What was old is… still old, but a lot newer (Update 2/20/11)

[aeiou]

Thanks Guys.

Those wheels are nice. Besides looking good, they run true and dirt doesn’t get clogged up in them.

Which BL motor do you run in it, and what pinion spur did you end up using?

The motor is an older Novak SS5800 with the sintered rotor and end bell upgrade. As of right now, I have the gearing pretty high as I’m just testing it around the back yard and working out the bugs. I’ll fine tune the gearing when I finally get it to the track. Here’s what’s in it now – 19/85 (the RPM tranny conversion is 2.65:1).

[Asso_man!]

Hey aeiou, this past weekend I did the same upgrade to my runner with RPM wrold's rear arms and RPM rear carriers with B4 CVD's, I have the following problem: when the rear end is at full compression, the CVD's are sort of cogging inside the outdrives and the diff can't work properly. How did you sort that out (if you have had the same problem)? I didn't measure yet, but I thought it could be due to a higher OD of the CVD nut compared to the RC10 stock CVD's... I also find out that the up and down travel of the rear end is overall very limited due to this problem and also because the CVD's are a bit too long?

[aeiou]

Hi Asso_man.

I would suspect your issue has to do with the hubs you are using. I’m pretty sure the RPM Worlds hubs have the same dimensions as the stock RC10 hubs, relative to the axle spacing. During the early experimentation with the prototype, I had the same symptoms you are experiencing with the stock hubs, and that’s what lead me down the path of using the RC10T hubs. On the RC10T hubs, the inside bearing is closer to the hinge pin.

As best I recall, the stock RC10T rear hubs worked without any adjustment. In the end, however, I used the RPM RC10GT truck hubs, primarily because they allowed a much higher axle height (lower CG) than the stock RC10T hubs (and they are readily available). As I mentioned earlier in this post, I ended up drilling the RPM truck hubs out slightly (with shims on the outside), to make sure there was no binding.

I hope this helps.

[Asso_man!]

thanks for the answer mate. I have those RC10GT hubs, but I'm afraid I don't have the correct bearings, what bearing size did you use? Flanged or unflanged? I'll try tonight with RC10T stock hubs and will let you know. On a side note, I guess you also drilled the front C-hubs to accomodate the larger OD hinge pins?

[aeiou]

... what bearing size did you use? Flanged or unflanged?

3/16" X 1/2" unflanged - http://www.avidrc.com/shop/?action=item&id=117

FYI - I used the revolution bearings in my runner with the rubber seals removed.

On a side note, I guess you also drilled the front C-hubs to accomodate the larger OD hinge pins?

That would be correct...

[Asso_man!]

damnit, I am supposed to take this car to an enduro race next Sunday and hoped to make use of the rear end revamping to run B4, I don't have time to order the correct bearings anyway, I could always switch back to the stock rear end...

[Asso_man!]

Well, I tried with the RC10T rear hubs along with unflanged bearings and it doesn't work withour any mod. I think I'll go back to the stock set-up and forget about using B4 wheels, I think that even if I drill the RC10GT/T hubs, the suspension will anyway have too little travel and this is not something you would like for a real off-road car...

[aeiou]

Sorry to hear your build is putting up such a fight, Asso_man. I know it must be frustrating trying to ready a new concept so close to an event. Those rear hubs worked fine for me during the early mock-up and the RPM GT hubs even better now after some adjustments.

Just curious, what size shocks are you using in the rear? Do you run a lot of negative camber?

[Asso_man!]

well I tried the B4 shocks and the stock ones both with a RC10t shock tower and a stock shock tower and almost no neg. camber, if I want to make it work properly, I end up with a ridiculous amount of shock travel and the chassis doesn't touch the ground when fully compressed... I also found that you can't use the outside hole on the rear arms, hence I need to change the shock oil and pistons too to have a good dampening.

[aeiou]

True, there’s just not enough clearance to use those outside shock mount holes without having contact with the wheels. With the Dynotech arms, that area is flat and you have the ability to drill an extra position between the two if you like, but I know that’s not the case with the RPM arms. Fortunately, there are some reasonable workarounds for that as you mentioned.

This is a modified B4 rear hub that I also tried. Although it took a bit more fabrication to get it to work, it actually provided the best clearance and travel of all the options (as best I recall). The downside is the higher CG. I reduced the outside profile and deepened the outside bearing slot. I used ¼” axle spacers inside the hub to get the bearing spacing just right. As you can see, there’s also an obscene amount of camber dialed into it…

I know you are pressed for time with your build / event, but I thought you (and others) might find this interesting.

[Asso_man!]

thanks for the info, please feel free to share everything you've tested, definitely not an easy mod. I think I'll try again when I have more time and will stick to what I know is working

[scr8p]

I also found that you can't use the outside hole on the rear arms, hence I need to change the shock oil and pistons too to have a good dampening.

actually, since the entire arm is moved out, because of using a stock rc10 arm mount, the inside shock mount hole on the arm is about the same as the outside would be if the chassis was modified to used the worlds arm mounts.

just something to think about.................

[Asso_man!]

you're right Jason, except that the arm isn't longer, the "lever effect" being more or less the same

[scr8p]

you're right Jason, except that the arm isn't longer, the "lever effect" being more or less the same

ya.... i didn't think that much into it before i replied.

[wyldbill]

hey scr8p, didnt the klein sprint cars use the losi/custom works hub carriers when they were using these arms? im not quite sure which ones they used because i've seen both the b4 and the losi ones used on local racers. wouldnt that take care of the problem, mabey?