Rebuilding a B Max

JAW · #1 13-04-2011

Hi all

I'm totally new to the RC world and recently bought a used B Max. I have a few niggles I want to sort. I have had excellent advice from Si Coe, but I don't want to be pestering him 24/7

This car is just mainly for bashing at the moment and I would like to make a few changes. What cheapish shock/spring combo's are there that fit the B Max?

Also I have a bit of play in the spur gear (looks like a buckled wheel). It's causing quite a bit of vibration. What steps would I need to take to remedy this, bearing in mind it will be all new to me

Any help/advice would be much appreciated.

discothesnake · #2 13-04-2011

Hi, b max is a cracking car. It's hard to advise on shock springs etc as you say you only want to bash with it. If it is standard plastic shocks you have on it then an easy upgrade is Associated B44 or Losi xxx cr shocks. Associated springs are easier to get than the Yok ones. As for the spur gear. when you say a buckled wheel, i take it you mean the spur gear is damaged? You would have to replace it. They are really cheap and you can get them on ebay. If you were to post some pictures of the problem then we may be able to help you further.

Dave

JAW · #3 13-04-2011

It will be hard to take a pic of, as I can only see it when it's moving. Like it wobbles when rotating.

They are not original shocks, I think they are losi ones. I think the car is more set up for racing, but I find the back too soft and would like to stiffen it up slightly and riase it.

JAW · #4 13-04-2011

http://cgi.ebay.co.uk/ws/eBayISAPI.d...#ht_500wt_1156

Looking at these on ebay at the moment. The shock I have on aren't adjustable. Would these fit?

CODMAN · #5 13-04-2011

Jaw, the spur gear problem could be the spur holder/ bearings. First thing i,d do is see if the whiole slipper/spur gear assembly has any play in it. Grab both oudrives of the assembly and move it in every direction you can. While doing this, is the spur gear changing alignment (not staying straight)? if so, you could have a problem here causing this vibration. If all looks great at this point, disassemble the slipper and place the spur gear on a flat surface to check for evenness. If the spur isn't straight, that's the problem and is a cheap fix.

For the shocks, I'd buy a new set of the Yokomo shocks (the plastic ones), that way you're sure they are 100% compatible. But id the Losi shocks fit, why not use them? It is for bashing after all...

JAW · #6 13-04-2011

Yeah, true about the shocks

Maybe I just need stiffer rear springs. Like I say I'm new to this. The springs on the rear are about 70mm, but get so confused when searching for compatible springs.

Si Coe · #7 13-04-2011

The shocks are Losi, from a non-worlds XX4. They are better than the stock Yokomo ones, but as you say it is a touch soft. You just need some stiffer springs. I was using Associated springs, blue at the front, silver at the back.
The shocks are adjustable, they just work differently. Instead of threaded bodies, they use little plastic clamps. Loosen the screw on the clamp, move to the desired location and tighten up.
The wobble from the spur could be the centre bearings. They do need replacing every now and then. I thought they were alright but as I said I didn't use that one much so maybe not. The other option is the spur isn't quite round. You've got an 87tooth spur, only because I can't mesh that with the pinions I use for racing so must use 81 or 84t spurs. I know at least 1 84t spur I bought was off centre and wobbled in use, so much so i can't run it.

JAW · #8 13-04-2011

Hi Si

Cheers for the advice with the shocks. Like I said I didn't want you to think I was pestering you. I need to have a proper look really. Managed to buy a new battery, so thats on it's way.

http://www.wheelspinmodels.co.uk/i/24523/
Are these the springs you mean?

Si Coe · #9 13-04-2011

Thats the whole kit, good for tuning purposes, but bear in mind front and back are different lengths, so you need two kits. And then you'll probably only use the one set of springs from each!
You can buy the springs separate. If you want to play, I've got the front and rear kits you can borrow, decide what you want and order just those.

JAW · #10 13-04-2011

suppose I'll have a few options if I buy the front and rear kit though

Going to have to wait til next payday now. I will investigate the wobbly spur and the cutting out. Then when I get paid its new wheels/tyres, heatshrink and connectors, Lipo battery posts with carbon tie bars and the springs.

Si Coe · #11 13-04-2011

I deliberately fitted it with 12mm hexes so you can run these wheels/tyres for bashing about on tarmac, rears here. Cheap, long lasting and ideal for where you run.
The rather odd battery mounts you currently have allow you to fit lipos of any size, but admittedly aren't as pretty as the carbon straps on the FT version.

JAW · #12 13-04-2011

I remember you saying about the Fastrax ones. Probably get some road and off road while they are so cheap.

To be honest I just want to take it apart to learn more about it, might as well give it a refresh while I'm there

Right, just took the spur gear out and managed to re fit it without breaking it! Looks like it's slightly warped, so I will replace that with some fresh slipper plates and a pin too. Really chuffed with myself now