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914World.com _ 914World Garage _ My rear end alignment issues
Posted by: PanelBilly Apr 18 2016, 06:17 PM
When I originally went in for my alignment I discovered that the rear wheels were toed out and there wasn't any adjustment left in the trailing arms. You can see by the photo,
the arm is nearly up against the frame and it was still toe out -75.
So he fix was going to be modifying the outer mount, so the holes were made larger. Here is a mount before and after. 
That helped it move a tiny bit closer, but being that it was already so close to the frame before, moving it right against the frame was all that I could do.
So off came the trailing arm again and it went to the machine shop where I had my engine work done. We bolted it up to the mill and rigged it so it was plumb.
Now we could check the angle of the hub to see what it measured. Should be 12.5, but it was 13.
Now I didn't take a photo of the jig we set up, but using a press and several pieces of steel, we warped the arm so that it was 12.5.
Back to the alignment shop to see if it worked. Now the toe was only out a tiny bit. So I pulled the arms off again and on Saturday we bent them a little more. Tomorrow I go in
for what I hope is the final alignment. My trailing arms had been reinforced with three tubes so I think they could hold up to a bit more stress that an OEM.
Posted by: r_towle Apr 18 2016, 06:48 PM
Are those stock trailing arms or did you modify them?
Posted by: tomrev Apr 18 2016, 07:28 PM
Are those stock trailing arms or did you modify them?
They were modded by drilling and welding the tubes passing thru, and triangulating the arm. I was wondering when looking at the photo how accurate it would be to measure the hub, without the CV spline bolted tight to load the wheel bearing in the arm. Seems my hubs have always been pretty lousy-goosy when not loaded with the axle/CV assembly bolted and torqued.
Posted by: rgalla9146 Apr 18 2016, 07:34 PM
Were your inner ears replaced ?
Others here have modified their trailing arms like you did.
Did their arms change shape ?
It might be more effective to slightly move the hole in the inner ear by filing and welding.
I agree that you should have the hub/stub tight.
Posted by: PanelBilly Apr 18 2016, 09:12 PM
Inner ears were not replaced
Posted by: John Jentz Apr 19 2016, 08:19 AM
When I had that same problem it was a bent arm.
Posted by: PanelBilly Apr 19 2016, 02:38 PM
Everything worked out perfect. The car tracks down the road great. Shows that if you don't give up, you eventually figure it out
Posted by: ThePaintedMan Apr 19 2016, 03:37 PM
So Billy, given that they were both tweaked, are you guys thinking it was related to the welding done to stiffen the arms?
Posted by: Evil Older Brother Apr 19 2016, 04:07 PM
Billy,
Hope all goes well with the proctologist on your "anal"iment..............
Posted by: Evil Older Brother Apr 19 2016, 04:08 PM
Billy,
Hope all goes well with the proctologist on your "anal"iment..............
Posted by: Elliot Cannon Apr 19 2016, 05:13 PM
So Billy, given that they were both tweaked, are you guys thinking it was related to the welding done to stiffen the arms?
That was my exact thinking. The welding could have warped the trailing arm. Some of my most careful measuring has gone straight to hell after the welded metal cools.
Posted by: 914_teener Apr 19 2016, 05:29 PM
I have seen this done a couple of different ways.
In my opinion this (rods or tubes) is the only way to really strengthen the trailing arm most effectively.
The add on "box kits" do not approach this method in strengthening the section.
When you weld an assembly like this, the weld shrinkage is in the KIP range of force.
Tons of force in other words. So HOW it is welded is everything to keeping the right angles on the arms.
Posted by: 76-914 Apr 19 2016, 05:45 PM
I have seen this done a couple of different ways.
In my opinion this (rods or tubes) is the only way to really strengthen the trailing arm most effectively.
The add on "box kits" do not approach this method in strengthening the section.
When you weld an assembly like this, the weld shrinkage is in the KIP range of force.
Tons of force in other words. So HOW it is welded is everything to keeping the right angles on the arms.
Good info. Wouldn't pre-heating the arm first alleviate the warping?
Posted by: mgp4591 Apr 19 2016, 05:52 PM
Were your inner ears replaced ?
Others here have modified their trailing arms like you did.
Did their arms change shape ?
It might be more effective to slightly move the hole in the inner ear by filing and welding.
I agree that you should have the hub/stub tight.
Did you drill and pass the tubes straight through or did you drill and pass at angles? I've seen examples of both and wondered which would work better - I'd bet angles would bear the stresses better. Then comes the question of whether Jamie would have bent his ears when he hit the rail rather than just needing to replace the arm??
Posted by: ThePaintedMan Apr 19 2016, 05:52 PM
Or using a jig and distributing the welds evenly an minimizing heat.
Posted by: 914_teener Apr 19 2016, 06:36 PM
I have seen this done a couple of different ways.
In my opinion this (rods or tubes) is the only way to really strengthen the trailing arm most effectively.
The add on "box kits" do not approach this method in strengthening the section.
When you weld an assembly like this, the weld shrinkage is in the KIP range of force.
Tons of force in other words. So HOW it is welded is everything to keeping the right angles on the arms.
Good info. Wouldn't pre-heating the arm first alleviate the warping?
No....best way is to index the part and fixture it then strategically weld it so that the forces will counteract each other and then mechanically post relieve it if necessary. If done right no post relief would be necessary.
Posted by: 914_teener Apr 19 2016, 06:40 PM
Were your inner ears replaced ?
Others here have modified their trailing arms like you did.
Did their arms change shape ?
It might be more effective to slightly move the hole in the inner ear by filing and welding.
I agree that you should have the hub/stub tight.
Did you drill and pass the tubes straight through or did you drill and pass at angles? I've seen examples of both and wondered which would work better - I'd bet angles would bear the stresses better. Then comes the question of whether Jamie would have bent his ears when he hit the rail rather than just needing to replace the arm??
Angles. Yes......probably not the best or maybe not needed for a stock four street car. But....I also think that these weldments have stress relieved after the decades and have lost their original spec.
Posted by: PanelBilly Apr 19 2016, 09:38 PM
Tubes are not angled. Someone else did the welding The workmanship looks professional I just happy that I knew someone who could bend them and the task is over. I got real fast at removal and installation
Posted by: tygaboy Apr 20 2016, 04:15 PM
Great result but I'm curious:
How EXACTLY did you bend the arms back into spec. What "bent" during the correction?
Pics of the "bending jig"?
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