Center shaft...question

[Panic]

I m cleaning my pred x11, and I noticed that as i spin the center shaft by hand it doesnt turn smoothly...in fact in a specific point almost stops and you need more power to turn it. No tires on the car ,no motor , and everything is just rebuild , diffs are ok , no teeth missing from the bevel gear or crown .Also i have shimed the shaft to stop the play which had from factory. Anyone has any idea wht i might causing this bind ?

[Ron Burgundy]

good question!
I have a few preds (not the x11 yet as per thread) but I have always had this issue... in fact im turning the prop shaft on a brand spanking x10 that i have never run (and prob never will) and its doin it.

on previous cars it has gone after one run so it may just be a slight high section on the bevel gears (im talking a thou or even less) or slightly off line bearing carrier, again hugely minute measurements, but thats what ive put it down to..

Maybe niggs or kev or the other fellas have some more idea (as im sure they do haha)

[KevLee]

If its minor notches which go after a run then i wouldn't be concerned. As Ron says it will be minor inacuracies in the manufacture of the gears etc.

But, if its doing after some running it sounds like there is something wrong. Maybe a seized bearing? or the diff gear is shimmed too tight? (2 shims in the rear is the norm, i don't run any in the front)

how have you shimmed to shaft, could that be the problem?

Is it noisy on the track?

[Panic]

Originally Posted by KevLee

If its minor notches which go after a run then i wouldn't be concerned. As Ron says it will be minor inacuracies in the manufacture of the gears etc.

But, if its doing after some running it sounds like there is something wrong. Maybe a seized bearing? or the diff gear is shimmed too tight? (2 shims in the rear is the norm, i don't run any in the front)

how have you shimmed to shaft, could that be the problem?

Is it noisy on the track?

Have put an extra O rings in the ends of the shaft to stop the back and forth play . But anyways thanks guys. I found the problem though. The front crown was somehow bended/misformed (due to high temp? dont know how this can happen) in one spot and when the pinion reached that spot it was forcing the whole shaft away from original location. Replaced with a new crown and now is smooth again. No wonder i stripped 2 spurs the other day...

Also do i need to shim the diffs even if they dont have any play?

[Huw333]

Originally Posted by Panic

I have shimed the shaft to stop the play which had from factory. Anyone has any idea wht i might causing this bind ?

Thats probably the root cause of the problem - the prop shaft is supposed to have end float so when the chassis flexes (landing from jumps etc.) so the bearings dont bind. The end float should be 1-2mm (i'm pretty sure it says all that in the manual). It might have been possible for the prop shaft to be pushed forward and thats how the crown gear got deformed.

That might explain how you stripped the spur gears too.

I'm sure one of the 'experts' will correct me if i am wrong!

[mro_racing aka Doorbell]

yer u NEED 2mm float becouse the chassis flex.
ive seen propshaft shatter becouse of heavy landin of a jump and not even big crashes and if ya do have a big crash it will cause damage 2 both gear boxes as ive seen to many time

i hope that help?

[Panic]

Well it has some play but i say its not 2mm(its less-barely moves back and forth) so i need to free it a little bit right?

[Cooper]

Oh yes please !

[Huw333]

Yep! As said, it should move 1-2mm

[KevLee]

Originally Posted by Panic

Well it has some play but i say its not 2mm(its less-barely moves back and forth) so i need to free it a little bit right?

definately! i don't shim mine at all and never had any problems.

[Panic]

Originally Posted by KevLee

definately! i don't shim mine at all and never had any problems.

Wht abt the metal plates that hold the spur. Dont they touch the bottom sides? Mine is scratched (the one that faces the front of the car) ,apparently cause it was rubbing at the bottom sides due to excess play

[Huw333]

Originally Posted by Panic

Wht abt the metal plates that hold the spur. Dont they touch the bottom sides? Mine is scratched (the one that faces the front of the car) ,apparently cause it was rubbing at the bottom sides due to excess play

I dont think the graphite chassis would scratch the alloy plates, check its not your motor screws rubbing on them - i've had that before

[Panic]

Anyways, thanks for all the infos guys. Really apreciate it....