Cheetahchromes Peugeot 103 drive pully swap and modification
This wiki page started after I burned out the needle bearing sets on my Peugeot 103 Moped's drive pully.
Rather than just rebuild the old pully with new bearings since my pedal shaft was not damaged, I decided to install a more
attractive cleaner looking doppler pully that I saw advertised at a California aftermarket parts shop. Though the Doppler
pully is sleek, shiny, and modern looking, it lacks many handy features that the stock pully incorperates, such as a grease
zerk channel (very important) and the pedal lock-out lever (not so important).
With my stock pully which sports a factory grease zerk the bike performed well even though the zerk pictured above was missing and I just never screwed one in. Soon though, after installing a lot of performance parts like many of us do,
chasing that 50-60 MPH mark, I started to notice a lot of vibration on deceleration. I found that the drive pully had exsessive wobble or play on the pedal shaft, almost a quarter inch. Also I could see the "black dust of death" lingering
around the pedal shaft openings of my pully, a sure sign of bearing disintegration. Thinking quickly (or not thinking) I screwed in a grease zerk and pumped it full of grease, kinda like fixing a broken windshield with windex.
I then took it for a quick ride to see if there was any change in the vibration, but the only change was the changing of my socks from all the grease being thrown out. The bearings were history and I needed to rebuild the pully. I found relacement
bearings on a aftermarket parts website but the cost for the bearing set (it takes two bearings) was a whopping 53.00. I instead opted for this pretty aluminium replacement pully that has the two bearings already installed, I also picked
up a 12 tooth gear. Total cost was about 42.00.
Now I need to get started disassembling the drive pully portion of my bike starting with the two chain guard screws then the cover. Then I rotate the wheel till the chain master link is on top and I can more easily get at the links retaining
clip. You note I use two tools to remove this clip, one to gently spread the open ends and a small screw drive to pry the clip backward from the direction it is installed. This is the best way, if you try to pry the thing out sideways it wiill
bend the clip and then you can never trust it to not fail and leave you stranded.
Then use your small driver again to pop off the outer link and slide out the master itself.
Now the drive chain can be easily removed and set aside. I plan to replace this chain with a new one that I bought from Napa Auto Parts, you get 10' for about 20.00.
I like to use this Magnetic dish to keep all the tiny parts from getting lost.
Pull your drive belt towards you with one finger and rotate the drive pully forwards and the belt will slide off
Then you can just tuck it back out of the way behind the kickstand.
Use a 11mm wrench to loosen the crank key nut and back it off till it is up even with the top of the threads like in the lower picture.
I leave the nut up in this position because I plan to hit this crank key with a hammer and I need to protect the threads from being mashed and distorted.
There are two ways to proceed with removing the crank key at this point, you can just strike down square as you can with a hammer on the raised nut and this will drive out the key. Problem is you can only get away with the method a couple of times before the nut shears the threads off of the key stud and you left with nothing for the nut to bite on. I like to use a punch the same size or smaller than the key stud then line up on the center of the stud.
One good strike on the punch with my medium sized hammer and the key will usually unseat from its home position. Since I left the nut screwed on flush with the top of the stud I dont worry about the punch distorting or "mushrooming" the threads.
Now with the key unseated, it's just a small matter of unscrewing the key nut the rest of the way.
Then some love taps with my punch and hammer and the crank key is in the parts dish.
My pedal crank slid off very easy probably due to all the grease I pumped in the area but you may have to wrestle yours back and forth while holding the oppisite pedal crank. Note in the above picture that the pedal shaft thrust washer is stuck with grease to the crank arm. Dont loose track of these washers as they are not steel but made of some composite material and are unique to their placement. Chunk them in the parts dish.
Next the drive pully will slide off nicely and you can set it aside.
Here is the second "inboard" thrust washer, this too hits the parts dish.
This is a good time to do some cleaning since this area of the frame can't be accessed with the pully in place. I like to use spray style brake cleaner and a stiff brush but if you have custom paint or a "rattle can" finish you may want to use a gas rag or safer yet dishwashing liquid and a hose.
A side by side comparison of the two pullys reveals intricate casting work on the stock pully. Ive only recently discovered that the stock pully is made of plastic. I had always thought it made of pot metal. I plan to get the bearings and restore
the stock one for use on another bike, no sense wasting a still salvagable bike part. With all those casting lines one has to wonder about how ballanced it is compared to the aftermarket pullys modern yet simple design.
Side by side views of the larger 12 tooth sprocket I plan to run with the new pully shows that 1 tooth difference. The size difference seems like a lot and I wonder what the ride will be like.
Assembling the sprocket onto the pully was very simple. You need only toslide it over the pully hub and rotate it till it sits home over a pre-installed allen bolt that act as a keyway to delliver torque from the pully to the sprocket.
