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BSA A65 Gearbox Oil #554521
07/23/14 8:39 pm
07/23/14 8:39 pm
Joined: Aug 2001
Posts: 70
PA, USA
Rob Barker Offline OP
BritBike Forum member
Rob Barker  Offline OP
BritBike Forum member
Joined: Aug 2001
Posts: 70
PA, USA
Hi All. I can't seem to get the search engine to come up with answer to this: What kind of oil should I put in the gearbox of my 1970 BSA Thunderbolt? I have a workshop manual that says SAE 50, but the only fifty weight oil I can find is Valvoline "Racing Oil". Is this what I need?

Also: I don't know what was in it before, but when I drained the old oil it came out all creamy and emulsified. I can't imagine that it was water, because it sleeps in a dry garage. If it's just air, is it the fault of the old oil or what?

Rob

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Re: BSA A65 Gearbox Oil [Re: Rob Barker] #554530
07/23/14 9:18 pm
07/23/14 9:18 pm
Joined: Aug 2001
Posts: 4,254
Owego, NY, USA
Mark Z Online content
BritBike Forum member
Mark Z  Online Content
BritBike Forum member
Joined: Aug 2001
Posts: 4,254
Owego, NY, USA
80-90W gear oil.

Yes, the milky look is from water. Some say that condensation alone can result in that much water in the oil. If not, then water getting in through the filler cap or through the clutch cable stanchion - there's supposed to be a rubber boot on that, which is often broken or missing. The filler cap gasket (fiber washer) may also be worn or missing. The water could have gotten in there a while ago... In any case, water in there for too long can ruin your tranny bearings. Good idea to change the oil at least once a year.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: BSA A65 Gearbox Oil [Re: Rob Barker] #554559
07/24/14 1:01 am
07/24/14 1:01 am
Joined: Oct 2008
Posts: 4,877
Gnashville
DavidP Online content

BritBike Forum member
DavidP  Online Content

BritBike Forum member
Joined: Oct 2008
Posts: 4,877
Gnashville
Does the '70 model have the nylon cap with the dipstick?
Those caps are vented, and can admit water. I end up changing my gear oil quite often.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
Re: BSA A65 Gearbox Oil [Re: Rob Barker] #554563
07/24/14 1:30 am
07/24/14 1:30 am
Joined: Dec 2002
Posts: 3,235
arkansas
L
leon bee Offline
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leon bee  Offline
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L
Joined: Dec 2002
Posts: 3,235
arkansas
Modern gear oil for me as well. In my humid climate oil turns milky even with bikes mostly inside after a year or two.

Re: BSA A65 Gearbox Oil [Re: Rob Barker] #554572
07/24/14 2:01 am
07/24/14 2:01 am
Joined: Jun 2002
Posts: 9,463
Scotland
S
Stuart Online content
BritBike Forum member
Stuart  Online Content
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S
Joined: Jun 2002
Posts: 9,463
Scotland
Hi Rob,

Originally Posted By: Rob Barker
What kind of oil should I put in the gearbox of my 1970 BSA Thunderbolt?

Not specifically for an A65 but this was recommended by then British triples' dealer, builder and racer Phil Pick.

Originally Posted By: Rob Barker
when I drained the old oil it came out all creamy and emulsified.

It probably is emulsified old oil but, if that synthetic has a disadvantage, it's a similar colour to emulsified old dino juice. whistle

Hth.

Regards,

Re: BSA A65 Gearbox Oil [Re: Rob Barker] #554711
07/24/14 7:40 pm
07/24/14 7:40 pm
Joined: Aug 2001
Posts: 70
PA, USA
Rob Barker Offline OP
BritBike Forum member
Rob Barker  Offline OP
BritBike Forum member
Joined: Aug 2001
Posts: 70
PA, USA
It could have been condensation, but I would tend to doubt it. It does get pretty humid in my garage sometimes, though.

Yes, it has the nylon plug with the dipstick. And the boot around the clutch cable is intact and tight.

I'll try filling it with EP90 for now, but I may end up stripping the gearbox to see if everything's okay because I have a phobia about gearboxes seizing up while I'm dodging tractor-trailers on the interstate.

Re: BSA A65 Gearbox Oil [Re: Rob Barker] #555007
07/26/14 2:03 pm
07/26/14 2:03 pm
Joined: Aug 2001
Posts: 4,254
Owego, NY, USA
Mark Z Online content
BritBike Forum member
Mark Z  Online Content
BritBike Forum member
Joined: Aug 2001
Posts: 4,254
Owego, NY, USA
I don't know if it's necessary to strip the gearbox - you can tell if the bearings are ok by turning the shafts with no load on them. For instance, for the high gear bearing, remove the drive chain and, with the gearbox in neutral, turn the gearbox sprocket with your fingers. For the mainshaft ball bearing, remove the clutch discs and turn the mainshaft. Or, if you have the inner timing cover off, you can turn the mainshaft from that end. The bearings should feel silky-smooth. If they feel "rocky", time to replace. This is of course after changing the oil.

