How to check for drivetrain binding............

[chrisexv6]

Seeing as how I can't get my TRX to not overheat after 1/4 tank, I figured Id start looking elsewhere (I have a Fantom in the mail, which Id love to use, but I want to be sure I'm not going to roast that engine too, during break-in no less).

I've checked and re-checked everything on the engine, but I can't get the thing to run longer than 1/4 tank without overheating. Not even making any WOT passes, just some half throttle bursts while putzing around the front yard. (as far as needles, they've been all over........factory, factory +.5 and +1 on the HSN, but I always leave LSN around flush).

I'm giving up on the engine, so I want to look at the drivetrain. I've done a FOC and the spring-mod to the rear diff. I can push the truck and it rolls freely, doesn't feel like anything is binding. The only issue I had was I thought, when I put the FOC in the tranny and reassembled, the spur shaft seemed to spin a little slower than normal. With it on the truck, the motion from the weight of the clutch bell lets it spin fine, doesn't feel like anything is binding. I would like to know a really good procedure to check this, so I can verify that I'm not going to wipe out my new Fantom.

I did notice, however, that if I tilt the truck to one side, and spin one of the free wheels, it seems a little noisier than just pushing the truck on the ground, and it seems to have a little resistance against it. I could swear the truck has always done it, but with this going on I'm just not sure anymore. Does that sound normal?

Ugh!!! I'm regretting putting all the mods on during the off-season, now its tough to figure out if one of them caused this, or if the TRX is just kaput!!

Great thanks in advance!!
-Chris

 

[olds97_lss]

Is there any pinch left in your engine? Hows the compression? It almost sounds like the engine is on it's last leg.

You didn't happen to get new cvd's and outdrive cups did you? Sometimes, the aftermarket outdrive cups rub on the diff cases.

 

[chrisexv6]

Nope, no new cups. Only things drivetrain wise were the FOC and tearing down the rear diff for the spring-mod.

The compression feels weak, engine probably is on its last leg. At this point, I just want to be sure the rest of the truck isnt going to cause the Fantom to die even faster than the TRX did. This one has maybe about 1.5 gallons on it. I really really am beginning to hate this motor. Then again, if the Fantom lasts only that long, Ill hate it too!!!

I think I want an Emaxx.

-Chris

 

[bashmaster]

no no u dont want electric, my bet is that the trx is crap, i really hate traxxas mills, the 2.5 is a fast one but only for the 10 seconds it stays tuned... i tink the fantom will be fine, and u may want to clean and lube all the bearins as well as lubing all the frictonal areas

 

[olds97_lss]

If you did the rear diff mod, you may have to many shims in it that are binding on you. The only real way to check, is to pull the diff and spin the shafts while the diff is off the truck.

I did that on one of my diffs once. I figured it would wear itself in because it was only a little tight. After a quart of fuel and a really hot engine, I tore it back apart and took out a shim.

 

[chrisexv6]

I actually have NO shims in the diff. I dont know if thats correct or not, but I didnt see any when I tore it apart.

After I put it all back together, there was a little more resistance than the front, but I figured that was a function of the spring mod as well as the auto-wheel bearing grease I used to pack the diff.

I'm thinking about tearing it back out and removing the spring mod, cleaning out the grease, and just using a light coat of diff lube to make sure its OK.

As far as shims go, I didnt see any.........its very possible that they got stuck to a paper towel that I used to wipe off the inside of the cup, but I doubt that.

And all the while if I just push the truck, it feels like there is very little resistance.

-Chris