oil seal orientation question.

stainlesscycle · 05-08-2012, 02:18 AM

ok, so i'm putting new seals in a 2 stroke bottom end. it's 74 puch 175, and it's built a bit different then everything else i've worked on. normally i would place the seal lips facing the crank, and that's the way they were oriented when i split it (it's been opened before sometime in it's life). BUT the manual clearly states "large seals lips must point to the bearings" BUT the parts fiche (see pic) shows them oriented with lips facing the crank. obviously seal1 lips has to face toward the bearing. oh and before i split it i was wondering how the hell the ignition side bearing got lubrication (normally the dry side bearing in 2 strokes gets lubed with pre-mix) both bearings on this motor gets lubed from the gearbox - they cut a channel behind the bearing to feed it oil.

so do seal2 and seal3 go lip towards the bearing or crank? since neither bearing is lubed via pre-mix i would think the lip faces the wet side(bearing). but every 2 stroke i've ever done i put the lip toward the crank (and normally the bearing is inboard, and the seal outboard).. since the the seal works off pressure, and the crankside gets both negative and positive pressure.... but on this bottom end neither bearing gets lubed with pre-mix. so do the seal lips go towards the pressure (crank) or the fluid (bearings)??

had to split cases to replace seals, so i'd like to get it right the first time.

a picture helps.

motu · 05-08-2012, 03:09 AM

Yes, you are sealing the crankcase from gearbox oil, so sealing lip to bearing...or flat side to crank if that sounds better.

OldPete · 05-08-2012, 03:10 AM

Having only resealed a Yamaha and Hodaka,
i'd say toward the crank because positive pressure is higher than negative pressure.

stainlesscycle · 05-08-2012, 03:49 AM

hah! 2 replies, and both different.

ultimately what it comes down to is this:
do you place the lip toward the oil, or toward the pressure. on a normal bottom end it's kinda obvious. this one is different. if the lip is towards the bearing, won't the crankcase pressure end up fouling the gearbox oil (and the bottom end leakdown would suck). if the lip is toward the crankcase, the oil from gearbox could migrate to crank on every upstroke...

also if i put the lip toward the crank, as it was when i took it apart - it will be a bitch to install...very little surface on the lip side to push them in.

OldPete · 05-08-2012, 04:03 AM

Most any bearing house can supply you with a double lip seal that seals both ways.
I'd smear some light grease between the seal's lips.
Install with the major lip toward the crank case.

Measure shaft size, OD and width, order seals for high temps... like Viton.

stainlesscycle · 05-08-2012, 04:27 AM

Quote:

Originally Posted by OldPete

Most any bearing house can supply you with a double lip seal that seals both ways.
I'd smear some light grease between the seal's lips.
Install with the major lip toward the crank case.

Measure shaft size, OD and width, order seals for high temps... like Viton.

yes, i'm familiar with seals... i already have them in hand. double lip, but adl/hmsa10 style - just a wiper and a major seal.

OldPete · 05-08-2012, 04:46 AM

A wiper is there just to keep dirt from getting to the seal in an open air application. It offers no real sealing ability.

A pair of double lip seals can be had in my area for at the most $20.

The gear box had better be vented and as such offers no real pressure on the seal.

My $0.02 anywho.

EDIT: The oil squirting out of the ball bearings at the seals could offer some pressure... I'd still go double lip.

stainlesscycle · 05-08-2012, 04:53 AM

i already have seals, in the only design available at this size (ADL/HMSA10 DIN3760 etc..).. seals that were in it were single lip. both bearings get splash lubrication. gearbox is vented.

OldPete · 05-08-2012, 04:56 AM

Ask in the 2 smokers forum.

Not an easy call for nit-pickers like us.

ragtoplvr · 05-08-2012, 05:50 AM

The lip would face the crankcase. You need to keep the pressure in there so you can run the engine. Leakey seal 2 strokes are very hard to start and low on power.

