Little handling issue RB5 SP2

[carlin]

Hi Guys,

Well i decided to take the pludge & try out 2wd racing never done it for many years.

Anyways just built my SP2 what lovely build the car is to do.

Now i have just took the car outside for quick blast see how things handle & tell you what it's bloody horrible????

Now i think it's something i have done or need to change.

When i apply the throttle slowly the car pulls to the left (does go it straight line if rolled slowly) when i get half way it just spins out. Even when i apply the breaks the cars does the same thing.
What am i doing wrong???
Is my diffs to tight or the slipper. I have already backed the slipper off 1 full turn from fact settings.

This is what I'm running in the car anyways

x12 8.5t motor with 20t pinion think my gearing is right?
SPX Speedo
LIPO 5300

The car is as kit so no changes to setup at the moment & i havent added any weight just yet.

Any help would be great guys, as 2wd is new to me too

Thanks

[RogerM]

Rob, I will try to give you a call over the weekend to talk it all through with you. My RB5 has awesome stability and although there is a little torque reaction on throttle (all rear motor 2wds do have a bit, RB5 is actually better than most ... SP2 better than stock RB5 due to central motor)

Sounds to me like a combination of several things but start by checking droop is even side to side (RB5 is VERY sensitive to droop balance as the chassis is so stiff) and that nothing is binding. As for the gearing I run my SP V3.0 8.5R on a 27 ro 28 tooth pinion!

[carlin]

Originally Posted by RogerM

Rob, I will try to give you a call over the weekend to talk it all through with you. My RB5 has awesome stability and although there is a little torque reaction on throttle (all rear motor 2wds do have a bit, RB5 is actually better than most ... SP2 better than stock RB5 due to central motor)

Sounds to me like a combination of several things but start by checking droop is even side to side (RB5 is VERY sensitive to droop balance as the chassis is so stiff) and that nothing is binding. As for the gearing I run my SP V3.0 8.5R on a 27 ro 28 tooth pinion!

Hi Roger,

Well I've been playing with it most of the night tonight checking everything.
I've even had the diff loose as possible & then tightened this back up still the same.
I cant seem to find any binding either???

But you have pointed something out straight away, i think the reason it's pulling is down to my gearing (alot torque) i think as I have just chucked 20t pinion on so i will try going up 27t see if it's any different tomorrow.

Thanks for all the info & i will have another check over the car tomorrow, this 2wd stuff is very different

[RogerM]

You know where I am if you need any help bud, all part of the service ..

[bkelsall]

Hey rob, sounds like something is mis aligned as torque shouldn't factor at low speeds. I know this sounds daft, but check your rear toe inserts are the same....

[/tobys]

I reckon you'll need a couple pinions lower than Roger's recommendation on your X12; from what I understand, SP's need gearing a bit higher than the LRPs.

[carlin]

Cheers guys, yeah i might need you help Roger........ To drive the bloody car........

Well i went up to 25t pinion today, gave it little run outside was so much better.
If i put the power on fast it will spin out but if i do it smoothly like you should with 2wd lol it's fine.
Just need to figure out the braking now, spinning out when stopping or is this common with 2wd???

It might just because I'm running it on tarmac to trying it out?

It seems ok on the grass doesnt do anything like the above

[ApexSpeed]

I donno. I have a SP v3 8.5 in my RB5 and have run it on asphalt/tarmac with various tires and various gearing, and have never had an issue with any pull under throttle or braking. The RB5 isn't mechanically any different than any other 2wd rear motor car.

Sounds to me like something is not built properly somewhere in the geometry of the car. Do you have rear toe in on both sides? Is it equal? Is the front end aligned properly? are the shock collars all set to the same preload?



Has to be something simple in the wrong place or flipped or inverted. Check everything again for symmetry and if all else fails, post some clear photos of the front and rear of the cars, and maybe someone here can spot something you might have done wrong on the build.




doug

[carlin]

Just one thing i realised could it be that i havent got any weight infront of the car yet??

[ApexSpeed]

I have no added weight in my car and LiPos, and it runs and tracks perfectly at all throttle points.

I still think it was something overlooked in assembly.

[carlin]

Well I dont know what it can be I've been messing with all night still doing it?????

The only things i have on the car diff to kit is the alloy rear hubs thats it.
I have incl some pics for you all to look at see if you can spot anything wrong.

The car is all kit & has 1deg Camber all round. All wishbones are nuce free all shocks measure the same lenght even doen to the shock collars etc.
I've tightned the rear diff thight & then backed it off by half turn & the slipper is 13mm from the slipper plate to back of the nut as this is the same as my mate has on his car that was Chris Longs old car he said his is perfect even with 5.5t motor in.

Thanks

Does anyone know photos arent showing up??? there something wrong with the Oople website still

[ApexSpeed]

Originally Posted by carlin

The only things i have on the car diff to kit is the alloy rear hubs thats it.

Are they 0°, .5° or 1° rear toe in hubs?

Is everything in the drivetrain free? When you take the pinion from the motor, is everything loose and free, with no binds at all in the diff, CVDs or axles?

[carlin]

Originally Posted by ApexSpeed

Are they 0°, .5° or 1° rear toe in hubs?

Is everything in the drivetrain free? When you take the pinion from the motor, is everything loose and free, with no binds at all in the diff, CVDs or axles?

There the 0deg alloy hubs

Yeah it feels nice smooth to me when the pinion is off. The drive shafts spinn freely & the only only thing that i keep messing with is the diff.
I'm going to strip it down tonight & rebuild the bloody thing see if it changes

[gps3300]

Have you checked your electronics for interference? I had a car where the servo would twitch as the throttle was applied making it spin out.

[carlin]

Originally Posted by gps3300

Have you checked your electronics for interference? I had a car where the servo would twitch as the throttle was applied making it spin out.

Thats good question as i have been messing with my electrics because one of my Ko Rec is not binding for some reason have been rather annoyed so i ran two types of rec still the another 2.4ghz & 40Mhz radio still the same.

So the electrics are out of the question Buddy

[RogerM]

Is the servo your running a 3 or 4 wire one? Seen drop out on 4 wire servos with aging chokes doing the sort of thing Ian suggests ... swap out the servo for a proven good unit and see ... never rule anything like that out (and use Futaba servos )