Buying poly bushes, help needed !

[tuna]

Hi guys, apologies if this has already been covered but couldn't see anything via the search feature. Basically the entire front end of my e30 needs its bushings replaced, and as I tear through rubber ones I decided to get some poly bushes, now I've come across a couple of small obstacles.

First off I want to say that my e30 now houses a m20b25 with 51mm struts but was manufactured as a m40b16, however the ARB is still from the 316, alongside wishbones and drop links. Now when attempting to purchase some polly bushes im asked to specify two things;

What size front ARB bushes are required, the sizes range from 18mm - 24mm and each mm in between.

Secondly, it askes whether I need Eccentric or Concentric bushes? I've heard that the offset bushes are better but for what reason?

Anyway any help would be appreciated, thanks

[Grrrmachine]

Are you tracking the car? Many will tell you not to bother with Poly.

For OEM bushes, order the parts listed in the Wiki:

http://www.e30zone.net/e30zonewiki/index.php/Bushes

For your ARB, you can check the Wiki chart:

http://www.e30zone.net/e30zonewiki/inde ... i-Roll_Bar

or you can identify the size yourself using this guide (which talks about Rear ARB but the principle is the same):

http://www.e30zone.net/e30zonewiki/inde ... tification

As for Eccentric vs Concentric - the Eccentrics change the caster angle of the front wheel, which is usually set for self-correcting steering but, in track applications, has an affect on cambering when cornering, so you get better cornering behaviour:

http://en.wikipedia.org/wiki/Caster_angle

[mattbarber660]

You'll have to measure the ARB where it meets the bush to find out what size you have. There's a section about it on the wiki here: http://www.e30zone.net/e30zonewiki/inde ... i-Roll_Bar I just measured mine with a vernier calliper.

My car is a 320i and has a 18.5mm ARB which is annoying as powerflex don't make one for that size, hopefully they make one for yours otherwise you're stuck with rubber ones.

If you're doing all the front bushes yourself you'll want to read the wiki about replacing bushes.

You'll also need a few tools. I used a vice, a big socket and a smaller one to get the lollipop bushes out.

A gear puller to get the lower rear bushes off of the wishbone, then a hole saw to cut through the rubber and a hacksaw to sut through the metal ring.

Not the funnest of jobs! Good luck!

(I didn't use the eccentric bushes but apparently they make a difference to the steering by changing how the wishbone sits. Don't quote me on that though! I'm sure someone else will correct me!)

[tuna]

No im not tracking the car, and to be fair I don't really drive the car hard, I plan on taking it to santa pod in September but that's about it. I've heard poly bushing isn't worth it for every day driving as it compromises the comfort of the car but if you have seen any pictures of my 30 its pretty darn low, and that's how I like it, and because of that I seem to get through bushes pretty fast. Im not that fussed about comfort, is there any other reasons NOT to get poly bushes? Anyway thanks for the reply grrrmachine, that should be enough info for now

[tuna]

Thanks for the reply matt, I have a e30 mechanic who loves playing with e30's so im sure I can encourage him to do it for a crate I was aware of the difficulty of replacing bushes hence why im not bothering to do it myself

As for now im just doing the front, plan on replacing rear subframe bushes when I upgrade the rear end.

[milescook]

If it helps give you a small idea on the lolipop bushes, these are eccentric powerflex with the added bit for more castor (and require a bit of technique to fit):





Personally I don't think it looks much different, but as they say it does help the feel and camber on corners.