PROBLEM - LOSEN TO MANY REAR BELTS

Salinet · **Posted:** Mon Mar 19, 2012 15:13:03

kartdemon wrote:

On the layshaft check the play on the 20tooth pulleys where the pin goes through the layshaft. Within the pulleys the slot for the pin can have excessive play. This can give a bigger jolt as you accelerate hard. If so just rotate the pulleys so the pin goes through the unused slot in the 20tooth pulleys.

Both slots on mine are heavily worn so changing my pulleys this week. There will still be slight play but try and get it as best as you can. I may try and make it a little tighter somehow. But less play will also help under braking.

Brand new car!
No play at all.

kartdemon · **Joined:** Fri Jul 01, 2011 11:39:23 **Posts:** 25

Salinet wrote:

kartdemon wrote:

On the layshaft check the play on the 20tooth pulleys where the pin goes through the layshaft. Within the pulleys the slot for the pin can have excessive play. This can give a bigger jolt as you accelerate hard. If so just rotate the pulleys so the pin goes through the unused slot in the 20tooth pulleys.

Both slots on mine are heavily worn so changing my pulleys this week. There will still be slight play but try and get it as best as you can. I may try and make it a little tighter somehow. But less play will also help under braking.

Brand new car!
No play at all.

Worth a try.

I think someone else mentioned about sharp corners or maybe snagging on something.

Only times mine has snapped was from a smack (rear), belt (front) got caught on a cable tie or the odd small stone from the track snapping the belt(rear). May it is sabotage or Jasper the friendly ghost :-)

Hagberg · **Posted:** Mon Mar 19, 2012 18:14:12

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

CharlesF · **Joined:** Fri Jul 15, 2011 10:18:37 **Posts:** 35

I am very surprised that you are having such problems :shock:

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 !

Skiddins · **Posted:** Mon Mar 19, 2012 23:08:06

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.

UrabusDenis · **Posted:** Tue Mar 20, 2012 00:02:48

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?

Skiddins · **Posted:** Tue Mar 20, 2012 01:28:37

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.

Stusdal · **Posted:** Tue Mar 20, 2012 14:46:59

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.

Salinet · **Posted:** Tue Mar 20, 2012 15:11:54

Hagberg wrote:

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

The eccentric is set to middle to 2 steps looser.
Nothing wrong with the pulleys.
I checked.
We are having this problem in all cars with geardiff.
My own car is new!

Hagberg · **Posted:** Tue Mar 20, 2012 22:39:23

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.

YELLOWSHARK · **Posted:** Wed Mar 21, 2012 02:18:19

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)

Salinet · **Posted:** Wed Mar 21, 2012 14:26:02

Hagberg wrote:

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.

Bad batch? I pretty sure that was not the problem because I had here some belts from early 2011 and some belts from 2012.
All belts broke.

We are having a problem that is not pulley, tension, etc
We check and test everything. Since 2003 I use XRAY and I just broke belt on dirty tracks.
At the track we are racing now I never broke a belt untill now so....
I had in january 11 belts (all belts that I have for 2011 and never used), in 2 weekends I sold all belts.
Something is wrong, isn't it?

David_Ehrbar · **Posted:** Thu Mar 22, 2012 10:23:16

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.

Salinet · **Posted:** Thu Mar 22, 2012 14:39:09

David_Ehrbar wrote:

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 already tried everything you said!

Ruben_qlc · **Posted:** Thu Mar 22, 2012 14:58:00

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.

Salinet · **Posted:** Thu Mar 22, 2012 15:03:41

Ruben_qlc wrote:

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.

Yeap!!!

gusbak · **Joined:** Sun Jan 15, 2012 22:20:33 **Posts:** 8

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....

Salinet · **Posted:** Thu Mar 22, 2012 15:39:55

gusbak wrote:

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....

I think you read all the posts right?
If you tried everything...I think your solution from now is use a balldiff.
I talked to Martin Hudy and I will test the last thing before get my balldiff back.
I will use my belt a little more tensioned ok.
I will let you know if worked but I think the problem is a combination of track and geardiff.
We have here an slippery track sometimes and when the car get some track the force on belt is to high...after 2 or 3 batteries... gone!
With ball diff I used a single belt for a year.
Saturday is track day and I will test the last thing so, let's see what happens.

gusbak · **Joined:** Sun Jan 15, 2012 22:20:33 **Posts:** 8

Salinet wrote:

gusbak wrote:

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 chaging to ball diff or making tighter, so your feedback on the results of your test would be great....

I think you read all the posts right?
If you tried everything...I think your solution from now is use a balldiff.
I talked to Martin Hudy and I will test the last thing before get my balldiff back.
I will use my belt a little more tensioned ok.
I will let you know if worked but I think the problem is a combination of track and geardiff.
We have here an slippery track sometimes and when the car get some track the force on belt is to high...after 2 or 3 batteries... gone!
With ball diff I used a single belt for a year.
Saturday is track day and I will test the last thing so, let's see what happens.

Thanks for your feedback.

Will be waiting for your post on Saturday to see the results and what you tried.

b.wihardja · **Joined:** Thu Feb 02, 2012 09:43:34 **Posts:** 9

Me too. Broken rear belt around 6-7 battery

XRAY - Model racing cars

PROBLEM - LOSEN TO MANY REAR BELTS

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