Rear Wheel Conversions and Wheel Bearings/Modifications

[Desmo_Demon]

Another member and I were discussing different rear wheel configurations and some of the confusing information that is scattered on various threads, so....I'll try to put all of this into one thread.

Paso 750 with Original 16" rear wheel:
1) Rear axle is 20mm in diameter
2) Rear wheel bearings are SKF #63004-2RS1 with measurements of 20x42x16mm.

Paso 750 with early Ducati rim for 17mm axle:
1) Rear axle is 20mm in diameter
2) Rim's original bearings are SKF #62203-2RS1 with measurements of 17x40x16mm
3) The ideal bearing would be 20x40x16, but no such bearing exists through SKF or other manufacturer.
4) The closest available bearing is SKF #63004-2RS with measurements of 20x42x16.
5) The hub will have to be machined from 40mm OD to 42mm OD to accept the new bearing
6) A new spacer with an ID of 20mm will need to be made for the hub of the rim.

Paso 750 with 907 Swingarm and Axle Assembly and Original 16" Wheel:
1) 907 rear axle is 17mm
2) The ideal bearing for the wheels is 17x42x16, but SKF and others do not make a bearing this size.

*To use the original 16" rear wheel with the 17mm 907 rear axle (if a 907 swingarm conversion was performed):
1) it would be required to fabricate a sleeve to go over the axle to increase it's diameter to 20mm, or....
2) the chain adjusters would need to be bored out for a 20mm axle and a new axle of 20mm would have to be used. The 20mm diameter axle may have to be fabricated if an existing one will not work. The OEM Paso axle is too short in length to reuse in this application (750 axle length is 280 mm and the 907 rear axle is 350 mm with a center, non-threaded section of 305 mm), or...
3) A person may be able to make individual bushings for the inner race of each bearing (don't forgot the bearings in the sprocket carrier!!!) and necessary spacers would need to be machined for the wheel hub and any spacers between the wheel and sprocket carrier and external spacers between the wheel and swingarm....also a bushing would need to be machined and pressed into the rear brake caliper bracket.

*NOTE - With any wheel conversion, the alignment of the rear wheel with the front wheel, and also the alignment of the sprockets with a rear wheel conversion, MUST be checked.


*I believe all of the above information to be true and accurate.

[paso750]

I love you man, thanks for the summary
The Paso 750 rear axle is 17mm, the bearing spacer in the wheel brings id up to 20mm.
I put the bearing spacer on the 907ie rear axle and it`s no problem as both axles have the same diameter. So if one wants to use the OSCAM wheels in the 907ie swingarm, just swap the wheels. Some spacers will be necessary to correct wheel alignment. (probably noone will do this, I`m considering it as I would like to try different tire widths in future)

My remaining problem is to understand the modification described using a 17" wheel.
The axle of the 907ie is 17mm. I have 2 swingarms laying next to me. So if SS and Monster also have a 17mm rear axle there`s no need to change bearings at all unless there are two different 907ie rear axles which indeed have a diameter of 17 or 20mm.

G.

[nilaus]

Hi
I was inspired of “ansim” and his 17” conversion "http://alltomingenting.no-ip.info/gallery/ducce" and I am thinking of going up that road with a new 17mm axel and new eccentrics. You can see my drawing at “ http://www.bikepics.com/members/klaus/90paso750/ ”. I am waiting for a offer from the machine shop. as soon as I have more data, I will return.
Klaus

[paso750]

Paso 750 with early Ducati rim for 17mm axle:
1) Rear axle is 20mm in diameter
2) Rim's original bearings are SKF #62203-2RS1 with measurements of 17x40x16mm
3) The ideal bearing would be 20x40x16, but no such bearing exists through SKF or other manufacturer.

Assuming that there are no different diameter Paso rear axles and all are 17mm I would use the original bearings that are in the 17" wheels and make a simple tube as a bearing spacer.
Only if you try to use an original bearing spacer you`ll have the problem that bearings with id of 20mm are required which only exist as 42 od, which consequently require machining of the wheel to fit the bigger bearings.
Correct me if I`m thinking wrong.



G.

[Desmo_Demon]

The Paso 750 rear axle is 17mm, the bearing spacer in the wheel brings id up to 20mm. I put the bearing spacer on the 907ie rear axle and it`s no problem as both axles have the same diameter. So if one wants to use the OSCAM wheels in the 907ie swingarm, just swap the wheels.

That's weird.....both of my 750 axles are 20mm. Here's a picture I took of a 750 rim with the 907 axle going through it....

My remaining problem is to understand the modification described using a 17" wheel. The axle of the 907ie is 17mm. I have 2 swingarms laying next to me. So if SS and Monster also have a 17mm rear axle there`s no need to change bearings at all unless there are two different 907ie rear axles which indeed have a diameter of 17 or 20mm.

