Urethane Vs Genuine Rubber Bushes.... opinions?

Post by **Aidan** » 07 Dec 2006, 21:39

a new rubber bush is remarkably pliable considering it's got a steel rod through it - you can compress it by 1/3 it's diameter to get it into the control arm - that's a lot of give to help absorb shocks and rotational forces.
I have the genuine tool for pressing in the front bushes if required.

Post by **sonic23** » 08 Dec 2006, 14:08

Well thanks for all the input. It's made for very interesting reading.

Seeing as I aim to use this van off-road, it looks like opting for genuine rubber makes a lot of sense. Still approx £100 for 4 genuine upper wishbone rubers is quite a hit on the wallet, when taking into consideration all the other bits to buy..... but if it all lasts another 10 years+, then it's money well spent.

Rich

Post by **Simon Baxter** » 08 Dec 2006, 19:13

Just a thought.
On a off road vehicle then more axle articulation is a good thing right? Keeping your wheels on the ground where they belong and all that, more wheels on the ground more traction.
Okay, the standard rubber bottom arm bushes have 3 "teeth" cut into the metal sleeve to get it to "bite" into the chassis where it mounts.
So, when the rubber bush is fitted and the bolt tight, when the arm moves the rubber twists giving a certain amount of resistance to arm movement.
With the poly bushes the sleeve is designed to turn in the bush, giving less resistance to the arm moving and in my opinion giving greater ease of arm movement.
Just a thought.

Another thought is that the upper wishbone bushes although rubber have a nylon sleeve between the rubber and the metal outer to allow them to twist with less resistance. Make of that what you will.

Just ramblings..

Oh, and the "good enough for VW" comment, just remember that car companies are also run by accountants, a cost saving here or there makes more profit in an already overpriced product. Poly uretahne is more costly that rubber.

I have a few customers with poly bushes fitted and their vans certainly aren't vibrated to pieces, nor do they wear ear protectors when driving.

Again, I like them but I would say that wouldn't I!

Poly bushes, good enough for Gordon Craig... Good enough for me!

Post by **HarryMann** » 08 Dec 2006, 19:46

Poly-urethane is more costly that rubber.

Yes, 10 times 'ish

Design-engineers do know what they're doing, even VW and SDP ones

but they are also masters of compromise - it's imbued in their education and sometimes even, their make-up. Cost is just one of many factors though, and not always high up the list.

Polyurethane bushes were not developed to such a level when these vans were designed, so whatever the [cost] compromises made at the time, I doubt this was one of them.

This makes interesting reading from an off-road point-of-view, but once again, it is hard to find independent appraisals...

http://www.polybush.co.uk/4x4.html

Post by **Simon Baxter** » 08 Dec 2006, 20:00

Yep, masters of comprimise.
But if VW/SDP did such a brilliant job why do people lift their suspension, fit longer springs, different dampers, wheels, tyres, use fancy oil in their gearboxes, put different engines in la di da...

VW and SDP built a van, but it was built to suit a broad range of people and conditions, like noted comprimises are made, some to cost, some for economy, some for power etc..

Post by **toomanytoys** » 08 Dec 2006, 21:00

What combination of classic red/comfort blue are the T25 kits then Si??

Post by **Simon Baxter** » 08 Dec 2006, 21:16

Purple.

Powerflexes special blend to keep T3 owners happy.

Post by **HarryMann** » 08 Dec 2006, 21:24

The only possible answer

but it is a very pretty poirple I must say!

Post by **Simon Baxter** » 09 Dec 2006, 00:00

syncroandy wrote:
For the ball-joints, only use the best OEM (Febi again)

Last OEM ones I bought were made by Lemforder, that was about a month ago.

Post by **HarryMann** » 09 Dec 2006, 00:12

I have so far failed to find any evidence that polybushes wear out/fail/tear/compress in any way quicker than rubber ones. Quite the opposite in most cases, including the review below, coming from Bonaprene's website..

http://www.bonaprene.co.uk/products/sus ... bushes.htm

The Mercedes 309-814 and Vario range of buses are the workhorse of the First Bus, Stagecoach and Arriva bus fleets.

Mercedes Bus

The constant stop-start regime, poor roads and speed bumps cause havoc to their van derived suspensions. High bush wear leads directly to the bus not being out earning money.

For over 10 years we have been supplying the after sales market with Polybush link, spring eye, anti-roll bar clamp and shock absorber bushes for this range of buses. Our specially designed link bush is shown below:

Bush

These link bushes trialed at Travel West Midlands and First Bus PMT exceeded 50,000 miles of 12 months and still did not need replacing. This compared exceptionally well with the 6 - 8 weeks and 6,000 miles that they used to get with rubber bushes.

I don't think they'd get away with that as advertising material if it didn't represent fairly well the facts. It's supported by material test data everywhere and countless other reports..

Seems that whilst rubber is much cheaper, it's tooling is much more expensive with longer lead times so is suited more to high volume production.

Urethane seems better in most respects, when designed and graded correctly, other than that currently industry capacity couldn't cope with large production runs for OEM manufacturers...

Let's hope we are getting nearer the truth about these replacement bushes

Post by **bigbluebus** » 09 Dec 2006, 09:18

go on Andy, buy some and see.....

errrr . . no ha ha

Cheers Aidan, I did imagine brand new rubber ones would start life pretty damn solid (hence the requirement for special tools / presses to fit).

I'll stick by my choice to fit them, if, as promised they maintain the current level of increased stability & feel I'm enjoying (with no discernable increase in road noise / vibration) I'll be a happy man