86 C10 Trailing Arm Conversion

[JW76]

Thanks for all the responses. You've made it clear that the crossmember needs to go between the frame rails so I will follow the advice. N2TRUX had a good point too. Putting it between the rails will open up more options for ride height, etc. later. I am currently not with the truck and am in Germany, so when I get back I can get more hands on. I am trying to get more of the theory straightened out now and will really delve into the project around Christmas time. These trucks are addicting. I'm on another continent and still thinking about it. Thanks for your help.

[SCOTI]

Be sure to update.

[terrellautosports]

JW76,

to me when you mocked this up you still have the leafs on top of your rearend housing. in turn making the drive shaft and cross member below you frame rail. if you take the leaf springs off you should gain 3 inches for sure possible a little more. that should move your driveshaft up and your new crossmember up in the frame rails.

[N2TRUX]

Lots of good conversation on the topic. It's a lot easier to make changes now than it is "after" you started cutting and welding....

[JW76]

Thanks for all of your input. I really appreciate the advice and I agree its a heck of a lot easier to think and rethink and make changes now then after you cut.

[Wild83C10]

Looks like we will be doing this at about the same time. If I attack mine first I will let you know what I had trouble with or what worked better for me. Hope to hear the same from you. Good Luck!

[falze]

Does anyone know the length of the trailing arms of a short bed? I'm starting a buiild this winter with an orginal 2wd blazer frame with a manual trans. Sorry didn't mean jack your thread.

[SCOTI]

Originally Posted by falze

Does anyone know the length of the trailing arms of a short bed? I'm starting a buiild this winter with an orginal 2wd blazer frame with a manual trans. Sorry didn't mean jack your thread.

From what I remember, they should be 51" from C/L of the front bushing bolt to the C/L of the rear u-bolt/axle tube.

[JW76]

So, here is some food for thought I guess. Talking do you guys I realized I didn't know quite as mush as I thought so I started doing some homework. I did a search for some suspension design info and read through a lot of it. I looked at the HRH kits again, too and what other people have done with trailing arms on their trucks within this forum. I learned a lot but am confused too.

HRH sets their vehicles up almost identical to NASCAR. They install the trailing arms almost level with only a slight maybe 6 inches of pitch to the crossmember. They use screw jacks and coils for easy adjustment. For the panhard, they attach to either the drivers side axle tube above where the trailing arm connects or they catch the trailing arm then they anchor it on the right side frame rail with an adjustable mount with maybe 4-5 inches of vertical adjustment. They then set the panhard bar so that it is level at ride height. The panhard seems to run horizontal right along the axle tubes. This setup seems to work perfect form them allowing them to adjust to run drag, drift, or road courses.

Reading some other articles I read that the panhard should run at an angle with the center of the panhard crossing the differential, or that the panhard can be over the axle running parallel to it.

Also, I've read that having the trailing arms flatter will increase traction without pulling the front end off the ground and that the more angle you get, the more it wants to squat the rear end and lift the front.

Also, when I mentioned putting the crossmember under the frame, it makes my geometry identical to that of the HRH truck. I intend to keep my 15 inch wheels and can only afford to drop the truck in the back about 3 inches or so so with that drop it gives me identical geometry to the HRH truck which the owner of HRH swears by.

All together, this is a bit confusing.

Here are a few pictures and diagrams i looked found

[JW76]

pictures

[JW76]

few more

[andrewmp6]

That camaro is from hotrodstohell.net they make a truck arm kit for a lot of cars even a s10.Its a good well rounded basic set up really only things to break are a arm or panhard bar.

[smashingchuck]

I'm really failing to see where they have a stock crossmember mounted to the bottom flange of their frame in this picture:


It looks TO ME as though they are building a custom, low profile crossmember that mounts to the bottom of the frame:

[JW76]

I was not inferring that they mounted a stock crossmember under the frame. They made a custom one, however it works the same way AS IF you were to mount a stock one below the frame. The driveshaft goes through the hoop and in both scenarios the mounting brackets for the trailing arms are at the same height in the same location. Their custom member works out the same as the way as the way I mocked it up.

The geometry of this move has been questioned in previous posts so I was just asking for more explanation as to why this is poor geometry. I am just trying to fully understand because if I move the crossmember up between the rails it is higher than the HRH truck and therefore there is more angle on the trailing arms. It seems like all HRH vehicles strive for a minimal angle in the arms.

[SCOTI]

The HTH set-up does mount between the frame rails, not under. In that pic, the c.member was being installed. If you look @ the side view shots of the truck on the ground w/wheels & tires installed, you can't see the truck arm forward pivots (below the frame rail).

[JW76]

Are there more pictures of the HRH truck available? Just curious has anybody seen the truck first hand?

[tymbom]

The truck that HRH built was designed to look stock and not lower at all. If you put the cross member between the flanges of the frame like it is on the stock 67-72 style frames then it won't need to be custom fabricated at all. You could even use the CPP cross member.

[Damien]

I'm considering doing this swap on the step side I'm building for my dad, so I will be watching this thread. I found an istall artical of CPP's kit. There are some decent pictures of the set up. Here is the link. http://www.classicperform.com/tech_a...iling_Arms.htm

[JW76]

Seems like a lot of people are interested in doing this swap. I have also been thinking about the crossmember and agree that it has to go inside the frame rails like Scoti and N2Trux said. I want the truck lower than I was planning before. The CPP article has some good tips on setting up the suspension. I am also thinking about trying to run the 63-72 front and rear cool ride setup with the trailing arms. The coolride front is the same for 63-87 so I could just use the older kit. More research to come.

[bluex]

Bump.

I'm intrested in doing this to my '78. I'm thinking the best way for me to do it will be with CPP's kit, without arms ($609) and use some stock 67-72 arms. This kit includes everything of the $1200 kit, without the arms. What I like about it is the upper spring mount is built into the c-notch plate and I wont have to worry about figuring out a mount.

Anyone know if there is a difference in arm length from a shortbed to a longbed. I'm going to call CPP and check that the kit will work with some stock arms and then start checking the local yards for them.

If I cant find any, then I'll go with Nates arms since they are cheaper, and have a drop built in.....

here is another article on the CPP kit.

http://www.classictrucks.com/tech/08...kit/index.html

Here is a cool video of the '79 in the article. Bottom screen, left side. Titled '79 C-10 Truck

http://www.classicperform.com/Videos/Videos.htm

[SCOTI]

Originally Posted by bluex

Anyone know if there is a difference in arm length from a shortbed to a longbed.

They are the same length.

[bluex]

Cool, that will make it easier to find them then.

I'm thinking with used arms I could get it done for under 1k?

I've also seen ECE sells a kit to strengthen the factory arms, would that be a worthwile investment?

[SCOTI]

Originally Posted by bluex

I've also seen ECE sells a kit to strengthen the factory arms, would that be a worthwile investment?

Yes. Scrap steel would do the job too if budget is a factor. I simply put ~ 2" beads every 6" or so down the seam of the OE arms & weld up the extreme ends (front & rear).

[bluex]

Thanks Scoti, thats a great idea. Any pics?

From CPP about the kit:

Kit is designed for 63-72 arms and will work with a stock set of arms.
The truck in that video uses their modular brake kit with a 2" drop spindle
They also used a 2" drop spring up front for 4" total.
Their rear arms have no drop built into them
and the truck has 3" 63-72 drop coils in the rear, or can use any other drop or stock spring for those years.

[SCOTI]

Originally Posted by bluex

Thanks Scoti, thats a great idea. Any pics?

I can get you some.