X-5 belts breaking and pulleys melting

[stegger]

I've noticed in jimmys report at the euro's that ellis's and somebody else's X5 was snapping belts and stripping pulleys. Was this down to that track (dusty?) or if i got this car will it happen on our tracks as well ? :)

[Big E]

I didn't snap any belts but yes I did strip a couple of them mainly due to the fact I kept the car going round when it was skipping, had I pulled it in and tightened it it wouldn't have gone. If it skips and skips a fair amount then it wears the teeth on the pulley which then makes it worse and the end result is the thing heats up and melts and takes the belt with it.

As to why not sure, I have not touched my drive line once this year over here from when I built it November and it has run perfectly so why I had the issue it is not 100% sure but I don't think the dust helped. I did have an old chassis on (pre production squared) which may have been the issue as I changed it and it went away. But I also fitted the long belt as well at the same time.

E.

[Cockerill]

What Ellis said ^

[ben]

Was the track high grip tom?

[Lee]

True chaps but, when we set mine up with a new belt and pulleys and the belt as tight as we could possibly get it, it still skipped, the car felt tight to drive yet the belt skipped. Im not sure why either. Mine only managed 2 runs on the long fat belt before it took out the pulleys again :(:confused:

[stegger]

Thanks again E :)

[stegger]

Were you using the new pulleys that the car comes with as standard lee ?

[Lee]

I was using the bigger losi drive pulley to reduce belt skip, i had the std pulleys on, not the new ones. when i ran the long fat belt i added a 2nd roller to get more belt wrap, this is when it managed 2 runs. before that i was getting 2 mins :confused:

[stegger]

Or try this http://www.4wdrc.com/tech/BeltAdjuster.htm or http://www.4wdrc.com/tech/PulleyMod.htm

[Cockerill]

Was the track high grip tom?

At times yeh, but no more high grip than what we have here. I would have thought Eden Park would be much worse for the drive train (Bumps & Grip), yet nobody had any problems there (and Ellis hasn't been round there much :p), it really is a mystery :confused:

[stegger]

Maybe on the parts of the track were it had less traction wouldn't there be less load on the drive train causing it to rev higher ? How tight was everyones slippers?

[Lee]

If i backed my slipper off so the belt wouldn`t skip, the car wouldnt move:confused:

It was just very weird, i think toms drive train tightened up during the finals too. Im not sure if he found out why though?

[Lee]

Or try this http://www.4wdrc.com/tech/BeltAdjuster.htm or http://www.4wdrc.com/tech/PulleyMod.htm


The belt adjuster is a good idea but i have been told that it can twist the pulley plate so i have not bothered with it.

[stegger]

Or the belt is coming in contact with its self were i have marked in red ?

http://i12.photobucket.com/albums/a207/cheshiremodelcars/DriveTrainMod_3bi.jpg

[Lee]

I cant see the pic at work :(:thumbdown: just a little red cross

[Cockerill]

I don't think it's that stegger. The cars have been ultra reliable in the UK so that points to the problem been the conditions in Italy. It can't be grip, because we have high and low grip here. I don't think its dust, we have that here to. Heat is a possibility, but its hot in the USA and they've never had a problem. Track style/layout, again no problems in the USA. That's why its a bit of a mystery :confused:

[Lee]

It was very frustrating at the time :(

It still is actually. To the point the X5 is still in the boot of the car:lol:

[stegger]

Just throwing in a few idea's tom, know dought the answer will be found:)

[super__dan]

Ref the tensioner turnbuckle. Ellis originally pointed out to me that when getting to the correct tighness the screw(ball end) that goes into the tensioner bar actually bends slightly rather than adds tension due to the resistance of the tensioned belt.

So I still use it and take pop the slipper out (to take the tension off the belt), change the tension a bit and refit. Without the tension on the belt the screw doesn't bend and so the idea works perfectly.

Now this might sounds like a lot of work, but I personally change my belt tension so infrequently that it's not an issue.

Personally I run the XXX4 longer belt, not sure if this really helps reduce skip but as I still run the dual pulley from a while back, that's the belt I need. If you don't have/want the dual pulley then you can file the tensioner slots back say 5mm, which takes up the extra belt length.

The machined pulleys are very good, but I ran the stock diff pulleys and xx4 centre pulley for nearly the whole time I've ran an X5 and I have little/no skip and a free drivetrain.

[Lee]

Cheers Dan.

Thats the bit that got me, my drivetrain felt good, and from your tips when i built it i just used the bearing by the drive pulley and the losi drive pulley and it was fine for probably about 5-6 meetings. The problem must have been conditions but my biggest fear is spending the money on some machined pulleys and a belt and it shredding those as well after 2 mins :(

[bigred5765]

we have both belt tensioner mod and dual idler pulley on, and bearing on a threaded bolt in front of the slipper pulley,and our belt still skips under breaking i think it's riding the rear diff pulley now, so I'm looking at adding another roller in front of the rear diff to wrap the belt further around the rear diff,

[super__dan]

To deflect the belt or to just hold it down?

[bigred5765]

to lift it up so it wraps around the rear pully more,so kinda deflect it ya, any one tried that yet

[Gayo]

I experienced that too. When you get rid of the jumping on the center pulley, the belt begins to ride the rear diff.

We (Oliv and I) made that mod on our X-5s, it works. We used a shock shaft and 2 B4 direction bearings to push the belt to the ground, between the diff and the center pulley.

I can take some pics if you want.:)