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-   -   Clutch braking? (https://www.rctech.net/forum/nitro-off-road/387570-clutch-braking.html)

barrydidntknow 04-08-2010 10:27 AM

Clutch braking?
 
I am getting alot of off throttle braking, as in when i let off the gas my 8t 2.0 is acting like the breaks are on. I know it is not the brakes engaging and it rolls freelly when just i push it with everything in the neutral position. I am thinking it is the clutch not disengaging after i let off the gas. Got the required 1/2 mm play for the CB and I re greased the bearings and am about to clean up the shoes with my dremmel. Any other tips or things to look at that could cause this? Best description I can give is that it acts like a stick shift car that shifts into a low gear, like 1st or 2nd automatically after letting off the throttle. Clutch problem? engine bearing? Im running the stock losi 8t 2.0 clutch set up and a picco evo 2.

Racecrafter 04-08-2010 10:49 AM


Originally Posted by barrydidntknow (Post 7246964)
I am getting alot of off throttle braking, as in when i let off the gas my 8t 2.0 is acting like the breaks are on. I know it is not the brakes engaging and it rolls freelly when just i push it with everything in the neutral position. I am thinking it is the clutch not disengaging after i let off the gas. Got the required 1/2 mm play for the CB and I re greased the bearings and am about to clean up the shoes with my dremmel. Any other tips or things to look at that could cause this? Best description I can give is that it acts like a stick shift car that shifts into a low gear, like 1st or 2nd automatically after letting off the throttle. Clutch problem? engine bearing? Im running the stock losi 8t 2.0 clutch set up and a picco evo 2.


Sounds like your tune is too lean not allowing the engine to drop back to an idle which is not allowing your clutch to disengage.

Start by richening the bottom a couple hours.

barrydidntknow 04-08-2010 11:02 AM


Originally Posted by Racecrafter (Post 7247032)
Sounds like your tune is too lean not allowing the engine to drop back to an idle which is not allowing your clutch to disengage.

Start by richening the bottom a couple hours.

That would be odd as the only changes I have made since my break in from factory setting has been to lean about 3/4 hour on the hsn and maybe 1/4 hour on the lsn and I had this issue since break in. It might have been that i had the 4 screws that hold the shoes in place too tight, not allowing them to easily return to disengage. Gonna see if that works and will try richening the lsn if this didnt work.

aaron joy 04-08-2010 11:03 AM

Racecrafter, he is saying he is having a issue like he has drag brakes not clutch sticking. If your clutch was sticking you would see excessive wear, clutchbell discoloration, and your engine will want to shut off when you apply the breaks.

Shuming 04-08-2010 11:42 AM

Check and replace your clutch springs. Sounds like they are no good.

Or

Clutch bearings are shot.

Jerm13 04-08-2010 12:18 PM


Originally Posted by Shuming (Post 7247209)
Check and replace your clutch springs. Sounds like they are no good.

Or

Clutch bearings are shot.

I agree. Or you have too soft of a spring and/or to heavy of a shoe. Also, check the shoes for burrs on the edges. They can cause the shoes to move slowly or not at all and stay engaged after you are off throttle.

BTW, what clutch shoes/springs are you running? With a truck I run 3 different combos
1. 2 carbon w/ green, 2 aluminum w/ gold for loose tracks
2. 2 carbon w/ gold, 2 aluminum w/ silver normally
3. 4 aluminum with 2 gold and 2 silver for high bite tracks (NC clay)
I even experimented with all silver but it didnt feel good to me.

barrydidntknow 04-08-2010 12:24 PM

hmmmm.......I am noticing that the truggy doesnt roll very freely evn with the engine pulled out and the brakes not on. I am use to my hyper 9 buggy that rolls quite easily. Do truggies tend have more "slow-down" just from their gearing as compared to a buggy? The truggy and buggie would both roll down a slight hill but the truggy just kinda seems like it doesnt free wheel as easily. imagine a car going down a hill in 2nd gear(truggy) vs. a car in neutral(buggy). This is with no engine and no brakes.

I am running the stock 4 alum. shoe clutch with 2 green and 2 gold springs. I cleaned up the shoes and checked for burrs.

