RPM anti telescope rear carriers

[cautrell05]

I was skimming through all the build threads on here looking at chassis mounting holes and I came across this thread.
http://www.rc10talk.com/viewtopic.php?f=36&t=3807
Part way down the page on the right side is an RPM kit for the rear suspension that has mounts and rear hubs with the hingepin moved down. When did they come out with these and why didnt it catch on? I always hated the way the rear dogbones were not level with the arms and pulled out if it had too much down travel.
This is from my 10T/C conversion here- http://www.rc10talk.com/viewtopic.php?f=36&t=3807

On the left is a rear hub from a traxxas slash and the right is the stock AE hub. From the looks of the pic the RPM hubs would do the same as slash hub and keep the distance from the trans to the axle more even through suspension travel. To me it seems like it would be better but evidently there is a reason it never took off.

Nick

[heretic]

In my experience it is a very bad idea to change maufacturer's geometrie so drastically. By using the slash part you are MASSIVELY modifying camber gain, and roll centre. Like you said, there is a good reason it was designed this way. RPM parts are great quality and if memory serves well they don't change the geometry at all, so if I were you I'd just stick with that.

[cautrell05]

I understand what your saying about the changes. Ive been an alignment tech on full size cars for 20 years now and been racing full size stock cars for 15 years. The geometry on these is pretty simple. Besides the protrac hubs for the slash have 6 holes for the upper link so I should be able to get it back to stock. The main thing I was after is why does the dogbones not run level with the arm factory? If the bone has to extend and collapse under suspension travel I would think it would induce binding in the rear suspension and as much as the manufacturers seem to worry about little things, it seems odd that this was never addressed.

Nick

[jwscab]

there is no reason you can't do it. Associated probably left the existing rear hub as is since it was used in a few places, and in a buggy application, the higher the axle, the less ground clearance you have. with a truck it's not so much of an issue because the tires are taller. the axle is situated as low as possible to provide ground clearance. look at a touring car rear hub, some have the axle right at mid-height so the suspension arms can float above and below center as the car drives through the course.

there are 2 trains of thought on the anti-telescoping, as least as far as I can see. if you don't allow the bone to move in and out relative to the diff hub, you will wear a narrow notch in the diff hub, which could cause some binding as everything wears.

allowing the bone to float in and out as the suspension articulates, allows the diff hub to wear over a wider patch, thus making the possibility of binding alot less.

having the extra friction of the bone moving in and out could provide some anti-squat effect as well.

I would say build the truck how you would like, and it could provide a tuning tool if need be; ie, one track likes anti-telescoping performance vs the standard bone scrub.

[cautrell05]

I forgot about the ground clearance side of it. That makes sense. I could see the wear part also. If I can get the travel down to 1/16-1/8" ill be happy. In stock form its close to 1/4 inch depending on how much travel it has.

Nick

[Jay Dub]

The hub with the pair of holes, was propably intended for use on multiple cars. However, having the ability to move the hinge pin upwards does two things that havent been discussed. Firstly, it is an easy and effective way of adding droop (down travel) which will in most conditions give more traction. Two, it changes the suspension arm angle at a given ride height. With the hinge pin in the upper hole, you will have a suspension that is more supple when going through rutty corners. Because of this, it will also help keep the car from bicycling as easy when hitting said ruts. This is accomplished because the side impact forces tranfered through the wheel will be transered further below the hinge position. You can however go too far with this type of peramiter (the front suspension on the RC10 stealth car from detroit comes to mind), and eventually suffer weight transfer issues, as well as suspension binding, and axle plunge issues. There are allot of things going on when you move hub from one position to the other, so it can be hard to tell what is really happening specifically with that peramiter change. -Jeff