Breaking B3 axle drive pins

[flipwils11]

In my bashing last weekend, I broke both rear drive pins in my MIP CVD axles for my B3. I have a hack fix right now, but before I buy replacement pins, is there anything stronger (and if so do I need it)?

I saw these "FActory Team" axle pins but I'm not sure how they are better than regular (and I want to make sure they fit the MIP CVD axles but the pins that came on the MIP units seems to be about the same thickness as the B4/B44 ones I remember).

Associated Factory Team Axle Pins (4) ASC1654

Do they make a titanium version of these pins?

[jwscab]

were the pins you had roll pins or solid? how were they breaking? snapping in half or bending over?

solid hardened steel will be about the strongest you can get, titanium will be softer. the pins you listed will probably be just fine.

[flipwils11]

were the pins you had roll pins or solid? how were they breaking? snapping in half or bending over?

solid hardened steel will be about the strongest you can get, titanium will be softer. the pins you listed will probably be just fine.

They were solid I'm pretty sure, not rolled like the ones on the original RC10. They came with the MIP CVD kit and I thought were quite thin at the time. They snapped in half on both sides probably due to some significant rolls after missing jumps this weekend. Still, the rolls didn't do anything else to the car like broken shock towers or other damage, so the pins breaking was really surprising.

[jwscab]

yeah, I am surprised myself.....i suppose though that if the pins are too hard, they get brittle.....maybe what caused the issue.

[flipwils11]

yeah, I am surprised myself.....i suppose though that if the pins are too hard, they get brittle.....maybe what caused the issue.

Gotta get replacements put in so I am set for my newly installed LRP sphere comp ESC and speed passion brushless motor. Sweeet!!

[kaiser]

i've broken a few of the solid pins on my b4. buy a bag and have some on hand.

they didn't cause me not to finish a race, i found it when i took the wheels off for cleaning.
1/2 the pin was still there.

[Charlie don't surf]

Did you have a flat spacer behind the axel pin that was at least as large as the space of the pin? If you just used a small diameter 3/16 spacer then the pin gets excessive stress and pinched at the axel hole, but with a large flat washer like the b4 then it is supported no matter how much you tighten it, and won't snap.

[flipwils11]

I think something's going on here then. I have some abnormal wear on the face of the hub carrier (see below) and the concave spacer is no longer concave, it's pretty flat. I'm not sure why the wheel back is apparently pressing up against and scraping away the hub carrier face, but I'm guessing it's related to the drive pins breaking in half.

[scr8p]

one problem i see is a 1/4" concave shim on a 3/16" axle.

[jwscab]

yeah i suppose you don't have the manual?

here is a copy of the 3/16" axle assembly diagram for your reference.

[flipwils11]

I have the manual. Background is the car was a B3 sport so it came with bushings and dogbones with stub axles. I converted to the MIP CVD's on it and bearings and when I did so, I'm trying to remember what I did but I bet I reused those spacers that came on the stub axles.

So what you both are saying is this probably is the root cause of my problem, but at this point I should replace the rear hubs since they were worn fairly bad, new drive pins obviously, and the correct spacers for my 3/16" axles?

[jwscab]

the hubs are probably fine if they are only ground up a little like your picture. But with the proper spacers and shims, you shouldn't see a problem even with the little bit of material missing.

I would assemble so that the pin is as far out as it can go, so put all the shims on the outside, to keep the wheel off of the hub. This of course assumes that the dogbone sits in the drive cup OK with it pushed all the way out.

I looks alot like the axle can float alot in the hub how you have it assembled, having the axle do that will put undue stress on the pin as well as allow the wheels to contact the hub.

[flipwils11]

Very helpful, thanks gents. I put her back together last night with new/used rear hubs, and shimmed with the right parts. I ended up with one stock mip cvd shim (thick) behind the hub and one stock mip cvd thick shim on the outside plus one thin (b44 cvd I think) shim before the pin. The axle sits perfect now, not too snug but with no float and the wheel sits off the hub as well.