It almost seems like the center diff is rubbing somewhere but I dont see any rubbing. It just doesnt seem to roll as easy as it should. Gonna see if my clutch dremmeling and not tightening the clutch shoe holders helped and go from there.

i am running 7 - 10 - 2 inthe diffs. Pretty sure it is something in the central drive train

jamiekerr14 04-08-2010 12:28 PM

Another thing is to check mesh ect like diff mesh... .. as to tight mess can cause some drag ect.. or dodgy bearings.. ect anything like that is hard to miss but may cause symptoms like you described...

Shuming 04-08-2010 12:32 PM


Originally Posted by barrydidntknow (Post 7247358)
hmmmm.......I am noticing that the truggy doesnt roll very freely evn with the engine pulled out and the brakes not on. I am use to my hyper 9 buggy that rolls quite easily. Do truggies tend have more "slow-down" just from their gearing as compared to a buggy? The truggy and buggie would both roll down a slight hill but the truggy just kinda seems like it doesnt free wheel as easily. imagine a car going down a hill in 2nd gear(truggy) vs. a car in neutral(buggy). This is with no engine and no brakes.

If i take my engine out, my truck will roll all the way down the hill

you know what - I wonder, check the rear wheel bearing. They are known to go out.

aaron joy 04-08-2010 12:40 PM

I would put your truck on a stand and be sure the main gear is not bottoming out on your stand since the gear sticks out of the chassis a little bit, than remove your center diff mount upperbrace (4 screws) and see how the truck free wheels on the stand.

If your truck spins freely with the plate removed, than check your brake pad to disc clearance: page 1
http://www.losi.com/ProdInfo/Files/L...ke_Linkage.pdf

barrydidntknow 04-08-2010 01:41 PM

Just did a test run. Deffinatley not the brakes at all. Did notice that my flywheel has a groove in it from the bottom of the clutch bell that was from when I had a different engine in the truggy and the cb wasn't shimmed right. Going to order a new clutch set up and try to smooth this one out with the dremmel. Also the cb might be shot as seems it is not a consistent shape around where it curves to the actual gear part of it.

Oh well. Going to install my new rear drive shaft that came today to go along with my new h9 animal chassis i got. Dont wanna mess with the 8t 2.0 till i get a new clutch and bearings on her. At least then I will eliminate the clutch or flywheel as the issue.

Frank L 04-08-2010 03:32 PM

I have had the brakes hang up due to binding somewhere in the cam mech. 1 time I had to remove one of the screws that hold the diff mounts together, I have also had the body on the buggy push down on the air filter and engage the front brake. Make sure the air filter has lots of clearance.

skidoos 04-08-2010 03:39 PM


Originally Posted by barrydidntknow (Post 7247589)
Just did a test run. Deffinatley not the brakes at all. Did notice that my flywheel has a groove in it from the bottom of the clutch bell that was from when I had a different engine in the truggy and the cb wasn't shimmed right. Going to order a new clutch set up and try to smooth this one out with the dremmel. Also the cb might be shot as seems it is not a consistent shape around where it curves to the actual gear part of it.

Oh well. Going to install my new rear drive shaft that came today to go along with my new h9 animal chassis i got. Dont wanna mess with the 8t 2.0 till i get a new clutch and bearings on her. At least then I will eliminate the clutch or flywheel as the issue.

i had same problem, it was my clutch, the actual shoes were stayin open and not closin, i even put the clutch in my hand and open the shoes with a screw driver and they wouldnt return back, so i filed the side of the shoes to give it more play and it works well now, the problem is when u tighten the screws to hold the spring and shoe in the fly wheel, there isnt enough tolerance and cause pressure on the shoes

rogermartinez 08-09-2010 12:08 PM

This sounds to be the drivetrain binding. Most likely at the bearings throughout the diffs or hubs. I change out my drivetrain bearings regularly. Swap them out, I bet that's your problem. If your clutch was truly binding, the engine would stall when you hit the brakes.

MattFL 08-09-2010 03:25 PM

My DBX has always done this, the clutch stays locked up until the engine is near idle. You can clearly hear it in thr rpm of the engine. I will say that when I recently changed to a new OS engine, the engine braking was significantly more. However as the engine breaks in and gets looser, the engine braking is going away quite a bit. If you've got a new engine, get a little time on it before spending too much time on the clutch.


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