X-5 squared shredded belt and pulley!

[Fiddybux]

Hi all,

Was at the Southport meet today and was getting some good advice on how to best setup my X-5 squared. Everything suggested worked a treat, which had me leading the pack in the B final until the car ground to a halt.

At first the general consensus was that I had stripped the rear diff, but having opened the car up it seems that the diff is intact (all good), but the belt was in bits, yellow bits everywhere, the fibres inside the belt had wrapped around the belt tension pulley and the slipper pulley was completey rounded.

The slipper pulley is not the crappy stock one either, it was the small Losi pulley from the centre shaft in the XX4. Now it is good only for the bin!

So, I want to know if anyone has had this before, what caused it and how I can avoid in future?

I wonder if I had the belt too tight and this is what caused it? It felt okay to me, skipping slightly under hard braking only...and it is meant to skip a little.

I also wonder if I should have blunted the edges of all the pulleys and diff gears when assembling to help prevent belt damage. I will certainly do this now with a small file.

Any ideas anyone?

Cheers all.

[super__dan]

Hhhhmmmm, chicken or egg?

I have only stripped a Losi pulley once, at last years Euros. I'd incorrectly set the belt tension and it was far too slack but cos it was a qualifier I carried on anyway. By the end most of the pulley teeth and a fair amout of the belt teeth were stripped.

Not sure what to suggest, both are quite robust normally.

[MikePimlott]

How Mad is this.
This happened at Batley today to Stu Hurley. At first Mr Long thought it was the rear diff but on further inspection the belt had torn to bits and wrapped all around the pulley.

2 in one day. Hmmm

[hickston]

Car was ace though :-)

[Fiddybux]

That is proper mad! Stu and I need to confer on this matter!! Mine looked very similar to the photo's, except my drive pulley was just a yellow colour and it was the belt tension pulley that had belt fibres wrapped around it. All bits of yellow belt everywhere as well.

I'm a bit suspect that the belt was too tight for another reason....when braking hard on concrete I sometimes nollied the car and sometimes flipped over front ways!!!! I got so much grip on the front that the back just lifted into the air. Had the belt slipped a bit more here then I don't think this would have happened....but what do I know!

Any other ideas why / how this happened?

[Chrislong]

Im wondering, if both you guys have had the belt running up against the side of one of the gears somewhere? or tensioner? More than likely the layshaft/slipper gear I think, but if its rubbers away the side then chewed the belt, and side of gear breaks away (like in Stu's picture), belt moves aside and as you rev it a 5zillion rpm, it goes into meltdown.

When you two rebuild the transmission, just check to see if the belt runs up the side of the gear. The way to stop it, is can moves shims around layshaft to adjust where the gear is, for small adjustments. Can also shim out the tensioner pulley, or flip the diff gear over (as it is marginally off centre), but don't just flip the diff as the bolt will go the wrong way - take diff apart and flip just the gear.

Erm. I have never experienced this, so don't shoot me if im wrong with the above.

[Fiddybux]

No Chris....this all sort of makes sense to me.

In the tuning section of the manual it warns about making sure the belt runs true and straight in all the pulleys and tells you how to do it...but this is only for reasons related to "efficiency".

I guess though it is how it started, a little chaffing on the edges of the belt soon turns into a big old ripped belt at very high RPM that you get in this car. I mean, with the Losi pulley, the internal ratio is a stupidly small 1.68:1 I think!!!

As to how the pulley got rounded is a little beyond me at present...maybe heat induced through running fast with a tight belt?

In any case, when I rebuild I will definitely get everything lined up in the middle to avoid contact with the edges as much as possible....plus I'll get a few belts and pulleys for spares just in case!

Wish I could be certain how this all happened though.

[MikePimlott]

My X5 belt rubs on the side of my rear diff gear as it enters the rear diff cover, Ive flipped the diff, moved it tried anything to stop it rubbing but it just doesnt run true.
I hope my belt doesnt fray away.

[Chrislong]

Hey Fiddybux, do I know who you are? I don't mind taking a look if you are ever in the area, unfortunately now Winter is here, I'll be racing over at York, the NE and Worksop, so I guess we won't cross paths for a while.. but please do ask away, PM me etc. Lets bottom this and get that X-5 bullet proof.

[Chrislong]

Originally Posted by MikePimlott

My X5 belt rubs on the side of my rear diff gear as it enters the rear diff cover, Ive flipped the diff, moved it tried anything to stop it rubbing but it just doesnt run true.
I hope my belt doesnt fray away.

