Adjustable trailing arm bushings viable?

[Spaceturtle917]

My P.O. installed Kmac adjustable rear trailing arm bushings. I just want to set it to stock camber and toe. But I've heard they come out of alignment pretty easily. I secondly I don't even know how to adjust them.

Would pulling them out and replacing them with normal polys be a better idea?

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[jmile46]

If they are the same as powerflex adjustables, which Id imagine they are. Go to Powerflex’s website and I believe they have instructions for them. Not 100% sure.

[93FIM5]

Spend the extra money and replace with M5 bearing assemblies and never worry about them again. Not sure on KMAC construction but OEM need a hydraulic press to press them out.

Greg
www.AngryAssSolutions.com


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[Spaceturtle917]

Spend the extra money and replace with M5 bearing assemblies and never worry about them again. Not sure on KMAC construction but OEM need a hydraulic press to press them out.

Greg
www.AngryAssSolutions.com


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The trailing arms? In the rear? Are bearings on the m5?

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[moroza]

Yup. E34 M5, E32 740 and 750 had cylindrical (not spherical) trailing arm bearings encased in rubber. The rubber is thinner than the bushings and the ride is presumably a bit firmer. Unlike the normal bushings, they do not resist torsion or axial deflection. Among the consequences are that they can be tightened in the air (though still not officially recommended, I think), last much longer, are more expensive because the bearing surfaces are precisely machined, and place more stress on the dogbones. They still wear out over time, though somewhere I saw someone drill them and the trailing arms to mount a grease fitting; in theory, the bearings can last forever that way, though the rubber boots and encasement will still eventually dry out and crack.

Not having personally done either, I would prefer welded-on tabs, bored-out holes, and eccentric washers for rear alignment, over eccentric bushings.

[fo3]

The best thing about kmacs is that they allow some camber, but more importantly toe adjustment and the factory system doesn't allow that. As to how good they are keeping their setting, get it aligned and then get it checked 3-6mth later. If it's bad then get another aftermarket weld in rtab solution like ireland engineering, if the alignment is good then the kmacs are good. But the answer is never factory rtabs -Ever, especially if you aren't keeping stock ride height - and who is these days?

E: I got my car ~18 months ago with huge sagging rear and camber/toe wear on the tyres. I have literally done nothing on the rear susp yet, ie shocks and springs not changed. I just did kmacs, subframe bushes and tyres.
The rear seemed 'lifted' after fitting, but seems to have settled back down to it's previous lowered height after a month . The camber looks closer to 0 (previously it looked to be 5+ deg!), and toe must have been fixed asthe tyres I bought 18months ago have barely worn, certainly there's no longer any excess inner only or uneven wear like before.

When I can be bothered doing rear shocks I'll probably get it rechecked and see if there was any huge change made, but that's going to be a long long time because I have lots of other issues to deal with (If I had huge funds or my own garage I would have gone for a weld in solution in the first place).

E: I thought I still had the kmac instructions, I know I searched a while back to find them online after I sent my kit with instructions to a mechanic already. I was pretty sure I still had a kmac pdf saved but I can't find it. But anyway, bav auto have a similar eccentric bush kit and they have something which may point you in the right direction (not sure really, as reading through their PDF it doesn't really cover toe adjustment - really any good place with an alignment rack will know about these kits, know their limitations, know that toe/camber is a trade off and these shouldn't be touched if not on an alignment rack anyway)

[ihm96]

The best thing about kmacs is that they allow some camber, but more importantly toe adjustment and the factory system doesn't allow that. As to how good they are keeping their setting, get it aligned and then get it checked 3-6mth later. If it's bad then get another aftermarket weld in rtab solution like ireland engineering, if the alignment is good then the kmacs are good. But the answer is never factory rtabs -Ever, especially if you aren't keeping stock ride height - and who is these days?

E: I got my car ~18 months ago with huge sagging rear and camber/toe wear on the tyres. I have literally done nothing on the rear susp yet, ie shocks and springs not changed. I just did kmacs, subframe bushes and tyres.
The rear seemed 'lifted' after fitting, but seems to have settled back down to it's previous lowered height after a month . The camber looks closer to 0 (previously it looked to be 5+ deg!), and toe must have been fixed asthe tyres I bought 18months ago have barely worn, certainly there's no longer any excess inner only or uneven wear like before.

When I can be bothered doing rear shocks I'll probably get it rechecked and see if there was any huge change made, but that's going to be a long long time because I have lots of other issues to deal with (If I had huge funds or my own garage I would have gone for a weld in solution in the first place).

E: I thought I still had the kmac instructions, I know I searched a while back to find them online after I sent my kit with instructions to a mechanic already. I was pretty sure I still had a kmac pdf saved but I can't find it. But anyway, bav auto have a similar eccentric bush kit and they have something which may point you in the right direction (not sure really, as reading through their PDF it doesn't really cover toe adjustment - really any good place with an alignment rack will know about these kits, know their limitations, know that toe/camber is a trade off and these shouldn't be touched if not on an alignment rack anyway)

How difficult was it to get the kmacs in? My car has some camber that is noticeably worse now that I have the smaller 15" 205 winters on my Coupe

[fo3]

The hard part is getting the old bushings out, typical drilling, burning or heat gun and home made janky press. Install is easy being a 2 piece bush.
My tyre shop didn't have much hassle or cost in setting them up for alignment. By memory they minimized toe because that's what I told them to do. I think -0.9 deg neg camber was the best they could get given toe being most important IMO.

