Home built independent suspension?

[GeoTracker90]

Adjusting for toe should be pretty simple if you added a threaded insert and a bushing with a threaded stud to the inboard side of the trailing arm. Picture of the bushing...

For camber I would have to make the outer trailing arm mounts slotted with a plate to lock in the camber adjustment such as ...

I forgot to show that on the larger bracket, the center bolt hole needs to be slotted. The red circle represents the OD of the bushings. The camber plate is attached to the larger bracket and locked into position with the two outer bolt holes (3/8") as well as the bushing's 9/16" bolt. This set up would be used on both the inner and outer sides of the outer trailing arm bushing.

Confused yet? There would be no gaurentees that this would allow you to get the alignment spot on, but it would help get it pretty close and compensate for any movement of the metal as I welded up the trailing arms.

What do you think?

 

[spencyg]

Metal does move around when you weld it, but with a proper design it shouldn't be a big issue. Proper gusseting is mandatory when constructing safety-critical components. Also, proper welding practice will minimize any movement by continually altering where you are focusing your heat. Don't just start laying a bead and truck right through the weld. Lay 3/4" here, then 3/4" there, then back again. This helps a lot. The key is to build the suspension on the trailer instead of as jigged up units on the bench. I like the idea about starting with a solid axle and then cutting it into independent sections after the suspension is complete. As far as adjusting toe, just have the connection points on the frame either be Heim rod ends or threaded stud bushings. You'd be able to adjust any variance in control arm geometry out with this setup. It really shouldn't matter if you end up with the CL of one wheel being off by 1/4" from one side or the other. As the suspension cycles, the wheels are going to move forward or backward in relation to each other anyway due to the geometry of a trailing arm suspension system. If you've got a good MIG welder and an angle grinder with a stack of cut-off and grinding wheels, a swing arm suspension could be fabbed up in a weekend.


Spence

 

[ExpoMike]

The VW bug isn't a great donor as it's IRS is part of the pan, but the T3 Variants use a removable rear subframe that could make a nice unit. I've considered building a buggy trailer out of one.

Some method of adjusting toe needs to be designed in. There are "rod ends" that use a urethane bushing instead of a ball. Most frequently seen on street rods.

I don' think the idea was to use the actual VW torsion housing but an aftermarket housing, which is nothing more then a piece of tubing with mounts on the end for the spring plates/bushings. Very light and compact.

The other nice thing about using a modified VW suspension is, the spring plates are slotted where they bolt to the arms. This allows you to set the toe.

BTW, my knowledge came from building 2 Baja bugs and 1 Manx type dune buggy. This idea really has me thinking....

 

[ntsqd]

......
BTW, my knowledge came from building 2 Baja bugs and 1 Manx type dune buggy. This idea really has me thinking....

Mine too!

One potential downside, depending on one's view of such things, is that the VW parts have a Camber curve. The axis of swing arm rotation is such that the top of the tire would get closer to the trailer near the top of the suspension's travel. I don't necessarily think this is bad, might even be good, as long as there's room for that to happen.

Occurred to me that if JY sourced spindles are desired then some of the Chrysler FWD products use a bolt-on spindle on the rear. Others may as well. Could start with something along those lines. Getting a matching BC would be the challenge.

 

[GeoTracker90]

Occurred to me that if JY sourced spindles are desired then some of the Chrysler FWD products use a bolt-on spindle on the rear. Others may as well. Could start with something along those lines. Getting a matching BC would be the challenge.

I'll presume that BC = bolt circle, but what does JY stand for? Nice idea about the bolt on spindles. With them you could use shims between the spindle and the trailing arm to make alignment adjustments.

My only concern with this approach is the size of the bearings. On a lot of the FWD vehicles that use a bolt on rear spindle, such as a Dodge Caravan, the bearings are much smaller than I would feel comfortable with for the abuse that they might see in an expedition trailer scenario.

 

[ExpoMike]

Actually and IRS ('68+) version versus a swing axle ('67-) car, there is minimal camber movement during the full travel. There is some but very minimal, especially when compared to the swing axle cars. This is one reason people will take a pre '68 car with the link pin front end (better for long travel and offroad) and convert the rear to IRS. Best of both worlds.

 

[ntsqd]

Sorry, yes BC = Bolt Circle; JY = Junk Yard

On bearing size, I think one could make that call based on the potential donor's rear axle gross weight. I've no idea what those numbers might be, could be plenty or donors or none.
I would expect the VW bearings to be on the low end & I know what I've put them thru in my DB (hint: pic is mild) w/o ever needing to replace them.
Even though the IRS' curve is nothing close to that of the S/A, it still is enough to be significant.

