Clutch & Transmission

Indians fortunately share many components from the clutch, and transmission among all V-Twin models from 1932 through 1953. There are only a few differences between the 741/Scout, and the Chief. The 741, and Scout are identical in design. There were three different main shaft lengths. 1932-1939 hard-tail Chiefs,and Scouts used the shortest mainshaft. The spring frame Chiefs used the medium length shafts, and the 1941-1942 Scouts with the spring frame used the longest shaft. The extra length was on the outside of the right side of the tranny. The internal dimensions for ALL V-Twin trannies are the same. The shifting fork assembly for the Scout, and Chief are a little different. These are all considered as "crash-boxes", with no form of syncronizer rings. If the idle speed is too high, there will be a nasty gear grind when putting them in gear. There are a few simple aids that can be used to lessen this gear-grinding. The first is a very slow idle speed, usually found at full-retard. Thinner oil in the primary helps to slow the clutch plates, so there is less grinding, as well as operating the clutch as far as it can to fully disengage the rotating clutch plates. More modifications will be mentioned later.

The clutch is a multi-disc wet clutch. The original design works very well, as long as the fiber plates aren't worn thin, or hammered at their (6) mounting holes. There are a few clutch kits available made from modern composites, but are only necessary under severe conditions, like sidecars, or motors that I build! When I need a stronger clutch, I use the clutch pack from Jerry Greer's. The clutches used up through 1945 had (7) steel plates, and the rest were a combination of fiber discs in either 1/8" or 3/16" thickness. In 1946 the factory decided to remove (1) of the steel discs, and make up the difference with an extra 3/16" fiber disc instead of the 7th 1/8" steel disc. At the same time, they shortened the clutch hub, so it could only contact the (6) steel plates. If you use the earlier wider clutch hub, (7) steel discs will fit. The Jerry Greer kit is designed to be the (6) steel combo, and comes with (6) steel plates, and (9) fiber discs. You install it by first placing a fiber disc into the clutch basket, then a steel, then a fiber, then a steel, etc., until you run out of steels. Then you add the last (3) fibers. The 8th fiber disc is just along for the ride. If you use the wider earlier clutch hub, you can swap out the 8th fiber disc with another 7th steel plate. You now have 18% more swept clutch area! I always use new clutch springs, because old used springs get tired. For proper spring pressure, you need to make sure that your clutch stack equals roughly 1.525" thick when new. The early clutch hub is 1.350" wide, the late clutch hub is 1.225" wide, and the 4-speed OverDrive clutch hub is 1.358" wide.The Chief primary chain has no master link, and can only be removed by removing the front drive sprocket, and clutch basket. It is kept semi-tight by adjusting a screw under the primary cover. The chain adjusting shoe can actually be installed backwards, so make sure it engages the chain properly. I have found it important to keep both the primary chain, and drive chain as tight as practical to keep the fiber clutch plates from ovaling-out their (6) mounting holes, especially for 80" motors with NO compensator sprocket. Watch this closely! The primary chain needs to be setup in close alignment with the front sprocket. You can lay a long straight-edge along the outer edge of both clutch basket, and front sprocket to see if there is any offset. The only adjustment there is will be at the clutch basket. It can be shimmed outward some, but not inwards. Therefore, when I build a motor, I shift my flywheel thrust washers, so the crank assembly, and front sprocket will be slightly to the left. This allows me some room to shim the clutch basket outwards. I'm talking very small amounts here. Note: The Scout uses a master link in it's primary chain, and there are several support plates as part of the master link. I have seen several Scouts, where people have left out these plates. This severely weakens the master link (weak link!).

