w126 - rear feels unstable

[john rh]

Hi,

Wondering if the experts can help me.

My 1986 500 SEL feels slightly unstable. It feels as if there is play at the back of the car that can cause a very small rear 'steering' effect, either left or right, depending on camber or bumps in the road.

On a smooth road it is better, but driving in a straight line requires more steering correction than it used to.

Any thoughts?

Thanks

John

 

[Dieselman]

Rear suspension and subframe bushes.

 

[john rh]

Thanks; that's what I was thinking. Is there a 'favourite' to do first? I.e. the trailing arm bushes or the subframe mounting bushes? I'm thinking the latter, or should I just bite the bullet and get them all done?

John

 

[W2--]

Get alignment done as well.

 

[grober]

The rear suspension bushes are more likely to fail an MOT than subframe bushes I would guess if that's relevant at all .

 

[john rh]

Get alignment done as well.

So can the alignment be adjusted on the rear suspension? I had thought the geometry was fixed by the subframe and the semi-trailing arms.

Thanks

John

 

[jaymanek]

Its normally the rear subframe bushes, but the actual arm does crack so get that checked.

 

[john rh]

Hi, a belated update and another request for advice!

The rear subframe bushes have been replaced and the car feels much better; the 'crabbing' feeling and rear instability are gone. But it still doesn't drive as well as it used to.

The car just passed an MOT, done by an old Merc specialist, so I feel confident that there is nothing immediately dangerous under there.

However, I still have an issue, this time with the front suspension I think. Unfortunately, i definitely can't a afford a 'replace everything that wears' approach at the moment, so I'll describe the symptoms in detail, in the hope that an expert will help me pin-point the particular problem.

Background:
- 1986 500SEL, 115k miles
- Front wheel-bearings and lower ball joints recently replaced
- Alignment checked several times: seems to move around?
- Poor roads and lots of speed bumps around here!

Symptoms:
- Steering feels mushy
- Car pulls down the camber of the road (left or right) more than it used to
- Wanders when braking, especially on bumpy roads (feels like wheels toe out when braking)
- Ride is good
- Handling is OK, apart from poor steering feel
- Creak from the left front when brakes are applied
- Seems to have more road noise from the front tyres than it used to
- Otherwise no clunks, bangs, rattles, etc
- Just occasionally, a shimmy through the steering wheel at about 60mph
- No visibly worn bushes or links

Any specific pointers much appreciated!

Thanks

John


PS... Volvo project car is coming on well

 

[ianrandom]

Have you had the full MB type alignment done? Need to use a shop that has a Hunter machine. Or an MB dealer. I tried many times before spending the extra and getting it done properly.
The creak, I wonder if its your brake support rod bushing thing. The rod that takes the weight when the brakes are applied.

The paint on your Volvo looks great!

 

[grober]

Have a look at these 2 DIYS

PeachPartsWiki: Suspension Bearing Bracket guide rod mount replacement

and

PeachPartsWiki: Guide Rod, Lower Control Arm Bushing and Eccentric Pin Replacement

 

[stwat]

The poor steering feel and wandering/following ruts in the road could be caused by a worn steering damper. I had the same symptoms on a 190 2.6 and a new damper cured it. The car felt so much better.

 

[ss201]

the poor steering feel and wandering/following ruts in the road could be caused by a worn steering damper. I had the same symptoms on a 190 2.6 and a new damper cured it. The car felt so much better.

+1

 

[john rh]

Thanks for the spot-on advice. New steering damper fitted and the car feels much better

John

 

[donubenz]

Hi, Pleased that your car is handling better. I had a creaking problem on the front of W126 I had a few years ago. The car had been through two MOT's and it was only when it went for a service that a garage noticed that a spring was broken on the bottom mount. Most Mercs have issues with springs, lots of threads here, however the design of these particular ones is such that a break occurs right at the bottom and is not easy to see with all the road crud that lurks there. Maybe worth a look as they have a lot of weight over the front end on these models and the spring is not so expensive £50 ish from memory.
Don

 

[john rh]

Hi, Pleased that your car is handling better. I had a creaking problem on the front of W126 I had a few years ago. The car had been through two MOT's and it was only when it went for a service that a garage noticed that a spring was broken on the bottom mount. Most Mercs have issues with springs, lots of threads here, however the design of these particular ones is such that a break occurs right at the bottom and is not easy to see with all the road crud that lurks there. Maybe worth a look as they have a lot of weight over the front end on these models and the spring is not so expensive £50 ish from memory.
Don

That is worth checking. Occasionally there is a creak when turning left in car-park manoeuvring.

It'll have to wait a while though. I can't work on it, or even drive at the mo - just had a hernia operation re-done on Saturday so drugged up and resting now!

Cheers

John