Rear Wheel Misaligned? (UPDATE: some rear axles out of spec; warranty replacement)

[GrnBn]

I had a thought for tracking this issue. I could add a poll to this thread where owners could "vote" to indicate their status on this issue, eg:

1) rear axle replaced under warranty; new axle A-OK
2) rear axle replaced under warranty; new axle also misaligned
3) awaiting replacement axle
4) DIY fix in place to temporarily align axle
5) axle inspected by dealer and deemed within specs; no warranty replacement offered

Multiple "votes" would be accepted.

Any other options I should add?

I would change "A-OK" to "Within Factory Specs".

[deleted user]

So 50% of the replacements are out of spec.

I pulled mine together today with the come along, rear lower spring mount (holes). It took a lot of force to move it .25 inch (6-7mm). Seems to have moved it enough to be in specs. Getting it checked Friday. I'll let you know what it reads. It's close to .0625 or 1/16th in, without the rods and turnbuckle.

It was almost as much force as the come along was capable of producing without risking breaking something, probably over a ton, just to move it 1/4 inch!

regards
mech

[deleted user]

It's fairly easy to calibrate the rear part of any alignment machine. Just put a solid axle vehicle on it like a pickup truck and all readings will be 0. The only exception is is there is a bent rim and even that can be calculated and eliminated as a factor.

I've had 3 alignments as of yesterday, two from a local shop, one form the selling dealership.

We'll focus on the rear axle.

Left camber is -1.2 according to the local shop.
Left toe is .05 in

Both easily in specs.

Right rear according to the local shop is -2.1 (max -1.8)
Right toe is -.30. (max .28, total for both max .55)

According the the selling dealership left camber is -1.9 while right side is -1.3.
Left toe is .11, right is -.40. Total allowable toe in is .55 degree, which is .25 inch, give or take a little.
Selling dealership measurements taken on aug 28th.

Second local alignment after all my fiddling.
Left camber -1.2
Right camber -2.1 (out of spec above -1.8)
Left toe .05
Right toe .030 (out of spec above .28)
Total a toe is now .35, well below the max of .55.

Apparently I was only successful at altering the toe readings on both sides, reducing to total toe from .51 to .35.

My rear axle is still out of specs and due for a replacement, confirmed by the selling dealerships readings.

My rear axle is NOT eating up tires. Wear is even across the treads and still very close to new dimension at just under 12k miles.
(I have a set of replacements that were taken off the car at 3k miles and they measure 8/32nds across all grooves).

My objective is to maximize the tread life of the original tires, That objective is being met with the present alignment specs as they are today.

Old school toe was .125 INCH as a standard from 40 years ago for rwd solid rear axle cars. The .55 DEGREE total toe maximum on the rear axle amounts to .250 inch toe in. In the old days that would eat the outside of both front tires up, on the old cars.

I will continue to watch my tire wear care fully and wait for Mitsubishi to replace the rear axle, hopefully with an updated one that is in specifications, preferably in the middle of allowable specs. Until then I think my tires will be wearing for at least 50k miles, possible over 60 k miles, which is about what their ratings predict.

With total toe down from .51 to .35 I think I'll stop trying to "fix' my axle. unless Mitsubishi decides to not do anything.

regards
mech

[deleted user]

My efforts and "adjusting the camber" seem to have been non productive, however the total toe reading has dropped from .51 to. 35. Not close to 0 but to get it there would require a lot of force, much more than 1 ton of force. I think the risk involved in the axle potentially bending too far is too great for me to go further at this point.

To reiterate, the issue that causes premature wear of the rear tires is total toe. I believe the maximum figure of .55 degrees ( 1/4 inch) will cause premature wear of the rear tires, but I would rather keep what I have until they can consistently replace rear axles with a 100 % success rate.

Not sure if this will ever happen and I feel for those owners who have rear toe in excess of the already very high maximum of .55 degree (or a full quarter inch).

regards
mech

[deleted user]

My advice to others.

Get a good tread depth gauge. Measure and record the tread depth at least every 5k miles. Keep meticulous records of the measurements. If you see a wear pattern developing, make sure to bring it to the manufacturers attention, probably during the "adjustment" period to be safe although I cannot understand how they could deny a warranty claim past the "adjustment period" on a component that has no adjustment capability.

I run 45 plus psi air in my tires which prolongs tread life.

regards
mech

[cyclopathic]

My efforts and "adjusting the camber" seem to have been non productive, however the total toe reading has dropped from .51 to. 35. Not close to 0 but to get it there would require a lot of force, much more than 1 ton of force. I think the risk involved in the axle potentially bending too far is too great for me to go further at this point.

To reiterate, the issue that causes premature wear of the rear tires is total toe. I believe the maximum figure of .55 degrees ( 1/4 inch) will cause premature wear of the rear tires, but I would rather keep what I have until they can consistently replace rear axles with a 100 % success rate.

Not sure if this will ever happen and I feel for those owners who have rear toe in excess of the already very high maximum of .55 degree (or a full quarter inch).

regards
mech

From my limited experience fiddling with front toe 1/4" vs 1/32 would cost you a couple MPG. 2) wear is subject to pressure and sidewall stiffness but you really don't want anywhere above 1/8"

[Eggman]

My efforts and "adjusting the camber" seem to have been non productive, however the total toe reading has dropped from .51 to. 35. Not close to 0 but to get it there would require a lot of force, much more than 1 ton of force. I think the risk involved in the axle potentially bending too far is too great for me to go further at this point.

That is why I suggested using a chain fall (or chain hoist) to cold set the axle. A manual chain hoist should (might??) be able to provide the force needed to pull the axle ends in, and in a steady, controlled manner.

Just a thought:
Anchor one end of the hoist at the end of the arm that needs adjustment near the spindle, and set the other end across the axle assembly closer to the point where the torsion axle attaches. The reduction gear of the hoist can give small, incremental adjustments that can be measured while under tension, and while relaxed. Measure the difference between the two states to use as a guide in cold setting the assembly.

This might be best to experiment on a spare axle, in case it might be ruined as old mechanic suggests.

[Eggman]

Also, someone else said this torsion axle assembly is spring steel. What proof do we have of that?

If spring steel is hardened, could this be measured? It should be noticeable, measurably harder than mild steel, like what would be found on the sheet metal of the body.

Sorry - maybe I ought to call it a twist-beam rear suspension, although Mitsubishi refers to this as a torsion axle arm assembly.

[Eggman]

Here is a link to a study on twist-beam axles. It's pretty detailed.

The team studied material strength at what they call Heat Affected Zones (weld spots) and how they impact - or degrade - material strength.

Regarding material strength, I'm impressed that old mech has been riding around with the turnbuckle attached, perceiving an improvement, over a certain period of time. But after however long he had his setup running, measurements show little measurable change. I wondered if the alignment problems were a result of use, but it appears in old mech's example that usage does not necessarily effect alignment numbers.

I would have guessed that usage with the turnbuckle attached would have cold set, or permanently moved the axle pieces into better alignment.

[TheTransporter]

Being a welder by trade could we not use localized heat spots to bend the axle to suit what we need? We can hear up the drum area (so to not affect axle) and just bend as required no?