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[Sir Tigger KC]

This makes me wonder at the wisdom about doing any modification to cheap wishbones. 

I binned a set of ATP wishbones recently when I noticed slight cracking in the welds around the rear bushes.  I'd polybushed the front a couple of months earlier and can't say that was the cause, but it makes you wonder.   

[X30XE]

No surprise.

If you consider the loads, the rear bush has to allow the suspension to compress and a stiff part will mean the steel will have to flex considerably, the result is a fatigue failure at the weakest point (in this case the weld).

Agreed. Uri Geller's wishbone. 

The front bush is very different, you could argue that the loadings are less as the poly is more likely to allow the wishbone end to rotate more than the press fit rubber variant.

Unless the crush tube is too short/poly too long, which seemingly is the case with most powerflex products. 

[VXL V6]

Clearly the stresses with rear poly is too much but equally, I've yet to see any first line product that I would fit to anything a human is being transported in.

[Shackeng]

No surprise.

If you consider the loads, the rear bush has to allow the suspension to compress and a stiff part will mean the steel will have to flex considerably, the result is a fatigue failure at the weakest point (in this case the weld).

Agreed. Uri Geller's wishbone. 

The front bush is very different, you could argue that the loadings are less as the poly is more likely to allow the wishbone end to rotate more than the press fit rubber variant.

Unless the crush tube is too short/poly too long, which seemingly is the case with most powerflex products. 

Glad that you are OK Al, and thanks for the heads up.
I asked the question a few years ago as to whether the poly front bushes caused unwanted stress elsewhere, and I think the answer was "No".
I am somewhat concerned about the comment on Powerflex quality given that I have them in the front of both of mine.

[Steve B]

Al do you think that had been going over a period of time then finally let go... or just sort of went...

[terry paget]

Any accident is traumatic, congratulations on your lucky escape, Al.

We discussed the strange layout of the Omega front wishbone rubbers in a thread earlier this year. Obviously if the bushes only allowed rotation about the bolts the suspension would not move at all. If owners restrict movement in the rubbers to improve handling they increase flexing loads on the wishbones. Whether they are strong enough to take these loads owners must decide. The calculations are beyond me, so I trust Adam Opel engineers and the test of time, and leave mine alone.

I thought you were on your hols in the South of France, Al, Adversane sounds quite exotic. Googling it I find it is a suburb of Horsham, Sussex. At least you are near home.

[05omegav6]

Let go all of a sudden... Had felt perfectly poised through the sweeping bends immediately prior.

Will compare the left and right arms once I have removed them...

New pair on order from ATP as I type...

[ted_one]

Glad you're OK Al, also glad I stuck with the standard set ups

[TheBoy]

Having experimented with rear vertical polys myself, I wouldn't recommend them.  I was lucky, in my case the poly failed in my GM wishbones, and you could see the loading stresses. With a poly, the wishbone is forced to flex, which will always result in failure.

Admittedly mine probably took more of a hammering than most, but didn't last long at all, so I'd always recommend Powerflex front, GM rear and GM wishbones.

[minifreek]

Glad your OK Al and nowt nasty happened

I polybushed new LemForder wishbones about 18 moths ago.... better get checking them...

[05omegav6]

Having experimented with rear vertical polys myself, I wouldn't recommend them.  I was lucky, in my case the poly failed in my GM wishbones, and you could see the loading stresses. With a poly, the wishbone is forced to flex, which will always result in failure.

Admittedly mine probably took more of a hammering than most, but didn't last long at all, so I'd always recommend Powerflex front, GM rear and GM wishbones.

It is worth noting for clarity, that the polys TB had fitted were a solid type with almost no give and were the same as Razzos iirc

The ones I fitted where designed as suspension bushes, albeit for a different car, and were dimensionally identical to the originals, ie they were a perfect interference fit to the wishbone and were the same height in the subframe.

[TheBoy]

Having experimented with rear vertical polys myself, I wouldn't recommend them.  I was lucky, in my case the poly failed in my GM wishbones, and you could see the loading stresses. With a poly, the wishbone is forced to flex, which will always result in failure.

Admittedly mine probably took more of a hammering than most, but didn't last long at all, so I'd always recommend Powerflex front, GM rear and GM wishbones.

It is worth noting for clarity, that the polys TB had fitted were a solid type with almost no give and were the same as Razzos iirc

The ones I fitted where designed as suspension bushes, albeit for a different car, and were dimensionally identical to the originals, ie they were a perfect interference fit to the wishbone and were the same height in the subframe.

I know you use those shitty ATP wishbones, but the fact remains that even your more complex bush setup caused the wishbone to fail catastrophically (and potentially lethally).  I think this finally puts an end to vertical poly experiments?

I'm just so glad that it happened at a time when you were able to control it and bring it to a stop, unharmed

[05omegav6]

Having experimented with rear vertical polys myself, I wouldn't recommend them.  I was lucky, in my case the poly failed in my GM wishbones, and you could see the loading stresses. With a poly, the wishbone is forced to flex, which will always result in failure.

Admittedly mine probably took more of a hammering than most, but didn't last long at all, so I'd always recommend Powerflex front, GM rear and GM wishbones.

It is worth noting for clarity, that the polys TB had fitted were a solid type with almost no give and were the same as Razzos iirc

The ones I fitted where designed as suspension bushes, albeit for a different car, and were dimensionally identical to the originals, ie they were a perfect interference fit to the wishbone and were the same height in the subframe.

I know you use those shitty ATP wishbones, but the fact remains that even your more complex bush setup caused the wishbone to fail catastrophically (and potentially lethally).  I think this finally puts an end to vertical poly experiments?

I'm just so glad that it happened at a time when you were able to control it and bring it to a stop, unharmed

Indeed, hence posting whilst waiting for the AA

[flyer 0712]

Glad you are all ok after such a shocking event......just looking and thinking what has happened to you should be a lesson to us all...leave well enough alone.

[joff]

Having experimented with rear vertical polys myself, I wouldn't recommend them.  I was lucky, in my case the poly failed in my GM wishbones, and you could see the loading stresses. With a poly, the wishbone is forced to flex, which will always result in failure.

Admittedly mine probably took more of a hammering than most, but didn't last long at all, so I'd always recommend Powerflex front, GM rear and GM wishbones.

It is worth noting for clarity, that the polys TB had fitted were a solid type with almost no give and were the same as Razzos iirc

The ones I fitted where designed as suspension bushes, albeit for a different car, and were dimensionally identical to the originals, ie they were a perfect interference fit to the wishbone and were the same height in the subframe.

I know you use those shitty ATP wishbones, but the fact remains that even your more complex bush setup caused the wishbone to fail catastrophically (and potentially lethally).  I think this finally puts an end to vertical poly experiments?

I'm just so glad that it happened at a time when you were able to control it and bring it to a stop, unharmed

Indeed, hence posting whilst waiting for the AA

This is not the first time we have seen this is it. So why keep putting them on Al, Poly the front and that's it Glad your still with us. Was this on the Irmscher estate