Wider RB5 Rear Setup!

[Andy Moore]

Joe Pillars posted this setup over on rctech, with the appropriate part numbers to complete it. Apparently the RB5 is slightly narrower than the B4/XXXCR, and this fixes that.

Originally Posted by Joe Pillars

I wanted to give everyone a heads up on some new parts we have been testing. At the Shootout Gil Losi Jr and Mark Pavidis were testing a new rear end for the RB-5. After the Shootout Ronnie Gardner and I have been running these new parts and comparing the two rear ends back to back for a few weeks now. These new parts make a big difference in the handling and overall performance of the car.

The RB5 rear end comes stock pretty narrow. The new arms widen the car 2mm on each side, 4mm total. This makes the width in the back very close to a B4/Losi car.

Here are the parts you will need:

LA243 Rear Middle Suspension Arm
LA232 Universal Swing Shaft 65.5 (use the dogbone/not the axle-too narrow)
W5183-02 Shock Shaft (L) (needed to run the middle and outer hole on arm)

This is the set-up Ronnie and I have been running with the new parts:

Front:
3-B Pistons
35wt Losi Oil
Orange Front Springs
No Limiters in shocks with shock ends unthreaded 4 turns
30 degree kick-up
Middle location on tower and outside location on arm
2-B Camberlink with 1 mm washer under the ball stud
Spindles in upper position
1/4oz of weight under steering rack

Rear:
3-B Pistons
30wt Losi Oil
Dark Yellow Rear Springs
No Limiters in shocks with W5183-02
Middle location on tower and middle location on LA243 arm
2-B Camberlink with 1mm washer under ballstud on shock tower brace and 2mm washer under ball stud on hub
Hubs in middle position
½ oz under rear tower

Extra Info:
Battery Position - Forward
Ride Height - 24mm Front / 22mm Rear

[KyoshoK]

basically same as the zx-5 law34 kit, but using the 65.5mm bone.

not sure about the 65.5mm dogbone. i already tried that for the zx-5 its too long for the zx-5 i cant see how the 65.5mm would fit for the rb-5

[bender]

I have to admit, I'm a little skeptical of this mod being a "major" improvement.

I mean seriously, widening the car by 4mm is not much at all IMO, and I whilst I think it would make some difference, it is not going to be a huge change.

For those who use the kit Kyosho rear wheels, surely you could just add spacers between the wheel and the hex-mount like they do with the touring cars ?

The internal hex on the inside of the standard wheel is deep enough to allow you to add at least a 1mm spacer per side - a much cheaper option at least

[_sleigh_]

I would think that the wider rear end will change the handling quite a bit, as atleast the outer pivot position will be moved, and quite possibly the shock position too.

Having experienced very similar changes when we changed the rear end on the XXX-BK2, I'd say don't discount the idea beore trying it.

On the Losi, even lengthening the driveshaft and shortening the diff out-drive made a big difference, and that change didn't even change the wishbone pivots.

Any how.... back to the RB5.. It's good to see the influence of Gil Jnr. coming through in the development of the cars...

[SimonW]

I've done this to my car after reading joe's post on rctech, the only problem i have is that my drive pins are hanging out the diff almost, (put zx5 law34 arms straight on thats it). Maybe i miss-read it and you need the bones from the old ZX5 cvd off the original width car ?

[johnnyboy]

You use the rear arms, dogbone (just the bone, use the stock RB5 Axle) and the 54mm shock shaft from the LAW34 Rear Middle Kit. The stock bones (and shock shafts) are too short. You need those three pieces to make it work. I have it on my car, but am still testing it out versus the stock rear end.

[elvo]

Originally Posted by bender

I have to admit, I'm a little skeptical of this mod being a "major" improvement.

I mean seriously, widening the car by 4mm is not much at all IMO, and I whilst I think it would make some difference, it is not going to be a huge change.

4mm is HUGE! It's gigantic, monstrous
On the S2, we widened the rear by 1mm each side (2mm total), and it was a huge improvement already.

On my B4 I used to put extra shims between the outer bearing and the alu wheel spacer, widening the car by 0.2 .. 0.3mm, and that was enough to produce a noticable difference on the track.

[mart]

Not sure whether this will have the same effect as the main mod, but has any one tried to widen the RB5 by using a thicker wheel hex? I have some Xray ones which will do the job nicely!

[pro4nut]

A wheel hex would make it wider, but would not change the pivot positions.

so, you would have a wider car but the effect you get with a longer wishbone and the spacers will 'feel' quite differant.

think about truggy's were the early models just had massive offset spacers to give the wider stance whereas the newer generation have longer bones.

this would suggest the handling would be better with the longer arms, If elvo pops by he will explain properly but if you think about opening a door, the furthur from the pivot the less effort required to open it. or in our case the furthur we are from the pivot the less effort required to keep it closed. so in theory the shock will can be set softer to get the same handling over the rough stuff.

make any sense?

[bender]

I have driven cars where you can't notice a 10w shock oil change

I guess we'll see what happens when more people try it.

A question though, is the improvement mainly from the wider rear or the geometry change by running the different length arms?