Balancing Rear Wheels (RWD)

Dades

Afternoon folks!

I've been supposed to get this done for a while but have been putting it off. The rear wheels on the merc (72 350 SL) are out of kilter so that the inside of both tyres are wearing quicker than the outside. I replaced both this year when I discovered they virtually bald on the inside while the outside looked fine.

Anyhow - my question is (1) what is involved here, and (2) where (in South Dublin preferably) might be able to sort this out for me? (Someone mentioned before a garage in Monkstown called, Kanes, or Keanes or something...)

Car is rear wheel drive which I guess makes it tricker.

Any help appreciated.

trevorbrady

it's not balancing the wheels that needs to be done, it's the rear tracking. It sounds like the camber is out a bit, wearing the inside of the tyres. I don't know how the Merc rear suspension is set up but it happens on old RWD VWs because the when the rear suspension moves, the camber of the rear wheels changes a lot.

With a bit of luck, it's just a matter of a few small adjustments or maybe replacing some worn bushes or something. I'd try to find someone who knows how to deal with old Mercedes rather than young Jimmy the apprentice mechanic with a shed out the back of his ma's house.

I'm sure someone who's familiar with Mercs can advise better than me

MercMad

Yeah, deffo not balancing.

I dont believe there is any adjustment on the rear of that car. I could be wrong but I suspect you have some bushings worn.

Does the rear end sit low on it ? Sometimes the springs sag, which gives increased negative camber leading to a low rear end and inside tyre wear. I'll find out more and get back to you.

Dades

Cheers Trevor & Ben,

I suppose the replies could have been worse. Like OMFG don't drive that thing!

I couldn't tell really if the end sits low, but it's a definite possibility. When my local mech gave it a quick service last spring he noticed the wear and suggested I get it looked at(!) He said there was some equipment necessary that he didn't have. I would have thought he could replace bushes/springs?

If I remember I'll take a sidelong snap on my way past tomorrow morning to see if a sag is obvious to anyone.

Any further thoughts would be great.

CHEERS!

hi5

Put it in for an NCT,it will cost €50 but they have some of the best suspension diagnostic equipment around and you'll get all the other checks done too:)

Abelloid

hi5 wrote: »

Put it in for an NCT,it will cost €50 but they have some of the best suspension diagnostic equipment around and you'll get all the other checks done too:)

My local tyre place only charges €40 for four wheel alignment.

MercMad

hi5 wrote: »

Put it in for an NCT,it will cost €50 but they have some of the best suspension diagnostic equipment around and you'll get all the other checks done too:)

...........I'd go along with this too. It's a very thorough test and at least you'll know if your car is safe, test all the other areas too.

Only downside is you then have to pay someone else to do the alignment if thats what is wrong.

My guess is that your inner bushings on the lower arms need to be changed. They are a cheap part but it does take a few hours to do. Its not a big deal though.

peasant

I don't think the NCT accepts cars that don't need to be tested by law.

I tried to get my old VW camper (85) NCT'd once and they wouldn't do it because it was registered as a camper ...I can't see them NCT'ing a classic.

Dades

Hmmm. I'm not gone on the idea of an NCT (if they would even).
The car is 36 yrs old and I'm not sure I need all the "idiosyncrasies" printed out!

Ideally I'd prefer to find a mech capable of such work who could then give the car a safety once-over.

I took a couple of pics this morning. Yes - the car is filthy. Haven't had 15 mins to wash it since a trip to Limerick last week. Shame - I know! The rear right is the spare (which is not gold despite the pic) which I had to put on in the rain in the hard shoulder of the M50 during rush hour. :eek:

Left rear side lower? Click for larger...

MercMad

Yeah the left looks slightly lower.

The ride height looks normal enough though, not obviously sagging. Can you take a photo from behind to see if there is obvious negative camber ?

Sometimes despite appearances the springs get weak and when you accelerate the car squats more than it should at the rear. Give the rear end a few bounces to see how quick it settles, this will really only rule out bad shocks as oppossed to weak springs but it may give a clue.

The rubber spring pads can be changed which increases ride height and alters the camber but from the photo I dont think that is the problem here, though with one side lower it could be.

Take the photo from the rear.

I presume these badly worn tyres weren't on the front at some stage ?

Dades

I'll take a snap of the back tomorrow morn after I pick up my new tyre, and give the rear a bounce!

MercMad wrote: »

I presume these badly worn tyres weren't on the front at some stage ?

Nope. In fact the new rears I got last Spring are even showing some signs of inner wear which is what has prompted me into action.

Thanks for the thoughts.