1971 Chevy C20 Trailing Arm Suspension

[jbwolfe]

Ok so I finally have an update. I've been crazy busy and haven't touched the truck since I parked it last December when the trailing arms gave out. Now I'm finally going to have some time this three day weekend to work on it.

I picked up some tools that I needed Friday:

- 25" 1/2" breaker bar
- Deep well impact socket set 1/2"
- 1/2" click torque wrench
- 3" pneumatic metal cut off tool
- PB Blaster

Also borrowed a 1/2" pneumatic impact wrench from a friend.

I still need to sand and paint the new trailing arms, but I'll do that later. I just sprayed down all the bolts I'm going to be removing with PB Blaster, and I'll soak them down tomorrow too. I need to move all the crap that has accumulated around the truck since it's been parked.

Monday I'm going to start dissassembling things. I accidentally ended up with a truck load of 4x6" treated wood blocks, so I've got lots of things to block the truck and axle up with.

Once I've got it all taken apart and jacked up, I'm going to order the new bushings for the trailing arms, and whatever bolts I wasn't able to save. While I'm waiting for those to get here I'll take a wire brush to the new trailing arms and then paint em up!

Can't wait to get this thing back on the road!

Big thanks to everyone for all the advice and help on this forum!

[NGN]

I got mine about eight years ago from LMC when they frist came out (control arms w/ bushing), came with the plateing on top, about a foot and a half , and two to like three feet plateing on the bottom, also U.S.A. Made at the time. Don't know if that's all the same now and yeah they were three bills a piece. Be sure to get the brake cable brackets, they don't come with arms. They worked out great no complaints. Nick

[fine69]

Make sure you dont install them on the WRONG SIDE. They have the e-brake cable bracket on the OUTSIDE of the arm.

[jbwolfe]

Originally Posted by NGN

I got mine about eight years ago from LMC when they frist came out (control arms w/ bushing), came with the plateing on top, about a foot and a half , and two to like three feet plateing on the bottom, also U.S.A. Made at the time. Don't know if that's all the same now and yeah they were three bills a piece. Be sure to get the brake cable brackets, they don't come with arms. They worked out great no complaints. Nick

Yeah I looked at those, but couldn't even afford to buy one control arm. I got mine from someone here on the forum. Used but rust free. And a lot cheaper than buying them new.

Originally Posted by fine69

Make sure you dont install them on the WRONG SIDE. They have the e-brake cable bracket on the OUTSIDE of the arm.

Thanks for the reminder. Very possible I would have forgotten that...

[jbwolfe]

So the dissassembly is going pretty well. I'm going to borrow a cheater pipe from someone to put on the end of my breaker bar to get the 1 1/16" nuts off the u-bolts.

So far though I've got it jacked up and the frame and axle supported, and disconnected the shocks.

Evidently someone has worked on the rear suspension before me, most likely replacing the shocks. I was surprised to find that when I disconnected the shocks they actually expanded pretty well. I figured they didn't really work. They do look newer though.

What I was really surprised to see was that the coil spring on the drivers side was not bolted to the frame at all. In fact the holder for the coil spring is gone all together on that side! Also, someone replaced the original bolt and nut that holds the shock onto the control arm with a bolt WAY to long, and compensated with 16 washers! Wasn't even the right size bolt!

Anyway, I'm going to go get that pipe in a bit here and hopefully get the trailing arms removed before dark.

[jbwolfe]

Didn't get a whole lot done the rest of the day. Got the cheater pipe, but still couldn't get the bolts loose. Then I came up with this idea: Put the cheater pipe over the breaker bar, support it with a chunk of wood, and then back my other truck into the cheater pipe. I actually managed to get one of the nuts on the u-bolt on the drivers side loose, then tried the same thing on the other nut. Broke the tip right off the cheapo Harbor Freight breaker bar. I was honestly surprised it didn't break sooner!

It's got a lifetime warrenty so I'm headed back tomorrow to get a free replacement. I figure it's good for normal use as long as I don't use my truck as leverage.