[Spaceturtle917]

I have access to welding through me dad for free. Could I install weld on kit without dropping the subframe or the arms?

Though I really just want to minimalize tire wear. Could I do that with new standard poly bushings?

The kmacs I have are cracked and worn and I think I should just replace them anyways they seem like a pita.

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[Hofmeister]

I have access to welding through me dad for free. Could I install weld on kit without dropping the subframe or the arms?

Though I really just want to minimalize tire wear. Could I do that with new standard poly bushings?

The kmacs I have are cracked and worn and I think I should just replace them anyways they seem like a pita.

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for welding you must drop subframe. For bushings only you only have to drop the arms. I did the powerflex ones a couple of months ago and it was a PITA

[Spaceturtle917]

for welding you must drop subframe. For bushings only you only have to drop the arms. I did the powerflex ones a couple of months ago and it was a PITA

They were a pain just to remove though right? I already have kmacs in which are too peice. I can't imagine they would be too hard to remove.

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[Hofmeister]

They were a pain just to remove though right? I already have kmacs in which are too peice. I can't imagine they would be too hard to remove.

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everything was a pain. it may have been easier had i done it at the shop instead of my driveway, but every step gave me trouble. The bushings stick out a bit more than oem so putting the arms back in isnt too fun.

[moroza]

Not having done it, I would think that there's sufficient access to weld on the adjustment tabs with the subframe in place, but it'd be overhead welding which is harder. Arms definitely have to come out.

The OE bushings (and bearings) are a *very* tight fit in the arms. The bang most of mine made when the 20-ton press popped them loose was comparable to a small gunshot. Consensus is that even using a grade 12.9 M12 threaded rod in a puller assembly is not strong enough to remove them. I initially tried to lay a single piece of steel tubing diagonally in the press. No dice; the force required was so high that it twisted the whole press like a helix. Welded up this contraption and it worked:

Picture 2187.jpg

[Spaceturtle917]

Not having done it, I would think that there's sufficient access to weld on the adjustment tabs with the subframe in place, but it'd be overhead welding which is harder. Arms definitely have to come out.

The OE bushings (and bearings) are a *very* tight fit in the arms. The bang most of mine made when the 20-ton press popped them loose was comparable to a small gunshot. Consensus is that even using a grade 12.9 M12 threaded rod in a puller assembly is not strong enough to remove them. I initially tried to lay a single piece of steel tubing diagonally in the press. No dice; the force required was so high that it twisted the whole press like a helix. Welded up this contraption and it worked:

Picture 2187.jpg

But I already have the kmacs installed so I don't think it would be the same as factory removal

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[93FIM5]

There are a lot of bad ideas floating around here. If you wanna go cheap drill and suffer with KMAC. If you want to do it right drop the subframe, replace all of the bushings and weld on adjustable tabs. Then you have bearings vs bushings and complete adjustability as the factory would of done it. Seriously don’t half ass it, let us know if you need the work done and we’ll do it. We also rent the tools to press out trailing arm bushings and subframe bushings (including differential bushings). Come on guys stop trying to find work arounds when the options already exist.

-Greg
www.AngryAssSolutions.com


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[5senses]

There are a lot of bad ideas floating around here. If you wanna go cheap drill and suffer with KMAC. If you want to do it right drop the subframe, replace all of the bushings and weld on adjustable tabs. Then you have bearings vs bushings and complete adjustability as the factory would of done it. Seriously don’t half ass it, let us know if you need the work done and we’ll do it. We also rent the tools to press out trailing arm bushings and subframe bushings (including differential bushings). Come on guys stop trying to find work arounds when the options already exist.

-Greg
www.AngryAssSolutions.com


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Need to use the rtab tool Greg... PM me

[Spaceturtle917]

There are a lot of bad ideas floating around here. If you wanna go cheap drill and suffer with KMAC. If you want to do it right drop the subframe, replace all of the bushings and weld on adjustable tabs. Then you have bearings vs bushings and complete adjustability as the factory would of done it. Seriously don’t half ass it, let us know if you need the work done and we’ll do it. We also rent the tools to press out trailing arm bushings and subframe bushings (including differential bushings). Come on guys stop trying to find work arounds when the options already exist.

-Greg
www.AngryAssSolutions.com


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As much as I agree with you here. This is my daily driver and I don't have the time to drop the whole thing and weld on adjustable stuff. My main question here was if replacing the kmacs with normal poly bushings would fix my inner tire wear. I don't think I need adjustability when I'm lowered 0.75" in the rear.

[93FIM5]

Definitely worth a shot if the KMACS can be removed without a press and new polys dropped in (again without a press) never installed either so cant comment. Best of luck.

-Greg
www.AngryAssSolutions.com


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[93FIM5]

Need to use the rtab tool Greg... PM me

PM’d sir.


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[fo3]

As much as I agree with you here. This is my daily driver and I don't have the time to drop the whole thing and weld on adjustable stuff. My main question here was if replacing the kmacs with normal poly bushings would fix my inner tire wear. I don't think I need adjustability when I'm lowered 0.75" in the rear.

2 main faults with e34 design, the steering box, and always wore rear tyres bad even when new. IMO you need adjustability for toe and camber - that's why people are still making them for a 30 year old car.