 

[GeoTracker90]

Well I'm starting to experiment with building the trailing arms for the independent suspension trailing arms. I ordered a 3' length of 9/16" threaded rod which I will use to hold the two bushings in allignment during the build.

This picture just mocks up the two bushings at approximatly the correct spacing. I'll actually machine a couple of alluminum pucks that will be used to center the threaded rod where it passes through the spacer tube between the two bushings. I might have to make a shoulder on both sides of these aluminum pucks to center the spacer tube and the bushing shell. I'd also need to make two more aluminum pucks to center the threaded rod where it passes through the outside of the bushing shell as well. By using these aluminum pucks I can center the threaded rod in the bushing shell with out having the urethane bushings inside the bushing shell. This will allow me to keep the bushing shells assembled while welding w/o harming or melting the actual bushing material.

After I get the sample spindle and some tubing bought I'll continue to develop the trailing arms for this suspension.

Wish me luck!!

Mike

 

[JeepN95YJ]

This picture just mocks up the two bushings at approximatly the correct spacing. I'll actually machine a couple of alluminum pucks that will be used to center the threaded rod where it passes through the spacer tube between the two bushings. I might have to make a shoulder on both sides of these aluminum pucks to center the spacer tube and the bushing shell. I'd also need to make two more aluminum pucks to center the threaded rod where it passes through the outside of the bushing shell as well. By using these aluminum pucks I can center the threaded rod in the bushing shell with out having the urethane bushings inside the bushing shell. This will allow me to keep the bushing shells assembled while welding w/o harming or melting the actual bushing material.

Mike,

Instead of going to the trouble of making inserts and using threaded rod to keep everything in line, wouldn't it be less work to just use a single tube as the bushing shell?

Then you can weld up the rest of the trailing arm with everything in line. Once the trailing arm is assembled and welded, go back and cut the single tube to length for the two separate bushing shells.

Does that make sense? Am I missing something as to why you would go to all the extra work to make only 2 trailing arms?

Certainly I wish you good luck. I check this thread often and plan to build my own suspension next summer.:26_7_2:

 

[GeoTracker90]

Mike,

Instead of going to the trouble of making inserts and using threaded rod to keep everything in line, wouldn't it be less work to just use a single tube as the bushing shell?

Then you can weld up the rest of the trailing arm with everything in line. Once the trailing arm is assembled and welded, go back and cut the single tube to length for the two separate bushing shells.

Does that make sense? Am I missing something as to why you would go to all the extra work to make only 2 trailing arms?

Certainly I wish you good luck. I check this thread often and plan to build my own suspension next summer.:26_7_2:

I already had the seperate bushing shells, so that is what I planned on using. Another reason to use this type of bushing is availability. Any decent 4WD fabrication shop should have a half dozen of these bushings laying around if I ever need a replacement. My question about using a single tube pivots (pun intended) on supporting the threaded rod for the length of the tube and the longevity of only having short urethane bushing inserts in the outer ends of the long tube. I guess that if I did as you mentioned and then went back and cut the single tube to make two bushing shells I wouldn't have to worry about that problem.

My reasoning for taking the time and effort to make the inserts to keep things alligned revolves around time and money and tools and material. I have some extra time to play with this project but not a lot of cashflow at the moment. I also have the material to make the inserts and a lathe to make them on. I guess I look at the build process as recreational as well as product development.

I'm finalizing the design of the arms themselves and I'll probably be using 1-1/2" round tubing to run from the bushings to the spindle. I'll also use the same round tube to brace between the two tubes running from the bushings to the spindle.

It looks like my next purchase will be about 10' of 1-1/2" DOM tubing, a little more than enough to build both arms, as well as the spindles and the tubing for the spindles to be mounted in. I'll have to do some searching for about 4' of 2-1/4" dom with a 1/4" wall to fit the spindles into. If any one has some laying around I'm open to donations!:xxrotflma

Sorry for rambling on; I'll post up again when I have more accomplished on this project.

Mike

 

[JeepN95YJ]

Makes sense...

I've got a few of those bushing sets in the garage as well.

This link might help find that large tubing:

http://www.complete4x4.com/catalog/

The guy that runs the place is local. He sells cutoffs of different sizes and usually has very good prices. AND he ships.

Keep us posted on you progress.

 

[GeoTracker90]

Thanks for the link. His pricing does seem very reasonable. I'll have to call and inquire about the 2-1/4" DOM with a 1/4" wall as I don't see it listed on the web page.

Thanks again!!

Mike

 

[UK4X4]

So have you found suitable spindles yet ?

looks like you'll be a couple of weeks ahead of me for the suspension, I'm still finishing off the cabinets on my trailer.

