XRAY - Model racing cars

You must be running your belt too tight. Also, check your diff pulley so it isn't broken or worn in any way.

I am very surprised that you are having such problems
I run belts for months without breaks (GM 13.5, Tekin ESC with turbo, rubber tyres). I run the rear belt quite loose because there is a good wrap around the pulleys. I set at least 3-5mm slack in the belt without any slip problems.

Are there any sharp edges on either of the pulleys that are cutting into it? Are the pulleys mounted left to right correctly? (the belt should run straight and not at an angle). Is the belt catching on anything? Is there any fluff or debris buried in one of the pulley teeth that is causing a temporary over-tension?

Can't think of anything else - sorry !

Might also be worth checking the individual gaps between the teeth in the diff pulley.

It's very easy for a small piece of dirt or dust to compact into the gap and raise it up slightly.

It's worse on the Xray pulleys as they are black so dirt doesn't show up well.

I have no problems (yet-knock on wood) with my rear belt, however I am curently running it on the softest (full left) position. It was on one hole tighter (one hole softer from initial setup position) but I felt that was too tight aswell. I'm running 10,5T boosted, how do others in similar conditions have their rear belts?

I atually run mine pretty tight.

My thinking was that with a loose belt and a gear diff, the belt goes slack into a corner, then as soon as you mash the throttle it suddenly tries to tension up and 'snaps' tight.
A bit like holding a piece of thin cotton between both hands, if you tighten it gently it it will take a lot more tension than if you hold it loose and pull your hands apart quickly.

Also, in my experience the belts weakens if you spill silicon oil on them, so make sure there is no leakage from the gear diff.

I definitely agree that the stress on the rear belt is higher after the introduction of the gear differential in the rear. However, I have not had any major problems with this, and usually replace mine after 20-30 runs. It might just be a bad batch of belts, and that you are unlucky.

LOL I have never broken an XRAY rear belt in 5 years. I was thinking of trying the gear diff on my '012 - guess I better order up some spares first (or put some negative curve on the the throttle profile)

We are running it with 4.5T and boost with speeds over 100 kph. I had one track where I broke one rear belt every 10 batterys (maybe because of too much tension, and some pieces of dirt on the track) but usually it holds much longer.

You should really try even less tension, and maybe reduce your brake-epa.

I can tell you that since I bought the car (two month ago), I always put the rear belt in the middle hole. As you know you can put the belt higher oo lower positions hole, I reffer the middle hole, and the middle rear (is the point for soft tension for the belt), and I raced on carpet, asphalt, stock, modified..., and my belt is perfect. And can't use other hole, because the belt is too tension.

Regards.

Hi Guys,

I am having the same problem with my car. I am using 1 belt per 2 to 3 batteries. Cannot handle it anymore, too expensive. I even tried other belt brand with no solution.

I am not sure which solution will help from chugging to ball diff or making tighter, so your feedback on the results of your test would be great....

Me too. Broken rear belt around 6-7 battery