Powerflex Bushings

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Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Powerflex Bushings

Post by Westfield 129 »

I just received half of my Powerflex bushing order so I have not been able to install them in the rear suspension of my W11.

However I have been able to measure them and compare them to the original metalistic bushings. They should fit, and they should work.

Since the Powerflex bushings are two piece, with thrust washers,it will be possible to torque down the bushings.

The center tube is lubricated and installed within the poly element, allowing for planetary movement, greatly reducing friction. The thrust washers will ensure that the bushing stays put, and moves smoothly through the suspension's range of motion.

The bushing doesn't have a shell so there is about twice the elastic content, which should eliminate the tearing and failure that we have seen with the metalistic parts. there should be enough compliance to handle the twist and shear that occurs with the 4 link in roll. This is what tears apart the old metalistic bushings in only a few hundred miles (or less. I have found failed bushings after only 50 miles of spirited canyon driving).

I hope that the rest of my order shows up soon, as I want to install them in the rear arms at the chassis end. The added compliance in twist should improve the life of the metalistic bushings that are installed in the axle.

If these work, I will change over the entire car. Bushing life will be infinitely longer with the Powerflex units with no down side (and perhaps a nice upside) in handling and ride.
bobwhittaker
Posts: 194
Joined: Sat Sep 08, 2012 5:42 pm

Re: Powerflex Bushings

Post by bobwhittaker »

I Came onto the website to query if anyone had made up rear suspension arms using rose joints instead of the metalastic bushes when I saw your reference to Powerflex Bushings . It is now my intention to investigate this option and I will probably convert to these . From viewing Powerflex website there appears to be no advantage pricewise in going direct to them instead of via Westfield . I don't expect any meaningful
comment from Westfield until Tuesday 26 May due holiday period and I will report on any progress and improvements as they occour .
Bob Whittaker
Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Powerflex Bushings

Post by Westfield 129 »

Been there, 'done that!

DON'T RUN ROD END REAR SUSPENSION ARMS!

I did this years ago when I could not get the metalistic bushings, and the results were not so good.

4 link rear arm setups are full of suspension bind, and require some compliance to work properly. Any body roll is arrested by the 4 links and the rod ends, which amplifies the high roll center's propensity to unload one of the rear wheels and snap into over steer. 'Not fun.

Then there is the problem of the rod ends wearing quickly as they are pulled, and begin to rattle and clunk. Not unlike a set of worn bushings.

The wear problem may be addressed with "heavy duty" rod ends, but these cost nearly $90 USD each, and I would need 8 of them... That's a lot of metalistic bushings and even several sets of Powerflex bushings. And, the problem of a more abrupt change in suspension articulation still remains.

One might think that the articulation would be increased, but it really isn't, and the roll center is still a limiting factor in the rear suspension's behavior. Compliance, even a little, works better.

AND, any error in length between the links will cause chassis failure, the pulling out of the rear suspension arm mounts and cracking the welds.

Understand that I write all of this, tempered by several thousand miles of experience with a rod end rear suspension setup.

The handling' predictability is reduced, and the thing can snap into oversteer, a result of limiting the suspension articulation. This, rather than the nice, gradual transition that the W11 is famous for. If you don't have an LSD, well, you can kiss half of your existing corner exit traction goodbye.

The fix is to reduce the rear suspension travel to minimum, but this causes other problems with handling and ride. Really it isn't worth it. Handling is never improved.

I was never happy with the rod end setup (I tried to develop it for 3 years), but it would probably work well if you had a set of arms that had a Powerflex bushing at the chassis, and a rod end at the axle. That would be the ideal setup, but making the arms is problematic, and expensive.

Really, once I had the new metalistic bushings installed, the difference was remarkable. Then, the fix to make the bushings last (al little longer) was easy. Just don't torque them down tight. That way, they act more like bearings, and the thin elastic element doesn't shear apart at the first bump.

The Powerflex bushigns should give the reduction in static friction of a rod end, with the additional articulation made available by the much larger poly elastic element (about 3X more flexible material as the metalistic). Since the internal element can rotate within the bushing, the problems with tear and shear should be minimized.

And, since the poly element rotates around the internal tube, you can tighten them down all you want.

Installing the Powerflex bushings at the chassis end of the arms should provide enough compliance that much of the flex/shear load at the axle end metalistic bushings should be reduced enough so that those bushings will last much longer. Just don't torque the axle end bushings too tight. They have to rotate, or else they will shear apart.

