R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro Off-Road

Reply
 
Thread Tools Search this Thread
Old 04-08-2010, 10:27 AM   #1
Tech Initiate
 
Join Date: Feb 2010
Posts: 30
Default 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.
barrydidntknow is offline   Reply With Quote
Old 04-08-2010, 10:49 AM   #2
Tech Elite
 
Racecrafter's Avatar
 
Join Date: Apr 2007
Location: RC Mecca
Posts: 4,138
Trader Rating: 25 (96%+)
Default

Quote:
Originally Posted by barrydidntknow View Post
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.
__________________
Jimmy Wright

www.trackstarrc.com ~ www.facebook.com/TrackStarRC ~ Home of the 2x's Stock Nationals Champion TS-Gold & TS-Black tire sauce, TS-1+ lubricants, TS-Precision bearings, XRG Xtreme Racing Grease, Scale Auto Engineering, ElevenTech, WRD2, Carbon 12, Stiff Products
Racecrafter is offline   Reply With Quote
Old 04-08-2010, 11:02 AM   #3
Tech Initiate
 
Join Date: Feb 2010
Posts: 30
Default

Quote:
Originally Posted by Racecrafter View Post
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.
barrydidntknow is offline   Reply With Quote
Old 04-08-2010, 11:03 AM   #4
Tech Fanatic
 
aaron joy's Avatar
 
Join Date: Oct 2007
Location: New Jersey
Posts: 825
Trader Rating: 16 (94%+)
Default

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.

Last edited by aaron joy; 04-08-2010 at 12:00 PM.
aaron joy is offline   Reply With Quote
Old 04-08-2010, 11:42 AM   #5
Tech Adept
 
Join Date: Oct 2009
Posts: 203
Default

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

Or

Clutch bearings are shot.
__________________
I'm not sponsored so it does not matter what I put here.
Shuming is offline   Reply With Quote
Old 04-08-2010, 12:18 PM   #6
Tech Elite
 
Jerm13's Avatar
 
Join Date: Feb 2010
Location: VB, VA
Posts: 3,237
Trader Rating: 36 (100%+)
Default

Quote:
Originally Posted by Shuming View Post
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.
Jerm13 is offline   Reply With Quote
Old 04-08-2010, 12:24 PM   #7
Tech Initiate
 
Join Date: Feb 2010
Posts: 30
Default

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
barrydidntknow is offline   Reply With Quote
Old 04-08-2010, 12:28 PM   #8
Tech Addict
 
jamiekerr14's Avatar
 
Join Date: Dec 2008
Location: Uk
Posts: 607
Default

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...
__________________
Xray XB4
Supported By:
RC Disco
jamiekerr14 is offline   Reply With Quote
Old 04-08-2010, 12:32 PM   #9
Tech Adept
 
Join Date: Oct 2009
Posts: 203
Default

Quote:
Originally Posted by barrydidntknow View Post
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.
__________________
I'm not sponsored so it does not matter what I put here.
Shuming is offline   Reply With Quote
Old 04-08-2010, 12:40 PM   #10
Tech Fanatic
 
aaron joy's Avatar
 
Join Date: Oct 2007
Location: New Jersey
Posts: 825
Trader Rating: 16 (94%+)
Default

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
aaron joy is offline   Reply With Quote
Old 04-08-2010, 01:41 PM   #11
Tech Initiate
 
Join Date: Feb 2010
Posts: 30
Default

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.
barrydidntknow is offline   Reply With Quote
Old 04-08-2010, 03:32 PM   #12
Tech Lord
 
Frank L's Avatar
 
Join Date: Dec 2008
Location: NorCal
Posts: 12,500
Trader Rating: 148 (100%+)
Default

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.
__________________
- X-Ray/ RC America Team Driver - MKS -
- XB8 - XB8T - XB8 E - OS Spec III - B2102 - 4PXR -
~ SSC ~ Godfather ~ Ironman ~ ButterySmooth ~
Frank L is offline   Reply With Quote
Old 04-08-2010, 03:39 PM   #13
Tech Regular
 
Join Date: Aug 2009
Location: toronto ontario canada
Posts: 405
Trader Rating: 2 (100%+)
Default

Quote:
Originally Posted by barrydidntknow View Post
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
skidoos is offline   Reply With Quote
Old 08-09-2010, 12:08 PM   #14
Tech Initiate
 
rogermartinez's Avatar
 
Join Date: Jul 2010
Posts: 35
Default

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.
rogermartinez is offline   Reply With Quote
Old 08-09-2010, 03:25 PM   #15
Tech Adept
 
Join Date: Mar 2010
Location: FL
Posts: 181
Default

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.
MattFL is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Vented Clutch Bell Discussion robbdny Nitro Off-Road 30 01-11-2009 04:09 AM
shoe type clutch tweaking sup Nitro On-Road 16 11-04-2003 07:48 AM
Is this a clutch problem? albertlam Nitro On-Road 31 03-17-2003 08:18 AM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 08:20 AM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net