Axle Wrap again Attn: Saddleup

[chris]

I have done some searching on the site and there's alot of opinions on which solution is best. I wanted to bring it up again as some of the guys working with ideas have not posted new stuff in over a year.

Saddleup, I'd like to hear what you have to say about your axle wrap bar, It looks like you had the best solution. Seems that a trianglated unit with a point at the bottom of the axle and top extending to the frame with a shackle at the end and a heim joint would be best to allow the unit to rotate but I don't see that on yours?

I was noticing my springs are getting that S shape and I do get axle wrap so I figure it's time to do something about it.

Wrap trap is nice but it seems there should be a shackle up there at the frame and I agree with Saddleup that it should attach to the axle in two places. How long should it be and where should it attach at the top, line up with the front spring attachment or CV joint for the driveshaft.

What do you think?

Chris

 

[Solar Aviator]

I've been looking at the geometry of some of these systems for some time. Geometrically, there is a lever arm between the front spring bracket and u-bolts. The axle is giong to pivot as the u-bolts hold is solid to the axle. The wrap bars attempt to eliminate the same role induced by torque. I think the two fight each other and the location of the shackle on the front of a wrap bar is important in reducing the induced forces. I've been thinking about some type of rubber bushing system where the springs attach to the axle to free up that axis of motion and rely strictly on a bar, or set of bars to handle torque. It or they would work like a parallelagram with springs. It would look alot the newer cars with rear coils where there is a set of torque arms that mount to each side of the differential housing and connect forward to the chassis. It might free up some articulation also.

Just some food for thought. Dave...

 

[SaddleUp]

In order for it to combat spring wrap it needs to be triangulated. I.E. It needs to attach in 3 points. With the wrap trap it only attaches in 2 places and then relies on the spring itself to provide the lower arm. It does work to some extent this way but has two issues. First is that it needs to be mounted solid on both ends without shackles (otherwise it wouldn't work) which will force the axle to stay at a certain position as it runs through its arc. (Potentially it could bend the springs by forcing them to buckle on compression) Seconnd is that the spring doesn't provide as solid of a link and therefor it will not be as effective at combating the spring wrap.

My setup (Which isn't really my solution but rather is a modification to solutions of others before me to fit my needs) does have a shackle up front which allows the axle to move forward and backward through it's arc. This reduces the necessity of the front mount being at an exact position such as a 4 link suspension would require. It still works because your just trying to keep the axle from twisting which is where the wrap comes from. I chose to just use bushings in front rather than a rod end (Heim Joint is a particular brand of rod end). A rod end or Johnny joint would work as well but they are not ncessary. The bushings provide for a full range of articulation that exceeds that of the spring bushings (By a fairly large margin). Duff's sells one that is identical in function that also uses bushings in the shackle which is why I decided to give it a try. (The Duff arm has a rod end but it only serves to adjust the position and is at the axle end)

My design isn't really that unique. It differs from most others in the use of bushings (Most people go with rod ends or johnny joints) and that I chose square tubing instead of round tubing. The square corners inheritantly add strength which in part was why I chose it over round.

FWIW, I plan to add these to my website for sale after I get the covers and tops off the ground. it will probably be several months before then however I'll entertain the idea of making them for people before then. Here is a picture of one that I built for another member recently.

 

[Frankenhorse]

Does Duff even still sell those? I was looking at there site and nothing there.

 

[mountainview68]

I bought one a few months back from duff.