crank seals --- which way do i install??

R

rjardo

Member

May 21, 2007

4

0

• May 21, 2007

• #1

k, dumb question here.
Yes i should have taken pics before tearing apart 2 mos ago, but i forgot which way the seals go in my YZ250.. should i see the spring or not? they go in after the cases are back together, so i have made it that far...

thanks

rj

 

IndyMX

Crash Test Dummy

~SPONSOR~

Jul 18, 2006

5,548

2

Amo, IN

• May 21, 2007

• #2

Logic says to put the spring towards where the pressure is... I'd say to install the seals so that the spring side is towards the rod..

 

B

Bunya

Member

Apr 26, 2007

147

0

• May 21, 2007

• #3

That's a good question really. The flaw in your logic Indy is the pressure side varies with crank position. During part of the cycle the crankcase operates under a vacuum which puts the pressure on the outside. Because sucking air thru crank seals can be catastrophic to the engine, my instinct would be to have the springs facing outward. I grabbed the Clymer manual for my RM to find out for sure. Unfortunately, it's only further confusing things:

NOTE
For the right crankcase, install the seal
with the open side facing out. For the
left crankcase, install the seal with the
closed side facing out. :whoa:

Go figure! Looks like you should consult the manual for your bike. If you don't have one, you really should get one. Otherwise maybe someone will check their manual for you.

Marc -

 

Last edited: May 22, 2007

IndyMX

Crash Test Dummy

~SPONSOR~

Jul 18, 2006

5,548

2

Amo, IN

• May 21, 2007

• #4

the Manual for my Honda shows the spring side going towards the crank case on both sides.

 

7

76GMC1500

Uhhh...

Oct 19, 2006

2,142

1

• May 22, 2007

• #5

The spring goes in on the Hondas.

 

C

Charlie Mix

Member

Feb 7, 2007

38

0

• May 22, 2007

• #6

YZ250 manual (00 & 01) shows these seals installed with the springs faced towards the bearings.

 

Last edited: May 22, 2007

7

76GMC1500

Uhhh...

Oct 19, 2006

2,142

1

• May 22, 2007

• #7

I just noticed that my service manual makes absolutely no mention of the crankshaft seals.

 

whenfoxforks-ruled

Old MX Racer

~SPONSOR~

Oct 19, 2006

8,129

2

Merrillville,Indiana

• May 22, 2007

• #8

I have a 76 rm125 and low and behold the right seal is spring facing the crank and the right bearing in the clutch oil,better check the book!

 

R

rjardo

Member

May 21, 2007

4

0

• May 22, 2007

• Thread starter
• #9

Thanks for all the great replies, I am going to install with the springs in. they do have a double lip, so there is a slight lip facing out. when i really thought about it, it occured to me that it would be a real pain to press the seal on the spring side, with no flat face to press against. i would almost surely damage the seal getting it in, now with the flat, i only have a 50% chance of dorking it up :^)
Thanks again for all your replies and time...
RJ

 

whenfoxforks-ruled

Old MX Racer

~SPONSOR~

Oct 19, 2006

8,129

2

Merrillville,Indiana

• May 22, 2007

• #10

http://www.prosourcemotorsports.com/fiche_section_detail.asp The microfiche,courtesy of prosource,shows proper alignment.