question about 40 rear with open drive

I have a 40 rear under my coupe with the wish bone split and tie rods as rod ends. I installed an open drive conversion (hot rod works) and was wondering about how to build an upper control arm to prevent torque twist.

I undersand the torquetube handled the rear end placement and the lower rods handled the twist. Now that it is open drive I need to handle those issues.

I have heard of kits but that isn't really an option so I would like some info on how to design some thing that will work for the home builder.


TIA, Jeff

 

would a simple pan hard bar running parellel with the axle work?

 

I dont think so. The main concern is the pinion rotating up and down.How do I stablize the twist with out a 4 link?

Hey Tim hows the shoebox comin? drivin yet?

 

run a panhard type link/bar but run it just on one side of the center section like 3/4 of the way to the center section

and have it run forward instead of parelll?

---long story on the box, its gone----

 

doesn't hot rod works make a kit for that? can you just copy it? i've seen it on their website

 

What about this method?

 

I'd run shorter bars from the center section to the frame rails. Triangulated 4 bars. Same set up as a Chevelle. It works.

 

stovebolt, that is what I was thinking about. I think I will try a web sight and see if there is any pics.

 

Tommy, If you used that method you would have to have the rear lower bars mounted on some sort of pivot arrangement. The typical '36 bone arrangement has the rear of the lower bars mounted solid to the rearend with 2 bolts. That joint would have to pivot for it to work like a Chevelle setup.

Frank

 

yeah that would be the ideal set up.

 

fab 32 you are right. The lower bars are fixed, no pivot, on the rear end. I need to do a little reengineering. How eles could mount an upper bar?

 

Normally with split bones you just use a panhard bar. If the existing mount on the axle housing is sturdy enough would not need anything else. If you are worried about the split bones allowing some movement you could make a mount on top of each side of axle, above where bones mounted, run it up to near where tie rod end is mounted in bones, weld to bones, make it into a ladder bar. Just a thought.

 

Get yourself a set of ladder bar brackets from Chris Alston Chassis Works.
Or make a pair from 3/16" cold rolled plate.

Drill a new mount hole for the top bar approx 5 1/2" up from the bottom bolt hole.
Cut off the original top hole and clean up the bracket.

Make a set - you'll need 8 rings and four bolts - bushing rings as shown on the radius rod in the pic below. (Unless you elect to retain your tie rod end at the front - the tie rod end should be 3/4" and not the common passenger car size of 11/16".
Easy to do, use DOM tubing 1 5/8" OD x .120 wall for the rings, a 3/4-16 grade 8 bolt for the threaded part and a jam nut (thin one) for the locknut.
1" x .156 wall is used for the upper bars.
The .156 stuff is usually special order, but .120 wall will work if you Helicoil it for 3/4-16.

Polyurethane bushings are available from Energy Suspension.

Alter the back of the wishbone to take a welded on bushing ring.
Make a threaded bung for the front of the wishbone if you wish to use poly bushings up front.

After a preliminary locating of the rear axles brackets, make the upper bar of what are now unequal length 4 bars - unless you have room to make them the same length, but unequal will be ok on the street.
A welded bushing on one end and a threaded bushing on the other.

What it all boils down to is you're setting up parallel 4 bars - parallel when viewed from the side - using your old wishbone for the bottom bar.

It won't hurt to have the upper bars inside the frame on their own bracket if necessary.

In any event, unless you run triangulated 4 bars - and you could triangulate the upper bars easily - you'll need to make a panhard bar as well.
Chassis mount is on the drivers side, axle mount as far to the right (in the US)- (OZ and UK guys have the steering box on the other side) side as you can get it.
Make this bar out of 3/4 - 7/8" with appropriate wall thickness.

If you're confused about the ladder bar bracket bit I can shoot and post a photo of that.

 

if you are just looking for something to control the axle with the original bones , why not just make a copy of Hot Rod Works torque arm kit?

http://www.hotrodworks.com/

 

I think I can picture the mount to make the rear into a four-link. I was hoping for something along the lines of the pic 36-3window posted. If I can , I would like to retain what is there and just correct the the problem.

If I have to start over on the rear sus. to get it right then that is what I will have todo.

I am held back by a few probs. like I don't have a good welder. My solution was hopefully to un bolt parts that could be taken to a welder. If I have to weld on the frame I would have to find a way to transport an almost complete car to the welder, who ever would let me use their shop.

I hope to find the best method before I make plans.

Thanks so far for the ideas and pics so far.