Rear Toe Adjuster Lock

#1

Having “had it up to here” with the rear toe adjuster bolts loosening all the time I came up with what I hope will be a fix this today. I’ve never had the camber adjusters loosen or move, just the toe adjusters. For a while I thought that it was the axial mis-alignment of the bushings that was the problem, but now I’m not so sure. Both see the same motion in the trailing arm as the suspension compresses and extends. So the forces on both adjusters should be about equal in that respect. If the mis-alignment of the bushings were to be the problem I’d tend to expect both to loosen. My theory now is that the toe adjusters loosen as they (unlike the camber adjusters) see fore and aft forces from power and braking.

I made my own eccentric bolts using 12 point aircraft bolts & nuts. Those fasteners are stronger than grade 8 fasteners and the heads and nuts are smaller in diameter. The bolt head takes a 1/2" 12 point wrench/socket and the nut takes a 9/16". The bolt head and nut are a touch taller than a standard bolt head or nut.

The attached pictures show one of the locks. The tab between the jam nuts gets welded to the subframe against the pinch weld seam. The sector arm welded to the socket has two holes 30 deg apart so no matter where the bolt head winds up one of the holes will be in reach of the threaded lock rod. I future that if I can keep the bolt from turning the nut can’t loosen and thus the toe should remain as set.

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[attachment=1683]DSCN0197.JPG[/attachment]

#2

looks good, but shouldn’t the holes be 15 degrees apart. With 12 points you already have 30 degree increments.

#3

Good point. I didn’t think of that.

#4

So the contraption you fabricated is just to go over the head of the 12 point bolt and keep it from turning? Could you not just weld that same adjuster to the eccentric and adjust with the lock rod/nut?

#5

It could be done that way, but that makes the eccentric & bolt special. Not to mention that if you bend the trailing arm (that’s really easy, the things are like wet noodles) the sector arm could wind up in the wrong place. I’ve stripped the threads on the grade 8 eccentric bolts, though not yet on these. So I want to be able to replace the bolts easily, which just capturing the head of the bolt accomplishes while still locking the adjuster down.

#6

If you welded one to each end/side of the eccentric bolt, the bolt would not have to be super tight as the adjuster rod/nuts would seem to be enough to hold it in location.

#7

What keeps the socket from rotating away from the bolt head?

#8

First of all the head of these bolts results in 3/8" or a little more of engagement in the socket. The flat plate at the end of the threaded rod is bolted tightly to the sector arm and once the jam nuts are tightened the socket can’t move at all. I don’t see the socket slipping off the bolt head unless something comes loose. You certainly can’t pull it off the bolt head by hand.

These will get their first track test this coming weekend during the Midsouth event at Memphis. I have high hopes for them.

#9

Were you able to find a M12 x 1.5 thread pitch 12 point nut? I’ve been looking and can’t find them in 1.5. Or did you just replace the bolt and nut with 12 point bolt and nut. Link to site where i can find them? Thanks.

My problem is getting to the outside nuts to tighten down. There isn’t that much room to work with. So i think a 12 point nut and 12 point wrench will give me just enough room to get the nuts torqued.

#10

I used 12pt NC aircraft bolts and nuts that I purchased from McMaster. I silver soldered the eccentric washers to the bolts and eliminated the eccentric on the nut side in order to not loose thread area (I’ve stripped the “standard” bolts). You just about have to drop the subframe to get the outboard nuts on, but an “artfully” bent box end wrench can get to those nuts to loosen/tighten with the subframe in place.

#11

Do you happen to have a picture of this? Did you just take the washer eccentric and weld that to the bolt and then got rid of the eccentric washer on the nut side? Just trying to make sure I’m picturing this correctly.

The eccentric bolts in most kits are just factory e39 bolts and washers. If i remember correctly. Part numbers are :
Washer 33 30 6 760 592 and Bolt 33 30 6 760 591. Those are showing M10 and not M12 like stock bolts and trailing arm bushings. Anyone have a extra kit that they would be willing to take some measurements?

#12

That is exactly what I did.

#13

Got it thanks.

#14

Well, the adjuster locks survived this weekend’s races at Memphis and I did challenge them on the gators. I think I have a winner!

#15

I’m requesting additional pictures of it install if you could do so please.

#16

http://forums.bimmerforums.com/forum/showthread.php?t=1768270&highlight=camber