Transmission oil weight, the same as your case oil?

Transmission, clutch, chains and belts
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57FLH
Posts: 12
Joined: Fri Jul 13, 2007 8:46 am

Transmission oil weight, the same as your case oil?

#1

Post by 57FLH » Tue Aug 03, 2004 9:39 pm

I've been reading some varying opinions about trans oil. The same as your case oil as Bruce Palmer says or 90 weight? or what? I'm running HD 60 the same as my case but would consider 90 if it would "smooth" the shifting a bit. Thoughts? I've heard 90 can wear flat spots on the roller bearings or something? True?



haggis
Posts: 158
Joined: Fri Mar 19, 2004 3:35 am
Location: Maine USA

Re: Transmission oil weight

#2

Post by haggis » Wed Aug 04, 2004 3:06 am

57flh, I run Valvoline 80-90 gear oil been happy with it ;) Haggis

kell
Posts: 369
Joined: Sat Jun 19, 2004 2:58 am

Re: Transmission oil weight

#3

Post by kell » Wed Aug 04, 2004 11:05 pm

57FLH
You may know this already but there are two numbering systems, one for "engine oil" and one for "gear oil". 90 weight gear oil is not necessarily any heavier than 60 weight engine oil; maybe somebody knows the exact correlation.

Cotten
Posts: 6791
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Transmission oil weight

#4

Post by Cotten » Thu Aug 05, 2004 2:43 am

Yes the rating systems are different. Probably even different from brand to brand.

There is nothing wrong with using motor oil as the Factory mandated, as long as you change it with regular maintenance.

Beware that your maindrive gear rollers and bushing will not get lube flowing through them if it is too thick.
Then you will be repeating the ol' "leaking seal" thread.

52WLCnFL

Re: Transmission oil weight

#5

Post by 52WLCnFL » Thu Aug 05, 2004 12:31 pm

SAE ratings do not differ from brand to brand but are standardised for viscosity (as measured by centiStokes).
Gear oils have a different numbering series than motor oils indeed. Gear oil SAE90 corresponds with SAE40 to 50 motor oils (gear oil numbers cover a wider viscosity range than motor oils).
So from the viscosity point of view an SAE90 grade would suit our transmissions. But.... many gear oils contain extreme pressure dopes like phosphorous and sulphur, that are eating away yellow metals like brass. These are at least the GL4 and GL5 rated oils. So I'm somewhat reluctant to put these oils in my gear box. Maybe lower-doped gearoils like GL1 and GL2 are harmless, but why deviate from the works prescription of using motor oil?

shaker
Posts: 56
Joined: Tue Aug 09, 2005 10:23 pm
Location: down south

Re: Transmission oil weight

#6

Post by shaker » Sun Aug 08, 2004 2:22 pm

I don't know if this was a coincidence or not but when i bought this bike 2 years ago the owner run 90 wt in trans , all was good but when shifting to 4th gear you had to be going 40 mph + or it would not take the gear, shifter would bottom out in the gate, it is tank shift , no funny noise or nuthing , but would have to go back to 3th gear ,and go up again, he said it had don this ever sence he went to 25 tooh gear and belt drive primary, anyway i changed trans oil this week and put in 20-50 syn , motor oil, same as in motor , now the bike will shift to 4th a lot better , so far so good.

Billy
Posts: 719
Joined: Tue Mar 23, 2004 6:57 am

Re: Transmission oil weight

#7

Post by Billy » Mon Aug 09, 2004 5:29 am

52WLC, I agree with you, I don't want anything possibly harmful in my Fresh gearbox.
It will have enough to deal with 'me' on the shiftknob.;)

I think motor oil as intended is fine. Except I prefer multi-grade Synthetics..Haven't used straight grades in a long time...

Shaker, being that I prefer Synthetics over fossil oil.
I think if your bike NOW shifts better. Happy Days.
I had a bike that had a slight whine in 3rd gear. Everything checked out fine. Switched out to Synthetic oil & the slight whine went away. Works for me.. ;)

adjustaglide
Posts: 6
Joined: Wed Oct 20, 2004 5:27 pm

Re: Transmission oil weight

#8

Post by adjustaglide » Mon Aug 09, 2004 7:01 pm

I started running Torco 75-140 syn. about 8 years ago and it smoothed out third gear real nice. Was thinkin I should change it one of these years,but it still looks like new after about 30.000 miles. Bought the Torco cause it was on sale and I am kinda cheap. :)

Sidecar
Posts: 248
Joined: Tue Apr 17, 2007 9:21 pm
Location: Southwestern, Pa.