You are correct. If the axle of the 750 is 17mm, then the modifications I describe above are not necessary.


On my bike, the only stepped spacer for the bearings is with the front wheel for the 17mm front axle, which is why I came up with this diagram a few months ago...



This is what I pulled out of the hub of my rear wheel.....notice that there is no special stepping to the spacer that goes in the hub...




Does this make more sense, now?

[paso750]

Does this make more sense, now?

I will think about it tomorrow.

I think your rear spacer could be a "gift" of the last owner as mine looks like the front one with the difference that the front spacer is 15,7mm wide, the rear only 12,2mm.

G.

[paso750]

fits on the 907ie axle

[paso750]

That's weird.....both of my 750 axles are 20mm. Here's a picture I took of a 750 rim with the 907 axle going through it....

have you really measured the actual axle. The pic looks normal to me considering that there`s no original bearing spacer in which case you have a gap of 1,5mm. (in radius).

[Desmo_Demon]

have you really measured the actual axle. The pic looks normal to me considering that there`s no original bearing spacer in which case you have a gap of 1,5mm. (in radius).

If you notice, though, that is the axle going through the sprocket carrier side through the rear wheel. There is excess clearance all the way through the sprocket carrier and wheel, not just the wheel...

Yes, I used a micrometer on the original axle from the "Pile of Paso". Now for the interesting thing......the rear wheels from my '87 and both '88s are the same, so.....I have three examples of the rear axle being 20mm and not 17mm. Also, on the Paso parts manual, you can clearly see that the front wheel spacer has a step to it, but the rear one does not (TAV.22 E3 - part numbers 037077293 for the front and 037080290 for the rear). Your two spacers definitely look original, though.......some interesting things we've been finding, lately.

[paso750]

I was wrong, the rear P750axle is 20mm.
I solved the mistery. Seems the issue was in my parts. What I had done so far was to remove the bearings and spacers from my black/silver OSCAM front wheel and from my spare red/silver front and rear wheel. And that is the key. Get it ?
Red/silver Oscam wheels, as far as I know, were only used on some Limiteds and the 750 Sport. There are no Limiteds (that I know of) in Germany so the wheels must be from a 750S. The 750 has the same (or similar) swingarm and axle as the Supersport, hence with 17mm and a different bearing spacer.

So I finally understand and totally agree to your summary.
I didn`t pull out my black/silver rear wheel from the bike to confirm the 20mm axle, but I may do so the next days as the bearings need to be changed anyway.

G.

PS: don`t totally believe the pictures in the parts catalogue. I`ve seen an exploded view of the 750 Sport rear wheel and the picture shows a simple spacer also, not the one I removed from the wheel.

[Desmo_Demon]

I was wrong, the rear P750axle is 20mm.

Dammit, Gerhard!!!!

Are you just testing my skills at searching through the threads and re-writing things? My fingers are sore, now!

Actually, with all the talk of conversions recently, this thread may be of good use in the future for someone. If not for any other reason than it has bearing codes. It is also good to note the differences in the Paso and 750 Sport rear wheels, as I doubt many people are aware of this difference. This way, we know have record on the forum to these differences in case someone else buys some nice Sport wheels and tries to use them on their Paso.

So.....if you do the 907 swingarm conversion and want to run the 16" wheels for a while, you can use your Sport rear wheel without any major modifications.

[paso750]

Well Terry, sorry for that. Happens ...
I guess I just have too many parts.
Actually I found a rear axle in one of my boxes on which someone wrote "907ie". I measured it and it has 22mm diameter Seems some guys sell parts w/o even knowing from which bike they actually came from. Sometimes it`s obvious, sometimes not. Luckily I stopped collecting parts so discussions like these will be limited
Thanks for the support !!!

So.....if you do the 907 swingarm conversion and want to run the 16" wheels for a while, you can use your Sport rear wheel without any major modifications.

Yep, in this point I was lucky.

For all swapping to 17" wheels on your Pasos, you may consider to get yourself a 907ie swingarm or keep the 750/906 swingarm and machine the rim and a bearing spacer (maybe also the sprocket carrier and the bearing spacers in it). Plus, you need 4 new bearings as you cannot use the ones that are in the 17" wheel and sprocket carrier. Bearings can be expensive and the modified wheel with bigger bearings cannot be used on a Monster or SS anymore in case one day you think about selling them (unless you machine a spacer like the one in my 750 Sport wheel), correct ?!
I wonder what is the cheaper or better way to go...
750 Sport owners are the lucky ones, a 17" wheel conversion is easier due to the same rear axle diameter used on Supersports or Monsters.

G.

PS: should we now talk about different front wheel combinations

[Desmo_Demon]

PS: should we now talk about different front wheel combinations

I want to put a 21" lace wheel (with chrome spokes) from a Harley Softail on my Paso.....how do you recommend I do this?

(I'm only kidding, of course)