Closer inspection shows terrible machine work on the sprocket. The uneven bumps cause the chain to skip when climbing on and off the tooth making the chain span between the front and rear sprockets to whip up and down causing vibration that is hard to diagnose. I will definately clamp this into a vise and dress it up a bit with a chainsaw file which works really well.
After the sprocket is in it's position, it is held in place by a stamped aluminum bracket and allen head bolt.
I like to put a drop of locktite thread adhesive on the allen bolt to make sure it wont back out.
Closer inspection of the new pulley and sprocket reveals that the machining profile of the new parts wont allow for a grease channel or zerk fitting to be created.
A zerk fitting will allow grease to be supplied to the void between the two needle bearings.
I decided the best way was to drill down through the center of the pedal shaft about a inch and a half and then drill in sideways at the void on the shaft between the two bearings till the channels meet.
After measuring from the end of the pedal shaft to the void in the bearing run pattern, I transferd this measurment to a 5/32th drill bit and marked it with a piece of tape
Useing some scrap wood bits and a welding clamp, I was able to secure the pedal shaft upright on my drillpress. You can use a bench vise and a hand drill also since drilling down the center of rolled steel is fairly easy.
Keeping the bit cool and lubed is a good idea when doing the actual drilling. I keep a dropper bottle filled with ATF near the drill press. It sure helps the bit cut and the smoke looks cool too.
Drill, drill, drill, when I drill down till the tape marker on the bit is even with the end of the pedal shaft, then I know I'm deep enough into the void between the two needle bearings.
Now I can come out of the hole and prepare to drill a hole into the side of the shaft to meet up with the hole I just finished.
Before I un-clamp the pedal shaft from the press I remembered I need to open up the first 1/4 inch of the hole so that I can screw my grease zerk into the shaft. In the above picture I'm holding the Zerk I plan to use along side a 9/32nd
drill bit which is just smaller than the zerk threads.
Then I swap the bit into the drill chuck and open up the top 1/4 inch of the hole.
With the horizontal hole complete I can now unclamp the shaft, turn it on it's side and cut in the connecting passage using my 5/32 drill bit.
With all the drilling complete I still need to cut some threads into the hole in the end of the shaft
so the grease zerk can thread in. I did'nt have the correct thread tap to match the zerk threads but it did'nt matter cause all I need is for the zerk to twist into the hole and stay for keeps.
A few tight turns on the zerk with my 5/16 nut driver and the zert is home for good.
Next I slide the completed shaft back through the frame and prepare to mount the new pully. A small dab of start-up lube on the bearings and I slide the new pully onto it's shaft.
After sliding the new pully onto the pedal shaft I noticed it touched the swing arm even with the inboard thrust washer installed.
To correct this I installed a steel spacer washer on the shaft between the frame and the thrust washer.
I discovered later that I did not need to install the steel spacer washer since the pully actually likes to have this play to walk back and forth on the shaft. The alignment of the rear wheel and axel dictate where the pully will want to run.
All thats left to do is follow my steps in reverse and reassemble the chain and pedals. I see a problem straight away when I lay the chain on the rear sprocket.
The problem is that since I installed a larger front sprocket the chain is now too short for this axel position.
After loosening the axle nut, I can now loosen the slack adjusters and allow the wheel to move to a forward position and in turn allow the chain links to climb further up on the sprocket.
Then I am able to easily slide the master link in.
With the master link clipped and secure, only thing left is to is turn in the slack adjusters till the wheel is centered in the swing arm and the chain has about 3/4 of an inch up and down play on the lower span. Now tighten up the axle in God we trust, throw on the drive belt and I'm gonna go out and rod the hell out of this peugeot. I will update as to this Mods performance. This Modification page is now complete, Many thanks to Linda Green for her help so that I was able to use this Wiki page building, even if the artical is drawn out and boring with too many pictures. In the future articals I plan to be more direct.
Update on pully modification:
This new shiny Doppler brand pully performed as well as the stock one for about 200 miles then the inboard bearing shelled out and disintegrated. It was surely not from the lack of grease since I had done the above modification and the
grease streaked out all over says to me that it had plenty in reserve.
The cause of this failure was the use of cheap China made bearings installed in an otherwise well made drive pully.
Closer inspection shows that the bearings outer cage remains behind while all it's rollers are out on the state highway. Some MA Landsquid chapter members suggested that I refurbish my original pully with new bearings which seemed
like the best option since I did have a stock pully that had been shattered on a curb. Using their suggestion I was able to push the good German made bearing sets out of the shattered pully and reinstall them in my original pully.
So as you can see thats where I am today, about 500 miles further down the road on 30 year old, (very greasy) stock bearings. I suggest If you want to run one of these shiny new doppler drive pullys that you should always swap the
bearings for the German made ones in your original pully. Dont forget to throw the China made ones in the trash. Several other people have said they had the same outcome using the doppler pully.