Gears slipping
 

Hi All.

I need some advice on the following problem I am experiencing. I am running a serpent 720 with a Rossi axe motor. Upon acceleration, the car jerks/ hops very slowly. It is not smooth at all. Second gear kicks in very early, even after adjusting the clutch and thereafter, the engine flat lines without gaining any further acceleration. Its feels as though I have to let go of the throttle incase I might damage the engine. PS. The engine had maybe 10-12 tanks through it already, which am not sure might also be the problem. I have checked the clutch shoes and it is fine. Not sure if the problems lies with the 2nd gear housing or clutch bell. Anybody had this problem before with some advice for a easy fix.

Bearing
 

It sounds like you may need a new one way bearing in your 1st gear hub.

Make sure your pully not slipping on your drive sharft!!

Hi, Thanks for the responses. I replaced the bearing on the 1st gear as well as replaced the car with new belts but I am still having the same problem. Could it be the cluth bell that might causing the gears to slip. The slipping does not happen when changing from 1st to 2nd, rather slipping whilst in gear.

any chance u over tighten ur clutch spring? :eek:

I'm not familar with the 720 but this happen to me on my Mugen. Make sure there is no lateral(side to side movement) in the 1st speed gear. A one way gear will engage very erractically if it allowed to move laterally while spinning.
the clutchbell moves lateral when engaging if this lateral movement is allowed to be transfered to the spur gears it will cause very erractic engagement of the 1st speed gear.

Hi everyone. I really appreciate the reponses provided. I will test the tension on the coil spring to see if that makes a difference. As for the lateral movement, I cannot see any movement on the spur or pinion gears. Are you talking about movement within the clutch system or the gears inself. The clutch bell is sitting firm against the yellow clutch shoe. Which parts in the centax or clutch assembly spins that might be slipping. I suspect that some components that are meant to spin smoothly are not due to either too much friction or a damaged part. I need to figure out which parts that turn, which in this case are not turning properly that might cause the car to stagger upon acceleration. Any ideas?

gday mate did u replace the gear shaft, becasue even if u did replace ur 1st bearing then the shaft might have worn down to much for it to grip on, it happend with my MTX4. just a question does it seem to rev up but then the car doesnt move, because if this is what is happening it means that the 1st bearing doesnt have any grip on the shaft, just to let u know

The clutchbell should have lateral movement about .3mm this is your end gap but your spur gears( the two black gears) should have next to no side to side movement.


Pass you soon...

If you say the clutch bell is firm against the clutch shoe it sounds like you dont have your clutch setup correct,
You should have a clutch gap of 0.7mm (distance between the clutch bell and shoe)

You didnt oil your roller bearings in the 1st gear one way did you?

Hi Everyone. Thanks once again for the time taken to respond:
Nitro Booster - I did not replace the gear shaft and yes, the car does need a bit of rev up for it to start moving. I assumed that this was because I was running a new motor, which is still in the break in phase. I will check the shaft.

Lil-bump/ Simon M - You are right, the clutch bell does not have a space according to the serpent setup documentation. I will adjust today and test.

G17 - Nope, I used greese. I use One way in my gearbox.

I will spend the weekend testing all recommendations and revert to you guys on Monday. Thanks for the help

Mischa - there's a distinct difference between clutch not engaging and 1st gear oneway not engaging. Clutch will eventually grip in a controlled manner, when the revs get high enough. When the one-way slips and then suddenly grips, it's a very jerky and violent action.
You should NEVER use any normal oil or grease in the one-way, it WILL slip. If you greased it, there's your problem. Wash it out thoroughly with brake cleaner or similar stuff, get all the oil/grease out, clean the shaft as well and reassemble with just one drop of special one-way bearing oil (Serpent has the good stuff) or if this isn't available, run it dry or with minimal amount of very light oil. THe special one-way oils are low pressure lubricants, meaning the rollers can cut through the oil film easily, whereas the normal oils/greases are high pressure lubricants, their films are very strong and the rollers in one-way just don't get good contact with the shaft.

Hi Everyone

First of all, I would like to thank everyone for their input in helping me brainstorm this problem. I managed to discover the cause: basically, I had a slight kink in my 2 speed clutch bell, so much so, the 2 speed clutch shoes would not spin freely within it and slip. I replaced it and the car works better than ever. Thanks again