Horrible Noises - X5
 

Finally put my leccy bits in my X5 tonight and gave it a quick spin.

Anyway, couple of quick issues:

1. It makes a quite horrible noise during acceleration, I think its either the belt or spur. Anyone know what noise a car makes when you run the pinion too tight against the spur?
This sounds like somethings slipping though, so I'm guessing its the belt, is that normal for an unused old X5? Is my quick fix the one where I make a belt roller to tension it up a bit? FOr anyone who's run them though, do they make horrible noises when the slipper/diff is loose, or do they sound like any other car ina similar state (I bought this car built and have never used a LOSI or similar before, so not sure if there's anything different in the drivetrain!)!?

2. There's bugger all lock on the outside wheel, but plenty on the inside, is there anything I can adjust for this or with a one way etc do I not need much lock? My servo is spannered I think (dumped an old one in and I think I need to change it again) so is it that they normally run with loads of lock on the inside wheel and I am just not able to reach the end points?

3. ANyone running one at mid west regional sunday that I can have a look at? Plus any spare spur gears!!

Wow, this is a difficult post to answer. In the Racer magazine article just out, it says the X - 5 is for the experienced hobbiest, and they are right.

Now if I bought a used R/C car, the first thing I would do is disassemble the entire thing and put it all back together for two reasons. First I'd know for sure it was right. Second, I'd be much better able to repair it, and if you know anything about my driving ability, you'd know why I say that...

The X - 5 instruction manual is on the Tech section of www.4wdrc.com in glorious color if your car did not come with a manual. If you want the printed version, E mail me, [email protected] and we'll hook you up fairly cheap.

One thing sure, I wouldn't run a car with a nasty noise more than 6 inches...

I didn't run it far at all, just enough to set the trim etc, and accelerating slowly which avoided the noise. I've got a couple years experience but never with a Losi drivetrain, if I got the same noise on cars I have run before I'd definitely say it's belt slip or chewing the spur, but I'd already checked the belt tension and the spur/pinion mesh is not too bad, I was just wondering if belt slip is usual on a brand new old version X5 if the mods (such as the additional tensioner) had not been done?

Haven't rebuilt it because I'm going to do the X5 squared upgrade anyway soon!

Dave,

I think if you make sure you have the correct tension on the belt, you should know what i mean you have run belt cars before, in this sense this one is no different.

I think the belt (drive gear) roller is a must, it just gives you an extra safe guard, while it is ok for the belt to skip a tooth here and there, it is nicer for them not to skip at all :). Maybe its just me but in you initial post you seemed to imply that this roller will add tension to the belt. It will not, it just sits as close to the drive gear as you can get it without it actually touching so if the belt does lift and try to skip, the roller will not let it.

If the belt is skipping it will sound like a clicking sound if its only 1 or 2 teeth at a time, if its more then it will sound like it is ripping. Thats probably the teeth on your belt :woot: (joke)

You say it sounds like it is slipping, personally i would tighten the slipper right up so you know its not the slipper, then set the diff (fully tighten then back off 1/8th of a turn for starters. and try it.

Its just a process of elimination.

You should have some backlash in the teeth on between the pinion and spur like any other car

a noisy noise dont tell us what sound it makes. is it a barking noise, awhizzing noise, a clicking or a whining noise, sounds daft to ask that but it will point to 4 different answers to help you

grrr lee you beat me to it :woot:

Hi Dave,
No, it shouldn't. Old or new.

You have seen mine at Southport, thats how it should sound.

How tight is the tension of the belt from the underside. Mine is quite literally tight enough to twang like a violin string. This goes against what would normally be recommended as a losser belt is more efficient - but with the amount of power we now have, I found it necessary to tighten the belt to this extent. To get it so tight, Id tighten it as tight as possible with all transmission parts in place, and then remove the layshaft and move the screw another 1/2mm - 1mm.

I also run the slipper locked. I say locked meaning the spring is completely compressed - but it does still slip a little.