So I'm planning on just cutting the u-bolts off with an air powered cut off tool.

[jbwolfe]

I finally found some time to work on the truck, and got both control arms removed . I ended up cutting both u-bolts off. I had to cut each one in two places, because even after cutting them I couldn't budge the two halves at all.

Next I'm going to order new bushings, and u-bolts, and any other bolts I need. In the mean time, I'm going to clean and paint the new trailing arms, and clean and paint the area around the axle that sits on the control arm. Here's some pics of my progress.

I think it's going pretty dang well, considering I have no idea what I'm doing.

[darush01]

Mine did the same thing, I put an ad on Craigslist and got a decent pair for $40 then had to drive 240 miles to pick them up but you could try that, it's apparently more common than I thought.
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[darush01]

I just saw you have some it's not that bad to replace just a few busted knuckles alot of grinding putting them back on is a walk in the park compared to getting them off
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[68 TT]

Originally Posted by jbwolfe

Didn't get a whole lot done the rest of the day. Got the cheater pipe, but still couldn't get the bolts loose. Then I came up with this idea: Put the cheater pipe over the breaker bar, support it with a chunk of wood, and then back my other truck into the cheater pipe. I actually managed to get one of the nuts on the u-bolt on the drivers side loose, then tried the same thing on the other nut. Broke the tip right off the cheapo Harbor Freight breaker bar. I was honestly surprised it didn't break sooner!

It's got a lifetime warrenty so I'm headed back tomorrow to get a free replacement. I figure it's good for normal use as long as I don't use my truck as leverage.

So I'm planning on just cutting the u-bolts off with an air powered cut off tool.

I did the same thing with a six foot piece of pipe but bent my Craftsman long flex head ratchet instead of breaking the square drive off like you did. I probably put 1000 pounds of torque into the ball joint nut I was working on before it moved. The guy at Sears just laughed when he saw it. The thing was curved in two directions. Still got a new one out of them though.

I got the nuts off the U-bolts on my truck but couldn't get the bolts out of the trailing arms. The threads got damaged too much knocking them out to make them usable.

Those trailing arms are scary. You are lucky the rear end didn't come out from under you.

[jbwolfe]

Yeah I was going 55MPH down the highway when I noticed something wasn't right and pulled off the road. Had it put on a flat bed and delivered to my house as soon as I looked underneath the truck. I am very glad I pulled over when I did.

Well the hardest part, taking it all apart, is done. Now I just have to order everything I need and put it back together, which shouldn't be too bad at all.

What should I torque the nuts on the u-bolts to? I've got a click stop torque wrench, or I could use my 1/2 Impact gun which is rated to 700ft lbs. What about the other bolts?

[jbwolfe]

Just placed my order with LMC! Ordered new bushings and all new bolts, washers, and nuts. The coil spring clamp kit is on back order, but that's ok because I probably won't get to work on it for a few more weeks anyway.

[jbwolfe]

I removed the bushings from the new trailing arms today. That turned out to be quite a process. I eneded up drilling out the rubber, then pounding out the inside of the bushing, leaving the outside shell. I then cut the outside shell in half, and cut the halves in half lengh wise. Then with the help of a lot of PB Blaster, hammers and screw drivers, I managed to pound out the rest of the bushing without damaging the trailing arms .

I decided instead of cleaning them up myself, I'm going to have them sand blasted, then I'll paint them. Now that the bushings are out, I'm going to take them into town tomorrow to have them sand blasted.

In the mean time, the new bolts and bushings from LMC arrived, except for the coil spring clamp kit which should be here Friday.

[68 TT]

Originally Posted by jbwolfe

...What should I torque the nuts on the u-bolts to? I've got a click stop torque wrench, or I could use my 1/2 Impact gun which is rated to 700ft lbs. What about the other bolts?

I haven't seen any torque numbers that I can remember. I would check a factory service manual or something similar like a Chilton or Haynes manual to get the right torque for the bolts. They are too important to guess at the right torque.

