Rear gear tolerances and handling.....

[slack11]

This may seem as if it is a very strange question, and one I think I already know the answer to.....
We have been fighting a car that is EXTREMELY loose when on the throttle, even to the point it is loose on the straight away under throttle as you just barely turn the wheel..... Trying to get to the throttle off the corners is like playing russian roulet with the outside wall.....   I have checked and rechecked everything on the car, and it is all allright in terms of setup.  The only thing that is left to check is the rear gear.  I removed the welded center and replaced it with a steel spool over the winter.  If this were put together with the wrong tolerances, (backlash etc.) could that ever cause a loose condition like I have under throttle?  Again, I have checked everything else, and am about out of patience trying to figure this thing out......  I am going to replace the spool with the welded piece tonight, but was wondering if anyone had any issues like this before.

[knoxracing]

No, this would not be an issue with a spool as long as the gear turns freely before and after running it. The result of a spooled gear set up wrong would be burning the gear and bearings if it were too tight or you would have trashed the teeth if it were that loosely set up. If the car is that loose you have a set up / geometry issue. The only other possibility would be a part hanging up or such.

[VMS Motorsports]

You could have spun the teeth out of the spool if you're on a very high torque application, ie. bullrings or road course, or, more common, broke an axle shaft

[knoxracing]

I believe its an ongoing issue, correct? he spooled it because he hoped it would solve the problem. I would make certain the rear is locked and you haven't stripped an axle, I agree this is possible as the axle was in the car with the welded gear.

[VMS Motorsports]

Not sure, doesn't really say. I read it as if it was new this season.
I guess we will see when he updates

[slack11]

Sorry.... was away from the ole computer last night trying to figure this thing out.  The spool was a winter project just to shed a couple of pounds of weight.  The car was not like this last year, I pulled to car apart over the winter, repainted and cleaned, put the same setup back in it, and it has been loose like this since.  I've rechecked every number in the car, all angles, checked the rear end for square and being bent, check all heims, etc.   Can't seem to find the reason. like I said I didn't think that the spool could cause anything like this, but it is the last thing that I need to rule out. 

I pulled the rear gear last night. All looks fine, the splines, rear axles, etc........  Just unsure where to go next.

[VMS Motorsports]

Assuming you scaled it after you put it back together and all was well....

The only failure that I can think of that would cause an un-driveable car like you are describing other than a broken axle would be a shock, most likely the right front.
I'd pull all the shocks off and check them, just take the springs off, and check compression and rebound.

I showed up at Nationals last year with a slightly bent RF shock, couldn't tell by the naked eye, but it was enough that there was no rebound. Couldn't even hold on long enough to get both of my qualifying laps in

[Earnst85]

Slack,

Reading back thru some of your other post you mentioned "about to get the frame done" around November.... Did you have it clipped, stress relieved, or what?

One thing to check is that your front clip is square to the crossmember or whatever you are using to square your rear.  Sometimes we assume it is square because we measure the rear from the crossmember, but I have seen frames that it was not square.  I had frame fixed that wasn't square between the rear crossmember and the firewall. We clipped the front end and put in trailing arm lollipops square to the rear crossmember.

Your wheelbase numbers on both sides should be close (unless you run a big caster split or toe) if your rear is square. If your loose, chances are that you right side wheelbase is longer than the left.

[slack11]

I had the chassis put on the jig over the winter, wanted to check to make sure it was still allright.. It was, I had the front clip stiffeners put on, and the thicker steering rack plate, but that was all. 

My left side is actually 1/4 longer than the right... Everything that is in the car is pointing towards being tight, but on throttle it is just plain loose...

There is a link to a video on you tube of someone who was behind me for most of the race, I should add the link here so you can see what I mean.  I'll see if I can figure it out.

[slack11]

Jim,
  Thanks for the heads up, I'll pull all the shocks tonight and check. I replaced the RR shock with new to try to eliminate that as a possibility already.....

[knoxracing]

There are several things that could contribute to your problem,
1)Cross
2)Squaring
3)Tires
4)A-Arm measurement (center of bolt to grease fitting).
5)Rear end offset
6)Akerman
7)Wheelbase
8)Spring package

Have you changed tire suppliers?

[VMS Motorsports]

Find anything?

[Earnst85]

I'm still waiting to see the video link....

[slack11]

I'm not the in car camera.... I'm in the white car with the black roof.  I start two rows ahead of the in car camera at the start, and I am the #11 that you can see later in the video.  I have the horizontal holes in the front fenders.  Looks/ feels like it lays on the right rear too much before getting loose.......

Let me know what you think, I appreciate all and any constructive criticism....

I been real busy lately, tonight I have to pull the shocks off and check them, other than that, I haven't found anything out of the ordinary with the car yet...

Nate

[slack11]

I'll save you some time, the first two minutes of the video are just the pace laps.....