I've broken another front anti roll bar mounting. Any idea why?

[GrahamFountain]

I've broken the nearside anti roll bar mounting bracket, the ? shaped one PN 153669, again. I'm not sure how may have bust in the last 6 or 7 years, but it's at least 4. Not sure they've all been passenger side, but the last one was for sure.

I know it's not a huge problem and they aren't massively expensive, about £29 for a pair from Wins., but why do they break?

Also, is it worth welding a couple of gussets either side of the bolt holes - they're breaking at the top of the top hole where the 90 degree bend is?

I don't imagine is matters, but I do have 175/60s on the front (had them on the back till recently as well), but only because it came with that size on, and I've never replaced all 4 at once.

Graham

[Aleco]

That does seem rather odd, I replaced mine 10 years ago and haven't touched them since.
Can you post a pic of the broken one

Is your anti roll bar bent/misshaped? That could out extra load on the bracket?
On that note is your subframe out true or misaligned?

Alex

[GrahamFountain]

I'll probably get the broken one off later today and post a picture tonight - in no rush till the replacement coil arrives. I don't know the break is fresh. I didn't notice it, it was one of the nut strippers at the tire shop who saw it.

If it's worth welding a couple of bits in, then I'll have to take them to the garage and get them to do it, as I've no welding kit and only ever learned how to gas weld anyway.

Graham

[Aleco]

If it's worth welding a couple of bits in, then I'll have to take them to the garage and get them to do it, as I've no welding kit and only ever learned how to gas weld anyway.

Graham

Before I welded anything I'd want to try and understand the fault a little more. I'm no expert but to be breaking the brackets so regularly tells me something else isn't quite right.
It may work out fine by welding in strengthening but you could also transfer the forces to other areas of the structure that aren't capable of carrying them.

[xvivalve]

Are you using second hand ones each time? They might just be inherently weak due to age?

Fitchetts sell good quality reproduction ones.

[GrahamFountain]

Are you using second hand ones each time? They might just be inherently weak due to age?

Fitchetts sell good quality reproduction ones.

I'm using new ones. I think the last one came from S&S, but they'll have got it sent from gRimmers. The one I have just put on, and the one in the photos came from Wins. I got two from them because they were less then £3 more than one from Rimmers. So If I do strengthen it, it's a straight swap.

The bit of the old one that's left looks the same as the new one to me. I do note it's broken about where there are two pressing marks in the new one, and it is where I'd expect maximum stresses and fatigue failure.

I can't see any issues with the roll bar or subframe, spacings look the same both sides and no obvious bends in anything. I didn't mention poly bushes, but they are blue ones.

Graham

[xvivalve]

If the bushes are harder shore and there is less 'give' then I'd suggest that as a possible culprit.

[GrahamFountain]

Suppose I could go back to rubber ones. If I don't notice when one end's not attached, I probably won't notice it the roll bar's a bit soft.

Graham

[geeksteve]

Stupid question maybe, you are using both halves of the bracket right?

Steve

[Carledo]

Ive had a few of these break especially a few years ago (99% in the same place as yours broke) when the pattern replacements weren't available and I had to fit good used ones from wherever I could get them. I've also lost the flat bit several times to breakage around the slot where the round bit hooks in.

But i've not broken a new Fitchetts one yet. Even on the hard worked Carledo! HOWEVER, I don't use Poly on the A R bar, centre or ends.

FWIW, Chris Witor's Superflex in blue is supposed to be the same shore as original rubber, so shouldn't affect wear rate of other related components significantly.

A combination of stinginess and "if it aint broke, don't fix it" attitude has made me very sparing in my use of Poly, I won't use the cheap stuff and won't splash out on Superflex if the rubber bush is Ok. Sometimes i'll even put new rubber in if it IS duff! Case in point being rear trailing arm front bush.

Steve

[GrahamFountain]

Stupid question maybe, you are using both halves of the bracket right?

Steve

If you mean the ? shaped bit together with the flatter bit the ?'s tip hooks into, yes.

Graham

[GrahamFountain]

But i've not broken a new Fitchetts one yet.
Steve

I looked and there's no picture on their site to compare with the ones I got from Wins International. It does seem odd that Wins' price is a fair bit less than the usual suspects and Fitchetts at 9.99+drat each - but they only sell them in pairs.
I can't see or measure any differences between the new one and the bit of the old one I have left that's not probably due to the way it's failed: the sidewalls are splayed at the ends of the break, suggesting to me it failed at the mounting hole and the crack spread outwards. To look at them, they could well have been made by the same tooling.

I wonder if it's worth asking if they have a photo, so I'll know for next time.

Graham

[cleverusername]

My money is on the problem being the polybushes, I would go back to rubber.

[xvivalve]

FWIW, Chris Witor's Superflex in blue is supposed to be the same shore as original rubber, so shouldn't affect wear rate of other related components significantly.

Having handled both side by side, I perceive there to be a clear difference. Also, as the base materials are quite different in composition, the Shore rating is not always directly comparable; there are infact several Shore rating scales applicable to different materials, the most common being A and D. Shore surface hardness alone should not be used in isolation for specification and design as factors such as plasticity and elasticity can vary between materials which share a common shore hardness.

Unfortunately, there seems to be an assumption that 'poly' is good, so change everything, but as the amount of threads I've heard sheared off rear radius arms when trying to get the nut and washer past the hole for the 'R' clip proves, it isn't necessarily the case.

The front ARB is designed to have some flex at the mounting points to the subframe, else there'd be a much simpler rigid fixing rather than the somewhat contrived bush carrier we have. If that ability to flex is restrained, the forces have to go somewhere...

[GrahamFountain]

Spoke to Fitchetts' and the ones Rimmers sell, and they're pretty sure the ones I got from Wins are made by them, and they aren't aware of an issue.

We had a bit of a discussion about the way the bottom hole is elongated in the fabrication process, and they think it failing there and spreading sideways at least sounds credible. Like I say, the sidewalls are both splayed, and at least one of them wouldn't both be so distorted if it started at one or both of them and went right across or in. But as to why, they don't know. Also, the broken bit is bowed across the width showing it was loaded against the bolts. But I don't know why it would be excessively loaded.

The other thing is that the bit the ? hooks into is fine, and there's not that much metal in the hook or eye. So I don't know how there can be so much load on the bend and little on the hook or eye. It has to be a fatigue failure in the movement the hook and eye allow.

That makes me wonder if gussets in the corners of that bend will help. They would have to somehow take the load of the mounting hole, and I'm not sure they wouldn't transfer more there, rather than less. Maybe the answer would be to weld the hole up and re-drill it round. That would put some metal under the bolt head between the hole and the bend, where there's currently none, or at least not much.

Both 9/16th AF bolts were still tight when I came to take it off. I can't get a torque wrench in, but I think I have them tight - it was a bit of a faff getting the nut and spring washer on the back of either bolt done first. But I think that's about where it is under the car - I'm doing it weight on wheels. In the end I put the nut on the bottom one with no washer, tightened it up, put the top set together right, undid the bottom one and re-did it with the washer in place. That was with the other bracket on and done up. It don't feel like the roll bar is loading the bracket a lot when it's just stood as I can get the bolt in and the nut on. It was just I kept dropping the damned washer trying to put both on together with the left hand where I couldn't see and hold the bolt and push the bracket back over the bush to get enough thread through with the right.

But Fitchetts have put me onto someone who may have some original brackets. And I'm trying to contact them.

Graham