R/C Tech Forums

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

Reply
 
Thread Tools Search this Thread
Old 04-22-2009, 08:50 PM   #1
Tech Initiate
 
Join Date: Jan 2009
Posts: 47
Default Differential Troubleshooting-Need Help!

At the end of last season a friend of mine and myself purchased the Losi RTR 8ight 1.0. We were able to run the vehicles for about 2 hrs, before putting them away for the winter. Over the winter both of us replaced the grease with Losi's recommended diff oil weights for front, center and rear. We both throughly cleaned the differentials of all of the existing grease before adding the oil.

My buddy's car is smooth, however my rear differential has a "crunchy" feeling to it. Similar to how wheel bearings get when they have dirt in them.

My center diff feels normal as does the front. This "crunchy" feeling causes the car to make a tinging noise when you roll the car back and forth. I believe it is cause from the drive shaft vibration as it come into the center differential housing.

Does anyone have any suggestions as to the cause? And how I might be able to correct it?

I would greatly appreciate any help.
tk1931 is offline   Reply With Quote
Old 04-22-2009, 09:39 PM   #2
Tech Prophet
 
tc5 man's Avatar
 
Join Date: Oct 2007
Location: levittown pa
Posts: 16,872
Default

ethier its a little chip in the gears or maybe they are worn down and just need to be replaced thats my guess
tc5 man is offline   Reply With Quote
Old 04-22-2009, 10:42 PM   #3
Tech Elite
 
looper's Avatar
 
Join Date: Feb 2006
Location: DFW area of Texas
Posts: 2,224
Trader Rating: 19 (100%+)
Send a message via Yahoo to looper
Default

sounds like improper diff shimming might want to check into that.
__________________
Looped Designs Paintwerks
http://ldpaint.webs.com/ Email: Looped.designs@gmail.com
looper is offline   Reply With Quote
Old 04-23-2009, 04:32 AM   #4
Tech Elite
 
DOMIT's Avatar
 
Join Date: Oct 2007
Location: Fort Worth, Texas, USA, North America, Earth, Solar System, Milky Way Galaxy, Universe
Posts: 4,034
Trader Rating: 1 (100%+)
Send a message via MSN to DOMIT Send a message via Yahoo to DOMIT
Default

Quote:
Originally Posted by looper View Post
sounds like improper diff shimming might want to check into that.
Are you using the upgraded aluminum "inserts?" The ring and pinion DOES need to "wear in." The Losi is very tight from the factory.

Also, check to make sure the CVD hasn't loosened up on the pinion shaft. If it has, be sure to get it put back with no slop.

Did you grease the teeth of the ring gear? You should every time you take the diff out... just a thin line around the gear tooth surface.

And the comment about worn teeth on the rear ring and pinion could be right. I replaced my rear ring and pinion 3 times on my Losi buggy... then I replaced the buggy. If the ring and pinion in the rear have gone bad, replace them, AND the bulkhead.
__________________
Brad "DOMIT" Smith - I'm not fast, but at least I wreck a lot.
Unsponsored, but I use/recommend: XRay XB9, Alpha A852, Dynamite 053, Airtronics M11, Hitec 5955TG & 7955TG, ABEC 35 clutch and chassis bearings, PTRCRacing shock and diff fluids, Ready Rollers ceramic engine bearings. ** Team Terribles Region 9 coordinator. ** JOIN TEAM TERRIBLES! All racers welcome! PM me for details.
DOMIT is offline   Reply With Quote
Old 04-23-2009, 06:14 AM   #5
Tech Elite
 
Join Date: Mar 2009
Location: Aurora, Colorado
Posts: 3,644
Default

the rings are good to have but should not be the problem since it is so new - when you reinstall the four gears in the diff cup, check to make sure you installed the correctly. there are 2 different notches on the sides of the diff cup, one slot goes to the bottom of the cup and the other goes half way down. You must install the bottom set of gears in the long slot

hope this helps
__________________
TLR - Spektrum - Horizon - TLR 8ight 4.0 - TLR 8ight-T 4.0 - TLR 22 4.0 - Orion
token is offline   Reply With Quote
Old 04-23-2009, 06:21 AM   #6
Tech Adept
 
Join Date: Jun 2006
Posts: 125
Default

the ringing sounds like the center diff and the engine are not meshed right are you sure its from the rear of the car
Garrison is offline   Reply With Quote
Old 04-23-2009, 08:12 PM   #7
Tech Initiate
 
Join Date: Jan 2009
Posts: 47
Default

No upgrades. I checked the CVD, and appears to be tight. After I cleaned out all of the factory grease, I just added in the correct amount of oil. These gears look brand new, no evidence of any wear at this time. I have yet to run the car, that's the good news, but I do plan on running it on Sunday at the track. The other good news is that when Amain dropped the price on the RTR to $374.00 I purchase another one, for a backup/spare parts.

Thanks for all the great information.

Quote:
Originally Posted by DOMIT View Post
Are you using the upgraded aluminum "inserts?" The ring and pinion DOES need to "wear in." The Losi is very tight from the factory.

Also, check to make sure the CVD hasn't loosened up on the pinion shaft. If it has, be sure to get it put back with no slop.

Did you grease the teeth of the ring gear? You should every time you take the diff out... just a thin line around the gear tooth surface.

And the comment about worn teeth on the rear ring and pinion could be right. I replaced my rear ring and pinion 3 times on my Losi buggy... then I replaced the buggy. If the ring and pinion in the rear have gone bad, replace them, AND the bulkhead.
tk1931 is offline   Reply With Quote
Old 04-23-2009, 08:16 PM   #8
Tech Initiate
 
Join Date: Jan 2009
Posts: 47
Default

Quote:
Originally Posted by token View Post
the rings are good to have but should not be the problem since it is so new - when you reinstall the four gears in the diff cup, check to make sure you installed the correctly. there are 2 different notches on the sides of the diff cup, one slot goes to the bottom of the cup and the other goes half way down. You must install the bottom set of gears in the long slot

hope this helps
I am going to take it apart tomorrow night, so I will definetly check that out.

Thanks
tk1931 is offline   Reply With Quote
Old 04-23-2009, 08:20 PM   #9
Tech Initiate
 
Join Date: Jan 2009
Posts: 47
Default

Quote:
Originally Posted by Garrison View Post
the ringing sounds like the center diff and the engine are not meshed right are you sure its from the rear of the car
Funny that you should mention that, because I originally thought that it was coming from the center diff, but when I pulled it off, that's when I could definetly tell that it was not there.

I also thought the noise was coming from an improper gear mesh, but I have checked that as well, and all appears to be fine.

Thanks for the info.
tk1931 is offline   Reply With Quote
Reply



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 06:14 AM.


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