Shoe clutch turns into transmission problem. need advice

[davidac49]

So after taking my transmission apart and looking at the differntial i went down to the store and picked up some mobil 1 grease just to see if i could slap it back together tighter. after tightening the spur gear i twisted the cups and everything felt snug and tight and i couldnt spin just one cup without the other cup moving or the spur gear moving. so it all seemed fine. slapped it back on the chassis put the driveshafts on and started to spin the spur gear. only to no avail. the front drive shaft was the only one spinning. i noticed when spinning the spur gear the back driveshaft with slack would rotate until it had a load and didnt move at all. rotating the back wheels on the ground the driveshaft would spin along with the spur gear. do i need a new bevel gear or what could be going on. I'm truly stumped.

 

[davidac49]

So I've devided to ditch this transmission and want to upgrade. my power plant is a hpi savage x4.6 big block. my old spur gear has 54teeth. i want to buy a new transmission. any ideas for what i should get? I'm having trouble looking online for a center differential 4x4 transmission assembly. probably because of the wording. will i be keeping my old spur gear and brakes or does that all come with a new transmission? both my driveshafts are the same length 4 and 1/16th inches. will i need new driveshafts or can i keep my old ones. I'm not to worried about price nor do i need a porfessional racing transmission. just something that equals my engine and can get the truck rolling better than my dead transmission

 

[RC/Racer]

Davidac49 I am not quite understanding your problem with your transmission thou your posting...

What is not happing with the Trans
What did you break to not make trans perform properly
You might have issues other than your tranny

 

[davidac49]

Davidac49 I am not quite understanding your problem with your transmission thou your posting...

What is not happing with the Trans
What did you break to not make trans perform properly
You might have issues other than your tranny

the center differential is not spinning the rear driveshaft.

i havent broke anything to my knowledge. only had this truck running back in march when i first got it which it was working then just no compression in engine so poor performance. it sat until now. bought a new engine. started breaking it in per manual that came with engine. threw it on the ground and truck would not move.

Hopefully it just needs some diff oil since there was very little to none black oil in the diff when i fist took it apart. ordered some online since i have no means of transportation til my daily driver is out of shop. thanks to whoever hit my truck in the middle of the night and drove off having to have it towed to the shop for a bent real axel and alot of body work.

 

[Snook Man]

Did you try the test method I mentioned earlier to see if the diff is putting any rotation to the rear?
With both rear wheels on the ground hold both front wheels (keep them from turning) and then spin the spur gear. The rear drive cup on the center diff should then spin (even without diff oil).

 

[davidac49]

I just tried that snook with rear wheels on the ground and front off the ground and holding the front wheels I turned the spur and the rear tires wanted to move so the center diff is putting rotation to the rear wheels.

 

[Snook Man]

I just tried that snook with rear wheels on the ground and front off the ground and holding the front wheels I turned the spur and the rear tires wanted to move so the center diff is putting rotation to the rear wheels.

Good, when you get some diff oil in the cup you may be good to go.

 

[davidac49]

Good to hear snook. I'm picking some up in a few hours from a lhs and hopefully I can get some run time in today. Now if I could just get this stupid brake servo back on there right I would be in business..

 

[davidac49]

So after dealing with this problem for 2 days i finnaly picked up some 20k silicone oil for the center dif. filled it up to the T in the spider gears and slapped it all back together. figured out how to install the brakes and fixed my dead battery issue. its almost 11pm here and i said screw it I'm going to run it. theres no street lights in the area so i stayed close to my house. after flooding the engine twice and checking the glow plug i got it started. let it warm for for a minute then gave it some throttle. and went no where. after giving it some more throttle it started to move a little bit and WOT it was going about 10mph. it seemed to get a little looser as i drove it more but i didnt want to break anything and ended the session. so my question now is, was the 20k silicone to much? should i go like 10k? should i buy new bevel and gears and toss the old ones, how long do the bevels and everything in the center dif usually last. its all metal, I'm assuming steel and theres no obvious signs of it stripping. going to tear back into it tomorrow morning, taking the day off work to figure this problem out.

