Now the show season is pretty much over, and the weather isn't horrendous yet, I thought I'd finally replace the bushings. I know I have a few that are badly perished and worn, and I am now feeling slightly vague handling with the occasional slight knock when changing directions.
So, should I go rubber or polyurethane? Is there really much of a price difference between the two? Is poly much more durable than rubber? Approximately how much would you expect to pay for a full bush refresh for rubber and poly?
I've been looking at www.camskill.co.uk, mainly because they have pictures that easily show the bushes you need to buy. It does list a range of size options though, and I'm not entirely sure what sizes to buy. Has anyone come across a 'pack' for a specific car, rather than ordering each individually?
While I'm there, would you recommend replacing anything else such as CV Joints, etc?
The OEM bushings allow compliance that assists the suspension but reduces induced vibration and stress into the car and mounting points. When the 944 was designed it had (compared to todays cars) a relatively high tyre sidewall aspect ratio and this together with the suspension design meant a fine handling car. Larger wheels with very low sidewall ratio tyres cause all sorts of problems - search for advice on this aspect and you`ll see what I mean.
If you have a track biased car then poly (type) bushes reduce movement but are harsher. Going cheap with poly (type) bushes can be a problem as they are rated by a 'shore' scale of compliance. Cheap ones are absolutely solid and can squeak no matter what lubricant you use but I would recommend you do a search for other opinions.
Going full poly (type) bushes can induce stress fractures at mounting points.
Having said all of the above OEM 968 castor bushes are a good upgrade as they reduce the amount of rubber involved
I do not have a massive amount of experience with 944s truth be told but I have changed quite a few bushes on many a car over the years for my sins! Hilux has hit the nail on the head for me though
IME, I would try to go with genuine bushes if it is a road car or for OEM bushes through a known supplier if it is a road car. The only place I would make an exception (at least for me) is for the ARB bushes where I would go poly (and oil change etc. seem to get them wet in oil (or at least the O/S, resulting in the bushes balooning out; this could be causing your knocking), and the 968 castor mounts.
The 944 is not the only car that is susceptible to fractures with poly bushes. My Stag is (rear damper bushes) as are Mazda MX-5s with wishbone bushes. As it has been said, many of the cheaper bushes are made from a shore rating that is simply far too hard for the application, in addition to being of a poor quality (Classic Mini owners here will know what I mean regarding Poly engine mount bushes which seem to oval/deform).
Superflex bushes seem to gat around this issue and last quite a long time (I know whenever I have used them, the ride does not seem to be impaired and the last time I checked my Stag still had good damper mountings in the rear aluminium trailing arms which seem to snap with the cheaper items). On many a car I could not really tell the difference between a new rubber bush and theirs. Cheap however they are not (well, in comparison to rivals). I know others have reported a great success with them too .
I have Floflex bushes on the front of my S2 with 968 castor mounts and SAR additional ARB supports brackets and no problems over the last 2 yrs. Not too hard on our rough local roads either.
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