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.

[pro4nut]

this is not far off the set up i have been running although without the wider rear end.

i am runing silver rear springs (zx5) and yellow green fronts (zx5) this got me BQ at the last mid south regional at CML.

car jumped well, and was very consistant which helps me loads at CML

[Andy Moore]

I dont think the setup will apply to the majority of the tracks you run on, but at least you can see what the starting US setup is and work from that.

[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?

[mart]

Thanks pro4nut, makes sense to me! My shock set up feels the same as the typical B4 set up but just doesn't seem to handle the bumps quite as well. So maybe this might be the key?

Think i will wait to see what happens before i part with the cash!

[pro4nut]

i feel the first mistake i made with my rb5 was to try to run b4 shocks and oil straight off my factory team car as i was not sure of a starting point. The car handled in an interesting way so i bit the bullet at my next regional, and having filled the shocks with 35wt front and 30wt rear i tried a lot of differant spring types until i found a combination i could drive with.

i would say that starting with zx5 silvers front and rear was a good starting point but i have not finished a day with that combination.

[caneye]

I used Serpent alu wheel hexes .. nice fit. Probably 1mm thicker.
Cheaper than kyosho’s.

Is there no need to change the rear toe on this car?? How do we do it?

[KyoshoK]

Originally Posted by caneye

I used Serpent alu wheel hexes .. nice fit. Probably 1mm thicker.
Cheaper than kyosho’s.

Is there no need to change the rear toe on this car?? How do we do it?

checked with your accurate 20c ruler ???

[elvo]

Originally Posted by pro4nut

this would suggest the handling would be better with the longer arms, If elvo pops by he will explain properly ..

*pop*

Your explanation is pretty good.

Wider hexes are a fix. Wider arms are a solution.

[caneye]

Originally Posted by KyoshoK

checked with your accurate 20c ruler ???

wow .. u've been had.
mine was only 5c, shipped from asia, of course

[Andy Moore]

I got my first chance to run the RB5 this weekend at out State Series race. I missed practice entirely due to a very limited release of the JC tires, so I was only able to get the 2 minute warmup on track. Qualified 3rd in the first round, and I still got bumped down to 4th after picking my time up 7 seconds in the second round.

The car seemed very planted, with decent steering. I ran the Orion 4800 LiPo and the 10.5 motor(24t pinion, thanks for the advice guys!). It was so quick out of the corners, even without the added traction of the NiMh battery. I couldnt believe how composed the car was jumping, and although the track was a little bumping (180 gas entries yesterday), it just cruised over them like a Cadillac.

After 2 quals(with at least 5 warmup laps each), the Double Dees were well worn, but I ran the 6 minute main with no problems. I had a rough start, but worked my way to 3rd, behind Eckert and Ruona, and thats the way it finished. I even let 3 people drive the car after the main and it was still planted.

Im pretty sure Im the first guy to show up at the track with an RB5 (in FL) and everyone who got a chance to drive it was impressed. After the 6th person getting a quick "rental" I had to call it a day, there was a line on the stand to get my transmitter, haha!

Hopefully I'll have some pics during this week so you guys can see my setup,etc. I ran the "wide" rear, with the exact setup JP had posted about 7 pages ago. Green Groovy fronts and Green Double Dee rears. Orion 10.5 geared 24/76. It was just plain good.

[encore75]

Originally Posted by Andy Moore

I ran the "wide" rear, with the exact setup JP had posted about 7 pages ago.

Hey Andy, when you cut & paste from rctech, be sure to proofread.