Subframe swap project

#121

My right toe turned out to be all out of whack after Mid-O. I had about a 1/4" of toe out which is pretty treacherous stuff. This is particularly irksome given that I didn’t push the suspension hard in the 5 days at Mid-O.

The problem is that the toe adjuster rotated. Probably because the bushing is binding on the aluminum sleeve inside of it.

Jim Levie is fighting the same issue with his.

I had a helova time getting the cam bolt adjuster rotated back last night. It was 3 hours of failed attempts and ideas. If I ground my wrench down anymore it wouldn’t exist. I tried all sorts of combinations of bending and grinding but couldn’t get the wrench on. Finally what I did is to weld a bolt on to the eccentric plate that sits under the nut. That gave me something to grab and pull such that I could adjust the rtabs location with either eccentric.

In a measure of my desperation I was grinding and banging up until 11PM last night, risking the wrath of the high strung cutie next door.

I’m going to have to drop the subframe after RA, pull the rtab bushings out and remove a little material from the aluminum sleeves.

#122

Which adjsusters (AKG, Dungeon or something else) are you using? I don’t have a problem with mine moving, but make sure the bolts are super tight.

#123

Mine are AKG. I’ll get the bastards as tight as I can.

#124

They never should have changed the rule to allow for these weld on camber toe kits

#125

I disagree. It’s a good thing to have options. Ranger was going his own way with using aluminum bushings and I haven’t heard of anyone else having a problem with the weld in kits. I heard bad things about the AKG bushings shifting and that’s why I went with the weld-in kit.

#126

I have yet to have my rear alignment survive through a race weekend. So far I’ve tried Powerflex and OE bushings. I have a set of AKG bushings on the way. I’ve been able (with modified) wrenches to get the adjusters pretty darn tight, but apparently not tight enough, or so I thought.

Last week I found that I’d run out of toe adjust on the left side, which means that the trailing arm is bent. While swapping it out I think I’ve found why the alignment drifts. There was noticeable scarring of the bushing inner sleeve ends and the inner faces of the mounting tabs. That suggests that the bushing sleeve is trying to rotate. That doesn’t happen in the stock configuration, but with the weld in kits the surface area where the sleeve hits the tabs has been reduced by the slots. Which means less clamping force.

The OE bushings have fixed sleeves and the Powerflex have sleeves that are effectively fixed (they have to be pressed in). It seems to me that a looser fit between the sleeve and bushing is needed so that rotation will occur between the bushing and sleeve. If the AKG bushings are tighter than I want I’m going to turn down the sleeves and see if that helps. The only thing I know to do past that is to tack weld the adjusters after alignment. Which would mean having to drop the subframe and grind off the tacks before a future alignment.

#127

My rtab bushings aren’t aluminum, it’s the subframe and diff bushings that are Al. Jim Levie is having the same problem I am.

I may have caused some of my own problems tho. Isn’t that a shocker? When I installed the rtabs months ago I had to drill out the aluminum rtab sleeves to get the bolts thru them. That was not easy. In one or two cases I had trouble with the sleeve locking up on the drill bit and I had to work that sleeve free. This marred up the sleeve. Then I attempted to repair the damage done to the sleeve by sanding off the marred material, but maybe some of that marred material on the sleeve is preventing the bushing from rotating freely around it.

So I damaged one or two rtab sleeves. Maybe one of them is at RR toe, I didn’t keep track.

It was so damned impossible to get to the adjuster bolt last night I started thinking fondly of inserting the bolt pointed outboard. But I’d hate to reopen that whole can of worms.

I think that allowing weldable adjusters is a good thing. The eccentric rtab kit is a kludge. They force folks to make compromises on alignment and that isn’t in the spirit of equal competition. And they don’t stay where you put them. I think that the weld on kit just needs a season or two for the community to understand it’s quirks. Anyone who reads this thread is going to learn a helova lot about how to install them, and is now learning about how to avoid their weaknesses.