There are a few very important points inside the trannies that need to be addressed. First, NEVER use the original thrust type bearing on the primary side. It causes twist in the clutch basket, which wears out the primary chain. Use the same bearing on both sides. I use sealed bearings on both sides, and I remove the seal off each bearing that faces the inside of the tranny. More on this later. There are thrust washers on each end of the main shaft, and I set the tranny up for .010" total end play. You can juggle the thrust washers around to move the mainshaft slightly left, or right, which can help in the primary chain alignment! The cluster gear normally rides against bushings that support the cluster shaft, and this is a source of trouble. I have seen several cases where the right side bushing is spun-out in the case. This causes the cluster gear to drop away from the gears, which can destroy your tranny! You can replace the original style bronze bushings in the cluster gear with needle bearing assemblies, and at this time, you press the bearings in a little deeper to accomodate thrust washers at both ends of the cluster gear against the case bushings. You want to shoot for .010" net end play as well. Starklite cycle sells a thrust washer kit for this job, and they also have the needle bearing kit. One thing to consider is that the spec for the cluster bushing's ID is .750" on a .749" shaft. The needle bearing kit is intended to use a .750" shaft, so there is .001" extra slop. I like a mod that uses thicker rear-end lube for the gears that will make up for the extra .001" slop. More on this later. I have a good trick for installing the thrust washer for the right side of the cluster gear on final assembly. Carefully "Super-Glue" the thrust washer to the right side of the cluster gear, so you can move it around, and the thrust washer will follow. The left thrust washer is easy to install. Make sure to place the small cardboard disc in the hole of the right side case bushing for the cluster shaft! Plus used gears often make noise, and can drop out of gear. I have found that Starklite Cycle's gears are the best on the market. They are hard to change, so get the good stuff, and don't worry about it.

The seal setup on the right side at the drive sprocket had a real crappy felt seal that always leaked. In 1948 the factory changed to a rubber type seal. It requires a different sleeve between the gear, and sprocket for the rubber seal. I use this setup on every motor I build. Another issue to watch out for is the fit of the kicker assembly parts. Theoretically, the cupped washer that supports the kicker gear spring is supposed to rest against the end of the mainshaft, but usually you will find it rubbing on the rotating sprocket driver gear's right end. This will wear out the cupped washer! You can take one of the little clip-rings that holds the kicker on it's shaft as a shim under the cupped washer (good fix!).

Now for some good mods. In 1952, the factory sealed the primary from both motor oil, and tranny oil. In the drive race of the motor, they added a rubber seal to keep 50Wt. oil from migrating into the primary. They modified the clutch basket to accept (2) rubber seals to keep the primary, and tranny oil seperate. The clutch basket is extremely hard, and difficult to cut to accept these seals. I have found in practice, that the seals are not needed if you use sealed tranny mainshaft bearings (remember, remove the seal of the bearings facing the inside of the tranny). The seals are to keep tranny oil from leaving the tranny. Now, you can use 50Wt. for the motor, 30Wt. for the primary, and 75/90Wt. gear lube in the tranny. Indians should have always been setup this way. There are (2) small 9/16" holes in the bottom/left side of the tranny case that need to be plugged up with freeze-plugs, so oil won't migrate from side to side. The 30Wt. in the primary for the clutch is helpful to keep the gears from grinding, and the 75/90Wt. is much better for the gear's life. You will have to drill, and tap an oil level hole on a factory boss that is on the trannies right/lower/front side. It is already dimpled for a drill bit. Use 1/8" NPT, and a plug. On Scouts, you have to seal the cross-over holes on the inner primary, not the tranny. You will also need to drill, and tap the oil level hole, as well as a fill hole on the top left side of the tranny, where ever it is convenient for you to add gear oil.

Often, you will see excess oil weeping from the clutch worm O-ring. When running, the primary will get higher in air pressure, which pushes oil out anywhere it can escape. There are small breathers that can be installed in a drilled, and tapped 1/8" NPT hole somewhere on the front/top of the inner primary. Make sure it won't be exposed to any slinging oil.

The lock washer that holds the left handed nut on the clutch hub is often too big in diameter, so that it interferes with the hole in the back side of the clutch worm. Check for this, and trim the OD down on the washer, so the worm will easily fit over it. Otherwise, it messes with the throw-out bearing. Also the lock washer for the clutch basket inside the tranny can be installed wrong! There is a little tab that fits in a slot on the clutch hub threads. The tab goes to the left, under the nut.

While you are setting up the primary, get the generator drive sprocket thrust washer kit. Make sure you have it's sprocket teeth in the same plane as the teeth on the clutch basket. Starklite Cycle also sells this kit. While you are at it, get their needle bearing, and seal kit for the generator drove sprocket shaft.

CONTACT INFORMATION:

James R. Mosher

(505) 466-7870