jeffreylin

Then you need to adjust your clutch spring nut as well as your two speed. I'd start with the clutch spring. Try tightening it first so that it engages at higher RPM. You might also have a bad clutch spring. I had similar problem before and then I realized I was using clutch spring for a different car. Once I changed that it worked perfectly. Also try to loosen your 2 speed screws and let it engage earlier. With the powerful engines today I don't see much downside of engaging early as long as you still have 1st at the very bottom.

RCGaryK

iTrader: (3)

checked that too. The frustrating thing is that it used to work perfectly, then the screw backed out and it dumped the thrust assembly and shims and all.

jeffreylin

Well, at this point if i were you I'd just replace any and all suspect parts in the centex assembly. Maybe the bell is bent? the bearing? or the thrust bearing? did you check if you put the thrust bearing in the correct order?

buboy28

JEFFREY: are the OFNA guy that placed 4th at the recent ROAR santionced race

RCGaryK

iTrader: (3)

That's the gameplan over the next couple of days. Going to pull the engine out, reseal everything with automotive gasket sealer for better compression, make sure everything is tight, and rebuild the clutch assembly completely.

jeffreylin

Ok, I know this is confusing but there are 2 Jeffrey Lin there. What adds to the confusion is that we are both from Taiwan originally and now both in LA AND races at Revelation. At last month's Airtronic Championship, the OFNA and Skyline sponsored pro driver Jeffrey placed 4th in the expert/pro class. I, on the other hand, not sponsored and do this for fun, placed 4th in the Amateur/Sportsman class.

The pro driver Jeffrey Lin is not on R/C Tech.

kyoshoBOY

Hey jeff wassup! Did you race yesterday sunday clubrace at rev?how'd you do?
Oh yeah the kawahara shock stay you gave to me for my FW05RR is working really great!thnx bro
Are u goin to race in VEGAS this weekend?
Ken li and peter chuu is goin I've heard.

jeffreylin

Hey wassup! Thanks again for marshling for me at the Airtronics race. I am in Asia at the moment and won't return until next week after the Vegas race so I will miss that. Bummer!

kyoshoBOY

Oh I see,are you in hongkong ryt now?or where in asia are you now?
No prob. About marshling anytime bro!
I'm not goin to vegas either,didn't get a vacation earlyanyways their still a lot f races to come

racegypt

CLUTCH PROBLEMS! Yes!! I had clutch problems with my GPX4 that wasted 2 race weekends! After finally getting the carb set to something like a decent operating condition - no thanks to the manual, I could not get any drive, even when the motor was screaming. Double checked the end float on the clutch bell and it was within the spec. Tried backing off the spring tension, but still no bite. Finally took the motor out and looked inside the clutch.
I found a washer between the rear of the clutch bell and the rest of the clutch 0- none shown in manual! So I removed it and placed it with the other shims on the thrust bearing side to maintain the right end-float. It still doesn't hook up as well as any similar style clutch I have used before, but at least it moves forward. Any clutch tips anyone?

For an RTR car, this has sure been a challenge. Not sure what a newbie would make of it!

I am now ready to make my first lap of a track this weekend, a full 6 weeks after I bought the car! Yes! I bought an RTR so that I could get out on the track quicker and have less work!

Now I know what RTR really means:
Ready to Rip apart, Repair, Re-align, Rebuild and then RACE!

buboy28

I THINK THAT THERE IS ALREADY A PRO VERSION OF THE GPX4 WHY NOT GIVE IT A TRY

racegypt

There probably is a PRO version of the car, but I am not sure that buying an upgraded version of a car that you are having problems with is the best solution. I would be more interested in some ideas about improving the existing car and improving the way that Ofna manufactures, assembles and markets these things!

I finally got 5 laps in qualifying and the car handled like a dream, but the clutch was still not hooked up correctly and it began to slip so badly that my race day was over at that point. Since I run the races I have no time to rebuild stuff on race day. I will strip the clutch again and see if I can find the problem.

I would love to hear if anyone else has had this same issue or any other problems with the GPX4 and especially what they did to solve them.

Genius

Regarding your clutch Racegypt. One thing you might want to try is to remove the clutch and shave out a little plastic from the 3 holes on the clutch. just enough to smoothen it out though, after make sure that the clutch is moving up and down smoothly on the post. Your clutch may not be engaging properly because there is some sort of binding between the three pins and the clutch. thats what i did on my GPX4. I hope this helps

Also don't forget to wipe off the excess grease inside of the two speed or else your car will not shift properly. The grease comes from the bearing.

racegypt

Thanks, that sounds like good advice. I suspect that either the clutch shoe is binding or the weights are not moving freely. I will strip it all and start again.

hooked_on

iTrader: (1)

Anybody have any more information on the Pro Kit?

H-O