Who’s turn is it to be pointman next?

#128

if we all started doing spec3 none of this would be a problem

#129

For the record, I’m using powerflex bushings. I only have a few days on the setup and I will be on the lookout for ‘drifting/dynamic’ setup. There could be some lessons learned from the PRO3 guys as I believe all of them are running the weld in kit.

#130

Have been using the AKG trailing arm bushings for 4+ years…but I buy them with steel sleeves and grease the hell out of them during installation. I actually turned slots in the sleeve to hold moly grease. You really only need one eccentric, on the outboard end, as the eccentric is to adjust only, not hold the adjustment in place. I use jet nuts on mine, and also use 1/2 x 20 bolts. I have not had one move from the original alignment. CB

#131

Or it might be cheaper just to do this:
NorCal Thread on Sphericals

#132

[quote=“Steve D” post=57681]Or it might be cheaper just to do this:
NorCal Thread on Sphericals[/quote]

how much did it cost to do that on your car?

#133

[quote=“jtower” post=57683][quote=“Steve D” post=57681]Or it might be cheaper just to do this:
NorCal Thread on Sphericals[/quote]

how much did it cost to do that on your car?[/quote]The expensive part was camouflaging it so it looks like your broke a$$ ride. :laugh:

#134

[quote=“Steve D” post=57684][quote=“jtower” post=57683][quote=“Steve D” post=57681]Or it might be cheaper just to do this:
NorCal Thread on Sphericals[/quote]

how much did it cost to do that on your car?[/quote]The expensive part was camouflaging it so it looks like your broke a$$ ride. :laugh:[/quote]
i’m gonna start calling your car the chameleon
http://www.break.com/usercontent/2007/10/Chamelion-XLE-383947

#135

This has been a terrific thread with lots of info. I am definitely in the take it all down as a single unit camp and have replaced everything w/o knocking out the bolts from the body several times. You just have to work very slowly, use lots of grease, etc. I also point the outboard bolts outward but trim the inside of the subframe bushing to make it easier to get to the nut. (Actually that most recent subframe I did was on an all electric conversion with the gas tank removed. I can’t tell you how much nicer it is to do all this whaen you have access to the subframe from the front and the rear!)

One of annoying fundamental problems with the E30 trailing arm adjustments is that the geometry forces you to have inboard and outboard bushings that are not co-axial. It is no wonder that alignments can change if not really tight since the trailing arms themselves are constantly fighting against the adjustments. one of the few engineering flaws in the E30.

#136

that design element has always bothered me too, any adjustment using eccentrics or slotted tabs results in non-axial pivots which is fundamentally flawed. guess that’s another bonus of the spherical design that steve referenced.

#137

I bet that the weld-on kit eliminates some of the of the “off-axis” problem. Consider the shape of the slots in the kit and how much room the bolt has to move perpendicular to the slot. That is to say that the slot isn’t a super tight fit so the bolt can wiggle a bit.

The toe adjuster has a horiz slot but the bolt is also free to move a couple mm up and down. Likewise the bolt is free to move a couple mm horizontally in the vert camber adjuster slot.

I’d guess that the adusters can give about +/- 6 of travel from the orig bolt hole. Mine aren’t anywhere near max’d out, so lets say I used 4mm of adjustment. If I adjust 4mm and the other pivot point can move 1mm to accomodate the change of axis, then the slop in the joint has reduced stress due to off-axis by 25%.

In order to do it this way you’d have to play with it a bit so that the pivot points could shift around to accomadate each other. If you tighten one down and then go do the other they won’t get a chance to adjust that 1mm.

#138

Yup - All four of the eccentrics loosened up this Saturday during practice at Hyperfest (Summit Point). I thought it was a bearing going bad, but when I came into the pits to check play I couldn’t believe it. I was able to swing the wheel front to back. Son of a!

#139

Didn’t seem to slow you down much! Great weekend.