# Slippery Rear on my Fray car



## slowslotslim (Apr 6, 2009)

Hey folks - I'm somewhat new to t-jet tuning and I'm working on Fray setups. I have now built my second or third straight car that seems to have the same problem: the rear end is very slippery despite the use of sponge silicone tires.

On one car I seem to have remedied the problem by shimming the play out of the rear gear mesh, using a tungsten axle, and gluing on an AFX specialty crown (I know this isn't Fray legal - I just wanted to give it a try - WOW!).

But now I have another one - yet there doesn't seem to be any problem with gear mesh, I'm using a Fray legal crown, and a tungsten axle. And the thing will spin out on a straight!

Thoughts?

Thanks for the help.


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## martybauer31 (Jan 27, 2004)

Is your track clean? What kind of tires are you using? Are they clean as well?


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## 2racer (Jun 15, 2008)

try using a lighter front end it worked for me


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## resinmonger (Mar 5, 2008)

2racer said:


> try using a lighter front end it worked for me


Or, check out your pick up shoe tension and shoe profile. Too much weight (as noted above) or friction at the front can make the rear seem loose.


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## slowslotslim (Apr 6, 2009)

I'm using Wizzard LTR .350 tires and the track is clean. Performance improves marginally for a minute or two after I clean tires again with a tape roller.

This car has Wizzard independent fronts with added weight. I'll try removing some weight. Sometimes I use RTHO front ends.

On this car I'm using Wizzard E82A shoes. More or less tension?

Thanks for your replies! I'll try some of these things over the next evening or two. . .


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## Brixmix (Dec 2, 2007)

What body are you running? Try taking all the weight off the front and try it Make sure the shoes are running flat on the rails and and are limited if you are running alot of shoes if the shoes are limited enough it should be ok make sure that the track is clean it may take about 10 to 15 mins of running the car and cleaning the tires every lap or two. Make sure all for tires are touching you might try a .310 front tires and .340 or .345 on the rears


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## smalltime (Jun 3, 2006)

You can try reducing front end weight, but I think your problem may be tire related.

Are the rears pressed on true?
You can check this very easily by simply turning your chassis backwards on your track and appying a small amount of power while holding the the chassis with the tires just tickling the track surface. You will feel an out-of-round tire, trust me.

Have you "scuffed" your tires?
As discussed in a prior thread, you will want to take the shine off your sponge sillys. Don't grind them, just take off the shine with a bit of 600-1000 grit paper.

Be shure the fronts aren't binding on the "keepers"

Be shure the body isn't dragging.

If you are running very small tires (.330 or smaller) be shure the crown gear isn't hitting the track. Apply a sharpy to the OD of the gear and run a lap, this will rub off if your dragging the crown.


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## mikeponiatowski (Jan 24, 2006)

*Agree with the front end people.*



2racer said:


> try using a lighter front end it worked for me


I have a few cars that do the same thing. I did some testing of my own. Minimizing front end friction and weight seems to be the best solution for me.

The front axle should spin freely through the holes. Fray style weighted wheels should spin freely on the axle. Too much pick-up pressure can cause drag. I even had one guide pin misaligned and catching along the slot side.

Tracks can be cleaned, tires can be cleaned and changed, but too much front end friction is the kiss of death.


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## 2racer (Jun 15, 2008)

I changed rear tires first than used a lighter front . I had the same problem of having to clean the tires every couple of laps . The thing that made the car come around was the switch to a lighter front end . If there was to much tension in the pickup shoes he would be desloting into the corners ( I didn't hear him say that )


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## mahorsc (Mar 26, 2008)

it sounds like the shoes on 1st car are hitting to far back this makes car fishtail out of corners 
the 2nd with wiz shoes they seem to make noise and drag if not very flat with rails just make light adjustments to shoes till it stops(if not flat the car acts like its pushing the frt end)and make sure you have cut the tail off shoes the will hit track and hold back wheels up just a little then you have to much wheel spin
at times with the wiz shoes i wll leave a stock shoe on one side and get 1 wiz shoe set the put 2nd shoe on that way you can tell which shoe is causing problem
hope that helps
kevin


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## slowslotslim (Apr 6, 2009)

Sorry it took me so long to get back to you all with my results - busy doing the real life stuff - it's crazy, I know. . .

I found the biggest culprit to be too much weight in the front end. I was under the impression that too much weight in front was impossible, so I was loading it up. Lesson learned!

At least one of my shoes had all contact in the back of the shoe. I think that was a contributor.

On this car I have not had to grind the tail end of my Wiz shoes. I did on another car once before - must have been lower rear tires. . .

Thanks everyone for the info!


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## smalltime (Jun 3, 2006)

Good call Kevin.
I need to look at mine to see that they aren't hitting.


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