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drive-side bearings

roy the mechanic

Well Known and Active Forum Website User
VOC Member
Hi, has anyone any experience of using Timken taper bearings for the drive-side on a twin engine? I guess i'm looking for reasons not to! Regards Roy.
 

Robert Watson

Well Known and Active Forum Website User
VOC Member
I typed this all once and lost it.

I have had Timkens on the drive side of my Rapide (The Great Woolly Mammoth) for more than 100,000 miles. Apart from the first 100 miles when a defective cage (Bower bearing) disintegrated and rolled up in the rollers with everything grinding to a halt, they have been fine.
I had to rebuild the crank at about 70,000 miles and so just installed new bearings as they are about $40 for a pair.
Preload is held on them at about .004" and is controlled by the width of the spacer between them. Nice bit of tool steel turned up too wide, hardened and then fitted. If there is .006" free, grind .010" off the width. Done.
The whole plot is in a top hat type housing shrunk into the cases and held there by 6 small countersunk screws in the outer flange. There is a seal installed as well outboard of the bearings. The seal is in a sleeve that is screwed (LH thread) into the I D of the housing and holds the cups in place.

Except for the defective bearing I have never really even had to think about it. When the bearing failed originally there was a huge discussion locally about the use of a pair of tapers and the crush (or not) required. After looking at several similer setups (Velo mains have .004" crush) and some industrial stuff, put them in at .004" and never had another problem.

Funny this comes up as just a couple of days ago whilst sorting thru my bearing inventory I found the other bearing from the original pair and lookd at it. The steel spacers between the rollers are almost crimped (cut) through at one end where they were stamped out! Reminded me of my first Vincent experience. Ride for 100 miles and tear it right to pieces!
 

Chris Launders

Well Known and Active Forum Website User
VOC Member
I think harley davidson have used twin taper rollers on the drive side of thier big twins for donkeys years and they run ok,dont know what preload they run but it should be easy to find out.
 

passenger0_0

Well Known and Active Forum Website User
VOC Member
After the Alpha big-end pin shearded in my racing outfit I installed a Terry Prince crank with a 30 mm drive side mainshaft. I used two taper roller bearings that had the standard size OD, back-to back as supplied by Terry on the drive side, and used 0.002" pre-load. Well thrashed and no problems with the engine to date. My logic for preload is that all matals are elastic and I wanted additional crank support by creating a tensile pre-load on the mainshaft. No problem with the bearings as car differential pinions run more preload than this and they survive just fine. Good luck - David
 

litnman

Well Known and Active Forum Website User
VOC Member
Robert,
I can visualize most of your modification but would love to see a sketch of it. The seal and the LH thread throws me a bit. I'm installing a TP kit in some HRD cases.
 
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Robert Watson

Well Known and Active Forum Website User
VOC Member
I'll make a rough sketch and make a picture of it, although I haven't seen it since 2001! Send me your email address

Robert
 

BigEd

Well Known and Active Forum Website User
VOC Member
VOC Forum Website Moderator
I'll make a rough sketch and make a picture of it, although I haven't seen it since 2001! Send me your email address

Robert

Depending on how "rough" your sketch is how about photographing your sketch and posting it to the photo gallery. I think that most mechanically inclined forum members are interested in seeing possible modifications.
 
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roy the mechanic

Well Known and Active Forum Website User
VOC Member
If you can find a manual for most all H-D big twins '1936 on you will see better than"a fag packet sketch". I dont have the scanner + such to post it .
 
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