Transmission rebuild or diagnosis help needed

jtiger12
Profile picture for user jtiger12
Posts
1720
Joined
8/2/2006
Location
Forest H Ill, MD US
jtiger12
I have a 2007 crf450 that has a little over 300 hours on it. The current crank has about 120 on it, so I am planning to do a full motor rebuild next month. All original transmission. At the end of last season, I had it pop out of 3rd on me twice, never had that happen before. What should I be looking at and measuring to determine the cause ? Center shift fork? The gear itself?
|
Paw Paw 271
Profile picture for user Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
Paw Paw 271 2/19/2017 6:50am
2/19/2017 6:50am
Shift fork wear, gear dog wear and shift drum wear. 3rd gear is always the most hammered gear and shows the most wear.

Paw Paw
captmoto
Profile picture for user captmoto
Posts
5140
Joined
4/22/2009
Location
Rancho Cucamonga, CA US
captmoto 2/19/2017 7:57am
2/19/2017 7:57am
Factory service manual to help you through it all. Will have wear specs and tolerances. It's nice not having to guess.
jtiger12
Profile picture for user jtiger12
Posts
1720
Joined
8/2/2006
Location
Forest H Ill, MD US
jtiger12 2/20/2017 4:03am
2/20/2017 4:03am Edited Date/Time 2/20/2017 4:03am
Paw Paw 271 wrote:
Shift fork wear, gear dog wear and shift drum wear. 3rd gear is always the most hammered gear and shows the most wear.

Paw Paw
Thanks. That is where I was going to start (drum and forks). The dogs are the knobs on the side right?
DTHA70
Profile picture for user DTHA70
Posts
336
Joined
9/25/2008
Location
Surprise, AZ US
DTHA70 2/22/2017 11:20am
2/22/2017 11:20am
yes the dogs are what engage each other (knobs or recesses cut into a gear)

The Shop

See All »
DTHA70
Profile picture for user DTHA70
Posts
336
Joined
9/25/2008
Location
Surprise, AZ US
DTHA70 2/22/2017 11:21am
2/22/2017 11:21am
if youre tearing it apart, it's worth sending to someone to have the whole thing ISF treated and then either coated by Microblue or WPC

Post a reply to: Transmission rebuild or diagnosis help needed