Having the newer pulleys and rollers will make a big difference, and make sure all of these are in a straight line, otherwise the belt will wonder up the sides and something will mangle very soon.

Chazz's recommendation of striping and rebuilding is a very adviseable one. If you don't have enough time, then do atleast completely strip the transmission and refit - pay attention to postion of belt on pulleys and make sure teeth on pulleys are all good.

Chris

Sorry, it was late, good point about the type of noise!

It's a ripping sound, if it happened on say a 501x I'd deffo say belt, but once had car with a diff that made a similar (weirdly) sound. It doesn't sound like the spur/pinion mesh, although I have that slightly tighter than I'd want there is a little backlash (for some reason found it really difficult to position the motor).

Belt tension wise, it's what I'd run on a 501/yok etc but I do normally run on the looser side for those, sounds from these posts that this needs to be a lot tighter so I'll try that and see. I know normally to just sit a roller "over" the belt without adding tension, but I just considered fitting an adjustable one and then dropping it onto the belt quickly to add tension as a "quick fix", as it's take all of 5 seconds to adjust! Anyway, first step tighten belt I think!

Yeah dave if you tighten the belt right up and try it you will know if its belt skip, it will skip less at least ;)

If it's the original car then the culprit is likely to be an out of round centre pulley. The moulding company got the original drive pulleys a touch out of round, but it's enough to not allow you to get consistant tensions i.e. tight/slack spots which promotoes belt skip at the drive pulley.

Solutions are either the DDP (or the new ones that are standard) or a quick and easy fix is a xx4 rear belt layshaft pulley which fits one with only a little shimming needed. Be sure to gear down 1 tooth on your pinion if you do this though as the pulley is 1 tooth bigger.

Like a dry bu..

I'd best not finish that :drool:

(In joke :p)

I allways ran my belt very lose and fitted 2 rollers
one like the team boys do in front of the center pully and one at the back pushing the blet down after the spurgear zero skip

i allso ran the shorter belt..dont ask me what Losi part number it was

never snaped a belt on the x5 after i did this

LOL ;)

:thumbsup: <<<< Chris long :woot:

what part number was it?

LOSIA-055NT 51\14P

Standard X - 5 belt (The short one, fits xxx-S.) is 3209.

Longer belt (Fits xxx-4 and needs dual idler pulley set-up on X - 5.) is 3213.

We stock both.

You guys in U.K. have much different conditions from what we're used to here, so this is somewhat different for you. But here is the "standard X Factory line" on belt/slipper adjustment and belt skip:

A little belt skip is desireable. If you get it to absolute zero your driveline is too tight and you could go faster. The really fast X - 5s skip 2 - 3 teeth on acceleration and 5 - 6 on hard braking. Best is to have an experienced X - 5 driver listen to your car at the end of the straight.

It's very much an art. I know we're all engineers here, so art is hard, but this is cool art. Slipper and belt tension work together and must be adjusted together, especially when at a new track or with a new car. Obviously a looser slipper will have less belt skip, and a super-tight belt will make the slipper slip a lot.

On first putting the car on a track you must run a few feet, then adjust, run some more, adjust, and keep working back and forth between the slipper & belt tension until you get it right. Sometimes this will require a trip to the pits.

But stay with it and you'll hit the "sweet spot." We knew these adjustments would take time and patience, and part of the design of the car is that once you find the sweet spot, you set it and forget it. No need ever to touch the belt tension again until you change belts. And to change spurs, count the revolutions taking off the nut, then replace to the same spot. That adjustment does not change until you change pucks.

When you get it right you have the fastest car on the track. Very satisfying...

LOL, thats more like a "aaaaooooh aaaaaoooooh aaaaooooh aaaaaoooooh" noise. :lol:

To get a rough start point for tensioning the belt, my idler mount thing is about in the middle of the sliders (the same amount of adjustment is available both front and rear), where have you guys ended up adjustment wise?

Comparring like that is virtually impossible becasue the the variation in drive pulley size, diff pulley size, belt length, idler numbers and positions etc etc.