Mono Final Drive bearings

Discuss all things 1970 & later Airheads right here
Post Reply
Nourish
Posts: 191
Joined: Tue Aug 10, 2010 5:15 am
Location: Bristol, UK

Mono Final Drive bearings

Post by Nourish » Tue Oct 17, 2017 11:21 am

I have a Mono final drive apart, whilst washing the crown wheel I lifted it by the Taper Roller Bearing and the cage came off scattering the rollers everywhere!
I've tried but I just can't put the cage back on I came off easy enough - how does it go back together?
Now the very expensive Double Row Angular Contact bearing (3305DA - what does the DA stand for?), it supports the input shaft both radially and axlially but I have what looks like at least 1mm of axial movement that would if I'm correct move the contact patch with the crown wheel in and out. Is this amount of play correct - I ask because the bearing doesn't run rough?
Thanks for your thoughts.

User avatar
jagarra
Posts: 763
Joined: Mon Dec 26, 2011 12:42 pm
Location: Reno, Nevada

Re: Mono Final Drive bearings

Post by jagarra » Tue Oct 17, 2017 1:18 pm

The letters probably have to do with special characteristics of the bearing, like contact angle, slingers, seals and so on. Looked in my bearing book, it just had basic information, Google, however, turned up more information.


Angular contact ball bearings 3305-DA-TVP
main dimensions to DIN 628-3, double row, separable, with split inner ring, contact angle α = 45°
1974 R90/6 built 9/73
1994 BMW R1100RS
1964 T100SR Triumph
1986 Kawasaki Concours

Roy Gavin
Posts: 383
Joined: Tue Aug 03, 2010 11:21 pm
Location: Adelaide Australia

Re: Mono Final Drive bearings

Post by Roy Gavin » Wed Oct 18, 2017 12:48 am

You cant do much with that bearing, or your new taper roller bearing, without the proper factory tools, and the guy with the tools will be able to source the correct bearing, so you dont need to know!
Adelaide, Oz. 77 R75/7. 86 R80 G/S PD, 93 R100 GS, 70 BSA B44 VS ,BMW F650 Classic

Wobbly
Posts: 102
Joined: Mon Aug 07, 2017 8:48 pm

Re: Mono Final Drive bearings

Post by Wobbly » Wed Oct 18, 2017 7:13 pm

Nourish wrote:
Tue Oct 17, 2017 11:21 am
3305DA - what does the DA stand for?
Probably "double row, angular contact"
Nourish wrote:
Tue Oct 17, 2017 11:21 am
...it supports the input shaft both radially and axially, but I have what looks like at least 1mm of axial movement that would, if I'm correct, move the contact patch with the crown wheel in and out. Is this amount of play correct - I ask because the bearing doesn't run rough?
Thanks for your thoughts.
Did you push-pull on the rear wheel before disassembly ?

If I understand you correctly, with that much play then the big ~170mm radial bearing is going bad. The smaller angular contact bearing doesn't give issues, and is cheap (~$35) and very easy to replace. The larger bearing is another story.

Image

You'll need a "bearing separator" able to span a 6-3/4" bearing. You won't need a press, but access to one would help. Install the new bearing first onto the crown wheel. Install the new big oil seal into the case. Then warm the case and install the crown wheel.

A housing gasket is offered, but don't install one unless one came out. Instead use a thin gasket maker compound, such as LocTite 510. Use the exact same shims in the original order and placement.

The 2 halves will mate together and can be drawn up using the 8 housing bolts. Keep rotating the input pinion shaft to insure proper mating of the ring and pinion gear teeth. Then just keep going round and round, adding 1/2 turn to each housing bolt in succession until full torque is achieved.

Don't forget to add new o-rings on the rear brake spindle.
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

Nourish
Posts: 191
Joined: Tue Aug 10, 2010 5:15 am
Location: Bristol, UK

Re: Mono Final Drive bearings

Post by Nourish » Thu Oct 19, 2017 7:14 am

No it's not the 120mm (170mm?) bearing on the crown wheel but the 60x25ish mm on the pinion shaft in the nose of the diff casing where the swinging arm bolts up to.
If it's knackered then getting it off won't be a problem (getting the cash out of my pocket for a new one will be!) But I thought that a bearing of this design wouldn't run this smooth with that much wear.

User avatar
jagarra
Posts: 763
Joined: Mon Dec 26, 2011 12:42 pm
Location: Reno, Nevada

Re: Mono Final Drive bearings

Post by jagarra » Thu Oct 19, 2017 12:00 pm

By just the series number FAG 3305 it is a dual row angular contact bearing. I was checking that series on the internet and they list a wide variety of letters behind the base number which list specific features for the bearing. I would make sure I bought the exact same bearing as it is specifically built for the application.

Found the designation:
DA BALL BEARING, DOUBLE-ROW WITH SPLIT INNER RING. N Now some of the bearings with the DA have other numbers which indicate the carrier style/material, yours should have a steel carrier for the bearings.
1974 R90/6 built 9/73
1994 BMW R1100RS
1964 T100SR Triumph
1986 Kawasaki Concours

Post Reply