 

[davidac49]

Is there a reason why the pin for the rear cup on the spur gear is so hard to get to slip in the cup shaft? Could the washer or cup be bad? I really have to force that pin in therl pin hole and I can start to see indents on the washer that sits on the spur gear for the rear drive shaft caused by the pin. The front cup is fine. Grabbing some needle nose pliers and slidding the pin in the cup shaft through the pinhole at the bottom of the housing is no problem. Just the rear drive shaft cup is giving me lots of trouble. After placing the bearing on the rear cup then sliding the cup through the spur gear, placing the washer on the shaft and placing the pin in the pinhole at the end of the cup shaft is a real pain. Is this a sign of having to buy new washers or cups?

 

[Snook Man]

The 20K diff oil wouldn’t be your problem. The bevel gear pin in the cup is a little bothersome to install sometimes. Once the pin is installed does the drive cup spin smooth and easy? It should, if not the shim /washer may be too thick or you may have used a bearing that’s too thick (depending on the setup). Once you have the diff assembled, you should be able to hold the spur in your hand and turn each drive cup and the other cup should spin smooth without any binding. There will be some resistance from the diff oil but the cups should still turn smooth.
What happens if you place the rear wheels on the ground and pull the rc forward while holding the 2 front tires (don’t let them spin) in the air? Does the rear center shaft turn?

 

[davidac49]

I disassembled the center did for the first time a few days ago. I used all the parts that I had when I disassembled. Didn't notice any difference in washer thickness or bearing thickness from rear to main so I just grabbed the closest one when reassembling. After the rear drive cup bevel pin is installed the drive cup does spin smoothly, but not easy and freely at all. The front drive cup after installed with the spider gears and did oil spins nice and smooth and that is how the rear should be but its not. I will reassemble the thing completely and put it back on the truck here in a little and let you know what happens with the rear drive shaft. I'm assuming it will spin with the wheels but I'll let ya know. Thanks snookman you've been a lot of help.

 

[davidac49]

With the rear tiles on the ground and me holding the front walking the truck forward. the rear tires spin, both rear drive cups spin with the driveshaft and the spur gear spins as well. going to go ahead and put the brakes on and give it another test run.

 

[davidac49]

so i ran it for a little and in the video I'm at full throttle going straight both ways:/ truck doesn't move much and it takes a decent amount of the throttle to get it up that driveway or even moving. I noticed though when i ran out of gas the thing kicked in high gear and really was performing like it should be, only for a few seconds though. could it need to be tuned or maybe new fuel?
[ame="http://www.youtube.com/watch?v=mYw87T52n4Q"]Full throttle at slow speeds - YouTube[/ame]


Could this be because the engine is new? i went through a tank and half of just idling, then the other half tank throttling up and down then ventually hitting full throttle before all this happened. it was during the break in process where i put the truck on the ground and do some circles that i noticed the truck wasn't moving.

 

[Snook Man]

Yea man it’s the engine not turning enough rpm’s that’s the problem. It’s barely reaching rpm’s above idle speed. Either the tune is way off (very rich due to factory break-in settings) or the carb throttle valve is not opening up all the way/very far. Remove the air filter and look at the throttle valve when you apply full throttle with the transmitter, if it’s not opening completely it’s probably just a linkage adjustment. If it does open fully then its tune related, rich, rich, rich. You should then slowly start tuning the engine for performance (lean it out).

 

[davidac49]

3 hours ago I started the tuning process found a pretty nice setup not too fast because I'm on a residential street that sees a car every minute and was swerving out of the way of the car and hit a curb bent the dog bone ha. There is a non maintained dirt track up the road a little ways. going to replace it with my last spare and give it a few runs. Thanks a lot snook and everybody who helped could not have done it without any of you fellas. Thanks again!