Polyurethane bushes

[BDA]

I'm considering replacing the rubber bushes on the front suspension with polyurethane bushes. If you have any experience with them, have a few questions:

How easy are they to install? I understand they don't require a press but they all have a shoulder on both ends and unless they are pretty soft, it looks like it might be difficult to get that shoulder all the way through the A-arm.

How soft are they? I assume they are stiff enough to provide the same functionality as the rubber bushes but the rubber bushes use very little rubber that is probably pretty stiff itself so the bush is very stiff as a unit. I wonder if a poly bush soft enough to squeeze through the A-arm would be much softer than the bushing it replaces and thus perform differently.

How do they work? I assume the clamping force is applied to the stainless steel sleeve that runs through the center. Since I believe lube that is provided goes on that stainless steel sleeve, the polyurethane part does not move relative to the A-arm. Do I have that right?

I know that the suspension does not have to be at ride height when it is torqued down unlike for the rubber bushes. Is there anything else I should know about them? If you have them, do you like them? Do you sense any difference between the polyurethane and rubber bushes?

[Arizona]

I've used them but only on shock mountings and sway bars. They're very hard but after soaking awhile in boiling water they soften up enough. They have a tendency to squeak, especially in cold weather.

[jbcollier]

They are easier to install than the bonded rubber bushings as you install them without the center SS pin.  The softness varies depending on the compound chosen.  But they still flex so installation is still ok. Yes, the bushing stays put on the arm and rotates on the SS pin so you lube the pin/bush area.  Use anti seize between the SS pin and the arm pin.  +1 on the squeaking.  Water can wash the lube out making it worse and possibly leading to corrosion issues even with SS pins.

Personal preference is for the stock rubber bushings.  Installation is not that much harder and no squeaking or corrosion issues.  YMMV

[Kendo]

What about tightening up the suspension at ride height vs jacked up, rubber vs poly bushings? That part had me confused.

[BDA]

Thanks JB & Arizona. I appreciate the information. I haven't made my decision yet.

Kendo, the rubber bushes are obviously retrained by the A-arm on the outside and the compression by the tightened nuts on the pivot pin so all the rotation is in the rubber in the bushing. (I hope that makes sense!) The rubber in the bush can only rotate so far before it will tear. If you tighten the nuts on your pivot pin with the suspension a full droop, when you hit a bump, the suspension may rotate enough to tear the rubber. By tightening the nuts on the pivot pins at ride height, you'll be somewhere in the middle of the suspension travel so you won't tear your rubber in bumps.

It's pretty easy to accomplish this. With the car on stands and the pivot pin nuts, lower shock mount bolt, and trunnion bolt loose, jack up the upright end on the disc till that corner lifts the car off the stand. Make sure you don't catch the trunnion on your jack. I have a rubber pad on my jacks but I don't think that's really necessarily. You can now tighten all the nuts on the pivot pins and the shock and trunnion.

[SENC]

I put them all around on my Elan - easy installation, no squeak, no noticeable impact on ride quality.  I'd have to look back to confirm, but think I used PowerFlex.  I've ordered some urethane rod so I can make some for the rear a-arm on my Seven (at least for the section that attaches under the diff that tends to get eaten up quickly).

Note that the central ss crush tube needs to be fractionally longer than the urethane bush, and that you're likely to need to add thrust washers as many of the kits don't include them.  Col Croucher (elantrikbits) wrote up a nice bit on polyurethane bushes on his blog a few years ago.

[BDA]

If I get them, these are the ones I’m thinking (https://autobush.com/8/Lotus/Elan-Twin-Cam) I’ll get but I’ll look around more since there seem to be more options than I was aware of. Thanks SENC.

[EuropaTC]

Hi there,

I fitted them to the Europa front suspension way back in 2015. From memory they weren't hard to press in but getting past the shoulder at one end meant I needed a vice, they weren't a "push in by hand" fit. The stainless crush tube goes in last and you get a tube of lubricant as well. I think the bore of the poly bush had rifling grooves for the grease but that could be memory playing tricks.

I bought the same ones you have in your link. The service was quick and afterwards I emailed them to say that the same bushes fitted the Europa. Back then they only listed the Elan, and only for the wishbone bushes.

An easy enough job. Initially impressive but with hindsight I think that was down to the old rubber bushes being tired, they'd been in there for many years.  The biggest advantage I see now is that you can tighten up the suspension whenever you like, you don't need to set to ride height like you do with the OEM bushes.

Having said that, a year later (2016) I bought new front wishbones for the Elan and fitted OEM rubber/steel bushes.

Brian

[Pfreen]

Rubber bushes last longer, as long as oil isn't all over them, since there isn't sliding motion with them like urethane bushes.

I just sent back to my vender urethane bushes and replaced them with rubber oem bushes for the Tiger because many people complained about how long the urethane lasted.  They are not the easiest things to replace.

[BDA]

Thanks Brian and Pfreen! Good stuff to know.

BTW Brian, Autobush didn’t listen to you. They still don’t list them for Europas!