[Shaky]

My 1967 Chassis Service Manual says 215 ft lb for the Axle to Control Arm U-bolts for a C-20.

You're just as well replacing the U-bolts. They're usually rusted badly down in the control arm.

My buddy had his break on I-95 during rush hour and he spun it all the way around! When I took mine apart it was less than half the diameter down in the arm...

[jbwolfe]

Originally Posted by 68 TT

I haven't seen any torque numbers that I can remember. I would check a factory service manual or something similar like a Chilton or Haynes manual to get the right torque for the bolts. They are too important to guess at the right torque.

Thanks for saying something, I was just going to guess, but I think I'll buy a service manual for the truck and borrow or buy a larger click torque wrench.

Originally Posted by Shaky

My 1967 Chassis Service Manual says 215 ft lb for the Axle to Control Arm U-bolts for a C-20.

You're just as well replacing the U-bolts. They're usually rusted badly down in the control arm.

My buddy had his break on I-95 during rush hour and he spun it all the way around! When I took mine apart it was less than half the diameter down in the arm...

I'm looking at Chassis Service Manuals on eBay right now, and I have a question. When the manual says "Series 10-30", does that mean C10, C20, and C30? Just want to make sure I buy the correct manual.

[Shaky]

Originally Posted by jbwolfe

I'm looking at Chassis Service Manuals on eBay right now, and I have a question. When the manual says "Series 10-30", does that mean C10, C20, and C30? Just want to make sure I buy the correct manual.

The '67 manuals cover 10-60, but that may have changed. Series 10-30 means that it covers 1/2, 3/4, and 1-ton trucks. Includes C and K trucks (and some others).

[jbwolfe]

Originally Posted by Shaky

The '67 manuals cover 10-60, but that may have changed. Series 10-30 means that it covers 1/2, 3/4, and 1-ton trucks. Includes C and K trucks (and some others).

Perfect. I just found a 1969 Chassis Manual that covers 10-60. Would that manual cover my 71 though?

[Shaky]

Originally Posted by jbwolfe

Perfect. I just found a 1969 Chassis Manual that covers 10-60. Would that manual cover my 71 though?

Some things are the same, but some things changed for '71. If you're going to spend the money I would wait until you can get your hands on a '71 manual. That way you don't have to guess.

[jbwolfe]

Originally Posted by Shaky

Some things are the same, but some things changed for '71. If you're going to spend the money I would wait until you can get your hands on a '71 manual. That way you don't have to guess.

Sounds good. I just bought a 1971 Chassis Service manual Series 10-30 off eBay for $13.99 shipped.

Thanks for the help!

[jbwolfe]

Originally Posted by Shaky

My 1967 Chassis Service Manual says 215 ft lb for the Axle to Control Arm U-bolts for a C-20.

I got my '71 manual in the mail. It says 145 ft lb for the Axle to Control Arm U-bolts. Wonder why the change...

[Shaky]

Originally Posted by jbwolfe

I got my '71 manual in the mail. It says 145 ft lb for the Axle to Control Arm U-bolts. Wonder why the change...

I'm not sure. That seems low, but maybe they changed it?. Here's the page I was looking at:

[jbwolfe]

I thought so too. Here is a picture of the book for '71.

In the mean time, I sprayed the freshly sand blasted control arms with a rust treatment primer. Then I put the new bushings in. That was interesting... I see why the Chassis manual says to use a shop press. I don't have a shop press, so i used a bench vise, and various tools to make sure I didn't bend anything. Then afterward I made sure that nothing had been bent by double checking everything with the original control arms. Next I'm going to paint them.

[68 TT]

Nice ingenuity to get them installed at home and not crush the arms.

[jbwolfe]

Originally Posted by 68 TT

Nice ingenuity to get them installed at home and not crush the arms.

Thanks! I was a little nervous about it so I'm happy it worked out. Now I can put the final few coats of paint on, and start installing them.