Rod

greywolf · 05-08-2012, 11:10 AM

It looks to me like the seal orientations are shown in the fiche diagram.

stainlesscycle · 05-08-2012, 04:14 PM

Quote:

Originally Posted by greywolf

It looks to me like the seal orientations are shown in the fiche diagram.

yes, it looks that way doesn't it.

concours · 05-09-2012, 03:23 AM

Quote:

Originally Posted by ragtoplvr

The lip would face the crankcase. You need to keep the pressure in there so you can run the engine. Leakey seal 2 strokes are very hard to start and low on power.

Rod

This is the right answer. The manual can be, and in many vintage cases is wrong. (DAMHIK)

marlboroughlad · 05-11-2012, 08:45 AM

Quote:

Originally Posted by concours

This is the right answer. The manual can be, and in many vintage cases is wrong. (DAMHIK)

Agree with this. Any leak from the crankcase will cost power.

The higher crankcase pressure will also prevent oil ingress from the gearbox oil.

05-08-2012, 02:18 AM	#1
stainlesscycle ^OP Beastly Adventurer Joined: Jun 2008 Location: morgantown, wv Oddometer: 1,662	oil seal orientation question. ok, so i'm putting new seals in a 2 stroke bottom end. it's 74 puch 175, and it's built a bit different then everything else i've worked on. normally i would place the seal lips facing the crank, and that's the way they were oriented when i split it (it's been opened before sometime in it's life). BUT the manual clearly states "large seals lips must point to the bearings" BUT the parts fiche (see pic) shows them oriented with lips facing the crank. obviously seal1 lips has to face toward the bearing. oh and before i split it i was wondering how the hell the ignition side bearing got lubrication (normally the dry side bearing in 2 strokes gets lubed with pre-mix) both bearings on this motor gets lubed from the gearbox - they cut a channel behind the bearing to feed it oil. so do seal2 and seal3 go lip towards the bearing or crank? since neither bearing is lubed via pre-mix i would think the lip faces the wet side(bearing). but every 2 stroke i've ever done i put the lip toward the crank (and normally the bearing is inboard, and the seal outboard).. since the the seal works off pressure, and the crankside gets both negative and positive pressure.... but on this bottom end neither bearing gets lubed with pre-mix. so do the seal lips go towards the pressure (crank) or the fluid (bearings)?? had to split cases to replace seals, so i'd like to get it right the first time. a picture helps. __________________ current bikes 07 gasgas xc300-94 duc 900ss-86 morini camel (2)-84 IT200-83 IT175-78 guzzi lm1-77 pursang 250-76 morini 3 1/2 strada-76 frankentaco pursang 200-74 frankentaco pursang 200-74 morini 3 1/2 sport-74 mz ts250/0-74 puch 175 (3)-73 can-am 175tnt-71 guzzi frankeneldo-71 ossa Stiletto-70 frankentaco sherpa s(2)-66 morini corsarino(2)-63 morini corsaro + many more stainlesscycle screwed with this post 05-08-2012 at 03:54 AM

05-08-2012, 03:49 AM	#4
stainlesscycle ^OP Beastly Adventurer Joined: Jun 2008 Location: morgantown, wv Oddometer: 1,662	hah! 2 replies, and both different. ultimately what it comes down to is this: do you place the lip toward the oil, or toward the pressure. on a normal bottom end it's kinda obvious. this one is different. if the lip is towards the bearing, won't the crankcase pressure end up fouling the gearbox oil (and the bottom end leakdown would suck). if the lip is toward the crankcase, the oil from gearbox could migrate to crank on every upstroke... also if i put the lip toward the crank, as it was when i took it apart - it will be a bitch to install...very little surface on the lip side to push them in. __________________ current bikes 07 gasgas xc300-94 duc 900ss-86 morini camel (2)-84 IT200-83 IT175-78 guzzi lm1-77 pursang 250-76 morini 3 1/2 strada-76 frankentaco pursang 200-74 frankentaco pursang 200-74 morini 3 1/2 sport-74 mz ts250/0-74 puch 175 (3)-73 can-am 175tnt-71 guzzi frankeneldo-71 ossa Stiletto-70 frankentaco sherpa s(2)-66 morini corsarino(2)-63 morini corsaro + many more