Re: Transmission oil weight

#9

Post by Sidecar » Mon Aug 09, 2004 7:51 pm

I don't know if this was a coincidence or not but when i bought this bike 2 years ago the owner run 90 wt in trans , all was good but when shifting to 4th gear you had to be going 40 mph + or it would not take the gear, shifter would bottom out in the gate, it is tank shift , no funny noise or nuthing , but would have to go back to 3th gear ,and go up again, he said it had don this ever sence he went to 25 tooh gear and belt drive primary, anyway i changed trans oil this week and put in 20-50 syn , motor oil, same as in motor , now the bike will shift to 4th a lot better , so far so good.
Been there same as you. Except I went back to 24 teeth because of the hilly countryside around here. I just need to "hold" the shifter in 4th when I engage the clutch again until I get a few miles on it. Of course, I could file the gate a little but that would take the fun out of it !!!

shaker
Posts: 56
Joined: Tue Aug 09, 2005 10:23 pm
Location: down south

Re: Transmission oil weight

#10

Post by shaker » Tue Aug 10, 2004 4:20 am

yes, I know about the hill riding, I do all my riding in Tn, and Ky, so i think i will go to 24 tooth as well, i plan on riding to smokies . and over to maggie valley this fall if all go's well, the traffic from sevierville to gatlinburg can be a killer when the temp's are in the 90's and traffic is backed up 10 miles! so i guess i will find out if the syn oil's are worth the big bucks . if i get to go i will be riding with frend's that have newer bike's , o2 and up. sure hope i don't have to wait on them to long after i get to the top. ;)

Sidecar
Posts: 248
Joined: Tue Apr 17, 2007 9:21 pm
Location: Southwestern, Pa.

Re: Transmission oil weight

#11

Post by Sidecar » Tue Aug 10, 2004 1:14 pm

if i get to go i will be riding with frend's that have newer bike's , o2 and up. sure hope i don't have to wait on them to long after i get to the top. ;)
Shaker,

It'll even out in the end because you'll never get out of the gas stations. Everybody wants to talk to ya about your bike when you stop. They'll all get pissed because you'll draw all the crowds !!!!!
;)

Topsy

Re: Transmission oil weight

#12

Post by Topsy » Sat Nov 20, 2004 4:21 pm

Good question, I run 50 wt engine oil which seems fine. Only trouble is finding neutral is a bitch with engine running & bike stationary. Who knows maybe I have clutch adjustment problems.

jimmy
Posts: 8
Joined: Sat Jul 14, 2007 5:55 pm

Re: Transmission oil weight

#13

Post by jimmy » Sat Nov 20, 2004 8:23 pm

hey topsy, i was having trouble getting neutral with the engine running and it was just a minor clutch adjustment. ever since a tranny rebuild i grind a little going into second gear then sometimes i get a good solid engagement iwonder whats with that?

VintageTwin
Panhead Register Member
Posts: 618
Joined: Mon Aug 16, 2010 7:18 pm
Bikes: '46 Knuck. '57 Panhead, '59 Panhead
Location: Repop Hell

Re: Transmission oil weight

#14

Post by VintageTwin » Sun Nov 21, 2004 12:42 pm

70 wt. Kendall for the trans. Leave it go at that. :P

Cotten
Posts: 6791
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Transmission oil weight

#15

Post by Cotten » Sun Nov 21, 2004 1:51 pm

Again I must point out that there is no provision for oil flow through the main drive rollers. It can only seep in (and out) past the the thrust washer. Since the book specs less than .014" endplay (if memory serves; many rebuilders set it up sweeter), there is a definite compromise if the oil is too thick.

I have taken a frozen fresh rebuild apart where the assembler had used disc brake grease glue the rollers in place, and 90 wt failed to wash it out.

And those of you who have the '65 seal on the the end of the drive gear stop the through-flow for the bushing as well!

Gee, could it be that the Factory had a reason to spec the same oil for the tranny as the motor,.. and to vary it with the season as well?

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