Help with setup needed.

[justo316]

My new Pro4 keeps doing RIGHT 180 turns when you go full throttle and then hit the brakes. My mates car does exactly the same thing.

I thought it was because of the extra weight on the battery side, but I added some counter weights and it still does it.

Any ideas guys?

[Matt]

a while back my buggy would do this when i merely let go of full throttle, i didnt even apply brake. it was because the drive train was too tight in the diff and as a result of being too tight, only one wheel was able to spin freely while the other was tight. this caused the car to rotate similar to the way a tank rotates.

does this help? how is your drive train? does it all move freely?

[justo316]

I just checked. It all moves freely.
I found something strange though. I have a front one-way which means if I try rotate the front wheels backwards, it should spin the motor. The right wheel sometimes feels like it's slipping. ie. spinning backwards but not moving any of the other drivetrain parts.

I'll have to rip it apart and see, but I have another problem. One of the hex heads holding the front tranny together is stripped. I got no idea how Im gonna get that sucker off.

[Matt]

suggestion: superglue the allen key into the nut, let it dry, and undo. you'll lose an allen key for good but it will get the nut out.

im not familiar with the drivetrain you have and how it works so i might take a backseat on that discussion and wait for one of the onroad experts to come on and check it out.

matt.

[justo316]

good idea with the allen key. Will try it.
Thanks.

[BALISTC]

When you spin the front wheels backwards, the motor shouldnt spin...thats what a one way is supposed to do. They should spin freely without affecting anything else.

If one of the front wheels turns the motor when you spin it backwards, and the other doesnt, thats why your car is turning when you go full throttle.

Take the one-way diff apart and make sure the one-way bearings in it havent seized up.

[bd581]

Chect the one ways. Im about 95% sure you will find lots of teeth in the casing.
This happened to dads and just about every HPI Pro 4. The gear flexes. Dad made upa washer to reinforce it. Some companies now sell this part.
This happened to Dads the first race. Ordered a new one way, made the washer and havn't had a problem since

[justo316]

bd581 - Could you explain further please? "Lots of teeth in the casing"? You mean broken teeth?

I think there must have been something wrong with the oneway cos they included an update (v1.1) for it which I think I installed. There was a new aluminium plate that goes on the one way gear which the screws go through.

[azzachaz]

that sounds exactly liek the fix bd581 is talking about.

[justo316]

....then I guess I should be wondering why mine isn't fixed then...:(

[justo316]

Got my stripped screw out and had a look at the one way diff. It looks brand new. I think there's too much grease in there and the right side is slipping against the one way bearing. I tried wiping some off but that didn't work. Considering de greasing it....

[Matt]

can you get us some pics of this diff?

[justo316]

Well, I just put it back in, but if I get any bright ideas and have to take it out again, I will get some pics. It looks just like the usual ball differential you get in every other car, except it has one way bearings on the inside (you can't really see them). You are supposed to be able to spin the outdrives forward but not backwards.

[justo316]

Well, I had some success last night. It turns out that it was my setup that was making my car spin to the right. I know this cos I was playing around with the setup and made it spin left instead! Now I just gotta make it neutral. I noticed that the one way doesn't let me spin the right wheel backwards anymore (maybe lube wore thin a little?). My friends still does though.

So anyway, what do you guys recommend to use to setup my car properly. Right now, I use a ruler and my eyesight.....I find that camber and toe on one side seems to always be different form the otherside if I make the turnbuckles equal size. I normally have to make the rightside ones longer.

[azzachaz]

Trial and error, or buy one of those dedicated set-up boards