Wishbone lower bar?

Edited: 1/20/2008 8:14:41 PM by iLLblazer

Just wondering if there are any noticeable downsides to running a wishbone as the lower bar? I've got a truck to do this week and I'm trying to keep it nice and clean and this is one of the ideas I'm considering. The bags are going on the uppers and I'd like to keep those bars parallel which means triangulating the lowers. However, i want ALL the tabs parallel so in order to get some adjustablity I'm thinking wishbone with the single adjustable end under the pumpkin. I just don't know if this will have any bad effects on the suspension and i don't see it done often...

When I talked to Max about doing a Satchell link, and also when I read about it, it seemed like it was advised against to have the lower pivot(s) close to each other. It was due to the amount of force the axle exerts on the lower links, that they should be spread apart on the axle, rather than centered. Apparently it can be enough force in some applications to twist or flex the upper bars and create some amount of torque steer. I'm not 100% sure on this, and I think there were other reasons, but thats all I can think of right now. I think it would be better to run the single link towards the frame, or just run a 4 link with all the mounts parallel with each other.

Yeah I considered that I'm just not a fan of the open tube ends. I'm also using 1.5" square bars but going that route would let me use some round tube for the adjustable end. I'd just have to cap it somehow.

I saw the one you posted over on s10forum. That lower mount doesn't look very strong to me but its a good visual for what I'm describing.

Look at the ends of the link bars above. They are capped with a round cap. And are you talking about the mounts on the 720 looking weak?

no sorry I meant the lower mount on the pic you posted above.

where did you get those caps and do they offer other styles?

Yeah that lower mount I think needs gussets towards either side.

I got the tube caps from Ballistic Fab.
http://www.ballisticfabrication.com/Billet-Steel-Tube-Caps_p_21-1498.html

They only offer them in round, but they offer a few different sizes.

OK well I decided to go with the 4 link with the lowers going to the outside of the axle. I checked the chassis book I have and it said the same thing you mentioned about the support being needed toward the outside of the housing.

I got it all drawn up and designed now so stay tuned I guess.

You have to remember that most of those books are assuming that you are building a racecar. Most of the time, the trucks that we are working on do not have the traction or the horsepower to cause the issues that the books describe. Also racecars use thinner tubing because of weight and minitrucker use overkill offroad sized tubing because they are uninformed. In my oppinion, you can get away with the wishbone being installed the way that you originally planned to, but to do it right, keeping the mounts wide on the rearend is best. Also, another reason the run the bars wide on the rearend is to keep the roll-center "attached" to the chassis instead of the rearend housing, which is moving up and down in relation to the chassis, thus constantly moving the roll-center up and down creating an unstable chassis.

Edited: 1/21/2008 5:54:37 PM by iLLblazer

Well I'll save the idea for another project someday I guess. I built the 4 link bars today.