Dear Brickboard, we meet again..

Question about solving a rear alignment problem.

When I first bought this car I did a bunch of front end work like bushings, ball joints and tie rod ends to get everything snugged up. Then I brought it to a Volvo dealer for an alignment job because everything was out of whack. The service guy, who was especially knowledgeable with these old 240's (increasingly becoming a rarity at the dealerships) told me that the rear was out of spec (he even produced a copy of the report and told me by how much) He said that there is no adjustment to be done in the rear and that it was likely my TABushings. He was right .. or so I thought,

After building that special puller / pusher tool from some helpful plans on the internet I discovered that indeed the TAB's were totally shot. Perfect, I thought my rear wheel alignment problems were solved and I given the shape of the old TABs I didn't spend another $ 100 on an alignment to find out one way or another.

...two years go by and I wore my way through the outside treads of my first set of summer tires (and had a blowout on the highway). I suspected the old virgo rim had a wobble so I swapped this one with a spare virgo rim i bought off craigslist. And then had 4 very evenly used set of tires that I found in the alleyway balanced up at the garage and mounted on the car. Then that same driver's side rear wheel a couple summers later ate through the outside tread on another tire. Now I could say maybe it's the rim again, But I noticed that same driver's side rear wheel also wears unevenly on my winter tires mounted on the OEM steel rims.

So .. should I always source/buy cheap used tires and just chalk this up as one of the quirks of this particular machine? Its always that one rear tire that wears unevenly. Has anyone found a way to adjust an offending rear wheel with shims or a new trolley truck of a parts car or something ?

ideally i'd like to feel good about shoeing my car with a nice set of $500 winter Gislaved's again, because I can get 5-6 winters out of them but it pains me to scrub them out cus of an alignment problem.
Which brings me to another point. the outside tire wear of the offending rear wheel, is worn in a lumpy bald spot fashion. Even in it's worn out way the wear isn't even. it's as if there's a scrubbing problem (crab walk) rather than a camber problem.

Any ideas ? has anyone ever dealt with such a problem successfully ? or am I doomed for the remaining life of this car (5-10 years given the rust situation in Quebec) to give it crappy used tires that it scrapes thread to their death in a season or two.

From what I can gather, the left rear tyre wears out on the outside edge, yes?

Are the springs stock? Is the ride height stock?

Most likely, it is rubbing on the mudguard somewhere, jack it up, block it up safely, take the wheel off & have a good look for a black mark in there, probably on the rearward side of the lip.

If there is something wrong with the rear suspension or diff housing, then both rear tyres are going to wear out funny. That is the nature of trailing control arm live rear ends.

--
69 142S Overdrive + 69 164S Manual

Questions :

If you have someone else drive your car and you follow behind them, do the front and rear tires follow the same track ?
If you park on a flat surface and put a good carpenter's square against the rims, are they straight ( or at the same angle ) ?
Same flat surface, steering wheel straight ahead, run a string up both sides of the car at the height of the hubs. Are the distances to the rims symmetrical from side to side ?

Greg

Hi Greg,

thanks for the suggestions.

I'm going to wait for some daylight and take some measurements.

I've thought about following my car and observing the rear wheels and suspension to see if there was any unusual bouncing going on, but with a worn out tire, i'm not sure if I could know for sure if it's because of the suspension or if it is the suspension reacting to the oval tire bald spots.

hopefully the measurements will tell us something,
I'll post back soon, (probably not tomorrow because I have to volunteer)

You do need to follow the car. It will be obvious, if it's bouncing it's not the tire it's the shock.
--
Bruce S. near D.C.

Whoever tries to tell you your "alignment is off" on the rear wheels of a rear wheel drive car with a solid rear axle is well ,full of shit. Nothing to align back there.

I'd have to disagree with joekidd's statement. Alignment in the rear can be "off". Fixing it doesn't necessarily mean making an "adjustment" -- could require bushing replacement or chassis "tweak". An MGB has king pin and trunion front suspension. There are no adjustments to be made--if the alignment is off something is worn or bent. Same principle. -- Dave

Thats a bad part problem not an "alignment" problem like I said you cant align the rear wheels of solid rear axle rear drive car as there is no adjustments to be made period........ Over the yrs of driving 140s 160s 240s 740s so many shops trying to sell me a "4 wheel alignment" for these cars. Just trying to rip you off as it cant be done.

I do agree with you that a "4 wheel" alignment on a solid axle RWD Volvo would ordinarily be a waste of money - unless there's a particular unidentified problem. In that case having the rear measured could pinpoint a/the cause - and the "alignment" would consist of repairing the worn or bent part(s). -- Dave

Dave, a visual inspection with a big screwdriver would suffice.

Just to muddy the water further. I worked for years in my and others body shops, including clipping on big Chief and B-Line frame racks, and seeing only original paint will not tell you if damage has occurred. My advice is to find a frame shop and have them check for body alinement and a good look at that Dana axle and mount. Time to stop guessing. I would look for a stand alone frame shop, someone with pickup truck ability, they're use to solid axles. It probably is a simple solution and they will quickly find the cause. Keith

Has the car ever been in an accident? Has it been slid sideways into a curb?

Check for a bent panhard rod, or bad bushings on it or the torque rods. Measure the distance from tire to fender on each side.

Also from your description of the tire wear I'm not sure if your talking about feathering or cupping. If it's cupping, that could be a bad shock causing the wheel to constantly bounce down the road.
--
Bruce S. near D.C.

Hi Bruce,

those are good suggestions,
This car has all original paint on it, so it's safe to say it's never been in an accident.
As for sliding into a curb hard enough to knock things out of whack, maybe on snow it's possible if the previous owner did this.

the pan hard rod bushings are the only bushings I haven't changed while I've owned the car (last 6 years)
the torque rod bushings were changed about 5 years ago.

I'm going to need a bit of daylight to do the measurements but I'll report back soon

Greg in the next reply also suggested some measurements, I guess that's the only way to know for sure.

As for the description of the tire wear,
I looked into 'feathering' and 'cupping' and from what I could find on this website of different tire wear patterns and diagnosis, it doesn't seem to be cupping, it's only on one side (1") of the tire's edge that's worn out, but it does seem to be what they call "alternate lug wear" where one tread lug is high and then the next one low (or the next 2-3 are low and then there's a high lug again, but only on one edge of the tire. These low lugs will bleed into bald patches that rub out 2-3 lugs and then there will be a high lug again. maybe i'll try to post a photo.

Thanks for the suggestions, I'll be back with some measurements, hopefully then we will have a better idea what is off