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[05omegav6]

Which brings us neatly back to the Sierra bushes, which are exactly the right size but lack a ball...

[chrisgixer]

Can't see what car these are for.

http://www.modified.com/tech/modp-1103-suspension-buyers-guide/photo_02.html

[elvin315]

Anyone given thought to drilling small holes through the meat of the bushing, between the tube and outer-case? They would provide "squish room" similar to the voids molded into the Poly-Joints from DayStar. These holes, 3 at the very tip of the wishbone and 3 opposite those, would make the bush more pliant and relieve tension along its pivotal axis reducing stress to the wishbone. The action of the wheel rising and falling would cause the poly material to "squish" and fill the holes. We could also drill even smaller holes to the "left & right" of the tube that would allow a lesser "squish" under braking to mimic the function of the OEM bushing.

I wish I could illustrate this but I don't have photoshop  with which to create an example, but if you refer to the picture below, imagine drilling 3 holes through the "top" of the bushing and 3 through the "bottom" and then 3 smaller holes to the "left and right".

How do you think the polyurethane would hold up during road use? Would it function as I pose, or tear and shred itself to bits? Maybe this is a crazy idea but that's what's fun about this forum, exchanging ideas with likeminded crazy people like yourselves.   

[elvin315]

Can't see what car these are for.

http://www.modified.com/tech/modp-1103-suspension-buyers-guide/photo_02.html

I think the site used them as a general illustration of a joint and purposely didn't identify the vehicle.

[chrisgixer]

Bit wary do sounding too negative at every suggestion here, "but" the issue I see there is the rigidity required to keep the steering accurate is needed on the same plane as the relief needed by the bush when the wishbone tilts.
 Drill holes,  helps one, but detracts from the other. Arse! (If I understand the description correctly of course...? )

[chrisgixer]

Can't see what car these are for.

http://www.modified.com/tech/modp-1103-suspension-buyers-guide/photo_02.html

I think the site used them as a general illustration of a joint and purposely didn't identify the vehicle.

Yes, shame, they look tasty, and the eccentric could alleviate some wheel rubbing issues by altering the track too.

I can't get a sense of scale either. They could be massively too big.

[elvin315]

Bit wary do sounding too negative at every suggestion here, "but" the issue I see there is the rigidity required to keep the steering accurate is needed on the same plane as the relief needed by the bush when the wishbone tilts.
 Drill holes,  helps one, but detracts from the other. Arse! (If I understand the description correctly of course...? )

I see your point. My mind was set on relieving the stress on the wishbone to prevent cracking and I didn't consider the rest of the forces involved. Damn. Genius idea while it lasted though.

[chrisgixer]

Yes that why a solid lump style poly will never work to complete satisfaction IMO. The danger is they are made hard enough to work initially, which satisfies the first criteria, but does so at the detriment to wishbone strength.

They will eventually fatigue the wishbone. There's no compromise to satisfy both.

If its to be upgraded, the rearward bush MUST be a ball joint design. And to be usable in a passenger car it MUST have some sort of damping quality or harshness will be the over riding sensation. The car can be as accurate as it likes but if the drivers hands are numb with tingling vibration after half an hour its no use.

I already get slight tingling from long journeys with front poly as it is, but then I have a compressed vertebrae that aggravates nerves anyway so it might be that.

It's certainly not as straightforward as fitting a rose joint, or a solid lump of poly.


I did speak to Powerflex re measuring up the omega for poly rear subframe bushes/donuts a couple of years ago. They even measured the car for dimensions etc. However the sales team decided that there where more lucrative models to build bushes for first, cars that sold in bigger numbers or models that had greater numbers on the road certainly.
 So us poor omega owners had to wait as far as they where concerned. Luckily Al found the monaro ones by Pedders to be a good enough fit.
 But the point is, just asking a poly bush manufacturer to make a bush for a certain model doesn't mean they will just make the part for us either. They have to see a good business decision first, which is fair enough.

There are plenty of engineers that will make the metal parts, but poly up to a certain shaw needs to be moulded. Freezing it doesn't work either. Black poly, is just about hard enough to machine, but the second it gets hot, the hardness needed to machine it to any real accuracy or detail such as poly ball joint ( not simply a poly lump ) is lost.

Therefor a mould is needed, and from that point ease of manufacture for Joe bloggs on the street, or even us lot, becomes a lot more expensive. Its doable, that's how powerflex started. But certainly not straightforward.


....IMO of course.

[chrisgixer]

Ps, its a shame those 3d printers aren't a bit more advanced.

[Nick W]

3D printers are perfectly capable of making the part. But, the materials that they use aren't going to be much use as a bush. They'd probably be up to the job of making one-off moulds to make a bush though.

My opinion is that the rear bush is a poor design; it should have been a similar bush to the front, in the same plane and axis. Just like a proper tubular wishbone would have been. Just about everything that use front and rear at 90degrees to each other suffer from shortterm wear. Just ask anyone whose had mk4/5/6 Escorts or later Fiestas, where replacing the wishbones every couple of years is a requirement. Although at £15 a side it isn't too costly.

[chrisgixer]

Would it be fair to say that mostly front wheel drives have the bushes both pointing forward?

[chrisgixer]

Volvo c70 has a similar set up with a cast wishbone.

The arm itself is quite short though.

[chrisgixer]

Like this?

http://oldsite.omegaowners.com/forum/YaBB.pl?num=1232197401


Note the king pin is central though, compared to the inline rear arm of the omega

[Nick W]

Would it be fair to say that mostly front wheel drives have the bushes both pointing forward?

No.

Look at a Jag, Cortina, Superminx, Granada, Manta, Triumph, Corvette etc, etc.

[elvin315]

Which brings us neatly back to the Sierra bushes, which are exactly the right size but lack a ball...

I give up. Like I said before, I'm not ready for new ones yet but when the time comes I'll be asking you how those Sierra bushings are holding up. I was leaning towards the DayStar Poly-Flex bushes but if the Sierras slip right in without any machine work, and the handling is improved over stock, then I'm sold.