Thread: triangulated 4 bar

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I'm trying to set up my rear suspension on mt '27 T sedan frame and need some ideas. I'm assuming the diff is cast iron (1980 Chev 1/2 ton) so I'm not sure if I can weld to this. I want a triangulated four bar but the space constraints are kinda tight, the uppers would be about 12" and not at 45 degrees more like 60-70. Here's a bunch of shots:

http://www.flickr.com/photos/12817213@N06/?saved=1

I don't want to move the kick up forward as seat space is at a premium and the axle would look funny if I move it back. Any ideas or input would be great, might even have to go parallel 4 bar, but those would be quite short as well. I've been kinda thinking of making a long bracket that goes across the pumpkin and welds to the axle housings???

Oh yea, I've got coilover shocks and a 383 SBC with AFR heads and the works so it has to be sturdy. Sorry I posted a similar question before but it was on the old site.

Thanks,
Sean.

Why not go with a parallel 4 bar with the mounts on the outside of the frame rails and a Watts linkage???? Parallel bars about 24" long bolt to bolt with a Watts linkage with the center bracket attached to the rear end with 4 or 6 bolts in the rear cover and a bar to either frame rail would be very good at hooking the car up, and look good too!!!!!

A triangulated 4 bar with arms too short and not angle properly can bind up terribly and do some nasty loading and unloading of the chassis torque making for lousy handling and a bad ride. Yes, the center section is a cast piece....

I had exactly the same space problem you have with my '39 Dodge truck I am doing. We looked at all kinds of options and finally settled on a three bar set up from Suicide Doors. Now, on mine it was pretty easy because they make an adapter plate that goes behind the rear cover of the rear end housing , and off of that the top Y bar is mounted. Then two lower parallel bars come off of the bottom of the axle to the frame.

You will have a problem though because they do not make an adapter with the same rear cover bolt pattern your Chevy axle (mine is an S10 rear, the only one they make an adapter for. My Son Dan was using the same rear axle as you under his '29 and he wanted to use the same Suicide Doors setup, so what he did was make his own adapter plate. He simply took a big piece of 1/4 inch thick steel plate, used the proper gasket to transfer the pattern onto it, cut out the center and drilled the mounting holes so it could be mounted behind the rear cover and housing. He did some reinforcing at the top, mounted ears to fasten the Y bar to, and he was home free. He did have to make a flat steel ring to go down into the groove of the rear cover. Otherwise, the adapter plate won't sit flat.

Suicide Doors will custom make these to any length you want. Here are some pictures. Mine is the black truck and his is the bare frame in these shots.

Don

BTW, my bars are only 16 inches long overall, and will handle a four inch up and four inch down travel in the rear end.

It looks good Don, just curious how well it will work with such short lower arms and such a tight angle on the upper bar...... I'm not saying it won't work, just wondering if the short bars might react too fast to torque loads....?????? We've used setups similar in design on circle burners and always went to shorter arms on shorter tracks to make the chassis react faster..... Anxious to hear how it works.... Now, to lighten the hook you could always put a torque absorbing spring/shock setup in the upper link and..... ahhh, never mind!!!! I'll have ya out dirt trackin'!!!!!!!

Oh, here is a link to Suicide Doors in case you wanted to check them out.


http://suicidedoors.com/S103-LinkKit.php

Don

They work surprisingly well Dave. Both my Son's had these on bagged S10's, that is how we knew about them. Even raising or lowering the truck 4 inches each way had very little effect on them. Some have questioned that these might allow the rear axle to move sideways on turns, but the top bar prevents that from happening.

Both of their trucks had tons of miles using this setup and they had no problems at all. I was skeptical the first time I saw them too. For my Dodge it was the only suspension set up I had room for because of being bobbed so short in the back.

Don

Thanks Don, those pictures are enough to get the wheels spinning again. I just got a new plasma cutter also, so it will give me something to do with it. I was searching through Jegs website and they had uppers as short as 11.5" with a spherical rod end. I'll have to check it out tomorrow.

Thanks again,
Sean.

BTW, I enjoyed your photos. You are really doing things nice and strong on the frame, good job. You might want to hang onto that motorscooter with gas prices getting nuts. I'm thinking moped myself.

Watch that plasma cutter, those things will put hot sparks down your socks in a heartbeat. I'm still sporting scars.

Don

That axle tube warped pretty bad when you welded the brackets to it!

Itoldyouso,
Just wondering, How come you didn't turn the triangle bar around, so that you didn't need such a large bracket on the rearend?

Pat

Originally Posted by R Pope

That axle tube warped pretty bad when you welded the brackets to it!

What? No it didn't.


HemiT, it is designed to work facing that direction. On something like a 9 inch rear end you just weld a couple of tabs on either side of the pumpkin portion. but on an S10 that entire center is cast iron so you can't weld to it (easily anyway) so the bracket is made to bolt on through the 10 rear cover bolt holes. They supply grade 8 bolts and a ring to fill up the sunken in portion around the cover so it sits level and bolts down tight.

Don

I don't think mines warped either?????

Thanks, I restored that '63 Vespa for my girlfriend but I think I've ridden it more than her, that's why I have to build a hotrod so my friends think I'm cool again!
I was also thinking maybe I should turn that around and have the triangle the other way???

Sean.

Didn't Toad in American Grafitti ride a Vespa?

I don't think the top bar will work turned around, but you might want to call them and ask. I've just always seen it done this way. Something to do with geometry and other subjects I have no idea about.

Don

Originally Posted by Dave Severson

It looks good Don, just curious how well it will work with such short lower arms and such a tight angle on the upper bar...... I'm not saying it won't work, just wondering if the short bars might react too fast to torque loads....?????? We've used setups similar in design on circle burners and always went to shorter arms on shorter tracks to make the chassis react faster..... Anxious to hear how it works.... Now, to lighten the hook you could always put a torque absorbing spring/shock setup in the upper link and..... ahhh, never mind!!!! I'll have ya out dirt trackin'!!!!!!!

Dave, I was thinking about the same thing.
I am surprised you did'nt bring up putting in a "Z-bar".

Originally Posted by erik erikson

Dave, I was thinking about the same thing.
I am surprised you did'nt bring up putting in a "Z-bar".

Well, can't say the idea didn't cross my mind..... Often wonder how some of the race car stuff would work with a bit of redesign to facilitate a right hand turn and substituting polyurethene ends for those noisy, clanky heims!!!!

I like the design on Don's, really curious to see how it works on the street!!!!!