X5 spur gear and more
 

Guys,

Only had my x5 a couple of weeks and gone through 2 spur gears, my own fault, not meshing properly, but at £11 quid each its getting to be expensive. Can you buy different ones?

Also, is the slipper ment to slip, cause i have heard to keep it tight so it doesnt damage the pucks on the slipper.

The spur gears are custom, hand made for the car, hence the expense. The one on my car is the original one from the start of the 2007 season. I have been meshing mine properly though ;)

Slipper setting is up to you. Best is to let it slip just a fraction on take off from a standing start on a surface of reasonable grip, this will then protect the rest of the tranny.

I had to laugh slightly at your comment that someones said to have it tight to protect the pucks as the pucks are the very component designed to wear out and so are the consumable components. If you're protecting those, it's too tight and so will pass the strain onto all the other tranny items so expect to go through drive and diff pulleys and belts MUCH more often than you would otherwise. The front diff and drive pulleys in my car are also originals from the start of the year in my car, I did preventativy change the rear one when I had the rear diff out last, so have used 2 all year.

When we originally designed the X - 5, back in like 2003/2004, we wanted to use the XXX-4 spur gears, either the 92 or the 94 spur. Unfortunately, it was just impossible to get the gearing right with that small of a spur - because the internal ratio of the car is only 1.75, with a 94 tooth spur gear we ended up using like 13 or 14 tooth pinions. The larger spur gear really opens up the gearing options.

So, since we had to make spur gears, we went and found the best gear-machining company in RC: Precision Racing. They do charge us a little more, and thus the spur gears are a little pricey, but if you treat them right they'll run forever. I've used the same 3 spur gears (a 102, 104, and 106) for the last two years at least.

I suggest really taking time when you set the gear mesh. Be really careful as you tighten down the motor strap, as it can sometimes shift the motor one way or the other as you tighten. I usually tighten the bolts together - one turn on the front one, one turn on the back, one turn on the front, etc - and examine the gear mesh frequently as I tighten. Make sure your pinion gear is in good shape too - I don't usually think of pinions as wearing out, but just this last summer I took a hard look at my pinions and replaced a lot of them (they were like 6 years old, lol).

So take some extra time setting the mesh, checking often as you tighten down the screws, and the spur's should last a good long time.


If you're the adventurous sort, you might check into finding some on-road spur gears from a touring car. You might be able to find one that you could make work; I don't know. Not sure I'd recommend it as the gears are 64 pitch and thus even more fragile, but the gears themselves might be cheaper.

Cheers guys,

The gear mesh was my fault, totally. So the slipper pucks are a consumable, thats all i needed to know, i will set it so it slips on power from a standing start on a grippy surface. i.e. teeside.

I also got some machined pulleys from lesro, which seemed to be too big, its melted away and knackered the belt. Am going to go for the xx4 rear diff pulley with the xx4 17t pulley. Also just ordered the second idler pulley people seem to be taking about try and kill some belt skip.

Just a note, didnt skip at all with a brushed motor in, just when i put the brushless in.

Over all seems a fast car, as long as i can get the transmission set correctly.

HIya,

Not sure I follow on the pulley thing, they only come in 1 size which is the same as the stock X Factory ones. I run the 17t xx4 centre pulley as unfortunatly the stock X factory one is not perfectly round. That and a hold down roller in front of the pulley makes a MASSIVE differene to how slack you can set the belt with zero skip.

If you come to what is likely now a club meeting at Batley on Sunday I can show you these mods on my car if you like?

Ref the slipper again, it shouldn't be slipping much, just a wafer on standing start take off. Also when you take it apart you might see that the spur can 'wobble' side to side by hand. This is correct as the slipper pucks are wider than the spur so the slipper plates clamp on them and not the spur gear. Your pucks are worn out when they have worn to the same thickness as the spur so the tension of the slipper is clamping on the spur gear and will very quickly wear that away.

There is a slipper rebuild kit avaibale for the Losi XXX4 which is excatly wht you need when it comes to maintaining it, it comes with a couple of washers and odd spring things, just chuck those away, it's only the pucks you need.

just i quick thought when u said the machined pulleys melted away and ruined your belt ,you did remove the little pips from the bottom of the bearing holders as mentioned in the manual didn't you,

By doing this, the internal ratio will be very tall so be sure to use a mild modified and/or a very small pinion. Check the overall ratio here : http://www.4wdrc.com/tech_X-5_drive_ratio_chart2.htm

Like Dan, I strongly suggest to use the X-Factory or Lesro diff pulley and a XX-4 17t center pulley. The hold-down roller is a must on astro but I found the second idler useless.

Where would you guys recommend putting a roller bearing to minimise skipping. It seems more accessible to put it up on the spur side (and under breaking this would be he area where the belt would lift off).....but putting one near the pulley might be more effective.

