Torsion Bar Rattle / knocking sound

[element]

Last year I became aware that there was some kind of suspension knock sound coming from the passenger footwell area. I decided to deal with it over the winter... Well, winter came and... looking outside - its still here! I have now got the car up on blocks in the garage and can get at the situation underneath. So I'm working through a few maintenance jobs and this knocking sound is one of them.

I can see that the nearside torsion bar attaches just forward of the passenger footwell and that there appears to be a vertical bolt that seems to be for adjusting the set up. In the attached photo's - one shows the torsion bar fixed to the outside forward face of the footwell and held in situ with the 'adjusting' bolt to the left. Ignore the smaller threaded bolt - that's just from the clutch lever sited just in front of it. In the other photo the vertical bolt is more obvious. I suspect the knocking sound is the head of this vertical bolt rapping against the flange immediately beneath it.

Would I be correct to think that the bolt simply needs to be 'undone' a little to lower it down tight against the flange? If someone else has encountered this noise - in this area - how did you fix it?

Ta very much...

[meverett]

Re: Torsion Bar Rattle / knocking sound

Hi Element, there shouldn’t be any slack under that bolt when the car in under its own load. Have a look when it’s on it’s wheels.
The build manual explains the setup for the tosion bars, if you don’t have a copy it is on here somewhere.
Cheers,

[element]

Re: Torsion Bar Rattle / knocking sound

I don't know whether there is any play in the bolt when its on its wheels; but I can't see any other obvious cause for a rattle noise there; I'll tweak it a bit and see if there is any play. The only other possible cause might be the front end of the torsion bar - there might be something loose there or perhaps the bush has gone on that suspension arm that leads off it - maybe the noise would travel down to the footwell and the latter might act like a soundbox ...?

[meverett]

Re: Torsion Bar Rattle / knocking sound

Try pushing and pulling the torsion bar near the footwell to see if there is any play, the small bolt beside the torsion bar may be slightly loose which could cause the rattle.

[stevejgreen]

Re: Torsion Bar Rattle / knocking sound

There should be no play in the vertical adjusting bolt when the front wheel is loaded. If the horizontal bolt is insufficiently secured it will rattle as the load varies.

There are two possible torsion bar diameters, that from the car and a larger diameter one from the commercials, it’s worth a check. The larger diameter bars are considered to be too stiff for a Roadster.

[b_caswell]

Re: Torsion Bar Rattle / knocking sound

According to the Marlin build manual the adjusting bolt should have a lock nut on top of the reaction arm to stop it backing off.

[meverett]

Re: Torsion Bar Rattle / knocking sound

If the adjustment bolt has come loose it would be a good idea to set up both sides again as in the build manual to get them equal.
To set the torsion bars it is just a couple of measurements and calculations from a level floor.
If you don’t have a copy of the build manual it is well worth downloading it for reference. I have it as pdf so if you need it send me a PM with your email and I will pass on.
Cheers,

[element]

Re: Torsion Bar Rattle / knocking sound

Ok, thanks for the replies, I believe I have a build manual - I'll look it up and when I lower the car back to the ground can put the front wheel on and see what's what... Meanwhile I'm busy with the rear diff and another job...

[Sidon]

Re: Torsion Bar Rattle / knocking sound

Are you sure it isn't the infamous steering rack bush that is rattling?

[HairyDave]

Re: Torsion Bar Rattle / knocking sound

In the photographs there does not appear to be any movement by the lever against he footwell ie no paint damage. If the big blt is hitting the bracket the end could be shiny. Might the rattle be coming from the front end and traveling up the torsion bar?

[stevejgreen]

Re: Torsion Bar Rattle / knocking sound

In the photographs there does not appear to be any movement by the lever against he footwell ie no paint damage. If the big blt is hitting the bracket the end could be shiny. Might the rattle be coming from the front end and traveling up the torsion bar?

It might just be that it’s the bolt running through the reaction lever into the footwell that has come loose.
Either way a very small gap has a big bulkhead to rattle against.

There are many possible sources of rattles, start with the obvious ones, check through the Marlin Roadster build manual and the Morris Marina Workshop manual and parts lists. You know where to find them. Follow the link in my signature below (here or there)https://www.keepandshare.com/visit/v...&an=jiversteve

[HairyDave]

Re: Torsion Bar Rattle / knocking sound

I would still expect some signs of movement, disturbed paint etc if the reaction arm bolt was even slightly loose. So now the un starts, checking everything on the suspension. Possibly everywhere else too.
Just thought, its not the exhaust rattling on the torsion bar is it . Mine did that.

[element]

Re: Torsion Bar Rattle / knocking sound

The sound definitely used to come from the passenger footwell - so it is a nearside issue and the exhaust exits on the offside & the noise cannot be linked to that. There is no locking nut on the bolt - I will tighten it up and then fit a lock nut. If, when I put it back on its wheels this doesn't cure it then I know it is the front end and the vibration just travels up the bar to the footwell. As far as I know, I don't have any steering bush wear; other than a noise (which I'd need to be able to distinguish) - what other symptoms would there be? - vibration to the steering wheel for instance?

[meverett]

Re: Torsion Bar Rattle / knocking sound

Also make sure the smaller bolt going through the reaction arm and through the bulkhead in the footwell is done up tight.

[Sidon]

Re: Torsion Bar Rattle / knocking sound

The sound definitely used to come from the passenger footwell - so it is a nearside issue and the exhaust exits on the offside & the noise cannot be linked to that. There is no locking nut on the bolt - I will tighten it up and then fit a lock nut. If, when I put it back on its wheels this doesn't cure it then I know it is the front end and the vibration just travels up the bar to the footwell. As far as I know, I don't have any steering bush wear; other than a noise (which I'd need to be able to distinguish) - what other symptoms would there be? - vibration to the steering wheel for instance?

Is there any movement up and down on the nearside steering arm if you grab it at the inner wing end? This really does sound just like mine when my steering rack bush failed.