So are you just having one large mount or two standard ones like this

Obviously you would need cross linking, and instead of the bushing at the end you'd have the spindle mount.

I don't have access to a lathe etc so I need to be real carefull on the parts I order...

For the toe in toe out had you considered using bushings with the thread you'd posted previously.

Are you home building or have access usage to a workshop..?

I've left this bit of my build till last to further my investigations....what size wall thickness will you be using for the arms themselves ?

and is the size guess work, experience or calculations....ie you used X size before on a rock crawler and never had an issue..

Arms I'm guessing will be about 24-30" long ?

Ie depending on what height airbags your going to use, will make the angle and length of the arms important, against shorter stronger and less twist.

I have my bags already.....the frame is done......just need to finish the top...turn over and start on this..

I'm too on a budget...my time V's cost of the materials......man I don't want to count the hours so far......but its all fun....

and then if i subtract the cubalibre thinking time and measured the actual work time.....it would be way less..

 

[GeoTracker90]

So have you found suitable spindles yet ?

I believe that I'll be using the spindles that are high-lighted in the following picture.

The mounting portion of the spindle shaft has a diameter of 1-3/4" as indicated in the chart, and a 6-1/2" length. I plan on pressing this into a section of 2-1/4" DOM tubing with a 1/4" wall giving it an ID of 1-3/4". The spindle will be welded around the circumference as well as having a few rosette welds for good measure.

looks like you'll be a couple of weeks ahead of me for the suspension, I'm still finishing off the cabinets on my trailer.

I'm not sure about that. Remember that $'s are some what scarce for the moment.

So are you just having one large mount or two standard ones like this

Obviously you would need cross linking, and instead of the bushing at the end you'd have the spindle mount.

I'll be using the two seperate bushings to mount the arm to the trailer frame. The brackets that will weld on to the outside of the frame will have my attempt for minimal camber adjustment. See first picture below. The second picture is of the bracket that will wrap around the rectangle tube crossmember to mount the inner bushings and the inner mount of the outer bushing. I hope that made sense.

I don't have access to a lathe etc so I need to be real carefull on the parts I order...

For the toe in toe out had you considered using bushings with the thread you'd posted previously.

Yes, the inner bushings will have the threaded stud on them. I might just order two new bushings with the stud or just order the stud(pictured below) and have it welded on.

Are you home building or have access usage to a workshop..?

All three! :smilies27 I do have my own metal lathe and welding equipment. I also might have some limited access to the machine shop at work. I'll also farm out the cutting of the brackets to either a waterjet shop or laser shop depending on price. I'll have to get one of the guys at work to contact the place where we have stuff cut out and have them quote me a price from the DWG files I have created for the brackets. I also have access to friends with tube bending dies that will fit my Pro-Tools 105 bender.

I've left this bit of my build till last to further my investigations....what size wall thickness will you be using for the arms themselves ?

and is the size guess work, experience or calculations....ie you used X size before on a rock crawler and never had an issue..

Arms I'm guessing will be about 24-30" long ?

Well for the arms I'll probably try and use some 1-1/4 OD x .125 wall x 1.00 ID so that I can use some threaded inserts from A&A Manufacturing. Their 3/4" threaded insert fits inside of a 1" ID tube. The other option is to go with 1-1/2" OD tube with a 1/4" wall. No worries of bending with this tube, but heavier than I think I want. Still need to do some thinking on this. I'm planning on having the arms approx 24" long.

Ie depending on what height airbags your going to use, will make the angle and length of the arms important, against shorter stronger and less twist.

I have my bags already.....the frame is done......just need to finish the top...turn over and start on this..

I'm too on a budget...my time V's cost of the materials......man I don't want to count the hours so far......but its all fun....

and then if i subtract the cubalibre thinking time and measured the actual work time.....it would be way less..

I hope that I answered your questions in a helpful way. Do you have a build thread for your trailer? I'd love to check out some pictures of what you have accomplished.

Mike

 

[Grim Reaper]

I have thought about how I would build these sort of A-Frames and I think I would start with a complete axle of the correct width. Strap the axle and the pivot to a table get them square and build as a single unit. Then cut the axle tub as the last step. It’s the only way I think I could keep the two A-frames square and true. Even minor length differences in the parts would throw off the A-Frames but built as a unit and then cut apart I think it would be the best shot at ending up with a perfectly square set up.

One thing I have been trying to figure out is if Martyn has built a little bit of camber into their A-Frames. It almost looks like it in some of the pictures. Maybe he will chime in about it. That said even with a little camber I would just bend the center of the tube the correct amount for the camber and still build as a single unit.