poly bushes

Post by **aupickup** » Fri Jun 13, 2008 7:46 pm

ok so bmcecosse reckons that poly bushes can crack certain areas if we use these

can any one throw any light on this subject

Post by **minor_hickup** » Fri Jun 13, 2008 8:04 pm

They don't damp vibration as effectively (being harder) so can therefore place mountings under more stress and cause them to fatigue.

Post by **jonathon** » Fri Jun 13, 2008 8:30 pm

I can only add that all bushes, be suspension or other wise have a shore rating which is normally adhered to by the major manufacturers of poly bushes. We only supply Superflex bushes for this very reason.
A while back hard nylon bushes were popular 'upgrades' which really were not suitable for road use and carried only the properties of the parent material rather than an engineered reference point.
The popularity of the Poly bush has led to some fringe companies cashing in on the limited knowledge of the buying public, by producing poor quality non specific bushes which were not at all suitable for the wide variety of applications.
We have been using Superflex for over 10 years on both standard and heavily modified minors and have yet to encounter either a problem with a bush or the area to which they are fitted. Over 5,000 miles have been covered on the race track in this period, which is where any potential problem would be highlighted.
Use poly bushes , but be sure of their suitability and construction before purchasing, and do not be tempted to always buy the cheapest, as they are often false economy.

Post by **bmcecosse** » Fri Jun 13, 2008 8:38 pm

I agree - black nylon is certainly not suitable. It's great stuff and I used it in 'industry' before i retired, but not suitable for road going cars. May be ok on 'racer' as an alternative to Rose joints.
My comment on cracking refers mainly to the front chassis legs - these are prone to stress cracking anyway - and any harder/less resilient bush can only tend to increase this risk. As long as owners are aware - and carry out regular maintenance and inspection - there should be no problem. I used poly bushes on my 1380 Mini - and they were great, and I do have them on the top king pin/damper link on my Minor where they do a grand job.

Post by **aupickup** » Fri Jun 13, 2008 8:46 pm

thank you jonathon

Post by **PAULJ** » Fri Jun 13, 2008 8:52 pm

Who would supply superflex please

Post by **Packedup** » Fri Jun 13, 2008 9:05 pm

I'm not tremendously happy with the squishiness of the n name poly ones I bought from a well known supplier - But I am content I got my moneys worth, if that makes sense?

If funds had allowed, I would have fitted Superflex, and if I do keep the pickup then one day if I ever have spare funds, I *will* fit Superflex anyway, regardless of how well the no names have lasted by then.

My Midget has Superflex all round, and I haven't noticed (not really looked either) any problems from using them. In terms of feel, quite the opposite, the car is much tighter and precise than on rubber.

Post by **jonathon** » Fri Jun 13, 2008 9:56 pm

Superflex bushes are more expensive than most ,mainly only at full retail price. A substantial discount can be had if you track down suppliers, specific to minors, if you know what I mean

Superflex also do two types of bushes, the 'classic' range which is more suited to standard cars and the 'sports' which is more oriented towards modified cars.
Uprated bushes should be viewed as any other modification, in respect of the condition of chassis in key areas, only if you are 100% sure of its integrity, should you modify. Also if fitting uprated bushes, you are also likely to have fitted better suspension,handling packages and uprated brakes and wider tyres, all of which will be adding their own challenges to the structure of the car, so always view mods as a whole and not necessarily as individual components.

Post by **rayofleamington** » Sat Jun 14, 2008 6:09 pm

I've seen a new replacement chassis leg fail in record time - due to missing welds between the skin and the inner strengthening for the eyebolt. I've had one faild due to rot. Both had standard new (rubbish) bushes. If the chassis leg is poor in this area it will fail - regardless of other problems.

As for poly bushes - at least half the minors I've bought have had metal to metal contact in the front eye bolts!! Some of them had been like that so long that the pivot pin through the eyebolt has worn through over half of its diameter! If that doesn't lead to a cracked leg by the eyebolt, then I have vey high confidence that poly bushes do not make a significant influence.

Post by **Stig** » Mon Jun 16, 2008 8:03 am

I have to agree with Ray on this one, I'd blame the chassis leg rather than the bushes if it started cracking. I fitted hard plastic bushes in the eye-bolts some years ago (before poly bushes were so widely available) and there's no cracking yet - I'm not recommending the hard plastic at all, but if they haven't caused any problems then poly bushes will be fine. Ignore the scare stories.

Post by **Spag** » Mon Jun 16, 2008 8:41 am

Paint the underside of your car white, or a light colour, and the same for any suspension mounting points or stressed areas.
Cracks show up oh so much quicker on a light colour and the extra 'passive' light working under the car is fab !!!

Post by **bmcecosse** » Mon Jun 16, 2008 9:25 am

I agree - it's the chassis leg structure that is the weak link. Poly bushes there may just push a marginal leg over the cliff!