Bent rear anti roll bar

[dnb]

I have at long last found out why my Griff breaks its rear ARB mounts. The two mounting points are not in line so when it rotates it applies all sorts of bad loads on the mounts.

Anyone have any bright ideas about replacement or straightening the thing? I see Clever Trevor has replacement mounts. Thanks.

[phazed]

I fitted Mondeo estate rear drop links and adjusted the bends on the ARB so they were in line.

Excuse the shoddy underside.

[spend]

Surely just adjusting the bolt holes in the bush cap will allow you to mount it straight. They only clamp down so cant see any harm being done but if you feel they get weakened pretty sure Cliff could reinforce them in a few minutes.

[dnb]

Unfortunately not. The bar itself is bent beyond what the bushes will take up. So the two ends try to rotate around different (but intersecting) vectors.

[Loubaruch]

The original rear ARB mounts have a reputation for failing as they are not up to the job. Many owners have beefed them up.

Mine failed so I removed the ARB intending to replace the mounts at some time but not sure now that I will bother as with my type of driving (fairly docile) I could not tell the difference.

[Bluebottle]

dnb said:

Unfortunately not. The bar itself is bent beyond what the bushes will take up. So the two ends try to rotate around different (but intersecting) vectors.

if the bar is bent beyond the wishbone mounting point, can the bar be bent back to line up?

[Chuffmeister]

phazed said:

I fitted Mondeo estate rear drop links and adjusted the bends on the ARB so they were in line.

Excuse the shoddy underside.

+1

[dnb]

It seems I may not have explained myself properly. The problem is not with the wishbone mounts or the droplinks (the rose jointed droplinks take up all sorts of errors without too much issue). The problem is the chassis mounts of the bar itself. My ARB looks like the exaggerated sketch below:



The ARB mounts are shown in red. You should be able to see that as the bar rotates in use, it will apply a twisting force to the mounts, eventually destroying them. The two mounting points on the bar should be parallel and in the same plane. The questions are how to straighten the bar with sufficient accuracy to fix it and have it stay fixed, and to ask if this is a normal Griff problem.

[phillpot]

I had to "tweak" the Chimaera rear anti roll bar I fitted to my S series, a hydraulic press did it a treat.

[Chuffmeister]

dnb said:

It seems I may not have explained myself properly. The problem is not with the wishbone mounts or the droplinks (the rose jointed droplinks take up all sorts of errors without too much issue). The problem is the chassis mounts of the bar itself. My ARB looks like the exaggerated sketch below:



The ARB mounts are shown in red. You should be able to see that as the bar rotates in use, it will apply a twisting force to the mounts, eventually destroying them. The two mounting points on the bar should be parallel and in the same plane. The questions are how to straighten the bar with sufficient accuracy to fix it and have it stay fixed, and to ask if this is a normal Griff problem.

Pop it down to a local metal workers. Nothing a bit of heat and bending wouldn't sort out!

[spend]

dnb said:

It seems I may not have explained myself properly. The problem is not with the wishbone mounts or the droplinks (the rose jointed droplinks take up all sorts of errors without too much issue). The problem is the chassis mounts of the bar itself. My ARB looks like the exaggerated sketch below:



The ARB mounts are shown in red. You should be able to see that as the bar rotates in use, it will apply a twisting force to the mounts, eventually destroying them. The two mounting points on the bar should be parallel and in the same plane. The questions are how to straighten the bar with sufficient accuracy to fix it and have it stay fixed, and to ask if this is a normal Griff problem.

Correct me if I'm wrong but from memory the bits in red should be straight, and the ARB Bush caps perpendicular, hence my original post.

The middle bit of the bar is just cranked for clearance, but the bearing surfaces in the bushes should be a straight line across the chassis, then the cranked ends to go round to the wishbones...

.._.........._
./...\____/...\
/..................\

[Chuffmeister]

spend said:

Correct me if I'm wrong but from memory the bits in red should be straight, and the ARB Bush caps perpendicular, hence my original post.

The middle bit of the bar is just cranked for clearance, but the bearing surfaces in the bushes should be a straight line across the chassis, then the cranked ends to go round to the wishbones...

.._.........._
./...\____/...\
/..................\

Yes. That's how it is on mine.

[dnb]

Straight is exactly how it's supposed to be, and exactly how mine isn't. The bar needs to be straightened somehow, but question is how to accurately get it to be like that... It's a non-standard ARB too - considerably thicker than normal Griffs for some reason, and this will make the fix much harder to implement. I think we know who my "local metal worker" might be I'll see what he says.

[Adrian@]

100% straight, it is possible put these on wrong, IF you have them bolted directly to the chassis ..the bolt that is bolted to the edge of chassis body mount plate has a bolt, bolted to the chassis mount plate, with a pair of flat washers and a std nut, THEN, a flat washer then the ARB mount plate then a flat washer and Nyloc.
Adrian@

Pictures please...

[dnb]

Pictures of what? The car has been in pieces for 13 months now so I have no pictures of it assembled. I remember there being an awful lot of washers to make the mounting plates line up properly but stupidly I didn't take pictures. It's always had a problem with breaking various parts of the ARB mounts on the back - even before I bought it.

You can see the bar is bent by eye (I'll try to capture this as a photo), and if you put a straight edge on it and use feeler gauges you can spot a greater than 1mm deviation in the length of the bush in the two orthogonal axes. If the bar mounts aren't at least approximately straight it can't work properly as designed, no matter how many washers are used, can it? You can't compensate for the twisting motion it imparts to the mounts...

I am wondering if I can fashion some form of spherical bearings to hold the bar on. These will deal with the twisting motion on the mounts. There's little chance of cold bending a 22mm ARB with any accuracy.

[Chuffmeister]

Are the ARB mounting plates/ brackets that attach to the chassis, to which the ARB bushes and bush retainer attach to, on the wrong side and thus the wrong way around, which would cause them to sit at an angle?

Sorry, just thought I'd ask, not meant to patronise.

[dnb]

No... They are handed, so even I couldn't get it wrong unless I fitted them upside down.

[spend]

dnb said:

It's a non-standard ARB too - considerably thicker than normal Griffs for some reason,

Not sure 'non-standard' is the correct description? There were options for a thicker / stronger rollbar from the factory.

I think I'd go to the standard one, can't really see the benefit of the stronger rollbar but lots of knock-on negatives (like extra stress on pivots as you seem to have suffered?).

[dnb]

But if the bar were correctly made tge stress that appears to be breaking the mounts would not be there.

[spend]

dnb said:

But if the bar were correctly made tge stress that appears to be breaking the mounts would not be there.

Huh don't get that????

As I see it, if bar is stronger all the bending force to twist (after all thats simply how it works) it still HAS to be restrained by where it is pinned (ie the bush brackets)?