To polybush or not?

MrMickS

Member
Messages
3,945
The bushes are worn on the rear suspension on my 916 Spider. Specifically those on the shock absorber carrier arm. I've been given a choice of replacing the arms with new ones or to replace the bushes with a polybush set. My understanding is that the polybushes will last forever but give a slightly firmer ride.

I'm sure that this is a choice that the other Spider owners here will have made at some point. It would be interesting to know which way people went and how much of a change the polybushes make.
 

lisknik

Member
Messages
5,524
Not sure about the spider, but I am but I am about to polibush the front of my 33, was advised not to do the rear as the arms don't flex enough... as I said not sure about the 916 though.
 

P R

Member
Messages
1,381
I used to have issues with my 2 156 GTA front ARB bushes. On my last one I fitted poly bushes at around 40k miles. At 160k when I sold it they were still fine.

I know the ARB wont be as noticeable as the arms, but I couldn't really notice any difference.

You can also get different hardness.. (see superflex) https://www.superflex.co.uk/hardnessguide.php
 

midlifecrisis

Member
Messages
16,076
I was having a chat with Maverick on Sunday about this, he's recently done some machining of polybush material and he was telling me that it does come in various densities. This will allow that little bit more 'give' so that suspension arms etc are reasonably isolated from the worse of the shocks. I'm seriously considering re-bushing the suspension of my 4200 as mine are showing signs of age, despite them passing MOT every time, they have the usual 'dry rubber' look to them. Polybushes are the way forward though. They've been around for nearly 30 years. (Used one on my old Suzuki!)
 

philw696

Member
Messages
25,016
I love them.
Use them all the time down here far superior to oe bushes.
We use Nolathane made in Australia.
 

dickyb

Member
Messages
432
Not sure about the spider, but I am but I am about to polibush the front of my 33, was advised not to do the rear as the arms don't flex enough... as I said not sure about the 916 though.

I'd advise you not to polybush the front either, they don't fit very well and are too stiff for the 33 and can lead to cracking on the front chassis legs
 

alfatwo

Member
Messages
5,517
Trouble is there are spherical bearings in those trailing arms that give a certain amount toe out on roll, designed in by Alfas chassis engineers when the car was in the design stage

If you then go and fit plastic bushes everywhere it ruins everything...just stick to the original parts..

This goes for Masers too!

Dave
 

luckesGTV6

Junior Member
Messages
327
This subject keeps coming up on forums.

IMHO Polybushes for the 916 are not in harmony with the designers intent for the rear suspension.

Compare them with the original design concept of the rubber bushes on the early Alfa 916's.
These were cylindrical in form and when they suffered de-bonding of the rubber Alfa decided to use expensive Sphericals rather than inexpensive flanged rubber bushes.

I ask WHY - and offer an explanation.

Flanges introduce conflicts in the suspension geometry as their lateral compliance is increased.
A well known 'Indy' a couple of years ago suggested that their use may be a factor in subframe lug breakage.

The OEM spherical joints will last for years if the protective gaiters are checked for punctures before the salty season.

My 916 is a daily driver still using original 19 year old sphericals in most places.

Replacements I have made are due to my own negligence in the above check.
 

conaero

Forum Owner
Messages
34,582
I polybushed the rear fully of my 916 and it ruined the ride if I am honest.

If I was doing it again and the bushes were the same price, I would go OEM.

You cant deny the fact that if you do polybush the rear, you will never have to do it again.

I would definitely not polybush the front, that would be terrible.
 

alfatwo

Member
Messages
5,517
This subject keeps coming up on forums.

IMHO Polybushes for the 916 are not in harmony with the designers intent for the rear suspension.

Compare them with the original design concept of the rubber bushes on the early Alfa 916's.
These were cylindrical in form and when they suffered de-bonding of the rubber Alfa decided to use expensive Sphericals rather than inexpensive flanged rubber bushes.

I ask WHY - and offer an explanation.

Flanges introduce conflicts in the suspension geometry as their lateral compliance is increased.
A well known 'Indy' a couple of years ago suggested that their use may be a factor in subframe lug breakage.

The OEM spherical joints will last for years if the protective gaiters are checked for punctures before the salty season.

My 916 is a daily driver still using original 19 year old sphericals in most places.

Replacements I have made are due to my own negligence in the above check.

Exactly, polybushes are now over used and a easy way out ...The original designers engineered compliance into the chassis for a reason..

Just because the original bushes failed after a few years doesn't mean to say they were rubbish, they just came to the end of there lifecycle

Original parts guys... as were all beginning see original cars make the best prices!

Dave