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[Doctor Gollum]

http://i1277.photobucket.com/albums/y486/05omegav6/Why%20polybushing%20front%20wishbone%20rear%20bushes%20is%20bad/IMG_20170408_143728_zpsqw5v2m4d.jpg

Apparently not

Picture in your mind, the ring that the rear bush sits in being snapped off completely causing the arm to bend forward where the front bush is located.

Now imagine this happening as you crest a bump in the road on a slight bend at around 130kmh.

If those cheapy ones haven't snapped your wishbones yet then there are 3 possible reasons...

1. you're simply not driving hard enough.
2. they are too soft to be useful.
3. you haven't found the cracks yet.

At least two of those statements are likely to be true.

[Muroman]

http://i1277.photobucket.com/albums/y486/05omegav6/Why%20polybushing%20front%20wishbone%20rear%20bushes%20is%20bad/IMG_20170408_143728_zpsqw5v2m4d.jpg

Apparently not

Picture in your mind, the ring that the rear bush sits in being snapped off completely causing the arm to bend forward where the front bush is located.

Now imagine this happening as you crest a bump in the road on a slight bend at around 130kmh.

If those cheapy ones haven't snapped your wishbones yet then there are 3 possible reasons...

1. you're simply not driving hard enough.
2. they are too soft to be useful.
3. you haven't found the cracks yet.

At least two of those statements are likely to be true.

If I imagine it correctly we are now talking about front wishbone's rear mount and it being snapped? That must mean that the bolt also snapped?

[Doctor Gollum]

No, just the wishbone...

The bolt being 10 times thicker than the wishbone

[Muroman]

No, just the wishbone...

The bolt being 10 times thicker than the wishbone

Wishbone cracked!?

[Doctor Gollum]

Snapped clean through.

Draw a line across the wishbone on the balljoint side of the rear bush circumference. This is the point at which what is effectively four sheets of metal failed.

[mandula]

Google found some pics, dunno are these same as original..

[Doctor Gollum]

Those are Razzos pictures, mine were different bushes but same failure point.

[Muroman]

Well I have now ordered front and rear bushes for front wishbones... Maybe look into reinforcing the wishbone?

[Doctor Gollum]

Well I have now ordered front and rear bushes for front wishbones... Maybe look into reinforcing the wishbone?

Upto you, but there's only so much you can do to it... Don't forget that it's quite tight to the upright/track rod/subframe.

Ultimately even strengthen I suspect all you will achieve is to snap the arm where the ball joint is attached.

I really wanted it to work, but I won't be fitting those bushes to an Omega any time soon...

[mandula]

Well those polys from strongflex wont snap my arms anytime soon.

They let arm to move up and down but prevent arm to move against bolt axis. So there is maybe even less force applied to arm than with original rubber bushing.

It sure will snap if you put some BOM bushing or similar that wont allow arm to move up-down.

[Doctor Gollum]

The ones I fitted allowed the arm to move up and down too... Likewise the home made ones Razzo fitted

[mandula]

Well, compared to original vs strongflex polys, originals were much harder to get to move up-down.

So really if arms can handle original bushings, there is no problem with those polys I'm talking about.

My opinion is that faulty (shit quality) arms and/or too hard bushes (not allow up-down movement enough) will cause arms to break.

[Doctor Gollum]

Well, compared to original vs strongflex polys, originals were much harder to get to move up-down.

So really if arms can handle original bushings, there is no problem with those polys I'm talking about.

My opinion is that faulty (shit quality) arms and/or too hard bushes (not allow up-down movement enough) will cause arms to break.

Ok, but consider this...

Are you comparing like for like? I mean, are you comparing a pair of rubber gm bushes (front horizontal and rear vertical ) when comparing resistance of the gm bushes to poly?  Because the front bush has massive resistance, compared to the rearward which barely holds the weight of the arm on its own. This has even caught TB out when he sees wishbones that have been polyed fitted as he thinks there is some sort of magic touch, when actually there is almost no resistantance from gm rears as said (comparatively anyway)

Then place that in the context of suddenly catastrophic wishbone failure under load at speed...

Do ya feel lucky punk? Well do you?

[mandula]

I first replaced front bushes to polys.

Then after that, several months later, replaced rear bushes to polys. Here I could compare the up-down movement resistance.

It really does not matter if you have front bushing rubber or poly, because lets say 150000 km on rubber bush has same resistance to up-down movement as polybush have.
Rubber does loose its stiffenes/resistance and then eventually it will tear apart from metal.

And I believe nobody has any problems with front poly + rear original rubber.

Therefore only thing that propably causes arm to break from rear bushing is that rear bush is replaced with too hard bush that wont allow enough movement and/or shitty quality arm that would break anyway with original bushing and enought time and harsh ride.

[Nick W]

Therefore only thing that propably causes arm to break from rear bushing is that rear bush is replaced with too hard bush that wont allow enough movement and/or shitty quality arm that would break anyway with original bushing and enought time and harsh ride.

The reason is because the rear poly bushes that have been tried previously are designed to work like the front ones; where the arm rotates around the inner metal sleeve. But the rear bushes work in a different plane - they are more of a joint - and so transfer all of the force(from a heavy car, with large wheels) directly into a part of the wishbone that isn't designed to flex in that way. That is guaranteed to cause exactly the failure that Al's pictures show. Attempting to strengthen the wishbone(which don't fail there when correctly equipped) is a dangerous bodge. The Omega specific bushes mentioned in this thread look much more like the OE rubber ones, and hopefully won't cause such wishbone failures. They're cheap enough that I'm tempted to buy a pair to evaluate whether I am prepared to use them.