Mating a LeMans rear wheel with an 850T final drive?

[pat80flh]

I had a few spare minutes today and started mocking up my T/T3 bitsa project. First thing I see is that the rear axle I have will not work, axle is too thick, threads don't make it through final drive. Wheel is marked as off 78 LeMans, final drive supposed to be off a 75 850T. Is there an axle I can use or do I need to get the existing one modified?   Rear drive is 8/37 teeth.






photo upload in public

[Antietam Classic Cycle]

You need the correct spacer for the axle, part no. 1763 4150. Fits into the rear drive housing. #7 in this drawing



Used on a bunch of Tonti framed Guzzi with disc rear brake IIRC.

http://www.harpermoto.com/spacer-17634150.html

I might have an extra. Just checked - gone - must have used it on something.

[rodekyll]

Is this a disk or drum brake rear?  An 850T would be a drum.  A T3 would be a disk.  I might be confusing myself (and you), but the rear drive you picture seems to be the older drum version used on the eldos and early tonti.  The parts diagram is for a disk brake rear wheel.  I don't know what the interchange might be . . . but it might be why the axle doesn't fit.

WAG.

[pat80flh]

I bought a pile of parts, someones unfinished project.
75 850T frame and engine block.  A pile that included what look like LeMans alloy wheels(to my untrained eye)

I then bought a used engine, trans and final drive, ostensibly from another 75 850T.

So I believe the rear drive is from a drum brake 850T.

Since I already own these wheels, I'd like to use them, and put disc brakes on all around.

It does look like that spacer is what's stopping me, I assume it just presses out?

Could it be cut down to work?

Or Charlie, if you'd like to look around  and want to sell your extra, PM me. There is no rush, this is looking like a long term project.

I appreciate your alls help.

[Antietam Classic Cycle]

Is this a disk or drum brake rear?  An 850T would be a drum.  A T3 would be a disk.  I might be confusing myself (and you), but the rear drive you picture seems to be the older drum version used on the eldos and early tonti.  The parts diagram is for a disk brake rear wheel.  I don't know what the interchange might be . . . but it might be why the axle doesn't fit.

WAG.

The parts diagram is for a disc brake rear wheel because that's what Pat's using and so that is the spacer he needs. The axle doesn't fit because the spacer in his 850-T rear drive has a smaller i.d. than the axle diameter. I don't have the two spacers - drum and disc - to show a comparison photo of, but their o.d. and length are the same, the i.d. is what's different. Drum brake rear wheels have a smaller diameter axle and thus a spacer with smaller i.d.

I bought a pile of parts, someones unfinished project.
75 850T frame and engine block.  A pile that included what look like LeMans alloy wheels(to my untrained eye)

I then bought a used engine, trans and final drive, ostensibly from another 75 850T.

So I believe the rear drive is from a drum brake 850T.

Since I already own these wheels, I'd like to use them, and put disc brakes on all around.

It does look like that spacer is what's stopping me, I assume it just presses out?

Could it be cut down to work?

Or Charlie, if you'd like to look around  and want to sell your extra, PM me. There is no rush, this is looking like a long term project.

I appreciate your alls help.

I don't have a spacer - I think that got used on Dave Washburn's project. Yes, the spacer is what's stopping you. It does press out. It would be possible to machine the inner diameter to match the axle if the spacer isn't too hard.

Question: do you have a disc brake swingarm or drum brake swingarm? I ask because there are important differences there as well.

[Antietam Classic Cycle]

More sources for the spacer:
https://www.motointernational.com/store/product/GU17634150
https://www.motomeccaspares.com/products/browse.php?Category=TR
http://www.gutsibits.co.uk/pr/TheShop/index.php?q=WHA17150&f=d&Model=0
https://www.oemmotorparts.com/oem5.asp?M=Moto_Guzzi&T=850%20T5&Y=1988&L=MG-850T5_1&O=Rear%20wheel,%201st%20series&F=MG-850T5_1_27&L2=MG-850T5_1_27

[pat80flh]

I own one of each swingarm



From another thread, the one without the stay arm is the disc swingarm, correct?

[pete roper]

Yes, but if you bolt the bevelbox to the disc brake swingarm and try to install the spindle it won't align.

The drum brake models have a thinner flange on the pinion carrier. You can make a spacer, you can swap the pinion carrier, or you can modify the drum brake swingarm to take a brake plate stay.

Pete

[Antietam Classic Cycle]

I own one of each swingarm



From another thread, the one without the stay arm is the disc swingarm, correct?

The one without the stay arm/torque rod is a disc brake swingarm. Here's the problem: if you bolt the 850-T rear drive up to that swingarm the axle will be "cocked" and may not even go in at all. The flange on the 850-T pinion carrier is thinner than a later rear drive by 2 mm. So, you can either: 1) make a shim 2mm (.079") thick to go between the rear drive and swingarm, 2) use the drum-brake swingarm and weld a caliper carrier lug onto it, 3) use the drum-brake swingarm and use the stay arm to secure the caliper carrier (with some figuring/cutting/welding/machining?), 4) find a disc brake rear drive pinion carrier and move the pinion shaft/gear over to it, reshim to suit, then use the disc brake swingarm. 5) find a complete 7/33 rear drive which will bolt right onto the disc brake swingarm.

The easiest, if not necessarily the best, option would be #2 IMO. It would be nice to use the later swingarm with it's larger carrier bearing and more robust u-joint, but it's going to take some work and/or $$ to do that.

[pat80flh]

Thanks all so far, you guys are a wealth of information.

I ordered an axle spacer from MotoInternational,along with a copy of Guzziology.  And I'll carve out a shim for the rear drive housing.

Sorting through my pile, I have a u-joint that came with the rear drive and drum swingarm (it's nice,too), but I see that the disc setup takes a different carrier bearing and joint, correct?

I also have a rear caliper, but no bracket or rotor. I see a few on ebay in the $30-50 range, are all rear disc brackets the same T3/Lemans/Convert?

[rodekyll]

Thanks all so far, you guys are a wealth of information.

I ordered an axle spacer from MotoInternational,along with a copy of Guzziology.  And I'll carve out a shim for the rear drive housing.

Sorting through my pile, I have a u-joint that came with the rear drive and drum swingarm (it's nice,too), but I see that the disc setup takes a different carrier bearing and joint, correct?  Yes.  It was discussed above.

I also have a rear caliper, but no bracket or rotor. I see a few on ebay in the $30-50 range, are all rear disc brackets the same T3/Lemans/Convert?
All the mentioned should work.  Convert is not *exactly* the same as the others, but probably still a fit. 

Also, there is a brake-side spacer, called a "top hat" that goes between the wheel and the caliper bracket.

[pat80flh]

Thanks,  and yep I think I have that spacer, it's in with the last picture of my first post.