I worked on a T140 with a bad high gear bearing, and you could feel that it was bad just rolling the bike across the floor in neutral.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: BSA A65 Gearbox Oil [Re: Rob Barker] #555238
07/27/14 10:44 pm
07/27/14 10:44 pm
Joined: Oct 2008
Posts: 4,877
Gnashville
DavidP Online content

BritBike Forum member
DavidP  Online Content

BritBike Forum member
Joined: Oct 2008
Posts: 4,877
Gnashville
Also check for any end play (lateral movement) on the main shaft. I just replaced main-shaft bearings because of this. Both 'rolled' just fine, but the center was loose. Made my clutch act funny, hard to adjust properly.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
Re: BSA A65 Gearbox Oil [Re: Rob Barker] #555979
08/01/14 12:08 am
08/01/14 12:08 am
Joined: Jun 2014
Posts: 55
Victoria, BC
I
illingworth Offline
BritBike Forum member
illingworth  Offline
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I
Joined: Jun 2014
Posts: 55
Victoria, BC
Does old oil go bad sitting in a bottle? I just found an old half bottle of EP gear oil from about a dozen years ago. It was in the garage but the lid was on. Is it ruined?

jeremy

Re: BSA A65 Gearbox Oil [Re: Rob Barker] #557180
08/07/14 9:37 am
08/07/14 9:37 am
Joined: Aug 2001
Posts: 3,871
Cape Carteret, NC
M
Mr Mike Offline
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Mr Mike  Offline
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Joined: Aug 2001
Posts: 3,871
Cape Carteret, NC
I run gear oil in all the my BSA's. I rarely change it, just keep it topped off. The stuff lasts a long time. How often do you change it in the rear differential of your car?

Mr Mike

Re: BSA A65 Gearbox Oil [Re: Rob Barker] #557497
08/08/14 11:15 pm
08/08/14 11:15 pm
Joined: Aug 2001
Posts: 4,254
Owego, NY, USA
Mark Z Online content
BritBike Forum member
Mark Z  Online Content
BritBike Forum member
Joined: Aug 2001
Posts: 4,254
Owego, NY, USA
Gotta call you on this one, Mike, not a fair comparison. The rear end in your car is a much simpler and less delicate device than your BSA transmission. And for some reason, car diffs. don't tend to absorb moisture. Ever since I first saw milky oil come out of my gearbox, I change it at least once a year.

Actually, what did it for me was replacing the tranny bearings in a T140, ruined because of water in the gearbox. It was someone else's, so I didn't have to pay for the parts, and I did get a small stipend for my work, but I noted that this was not something I want to go through on my BSA, and it's completely avoidable, for the price of a pint or two of gear oil a year.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: BSA A65 Gearbox Oil [Re: Mark Z] #557514
08/09/14 6:25 am
08/09/14 6:25 am
Joined: Nov 2010
Posts: 2,848
Arlington, Massachusetts, USA
kurt fischer Online content
#irideslow
kurt fischer  Online Content
#irideslow
Joined: Nov 2010
Posts: 2,848
Arlington, Massachusetts, USA
What Mark said, absolutely. I change the gear fluid on my Britbikes every year, it usually comes out a little milky despite dry storage and mostly dry running conditions.


Kurt
1968-70-71 Triumph TR6R Bitsa - 1969 Triumph TR6R - 1971 BSA A65L - 1973 Triumph TR5T
2005 Ducati MTS 1000S DS - 2012 Ducati Hyper 796 - 2014 Kawasaki ZX1000
Re: BSA A65 Gearbox Oil [Re: Mr Mike] #557621
08/09/14 9:49 pm
08/09/14 9:49 pm
Joined: Oct 2008
Posts: 4,877
Gnashville
DavidP Online content

BritBike Forum member
DavidP  Online Content

BritBike Forum member
Joined: Oct 2008
Posts: 4,877
Gnashville
Originally Posted By: Mr Mike
How often do you change it in the rear differential of your car?

Mr Mike

Every 30,000 miles, got the 17mm hex key to prove it.
However, as Mark said, our gearboxes tend to admit water, especially with the vented nylon cap.
I think I've solved this problem by drilling a vent hole near the top of my inner cover and using an O ring on the cap. Still, I shall change the oil at least once per season.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"

Moderated by  Alan_nc 


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