reproduction trailing arm fit issues

[ryangreen19]

I discovered some serious rust issues, giant holes specifically, in my trailing arms while doing my rear drums. I decided to order reproduction trailing arms, they are dynacorn. I suspect they are the only manufacturer and everyone just re-sells them. Anyway, after bolting the end at the cross member I was horrified to see that the u-bolt was not going to slide into the arm very easily. The arms seem to be about half an inch short. That being said I did measure from centre to centre on the arm and it is ~51 inches. Could it be that my axle is out of alignment instead, the passenger side shifted back a bit? I don't have the drivers side apart yet either. Wondering if things shifted with everything being up on jacks other than the rear drivers side. Has anyone had any issues installing reproduction arms? I had to grind the bushing end of the arm on one half of the arm so I could bolt it in also.

[Ruscal]

You should be able to move the rear end to match the holes. What is keeping it from moving? The drive shaft should slip to allow the movement, and the shocks and panhard should also move.
Russ

[Katrina/10]

When you loosen the U-bolt on the other side, you can easily move the axle around to fit. But, I would carefully measure the length of the new arm to make sure it is the same as the old one.

[ryangreen19]

Thought I would add that I can get the old rusty, split arm to line up with the u-bolt though.

[Grumpy old man]

I'm wondering why buy new repop arms when nice condition used are so readily available ? And fit without issues ?
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[ryangreen19]

I did look into used but in Western Canada they don't seem to exist. Everything in the main part supplier's yard looked not a lot different than mine.

[ryangreen19]

Originally Posted by Ruscal

You should be able to move the rear end to match the holes. What is keeping it from moving? The drive shaft should slip to allow the movement, and the shocks and panhard should also move.
Russ

The other side is not apart yet. I am going to take that apart tonight. From the comments I hope that will solve the problem. I will let you know.

[ryangreen19]

Originally Posted by Ruscal

You should be able to move the rear end to match the holes. What is keeping it from moving? The drive shaft should slip to allow the movement, and the shocks and panhard should also move.
Russ

You were correct. Once the drivers side was free, I was able to loosen the two small bolts on top of the carrier bearing that hold it in place and move the axle ahead. The driveshaft slid about 3/8 of an inch further into the transmission. There isn't quite the 3/4 of an inch clearance that was factory, but I think it will be fine. Then the bolts on both sides slid into the trailing arms easily. Driveshaft angles remained the same.

I bought the arms from auto obsession. I haven't had a chance to talk to them yet but the new arms are definitely shorter than the original. See the picture. The bushing shafts are aligned for comparison. So it appears that once again reproduction parts need some work vs original. If you have the ability to slip your driveshaft ahead, great, but if not I would be hesitant about about ordering reproduction from anywhere.

[Ruscal]

Ryan,
That is a bummer. You would think they could hold much better tolerances than that. If your drive shaft bottoms out it will take out the U joints. With new urethane bushings you may be OK when launching the truck hard, but depends on how much working room you have. ??
Russ

[ryangreen19]

Originally Posted by Ruscal

Ryan,
That is a bummer. You would think they could hold much better tolerances than that. If your drive shaft bottoms out it will take out the U joints. With new urethane bushings you may be OK when launching the truck hard, but depends on how much working room you have. ??
Russ

I have a half inch space now. I am going to lift the axle up while there are no springs and shocks to see how much theoretical suspension travel would be able to happen before the driveshaft bottoms. I am thinking about upgrading the TH400 to a 4l80e in the future, necessitating a shortened driveshaft. That would be able to fix the problem as well.

[Katrina/10]

Your tires may not appear centered in the wheel openings, either. Take a look at that, too.

[Ruscal]

Originally Posted by ryangreen19

I have a half inch space now. I am going to lift the axle up while there are no springs and shocks to see how much theoretical suspension travel would be able to happen before the driveshaft bottoms. I am thinking about upgrading the TH400 to a 4l80e in the future, necessitating a shortened driveshaft. That would be able to fix the problem as well.

Hopefully the half inch will be enough. It's good you are running it through the travel to verify. Shortening the drive shaft 1/4" would be difficult, but more would be easy when switching to the longer trans. I just did a similar swap going from T400 to T56 Magnum. The Magnum is way longer than the 400.
Russ