saubererik

i had purchased a 72 tooth robinson racing spur gear and installed as directions said "remove very little of edge of transmission hex shaft"so i did a little too much and the gear and slipper plates wobble like so bad it rubbed on the battery box. anyone else had this happen to them

Nighthawk z450

wow, you sure you have your washers in the right places? that sounds odd. i never cut any shaft down with mine. im running a robinson haft though. but i have ran with the stocker without triming anything without problems.

HpiDrifter420

im running the robinson racing spur and have no problems with it. a re you sure that you installed it correctly? heres a pic of mine installed

RCCanuck

get a new shaft

systemlord

What is a hex shaft?

thesouth1

The shaft the spur is on...AKA the top shaft AKA the 2 speed shaft...
http://www3.towerhobbies.com/cgi-bin...7&I=LXJG99&P=K

systemlord

Ah ok, they call that the Topshaft. Its been awhile since I have worked on the tranny, a long time. All my gears in my tranny look like the one in the picture, CNC cut from 1 3/4 inch steel then hardened for stength.

saubererik

im putting the forward only conversion on it soon does that replace that shaft?

systemlord

Yes, you have to get a forward only shaft that has a gear on it, its a really cheap ($10 dollars at Tower) part. I'm not sure if the forward only shaft is the same for all traxxas trucks and buggies? You can either use the existing shaft leftover from tearing apart your tranny and use the hardend aluminum gear, or just buy a new shaft with plastic gear.

Nighthawk z450

i beleave he's refering to replacing the "topshaft thats damaged" not the forward only shaft, its 2 different one.

so to anwser your ?, no. you need a new topshaft.

systemlord

It seems he is going to be using the forward only shaft, the forward only conversion has nothing to do with the topshaft. You will need another topshaft also, the forward only conversion is completely different from the topshaft.

saubererik

ok thanks everyone the foc kit will stop the bucking at idle too right

charlieboy

I'm not sure why you'd need to modify the shaft, but if its bent replace it. I had the problem with the RR spur brushing against the battery box tho. the clearance in that area is quite close. I took off the battery box cover and used a saw and a dremel to cut a piece off, been working perfect since!!

systemlord

Yes it will stop the bucking, I remember when my T-Maxx did that and hated it. It happens when your idle is too high that the clutch engages and disengages over and over again.

jasytosy

when you buy a steel spur gear do you need a hardened steel clutch bell?

systemlord

No you don't and I'll tell you why, I have the Robinson Racing hardend steel spur gear 72T. I was running my truck normally and notice some strange sound coming from my truck, I had noticed that the edge (around the bell, not the teeth) of the clutchbell was chewed pretty bad. Then I saw that there was no e-clip holding the clutchbell on, so this means that as my clutchbell tried to slid off my steel spur gear would slam the clutch bell back everytime it moved forward. My clutch bell had visable damage, but my hardend steel spur gear had not even a mark on it. So you see if you use a R&R spur gear don't use a clutchbell from the same brand. I think the Traxxas clutchbells are weaker that R&R hardend steel spur gears and I'm going to keep it that way.

Yakueb

Generally, no. It is usually the clutch bell that is engaging when the truck is jumping at idle, not the forward/reverse clutches. If your truck bucks at idle that means it is idling too high. That said, bucking doesn't hurt it at all, so if it runs well, accelerates well, and hits a good top speed, I wouldn't bother to tune the bucking out. It might be a little annoying, but I would rather have a truck that runs well and jerks a bit at idle than a truck that idles well but doesn't run for crap on throttle.

The Topshaft is TRA4992, BTW, assuming you have a 2.5 maxx. It is different on the 3.3.