UKKid35

I can't decide whether to replace the rubber bushes with Delrin

I replaced the original bushes with new rubber about 10 years ago

I have bought a set of 2 part Delrin, but they are rock hard and have no compliance at all

The rubber bushes currently fitted don't appear to need replacing, but I have just had the rack seals replaced so the rack is off the car

Although I've replaced the bushes before, I can't remember how I did it, I know I didn't have access to a press, and I'm not even sure whether I removed the rack completely

My other car (not a 928) has the rack bolted directly to the chassis with no obvious negative consequences, so why did Porsche use rubber bushes?

Surely they are there for a reason?

The Forgotten On

They're there for vibration isolation.

I would stick to the original rubber bushings, especially if they are still good.

The delrin is a heck of a lot harder and will give more direct steering feel at the expense of more vibrations in the cabin. It's a trade off.

I personally prefer the rubber bushings as it helps maintain the 928's character of being a GT car.

DeWolf

Auto or manual. Like Blake says it is a GT car.......at least in auto form. In manual form it's a true grit sports car. I just got my old girl on the road after a 2 year build and used the Delrin from Roger. Great steering feel and I haven't noticed any unusual vibrations.

UKKid35

Manual, and it gets used on track more often than I'd like

FredR

I would suggest the first question you need to resolve is whether to change or not. Clearly you have the DIY capability so the only difference between leaving as is or change out is the cost of an alignment and although custom and practice suggests a new alignment would be needed, I suspect the difference before and after alignment will be minimal if the current bushes are good and were fitted for your current alignment.

As to the auto/manual discussion I think that is a bit of a red herring. I have an auto with the Delrin bushes and find it is perfectly OK but then I find 18 inch wheels with wide rubber quite OK and Eibach springs that are 25% stiffer perfectly OK. I dare say some would drive my car and be horrified in case their fillings or false teeth drop out.

Bottom line it is simply a question of what takes your fancy versus the inclination to do such. If your current bushes are OK and do the job, unless they have been sat soaked in power steering fluid they should be good for another 10 years I would think.

SRaouf

I've just fitted aluminium bushes ordered from Roger, after doing some research into pros and cons on this forum and would rather not have to ever change them again. The aluminium bushes just press in with a light tap using a rubber mallet. Cant help with fitting as both rack and engine were out of the car but I would certainly try to fit with the rack in situ in the first instance. If you do remove the rack dont forget to use a centering bolt to lock the rack in the center position.

UKKid35

If you have one that I could borrow that would be great!

SRaouf

Youre welcome to borrow it although its one i made myself with a grinding wheel so not the prettiest. PM me your address and Ill see if I can find it over the next day or two.

merchauser

factory OEM centering bolt is 000.721 913.20 and only about $10.

SRaouf

Ive texted you

StratfordShark

Paul I didn't need to remove rack entirely to fit the Delrin bushes, but I did have it unbolted from x-member of course, and removed the PS lines.

The original rubber bushes weren't bad at all so it was just a WYIT during an engine mount change — there wasn't much in the way of leaked oil on the originals. I replaced inner and outer steering rods at same time which had about 75K on them, so it's impossible to say what difference the new bushes made, but afterwards the steering felt very smooth and positive, and I wasn't aware of any extra vibration at all. I understand the aluminium bushes will create noticeable vibration.

UKKid35

Thanks Adrian - much appreciated

PorKen

Rubber, solid mounted

https://rennlist.com/forums/928-foru...ml#post7085294

Garth S

Are the 'cans' on your rack bushings rolled over ( thereby fixing the bushing to the rack) or simply pressed in to the OE flared flange of the bushing?

I had played with the non flared version many years ago .... and had added aluminium wire 'rings' to remove slack between rack ears and chassis, as seen in https://rennlist.com/forums/928-foru...down-long.html this link.

Billu