Rear Axle Poly Bushes

[retepsnikrep]

I have been working with my local garage on an insight Mk 1 rear axle assembly after I recently replaced one in one of my cars.

The axle contains two large rubber bushes which are not available from honda as seperate items. ASFAIK You have to buy the complete axle assembly at a cost of over £500.

Anyway to cut a long story short with the help of their press I mananged to get the one good bush out of my old axle and this was sent to a well known UK poly bush manufacturer for evaluation.

I now have a rough price and tooling costs for a run of 10 poly bushes, which works out at around £150 a pair. This is a massive saving and they should be much harder wearing and give more feeling to the rear suspension setup.

If anyone is interested in a pair e-mail me asap at 150mpg@googlemail.com

I intend to place an order next week, they will carry no guarantee whatsoever as this is the first run. I'm prepared to put the money up for the first ten as a calculated gamble.

If they work out I may well approach them with a sample bush from the front suspension arms which wear/dry out as we know giving the well known scrunching noise problem.

I'll try an post some pics of my disasembled rear axle to illustrate.

Peter

[jonnyvtec]

Nice work Pete.

Just out of interest what sort of dimensions was the original bush? If it one bush or is there a seperate thrush washer? I think one of the issues with the Insight stability is the sideways motion of the beam isnt controlled by the bushes and relies on the damper, the Jazz, Civic, Insight II and CRZ all now feature angled beam bush axis.

Do you have any pictures of it stripped down at the rear end?

Sounds good for cost, my only concern would be uniform compliance due to the poly is X and Z and then possibly more stiffness if there any toe change that occurs when only one side is in bump. Trailing arm bushes on other Hondas can make them a bit more prone to oversteer, which in mine is terrible (probably tyres), although that was on the far more complicated setups with the passive rear steer and toe changing independant rear setups.

The Insight rear suspension is quite agricultural so noise from stiffer bushes could be quite marked?

What shore rating are you looking at going for? This could be a really good mod to connect the rear end though

Thanks

[retepsnikrep]

Too many technical questions for me at the moment jonny. I'll pass them onto my partner in this. My knowledge is minimal in this area. I'll post some pics in due course but don't have the bush to photograph as it is with the poly man as a pattern. be a few weeks before we get any more updates I expect. Peter

[retepsnikrep]

This project is still ongoing and the manufacturer Powerflex is starting on our first prototype batch of 5 pairs of bushes next week. I'll be testing a pair and so will the Rally chap, that leaves three pairs. PM if interested.

[jonnyvtec]

Pete,

Good to hear, very interested in the results.

What size OD of the bush?

Cheers

[retepsnikrep]

50mm if I remember correctly. Powerflex are being slow but I hope we get them eventually! I'll keeps us posted.

[retepsnikrep]

Sadly Powerflex UK failed to deliver any bushes after having our pattern for over six months!!! Useless and continualy lied on the phone that they were nearly finished. So we are back to square one looking for an alternative supplier Any ideas?

[jimrm]

There is a company called Smooth-on that makes pourable polyurethanes. One called PMC-790 might work. It is 90 Shore A which is about as hard as a typewriter roller if you are old enough to remember those. Just pour your own. PMC®-790 Urethane Rubber Product Information | Smooth-On
Jim

[Hugh-Falls]

Once the durometer and sections of the existing bushings have been determined, it should be possible to machine a suitable replacement from readily obtainable polyurethane bar stock that is available from a die maker's supply house. This material is used in place of metal coil springs in stamping and forming dies. Assembling the outer housing, the rubber, and the inner steel bushing may require some simple tooling.

These Insight bushings employ the rubber in shear and compression similar to most automotive/truck spring shackle isolator bushings which are available in many, many sizes at very reasonable prices. It is possible that the Insight bushing is a standard size and is available at your friendly auto supply store. If the exact size is not found, suitable press on/in sleeves could make up a fit.

[3-Wheeler]

Originally Posted by Hugh-Falls

....Once the durometer and sections of the existing bushings have been determined, it should be possible to machine a suitable replacement from readily obtainable polyurethane bar stock that is available from a die maker's supply house.....

Hugh,

How would you machine the poly material???

Over the years I have machined rubber in a small South Bend lathe, but it involved the use of dry-ice to "freeze" the rubber and make it hard enough to actually "cut" material from the rubber.

At room temperature, the only practical way I know of to machine rubber is by high speed grinding, which creates a lot of dust and is slow.

Jim.