Better would be a complete set of the Powerflex bushings at the rear. Westfield's cost for the bushing set is about 45% less than the cost of the bushing set here from Powerflex USA. so ordering from Westfield is a good idea, or buying the bushings from a UK supplier. The US price is $100 for two sets (4 bushings). UK price is substantially less expensive, even with duty and shipping. Also, you get the bushings faster... I am still waiting after an entire month for my bushings to be shipped from the US distributor.

A local builder made me a lovely set of alloy rear arms made up for heavy duty rod ends. I have not used them, mainly due to the cost of the rod ends, and the poor performance over the years I tried to make that setup work.

However, if you want to make a nice, rod end equipped Panhard Rod, go ahead. It works quite well, and is easy to adjust if you use LH and RH threaded rod ends.
bobwhittaker
Posts: 194
Joined: Sat Sep 08, 2012 5:42 pm

Re: Powerflex Bushings

Post by bobwhittaker »

I have read all you say regards the use of rose joints on the rear suspension arms, it all makes sense ! It is now no longer my intention to go that route . However only today I have come across a supplier local to me who quotes some very advantageous prices for various sizes and configurations of rose joints you might need for other applications , see examples :-

CM economy range UNF 5/8" hole/thread RH/LH £5.oo
1/2 " " " £4.00
7/16" " " £4.10
3/8" " " £3.50

XM Racing series Chromoly with Kevlar Liners 5/8 R/L £9.50
1/2 " £7.50

All above prices include UK VAT at 20%

See their online catalogue at http://www.tmrsupplies.co.uk for full range of products and services .
Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Powerflex Bushings

Post by Westfield 129 »

Did that as well.

Only very high quality aerospace rod ends are suitable for suspension use. I have found that the medium and low price rod ends just don't last (at least in the rear of this short 4 link suspension). They do work fine for the Panhard rod, though.

High quality suspension grade heavy duty (larger shank, ball and housing) are not cheap (typically $75~$90 USD each). Pehaps they would work, but the short length of the links is still the main problem.

I am pretty sure that the Powerflex bushing is going to deliver a huge ride and handling improvement. Now, if Powerflex USA would deliver the rest of my order...
bobwhittaker
Posts: 194
Joined: Sat Sep 08, 2012 5:42 pm

Re: Powerflex Bushings

Post by bobwhittaker »

The format of my earlier response is not as I laid it out when typing the reply nor when it was previewed , my version made far more sense
than the published item.
For your interest ( See their catalogue ) TMR supply and maufacture items from single bearings upto complete cars for BRISCA Formula 2 Stock Car racing on oval shale cicuits using these rod ends throughout and I was able to inspect one of their cars at close quarters only
yesterday . Your comment regards the relatively short length of the Westfield rear suspension radius arms being a problem was endorsed
by the set up on the car I was inspecting , these arms were some four feet long , not the 12" of the Westfield . It was very interesting
to inspect the car and talk to the owner/builder .
Cheers , Bob Whittaker
jonclancy
Posts: 942
Joined: Tue Nov 01, 2011 9:30 pm

Re: Powerflex Bushings

Post by jonclancy »

I probably missed this, but what was the part number of these bushes, please? :)
Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Powerflex Bushings

Post by Westfield 129 »

PF99-116

Two to a package. Check the prices. Westfield may have the best deal for the full set.

They are far less expensive in the UK than in the US (Here in Sunny California, 2 packs of 2 each=$100 USD ). The car requires 16 (well, 17 if you include the Panhard rod).
bobwhittaker
Posts: 194
Joined: Sat Sep 08, 2012 5:42 pm

Re: Powerflex Bushings

Post by bobwhittaker »

Spoke to Westfield Parts Shop today Tuesday 26 May , no kits in stock and they have only ordered
" Race " spec bushes and expect delivery to them in 4 - 6 weeks , kit comprises of 16 bushes and
is priced at £189.00 including UK VAT . Was told they will not offer " Road " spec even though
shown on website , they may offer " Intermediate " spec but as yet not ordered as minimum order
is 1,000 units . I intend following this up a bit nearer the expected delivery date .
Bob Whittaker
Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Powerflex Bushings

Post by Westfield 129 »

At less than $300 USD, including shipping, but less your VAT, the bushings are far less expensive there then here, where the cost is about $400/set.

As far as "race spec" I would suggest using at least two of the road spec or intermediate (softer the better) bushings at the forward ends of the 4 link add a little compliance.

Otherwise, the race spec bushings will work perfectly well up front, and at the axle.

The nature of the 4 link favors a little compliance.

BTW, even Powerflex is having trouble delivering the soft bushings... I have been waiting for the rest of my order (two pair) for over a month.
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