Rear of car going back and forth

[Cubscout Dad]

I have 4" drift at 4' will more drift stop the rear of my car from shaking as its going down the track? This is rear canted 3* holes with a bent DFW axel and 4th wheel lifter rail rider.
Better yet what causes the shakes?

 

[BulldogRacing]

do you have 2 rows of tungsten behind the rear axle? I tried more then this once and it would not stop wiggling no matter the steer. 4" should be good but some need more.

 

[Kinser Racing]

Not enough steer (I don't like to call it drift, drift should be used for other things) or your axles are to small of a diameter (easy to do with scout axles). It could also be to much wheel gap or to aggesive COM.

 

[HurriCrane Racing]

I would start first by adding more steer. If it doesn't fix the wiggles, start moving the weight forward.

 

[jatofau1]

do you have 2 rows of tungsten behind the rear axle? I tried more then this once and it would not stop wiggling no matter the steer. 4" should be good but some need more.

 

[jatofau1]

I have 4" drift at 4' will more drift stop the rear of my car from shaking as its going down the track? This is rear canted 3* holes with a bent DFW axel and 4th wheel lifter rail rider.
Better yet what causes the shakes?

 

[Maglev]

Try balancing the weight on the rears (use small digital scale under each wheel) and see if it gets rid of the sway!

 

[GravityX]

Are you using wheel cavity weights? The full circle tungsten wheel cavity weights can cause this sort of thing.

 

[kcracer]

I would check the wheel gap first most people run them with very little wheel gap. This was one of the first mistakes I made

 

[Cubscout Dad]

For wheel gap you just a credit card?

 

[B_Regal Racing]

A credit card is too large (at least for me). I run as little as possible.

 

[Gtdhw]

This year, we are setting our gaps with an "axle just-barely visible" approach.

 

[Cubscout Dad]

I had box axles and wheels, I went to a 92x and rage wheels back there and ran at another scout pack race and did not notice the wiggle but I also bumped the steer a little more so I do not know. I will find out at Districts in March.

 

[True North Racing]

I had a car that had a COM about 5/8" and 4" of steer. Everything looked great until it went down the test track. It had the wiggles. I moved weight around from side to side and rear to front and nothing helped. I put it back on the treadmill and carefully watched the wheels and found the left rear wheel not looking right. I pulled the axle and inserted another one. I remembered one of the axles that the scout and got a little aggressive with the polishing. We replaced that axle and the car ran really well. We did have to go back and readjust the steering as the bad axle also compromised the steer.

 

[Mojo Racing]

I had a car that had a COM about 5/8" and 4" of steer. Everything looked great until it went down the test track. It had the wiggles. I moved weight around from side to side and rear to front and nothing helped. I put it back on the treadmill and carefully watched the wheels and found the left rear wheel not looking right. I pulled the axle and inserted another one. I remembered one of the axles that the scout and got a little aggressive with the polishing. We replaced that axle and the car ran really well. We did have to go back and readjust the steering as the bad axle also compromised the steer.

Be careful with using the treadmill...

They generally have the same affect as tying the derby car behind your normal car and taking it down the road to see what it does...

Treadmills are bad on the wheels and will cause more problems than they solve.

 

[Kinser Racing]

Be careful with using the treadmill...

They generally have the same affect as tying the derby car behind your normal car and taking it down the road to see what it does...

Treadmills are bad on the wheels and will cause more problems than they solve.

+1,000,000

The treadmill secret weapon trick was created by someone that either didn't know what they were doing, or they did and the intended puprpose was to slow you down.

 

[Gtdhw]

We used a treadmill for the past 4 years on my oldest's boys cars (and Dad cars). Now that it's my youngest boys turn (Tiger), this is the first year that we are tuning our cars on a tuning board (home-made). Hoping to see improvements.

 

[Kinser Racing]

It really just breaks in the graphite.

 

[True North Racing]

Be careful with using the treadmill...

They generally have the same affect as tying the derby car behind your normal car and taking it down the road to see what it does...

Treadmills are bad on the wheels and will cause more problems than they solve.

Thanks Mojo, I will cease from using it as that does make sense. After building cars for nephews, neighbors kids etc., I am now addicted to these things and have gotten pretty decent at building them. I have won a couple of outlaw classes. Now after finding this site I feel like I am starting a PhD program. lol I am now building a better tuning board and have ordered more stuff for my Besttrack to make it more consistent and will have to put about 10 hours of work in the track to bring it up to NPWDRL standards. I have not found a good way to tell my wife yet that you guys race year round.
Thanks for all the great advice and willingness to help out the newbies.

 

[Cramjet]

Back to the issue with the amount of steer...

My Street Stock got Post Office tuned on the way to today's race and had a whoppin' 11" of steer. That's almost enough to run in a circle on a kitchen table (ok, maybe not but still). I was lucky Bulldog checked it out on site to help fix that before the race.

With that much steer, it ran 2.991 on the league track. With 4" of steer it ran about 2.964. Now I can see why some start to obsess over tuning.