones as they were cheaper, had a good support network, and have more tread than the Goodyear or Michelins.

One final note, if you have someone use heat to straighten your rear axle be sure to change the differential fluid. That costs a bunch (included in the $900), but since the old fluid was exposed to a lot of heat it may be less than satisfactory in the long run.

== John

[Mike Canter]

John, when we weld on a rear axle in a race car we put a special bar through the axle from one side to another to keep it straight. Even then we only weld for a short period of time and rotate from one side to another to minimize warpage. I was under the impression that these axles come from Dana Spicer complete and ready to bolt in because there is a part number to them and you can order whole replacement front or rear axle assemblies. I don't know why Monaco would be welding on one.

[JohnCamelot]

All I can tell you is what the alignment shop told me. The owner is a Dynasty owner himself, and very familiar with the buildup process at the factory. Apparently it has something to do with the way the axle itself is mounted in the frame that Monaco builds.

I also confirmed the same issue with Josams in Florida. They use huge induction heaters to heat the axle to get it straight, but they are one of the few to have this equipment. But they tell the same story.

== John

[moisheh]

The RA is shipped complete but there are all kinds of brackets that have to be welded to the assembly. Someone ( John Camelot?) had a thread on this not long ago.

[bucks2]

I think we all know the real answer. At least anyone else who's ever driven a true muscle car does. Hmmmmm..... how does a right rear tire wear before the others. If Mark would stop the jackrabbit starts, quit spinning the tires so much, the wear will even out.

Truly tongue in cheek
Ken

[Mr_D]

Quote:

Originally Posted by bucks2 I think we all know the real answer. At least anyone else who's ever driven a true muscle car does. Hmmmmm..... how does a right rear tire wear before the others. If Mark would stop the jackrabbit starts, quit spinning the tires so much, the wear will even out. Truly tongue in cheek Ken

The problem I had with my '67 Camaro with a 396 in it was keeping the front tires on the ground. 11.99/126 in street trim through the mufflers.

Not much trouble with the MH though.

[Mike Canter]

Wow, that is slow. We run 5.96 sec at 244 mph in a '68 Camaro at only 20% overdrive on the supercharger Not in street trim . Our tires are slick when we buy them

[JohnCamelot]

Maybe we met on a track somewhere--- I campaigned a '67 Ford Comet with factory 427 and dual Holleys through a T10 tranny to a posi rear end. Low 11's and 140 on cheater slicks. We had SOOOO much fun...