What do you reckon?

I run with both rollers. The most effective is the center one, the rear one is more for ears convenience. If you don't use it, your belt will skip slightly on heavy brakings.

Hey Russ,
I use the optional large pulley for the XXXS to lift the belt and the small kit black pulley for tension. That makes a big difference to start with.

Then when looking down on the spur with the cover off, I have a 3/8 x 3/16 bearing on a roller over the belt. It is close enough to touch without pushing, the idea is that because the belt has to lift off the idler for the teeth to slip, it is not possible with the bearing there.

You'll need some sort of alloy collet to mount the bearings on, held with washers so it doesn't wander, and then a screw through a hole in the chassis.... I have e-longated my hole so the position of the bearing can be adjusted - as it was easier to do that than get the measurements spot on first time.. and with washers, the e-longated hole can't be seen anyway.

The bearing roller made a HUGE difference to belt skip :D

Chris

Mine is mounted almost directly in front of the main drive pulley a hairs width from touching the belt. I now have a VERY free transmission and no skip whatsoever..

right infront of the pulley i have pics but not of my car this is what i used to do minehttp://www.hobbytec.co.uk/index.php?...o_show&ida=114

http://www.hobbytec.co.uk/index.php?...o_show&ida=113

I'll show anyone trackside who wants to see.

Will be at York Saturday night, and Batley on Sunday. Worksop the follwing Sunday and Teesside Aces Sunday after that.

omg
chris u show urs and ill show mine hehehehe

I did in my second spur gear today and this time it wasn't meshing that was the issue.

For some reason the middle of the spur gear has rounded off so it spins on the shaft and is no longer tight fit.

The slipper plates have also cut into the sides of the spur gear, although the pucks seem okay (unlike last time when they were noticeably warped and blackened in parts).

I guess what has happened this time is that the slipper was too loose and it slipped loads, to the extent that it also rounded the centre of the spur gear.

Of course, now, even with the slipper tightened right up the car won't run under significant load from the motor because the slipper shaft just spins within the spur gear (or the spur gear spins around the shaft as it is driven by the motor - but doesn't engage and drive the belts as it is rounded).

Clearly the slipper setting is absolutely crucial and if I notice any slippage during the run (today it was slipping most of the way on the straight as I accelerated) I should come off and adjust immediately.

Can anyone confirm, correct or embellish upon my experience here?

Thanks (and Happy Birthday to me!):)

Your right, if it slips too much it will just heat everything up and your sur gear took the brunt of it.

This also happens if you run the belt too lose and it skips then that will heat it all up

E

The spur gears come rounded in the center, just big enough to fit around the slipper shaft. When you put a new one on the shaft (gear only on the shaft) it should be able to spin around. Otherwise the slipper would never be able to work.


The center hole can warp and grow under excessive heat, which certainly would be caused by too loose a slipper.

Here are the parts that should be on the slipper shaft after the drive pulley:
slipper plate, spur gear with the six pucks in, second slipper plate, a small shim or two to adjust end float, a bearing, a wider silver spacer (around like 5 or 6 mm wide), the wide plastic spring holder, the spring, the thin plastic spring holder, and the slipper nut. If you have all that stuff on there, you should be able to completely collapse the spring by tightening down the nut. From completely collapsed, back the slipper nut off about 1.5 turns, and use that as a starting setting. I wouldn't run more than about 2, 2.5 turns off of completely collapsed. If some of those parts I listed above are missing (I'm thinking mostly of the wider silver spacer), you would not be able to collapse the spring fully because the threads on the shaft would run out first. This could easily lead to a too-loose slipper setting.

Happy Birthday!

Okay...cool Paul...thanks.

I couldn't remember if the centre of the spur was rounded or squared off...but now you mention it I do recall it being round.

Now though, it is massive and you see where it has warped in the heat.

I don't understand why it could not run under load when fully tightened though as the spring was certainly fully compressed.

However, it could be because the slipper plates had chewed into the spur a bit and so was overall not as tight as it could be.

I've got some new spurs on order, so I'll check this all out as per your instructions when I'm rebuilding. Got no racing for 2 weeks so plenty of time to tinker.

Cheers.

Happy birthday Russ!!

Do you still have my email address to hand? if so, please can you remove the top cover from over the spur, take a photo and email it to me? If you can include the whole length of the layshaft from directly above, then I will confirm if built right - and if not, take a photo of my car and email it back to you.

I am not doubting you, but without the car in my hands its hard to diagnose a fault so starting from the basics is the easiest way.. ;)

Also, will you be racing between now and the Southport GP? As I will be there and will gladly go over anything then for you mate.

Chris

Are the ucks fubar now too? Are they still wider than the width of a new spur?