Hey Mike,
Check the inside edges of the sides of all gears, if they have rough bits in the moulding then scalpal them smooth - even if the belt runs in the centre this is worth doing, any rough bits can cause self-destruction, it doesn't take much with any belt car.

[Fiddybux]

Hi Chris,

Well I don't think we've officially introduced ourselves to each other, but I've certainly raced with you at Bury and Southport in the past....my name is Russ.

Thanks for you're kind offer anyway...I know you're a seasoned X-5 driver and really respect your opinion on matters.

Well...I managed to kill my X-5 belt and pulley in 3 weeks of ownership...anyone able to beat that!?

Maybe I just had a duff belt in this instance, but I'm going to get rid of all rough edges and sharp edges anywhere near the belt everywhere when I rebuild this, as well as trying to get stuff running true.

Any ideas why the manual says you have to face the diff pulleys with the flanged edge to the right of the car...because it makes sense to flip them if it centres the belt more?

Cheers.

[Chrislong]

Hi Russ,
To be honest with the manual, I don't know. I built my X-5 about 3 years ago and I am still using the same car.... but like trigger from only fools and horses, this old broom has had 15 new heads and 10 new handles. ... so my manual has seen updates since, and i can't find it to check anyway...

It is whatever is right for your car, if the belt runs better with the gears flipped, then go for it.

the Losi belts are pretty reliable in their quality, they're pretty good.

if you do spot fraying of the edge of the belt, then it can be fixed by cutting it with scissors (may take a 2nd person to pull it tight enough to cut) then a lighter to seal up the edge again without melting the belt - my current belt has had this done once atleast, and I can't remember how long ago I put it in.

If the sides of any gears spin on the gear or seem loose, some can, then don't be affraid of applying a tiny bit of glue - but don't get it in the gears.

Im trying to cover every base here, cos I can't workout how you have both had meltdown. I know Stu's wasn't set overly tight, his car ran very well today at Batley....

[Fiddybux]

Hi Chris,

Yeah I've already glued the edges on the diffs and pulleys a few times...damn sonic welds aren't much cop in my opinion.

When I was building the car the sonic weld failed on the drive pulley, so I glued it, then it was too tight in the chassis to spin freely (with no shims) so I fudged a fix and ground down the inside edge gradually to account for the extra width the glue introduced...it much have been fractions of millimetres though...but it all makes a different doesn't it!

Thanks for your advice on all this.The kit belt should have been a Losi LOSA3213 yeah? Or is it the LOSA3209? I hope it was the LOSA3209 because that suggests its a crap belt and the LOSA3213 will be much better.

Hope I can catch up with you at some point in the near future, rather than next summer!!

[Chrislong]

Hi Russ,
Not sure on what the kit belt is, like I said - my car is 3 year old on paper, but to split hairs its actually had everything replaces several times in that time - I know the cell brace over the 4 cells is original, LOL.

The belt I run is the LOSA3213, this is the yellow XXX4 belt. The belt originally used on the none-squared car was the LOSA3209, this is the yellow belt for the XXXS.

I beleive the XXX4 version is wider by 1mm too. but I have both here while I type, and I really can't see it, there is a width difference but it is slight, but every little helps.

[Fiddybux]

The more I think about it Chris...the more I reckon my belt was just a bit crappy when I got.

My whole kit had a few defects, like the sonic weld failing on the pulley, the manual has incorrect pictures in it (which I told Chazz about - he was actaully pleased I pointed it out) and now this.

Maybe if I just put the 3213 belt on it will all be ok.

Escuse my crude drawing, but is that what the idler bar looks like with both pulleys attached as you have said?




Cheers Chris.

[Chrislong]

Hi Russ,
The drawing makes sense. So the rear of the car is to the left of the drawing - yes, that is how it'll look, although the alloy bars would be infront of the gears from that side.

(get a mirror, then remember the rear of the car is to the right now, and that is perfect)

Chris

[Fiddybux]

Like this, with the rear of the car to the right (smaller pulley at the rear end):



And what path does the belt take through here? Does it go round the big one from the top and then in between both and round the bottom one and back to the front diff?

[bigred5765]

hi russ i have some pics that might help
clicky

[Chrislong]

Hey Russ,
The belt from the bottom, runs from bottom of rear diff pulley to bottom of front diff pulley, thats the simple part. Then it goes from top of front pulley, under the small roller and then bends over with teeth outwards, over the top of the big pulley and then under the layshaft and around it (teeth inwards) and to the top of rear diff pulley.

[Fiddybux]

Thats a nice looking belt in your pic Carl....mine's utterly buggered!