Roketa LT conversion.

[rgvkid]

Im rebuilding my friend chinese Roketa. It was a Super Kart so it already has 35HP Briggs with Gear box and Torque Convertor. The front end was damaged and it was ridiculous how much the replacement parts were so we decide to just hack the front and rebuild. It ended up being alot more then that.

My problem now is the Rack and Pinion setup. I miscalculated the Rack positioning and location area. I'll post some pics of the build and of the rack location.

I think im gonna need to get another rack but not sure which style will work. Oh, and this was suppose to be done by tonight for Glamis tomorrow.

[rgvkid]

pics

[rgvkid]

Pics

[rgvkid]

Heres where it came to a halt.

The frame rails are 16" on center, 1.25 tubing.
The pivot points are 19.5".
The rack measures about 22 when centered.

The white mark is center of rack and center of frame.

Any tips on how to remedy or what type of Rack would work?

Another issue is that the Rack cycles more upwards then droop. As you can see in the pic, it is at full droop. But when im at full bump on the A-arm, the rack still has more upwards travel to go.

[Martinm210]

What does the rack shaft look like? I had one I shortened about 5inches simply by cutting the shaft short of the ball knuckle the again before the gear notches and simply welded it back together. It has worked fine that way for me.

[rgvkid]

Thanks Martinm,

Im not sure if it needs to be shortened or extended. The splined shaft definitely need to be moved over a bit to clear the chassis rails.

So did you cut the internal shaft and shorten it? Then you lose some of the turning radius right? Or did you cut the outer housing also?

[Bullnerd]

The pic you have with the numbers on it-is the tie rod attached to the knuckle?

You should have designed around the rack if you knew you were going to use it.

[rgvkid]

I thought I was building to the rack. I tried to keep the knuckles about 1" over the lower arm pivot point. But i realize now it should have been before the pivot point along with keeping the steering shaft angle in mind. First time buggy front end build. Next time around will be different.

The pic above shows the tie rod connected to the knuckle. It looks like a ball knuckle. Im not worried about extending the tie rods, Im just not sure if im opening a can of worms by tearing apart that rack. But its a chinese cheapy so as long as i can get it to somewhat work through the weekend.

[Chikin]

I ran in to the same problem with my car. I changed out the entire front end and well on my car I have a motor up front..... so I couldn't move the steering rack back... But the pivots were narrower and well I had to extend my rack by making threaded shaft links and welding them on the shaft....

Post more photos with the boots off of the rack ... so we can see where and how.... It would give us a better response with answers.
And is it a hardened steel rack shaft in the steering(The one that moves left and right??)

What is the rack length from end to end...

[Martinm210]

This is how I set up my kids buggy which really has no bump steer at all. I think the trick is to keep all the pivot points in line with where the arms pivot is AND also make sure the points between spindle arm and rack are parallel with the arms.

Something like this:


This is what my kids buggy looks like, you can see how the boot on the right is way too long from the original shaft length that I cut off. Excuse the crappy welds, .049" wall tube and a $100 flux core welder is well..a challenge.



I did it by trial and error to some degree too, got the length right then adjusted the rack vertical position to get the tubes parallel. In the end the suspension travels without really any bump steer at all. I'm not sure that's technically what you want in all cases, but it works good for the kids buggy.

The front to back position I think is a bit more flexible, in my case it could be set back further to be in line, but this front to back part doesn't cause any bump steer. If anything it may affect the ackerman and response on steering at full steer, but I've generally been really happy with this too. I did find out the hard way about akerman being wrong too, but using banshee spindles forced my hand to get it right..