correct suspension bush sizing

Can anyone help in relation to correctly sizing the lenth of suspension bushes.
Had the hot rod on the dyno this week and while on the dyno all the suspension bushes in the rear 4 bar susupension where chewed out and elongated.
Bought the 4 bar suspension from the eastern states with bushes already in them.
The bar ends are about 42 mm wide but the bushes do not meet in the middle ( About a 15 mm gap between them.
I'm wondering if this may have caused the problem with the bushes,
Can anyone please explain the proper way to size the length of the bushes.

Thats how all of the poly bushings that I have seen are.Did they have the metal tube/sleeve in them ? And where they lubed @ assembly ?

If those bushings elongated then they evidently did not have a steel insert inside the bushing. There are numerous companies out there that make bushings and I would check the web for just those. I wouldn't go back to the company that originally sold you the 4 bar setup.

the ones supplied with the 4 bars did not meet in the middle there was a 15 mm gap in the middle.Was wondering if that caused the problem.

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Originally Posted by roadster

the ones supplied with the 4 bars did not meet in the middle there was a 15 mm gap in the middle.Was wondering if that caused the problem.

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No,as every poly bushing I have ever seen are like that.

I'm guessing that the bushings were not poly but whatever rubber is used now. Another guess or two is that were not preloaded from the side plus were a bit sloppy in the bore allowing them to "walk". That 15mm space sounds a bit large - in American, about 9/16". Myself, would have liked to have seen half of that, maximum, or even less, say 1/8" and with poly bushings, even closer. That 9/16" converts to less support where you need it the most ~ 35+% less. Mine on my '31 are continuous plus are well supported with some preload on the assembly - and so far have been just fine, but I do check them each time I have the car on jacks, JIC:D

I use the Speedway bushes and have had no problems, they have about a 1/8" gap, There are differing hardnesses with these bushes and the softer type do squash and remain that way.

Which reminds me - my latest Speedway SR drool over catalog just arrived on Friday just past. Sigh!!!!!