Powerflex Bushings

[bobwhittaker]

POLYURETHANE BUSHES :-
I have purchased from Rally Design Ltd. a set of polyurethane bushes,the set is
made up of 16 bush halves and 8 stainless steel crush tubes. They catalogue it as
Westfield Wide Track Polybush under part No. DAR007,price £28.00 but with VAT
and delivery it totals £40.80,they arrived within 24 hours.

Bush spec and dimensions:-
PolySport fast street usage, Shore " A " hardness 78 + / - 2
Bush diameter crush tube in place (Not installed) 24mm
Bush length (Two halves,not installed) 38mm
Crush tube 38.4mm long, OD to suit bush ID, tube bore to suit 7/16" bolt ,
not 12mm bolt the bore is too small.

It would appear to me they can be made to fit to the rear radius arms on an Eleven
without to much trouble and I will report back when done.

They also do PolyRace with Shore " A " hardness of 90. I want the compliance
of the softer PolySport.

A possible drawback for some is that they state that under the terms of their
product liability insurance Rally Design goods are not for resale in USA or Canada.
There must be an easy way round that,for example third party purchase and
shipping in a plain package.

[Westfield 129]

I have the Powerflex parts (finally!), and they are a perfect fit, by measurement, anyway. I will try to install them this weekend. I don't see any problems with them. Installation should be straight forward.

The Powerflex are only one piece of hard poly, with a rotating around a center tube and a pair of thrust washers. This should be a very low friction part, and should not shear as the metalistic parts do. They should offer enough compliance so they will last, without binding the 4 link. It is not necessary to put the weight on the suspension to tighten down these bushings, as the elastic element is not held in tension.

Here in the US, they have a "Lifetime" warranty. Of course, everything for which I have had a "lifetime" warranty, I am on my 6th... but we shall see.

I am not really impressed with the other poly bushes I have seen (especially the two piece, which I have on the front upper trunion mount), but the Powerflex seem to be a well designed part that actually fits.

The proof is in the driving. Hopefully, I will drive mine this weekend.

[Westfield 129]

I just installed 4 of the Powerflex bushings at the chassis end of the rear trailing arms. The work was done with a press, but it could be done just as easily with a vice and a couple of sockets. Very easy. I lubricated everything with a synthetic grease.

I replaced the axle end bushings with the standard bushings, using my usual "loose" setup.

The fit of the Powerflex was perfect, and they were easy to press into the arms. Nothing special about the installation is noted.

The standard metalistic bushings had extruded their rubber content over the last 3000 miles. This is the longest I have had a set of metalistic bushings last in the rear arms. Hopefully, the Powerflex will last longer.

Drive test later in the weekend.

[bobwhittaker]

Have today installed the Polysport Fast Road polyurethane bushes in all four radius arms,both ends.Found three of the four forward end metalstic originals where the inner sleeve was totaly loose and one of the rear where the rubber had sheared but it still had a grip.
Obviously there was an improvement,new metalastics would have done that.However the ride is less harsh than original with no apparent
loss of feeling / directness with the drive.The job was straight forward,taking about 3 hours total and pressing the old bushes out with a
bench vice and two sockets,the bush halves and crush tubes needed no modification.

If needed I will comment again later.
Cheers , Bob Whittaker.

[Westfield 129]

What color were your bushings? Mine are black, the only type available here, and described by Powerflex as "race". There is no "fast road" variation available here under the current available part number.

That they ride better is not surprising, they are two piece, and have far less internal friction and shear than the old metalisics. I am betting (about $210 USD) on them lasting longer than the metalistic bushings that cost about 1/8th as much. Next time, I will order from Westfield.

Mine are working OK (nothing unusual to report so far). I ordered another 2 sets for the rear to replace the new metalistics that I installed at the axle.

[bobwhittaker]

The Polysport bushes are yellow and described as " Fast road ", they also do " Race " in black . UK price
without tax and delivery was £28.00 for eight assemblies.However tax / pp pushed this up to £40.80.
Bob Whittaker

[Westfield 129]

Do you have the Powerflex Part Number?

We only have the black race bushings listed here in the US. I am going to try them, but I am thinking that a softer, more compliant bushing may be the better solution for the rear 4 link.

[bobwhittaker]

Have today replaced the Polysport half bushes ( Yellow Shore Hardness 75 ) and crush tubes with
eight one piece items made on the night shift at a local aerospace factory.These have an O.D. to
give a hand push fit into the eyes of the radius arms and an I.D. to suit the 7/16" bolt with no
crush tubeand are just a plain straightforward bush.The material is a red polyurethane which appears
harder than the yellow of the polysport which had distorted and was allowing the axle to rock and thus
clunk.I have no actual material spec,it was some that was available and the job was a freebie so it
was worth a try.The mounting bolts are installed with a firm nip and castellated nuts locked with split
pins instead of Nyloc nuts.
Have done about 30 miles and the clunk has gone and the ride is less harsh,due probably to the extra
material in the bush and the car is still surefooted.Time will tell and I will report anything of interest.

[Westfield 129]

The bushings that I have here from the Powerflex distributor here in the US are black ("race") and the tubes are steel, one piece, and don't "crush" at all. They are a perfect fit with the 7/16" bolts.

No modifications necessary with this part.

If the softer bushings are distorting to the point of the rear axle clunking (and don't recover from the distortion), then the softer material (at least from Powerflex) is not suitable. The looseness and distortion is the same problem that the Metalistics have when they extrude their rubber element

Note that with the 4 link rear end, there is quite a bit of suspension bind and distortion to the bushings during cornering when body roll becomes a significant factor. This pull and twist on the arms shears the thin rubber of the metalistic bushing, and causes distortion in the Powerflex bushing, Hopefully, with the extra elastic material and superior recovery to distortion, the Powerflex budshing will work a bit better, and prevent the axle rattle and imprecise handling.

So far, with 300 miles, no clunking. PN: PF 99-116 I installed them with a Mobil 1 synthetic grease.

I will be disassembling the rear arms to inspect the bushings next week.

[jonclancy]

Any update on this, please folks?

I've been needing to replace my trailing arm bushes for some time. Might just go with the standards for the time being to get the job done and save some funds...