Author Topic: Gearbox Oil (AOT)  (Read 436 times)

Offline dogshome

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Gearbox Oil (AOT)
« on: April 21, 2020, 02:41:56 PM »
Another Oil Thread :-)

Synthetic 75W90 works well. Castrol MTX 75W140 work really well!

My shifting technique is getting better: Pre-load lever before changing, move your toe quickly and positively and don't let the revs drop too low dropping into second.

Haven't had a crunch or a grrrrrrRRRRR-K-Runch! for a while now.

 ;D
肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline Justin B.

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Re: Gearbox Oil (AOT)
« Reply #1 on: April 29, 2020, 01:35:45 PM »
I use the thicker stuff in mine and it seems to shift better for me also.
Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!

Offline Tony Smith

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Re: Gearbox Oil (AOT)
« Reply #2 on: July 22, 2020, 10:13:21 PM »
I reject the use of synthetic oil on the basis of cost to no advantage.

However the input bearing on my R860 is on the way out and I must say that Penrite 85/140 has quietebned it a lot, along with a whole (small) tube of Moly for good luck.

I have ordered a shimming kit from Cycleworks and I already have the bearings, so hopefully I will do the rebuild in a few weeks time.

BTW, if you ever decide to do your own work on final drive or gearbox Cycleworks LLC is your go-to for the special tools and shims. I have beeen using their special tools for a long time now and the only one that has ever disappointed was their original tool for removing steering head races, I understand that their updated tool is much, much better.
1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline Barry

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Re: Gearbox Oil (AOT)
« Reply #3 on: July 23, 2020, 06:34:44 AM »
I use synthetic 75W90 purely for the big reduction in cold oil drag in the winter.  I can't say there was any improvement in gear change quality, nor did i expect there to be.  This is a dog clutch gearbox with no synchros to be influenced by the chosen oil.   The only variable which will be influenced by oil viscosity, is how quick the shafts spin down during a change.
Barry Cheshire, England 79 R45

Offline dogshome

  • Posts: 116
  • I Love YaBB 2!
Re: Gearbox Oil (AOT)
« Reply #4 on: December 04, 2020, 12:01:44 PM »
Snickety snick snick now. New clutch cable, some dremelling of the rubber gauge pod (underneath, where you can't see) and a new clutch lever needle bearing have all helped. Synthetic oil definitely a plus, I swapped the fork oil and the increased slipperyness is very noticeable there too. It makes sense as my RC engines ar much free-er on syn. You can tell flicking them over.
肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline dogshome

  • Posts: 116
  • I Love YaBB 2!
Re: Gearbox Oil (AOT)
« Reply #5 on: December 27, 2020, 11:00:17 AM »
Update in 1C. 75W140 is nasty until the engine is quite hot (10 miles or more). Nipping across town and back doesn't result in nice second gear downshifts. No matter how careful/rough/positive/fast/slow or what revs. So I've dropped it out and put 75W90 GL5 axle oil in. This stuff is noticeably wetter when it's this cold. A sploge on the bench spreads whereas the thicker stuff tends to sit. So it's low temperature viscosity is obviously less.

The dreaded 3rd to 2nd change at the end of our road resulted in a slightly clunky change, but not the nastyness with the wide range stuff. By the time I was in town, gearchanges were normal.

So if you live somewhere that doesn't go below 10C 75W140 works very well. Below that, thinner is better. I think I probably just re-invented the wheel  :steinigung:


P.S I've broken 4 car gearboxes in the past. Generally through thrashing, so don't listen to me!  :dankk2:
肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline mrclubike

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  • Jungheinrich Master Tech
Re: Gearbox Oil (AOT)
« Reply #6 on: December 28, 2020, 06:46:11 PM »
I use SYN in the Trans and engine  to help with the cold starting (40F)
I rarely have issues shifting 
But when I first got the bike it was terrible
I actually rebuilt it thinking there was something wrong with it
But when i seen how it was made I knew it was just me not doing it right  ;D
1982 R65 running tubeless Snowflakes
2004 R1150R