Drive Belts

[David Stinson]

My motorcycle is a 1958.  I was having some issues with belt slippage on the belt to the rear wheel.

Just want to share some information that I have learned while going through my clutch / transmission unit.  Mine has 2 bearings in it both being 6300 radial ball bearings available from any bearing supplier.  They are available from McMaster-Carr under part number 6661K121.  The idler pulley is machined aluminum and uses 1 each of the same bearing.  All three bearings had issues but the one in the idler was almost seized up.

My drive belt was worn to the point that it was seating all the way in the bottom of the drive pulley and slipping badly.

A suitable replacement for the long drive belt I have identified as a BX75, Gates number 90136075, also available from McMaster-Carr under their part number 6057K147.

I have not actually installed these items yet but will follow up to confirm that the belt is a fit.

What I need to know is has anyone identified the primary drive belt?  Mine appears to be the original with the original number.  I would prefer to have a new belt in hand prior to removing mine if possible.

[Ricks]

David, read this thread.  A lot of good info on the belts.


http://www.simplexservi-cycle.com/index.php?topic=238.0

[Mike Sal]

If your bike is a '58, it must have an earlier transmission in it.  The idler pulley should be stamped steel & the transmission should be bushings instead of bearings (or did you mean the 2 bearings that the axle rides on??) 

Do we have your frame/motor number yet for the registry?
Mike Sal

[David Stinson]

The 2 bearings are the ones in each end of the tube that runs the length of the clutch / transmission assembly and the axle for the assembly runs through them.

I sent Rick the numbers from my frame and engine.

Frame, under the front - 15242
Engine - M23270B

[Mike Sal]

Your bike is only 7 numbers off from my bike (mine is 15249).  what state are you in?  I know the old timers at Portland always debate on whether mine is a '57 or a '58, but the numbers seem to stack up as a '57.  We do know that there were a lot of '57's left over at the end of the year that were sold as '58's, so who really knows.
Mike Sal

[David Stinson]

Wow.  What a coincident.  I am in Georgia but the bike was originally titled in Ohio and then went to Illinois.
I am attaching a picture of the original title.

[Mike Sal]

Wow, what a great piece of history.  I really like the note "gift from mother to her son".  The lucky SOB!!!! 

It's interesting that it was titled in August of '58....well into the model year.  You got to wonder how long it was on the dealer's show room before being purchased.  If the theory of the numbers holds true that the bike was actually made in '57, it would further support the story that there were a lot of '57's left over & sold as '58's. 

My bike was in Illinois when I got it, but I don't know if that's where it started out, as the previous owner was dead by the time I got it.

Send us a close up photo of your back brake pivot arm.  The old timers seem to be able to judge the age by those (there were several different designs & lengths used over the years).
Mike Sal

[David Stinson]

Are you talking about the pedal or the lever on the wheel itself?

[David Stinson]

Picture of the rear brake showing the lever and rod.  The rod is currently just stuck into its connection.  I am in the process of reassembling the rear wheel, fender, cargo rack, etc after removing to install a new drive belt.

[relic]

Looks just like my 57

[Mike Sal]

Looks identical to mine as well.  I think they may have used this brake arm for the rest of production.  Maybe Rick can let us know if the one on his Sportsman is the same or not.
Mike Sal

[Ricks]

Looks identical to mine as well.  I think they may have used this brake arm for the rest of production.  Maybe Rick can let us know if the one on his Sportsman is the same or not.
Mike Sal

Yes, the Sportsman has the brake lever with built in swivel. 

The earlier style, that used the clevis, came in different length arms. The 1949 I had, used arms that measured 1 1/2" from pivot center points, where as the 1953 and 1954 I have both measure 2".   I guess Simplex decided a little more leverage wouldn't hurt.

Interestingly enough, The sportsman measures 1 3/4", where as another late style I have measures at 2".  I wonder if this length change was precipitated by the change in the brake lever action, as the sportsman uses a completely different brake pedal setup?

[David Stinson]

Regarding my statement:

"My drive belt was worn to the point that it was seating all the way in the bottom of the drive pulley and slipping badly."

After purchasing the new belt I checked it in the drive pulley and found that it also went to the bottom of the pulley.  I considered moving the fixed half of the pulley over on the bearing tube but did not.

After the reassembly and a test ride, I found that the new belt slips as badly as the old one.  While writing this it dawned on me that I have my wheel back far enough that the tension idler is not at the ideal position shown in the manual.  Maybe a first step will be to readjust the wheel to correct this and see if the additional if minimal wrap on the drive pulley has an effect on the slippage.

If the wheel adjustment doesn't make enough difference, I will remove the clutch / transmission and move the pulley enough to hold the belt up on the sides.  Wayne said that the pulley would have to be heated to be able to move it.

Has anyone else already made a similar adjustment to the fixed pulley position?

[Ricks]

I would look and make sure that the movable pulley is actually moving freely.  Mine all run in the bottom of the pulley, and as the RPM's increase, the pulley slides over and picks up the belt.  Make sure the weights are moving freely also.  They need to be lubed with a small amount of oil.

[David Stinson]

When I had the unit apart I noticed grooves where the weights set and push against the movable pulley.  I rotated the square part of the pulley so that the unworn sides are now in the "working" position and lubed every moving part.  It was dark last night when I rode so I couldn't see if the pulley is working or not.