05-08-2012, 04:46 AM	#7
OldPete Be aware Joined: Oct 2007 Location: Los Alamitos, CA Oddometer: 2,472	A wiper is there just to keep dirt from getting to the seal in an open air application. It offers no real sealing ability. A pair of double lip seals can be had in my area for at the most $20. The gear box had better be vented and as such offers no real pressure on the seal. My $0.02 anywho. EDIT: The oil squirting out of the ball bearings at the seals could offer some pressure... I'd still go double lip. OldPete screwed with this post 05-08-2012 at 04:49 AM Reason: noted

05-08-2012, 04:53 AM	#8
stainlesscycle ^OP Beastly Adventurer Joined: Jun 2008 Location: morgantown, wv Oddometer: 1,662	i already have seals, in the only design available at this size (ADL/HMSA10 DIN3760 etc..).. seals that were in it were single lip. both bearings get splash lubrication. gearbox is vented. __________________ current bikes 07 gasgas xc300-94 duc 900ss-86 morini camel (2)-84 IT200-83 IT175-78 guzzi lm1-77 pursang 250-76 morini 3 1/2 strada-76 frankentaco pursang 200-74 frankentaco pursang 200-74 morini 3 1/2 sport-74 mz ts250/0-74 puch 175 (3)-73 can-am 175tnt-71 guzzi frankeneldo-71 ossa Stiletto-70 frankentaco sherpa s(2)-66 morini corsarino(2)-63 morini corsaro + many more stainlesscycle screwed with this post 05-08-2012 at 04:58 AM

05-08-2012, 11:10 AM	#11
greywolf Unpaved road avoider Joined: Apr 2006 Location: Evanston IL Oddometer: 896	It looks to me like the seal orientations are shown in the fiche diagram. __________________ Pat in order of ownership 1971 Honda CB350, 2 1973 Honda CB500s, one was stolen, 1974 Can-Am 175 TNT, 1978 Yamaha XS11, 1978 Honda CX500, 1975 BMW R90S, 1983 BMW R65LS, 2005 Suzuki DL650 totaled, 2007 Suzuki DL650A, 2012 Suzuki DL650A

05-08-2012, 03:09 AM	#2
motu Loose Pre Unit Joined: Dec 2001 Location: New Zealand Oddometer: 3,977	Yes, you are sealing the crankcase from gearbox oil, so sealing lip to bearing...or flat side to crank if that sounds better.

05-08-2012, 03:10 AM	#3
OldPete Be aware Joined: Oct 2007 Location: Los Alamitos, CA Oddometer: 2,472	Having only resealed a Yamaha and Hodaka, i'd say toward the crank because positive pressure is higher than negative pressure.

05-08-2012, 04:03 AM	#5
OldPete Be aware Joined: Oct 2007 Location: Los Alamitos, CA Oddometer: 2,472	Most any bearing house can supply you with a double lip seal that seals both ways. I'd smear some light grease between the seal's lips. Install with the major lip toward the crank case. Measure shaft size, OD and width, order seals for high temps... like Viton.

05-08-2012, 04:56 AM	#9
OldPete Be aware Joined: Oct 2007 Location: Los Alamitos, CA Oddometer: 2,472	Ask in the 2 smokers forum. Not an easy call for nit-pickers like us.

05-08-2012, 05:50 AM	#10
ragtoplvr Beastly Adventurer Joined: Oct 2007 Location: S. W. Mssouri Oddometer: 4,602	The lip would face the crankcase. You need to keep the pressure in there so you can run the engine. Leakey seal 2 strokes are very hard to start and low on power. Rod

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