Do polyurethane bushes require preloading?

As title says?

I undestand that the original style bushes needed to have the shackle plates clamped onto the inner tube, after setting the spring deflection.

However, it seems that the tube used on the polyurethane bushes is able to rotate to a degree inside the polyurethane. Therefore, do these require preloading as the old type did?

Thanks for any info.

Hi, I changed mine on the back of the 300tdi disco 1 and lowered it to road before tightening fully, and it is fine. I assume you are talking about pre-loading the old matallastic ones?

Webley1991 said:

As title says?

I undestand that the original style bushes needed to have the shackle plates clamped onto the inner tube, after setting the spring deflection.

However, it seems that the tube used on the polyurethane bushes is able to rotate to a degree inside the polyurethane. Therefore, do these require preloading as the old type did?

Thanks for any info.

Click to expand...

set the same way once nipped up bush should be reasonable tight but not like std bushes as tube isnt secured to bush as they are

As the steel tube isn't secured to the inside of the bush, is there any need for setting at all?

Another problem I can see is that where I have fitted the poly bushes to the eyes on the rear springs, the tube is slightly too short. This means that the ends of flanges stick out further than the the length of the tube.

When it comes to reassembly, should I just tighten everything up and squash the flanges down?

Webley1991 said:

As the steel tube isn't secured to the inside of the bush, is there any need for setting at all?

Another problem I can see is that where I have fitted the ploy bushes to the eyes on the rear springs, the tube is slightly too short. This means that the ends of flanges stick out further than the the length of the tube.

When it comes to reassembly, should I just tighten everything up and squash the flanges down?

Click to expand...

because when you tighten it bushes are squashed in to a tighter fit ,hence best still to tighten with weight on wheels

I see what you mean now.

I had another looks at this thread as I still can't quite understand:

Do the shackle plates need to be clamped onto the inner steel tube of the poly bushes? I mean in the same way as they do for the old style metallastic bushes.

Also, do the spring eyes fitted to the chassis need to be clamped tight onto the bushes?

Chassis spring mounts should fit tight to bushes , who's make did you buy.

I bought floflex bushes.

What I mean about the spring hangers on the chassis is should the nut and bolt be done up so that it is not able to rotate in the bush tube?

I haven't got round to installing anything yet. At the moment it is still a chassis sitting on the ground. When I get chance I will fit the springs to the axles and turn it into a rolling chassis.

The fixed front end of the springs do not rotate much.
Rears of each spring set rotate some under load but not a lot . My parabolics are nipped up tight and seem to work ok.
Carried a full load a fewyears back and for months I thought it had flattened my springs it was only when I renewed my chassis I realised bushes must have been holding it down as now sits normal .
So I guess the secret is no too tight that they lock.