Trailfire 440 Engine Alignment Question

[Hec In Omaha]

Howdy all,

I recently rebuilt the 440 and now have 26 miles on the rebuild. I am slowly working out all the bugs on this sled and having fun doing it. I noticed the clearance between the primary clutch backing and the vertical framework that the crankshaft passes through is very close. Probably 1/32" or less!

Primary Clutch to Frame Clearance

With the drive belt removed I can rotate the primary clutch and do not feel or hear it making contact with the vertical frame. However, I can hear the primary clutch ever so lightly make contact with the vertical frame when I have a good load on the engine, like towing a sled etc.. I pulled the primary clutch off and sure enough there are small scuff marks on the backside of the primary clutch and I can see 2 areas on the frame where the paint has been scuffed off by the primary clutch.

Primary Clutch Scuff Marks on Frame

Don't worry the crankshaft end isn't grooved or stepped. The ridge is antiseize. That's my fault as I applied antiseize to the crankshaft when I installed the primary clutch.

I tried loosening the 4 engine mounting bolts and tried pulling the engine to the left to increase the clearance. I found out that there is no adjustment right or left by loosening the 4 engine mounting bolts. I also tried loosing the engine cradle bolts and pulling the engine to the left. Once again there isn't any right or left adjustment of the engine. The secondary and primary clutch has been aligned using the JDM-81 tool. Has anyone else run into this situation before? I am tempted to remove the primary clutch and smacking the vertical frame brace with hammer and piece of wood to push it toward the center of the engine compartment. I would smack it right where the two little rub marks are. By the way, I do have the snubber installed and it is set per the book at .035" clearance and the primary clutch bolt is torqued to 50 -ft-lbs too.

As always any help is appreciated.

Hec

[schavejdsnow]

It sounds like the crank shaft is to far to the mag side. There is retainers that go on each side of the crank shaft to prevent side play. Just my guess.

[rminier]

There are a few things I'm pretty sure I "know".
And some things I'm not certain about regarding your question. Some of the JD folks can chime in.
What year is your Trailfire?
Having owned a '79 Kawasaki Invader since 1982, I have had several years to learn some things regarding clutches.
The vast majority of sleds from all OEM's use a drive clutch that is called "flush mount".....probably 80-90% of them.
There are a few oddballs out there including the Kawi Invaders, Intruders, and some of the Deere's.
These sleds use a drive clutch with a negative offset of -0.200", or 1/5 of an inch....a pretty significant dimension.
This negative offset means the clutch sits further away from the engine than a more common flush mount style.
The inner taper of the drive clutch is designed so that is doesn't go on the crank stub as far as a flush mount.
We need to know what year your sled is.
You may get lucky and be able to read a 6 digit number (sometimes followed by a letter) on the face plate of your current clutch (something like 208306A) that would allow us to know if it is a flush mount....often the numbers have faded away.
If my suspicions are correct, your Trailfire came from the factory with a Comet 102C that has the negative offset.
Someone over the years has replaced the original with another Comet with the much more common flush mount, so it slides on the crank stub another 1/5" further.
This would absolutely explain what you are seeing.
If this turns out to be the case, it certainly is not the end of the world, particularly if your drive clutch is in good shape. You will just know why you are seeing that very tight clearance with your clutch.
If your Trailfire is one that uses the negative offset style there are certainly new ones available from a lot of suppliers, but they are around 300 bucks.
The 1 of the 2 problems you may have using the flush mount would be getting the offset correct. It sounds like you were able to get the clutches aligned OK.
If my hunch about all of this is right, there may enough adjustment that you can move the secondary clutch inward the same -0.200" to match the drive clutch.
The other problem is gaining the clearance between the inner sheave of your drive clutch and the frame, as you are seeing.
Again, I'm not certain if your Trailfire came with the negative offset clutch, and if it did it now has a flush mount style.
If my guesses are right, and you can tweak the clearance between your inner drive clutch sheave and the frame, and you get get the clutches aligned close, I say go for it and enjoy life.

[Hec In Omaha]

Update:

First I would like to thank Schavejdsnow for helping me solve my problem! Thanks a million John!

So here is what we found out. The Comet 102C Clutch (Incorrect Clutch) that was on my 81 Trailfire can't possibly be the correct one. This sled has has had numerous things done to it by the PO and this is another to add to the list. I have been systematically undoing what the PO has done to this sled. As I said earlier the backside of the clutch was making contact with the frame when the engine was at full load. John went and measured the clutch to frame clearance on his Trailfire and my measurements are nowhere close to his measurements. I even measured the distance from the PTO crankshaft seal to the end of the crankshaft and compared that to another 440 Engine I was given. Those two measurements where the exact same so that ruled out a crankshaft alignment issue. I also mentioned to John that I happened to have another Comet 102C clutch that was off a Trailfire 440 that I received in trade for some liquifire parts. John recommended that I install it and see if the clearance was better. So I did and the clearance was way better .

New Primary Clutch to Frame Clearance

In fact the Clutch to Frame clearance was now very close to what John had measured on his Trailfire. So I removed that primary clutch and compared the two clutches side by side to see what the heck was going on here.

These two Comet 102C clutches are different!
Here's the differences:

The face plates are different. The stampings are a mirror image of each other and the one on the right doesn't have any patent numbers.

Face Plates

Notice the rub marks (Shiny Metal) on the clutch on the left. The rubbing of the clutch on the frame also explains why my engine was so hard to pull start. It took two hands and 10 pulls to get it started with the old clutch. The force of pulling on the rope would rotate the engine, due to the rubber mounts on the engine cradle, enough that the clutch would hit the frame. It didn't take much for the contact to happen due to the tight clearance. I couldn't figure out why the pulling force required to start the engine was so high. In fact, I even removed the drive belt in case it was dragging to see if it helped but saw no change. With the correct clutch, now I can easily start the engine in 1-2 pulls and can spin the engine over faster when pulling on the rope!


The wall thickness of the hub bore of the correct clutch (Right) is thicker too. Also the radial castings on the back side of the clutches are different. The clutch on the left has a U-Shape where the radial lines intersect the center, the one on the right doesn't.

Clutches

Rminier you are right about there being different offsets!

I measured the insertion depth's of each clutch. The correct clutch has a longer insertion depth than the incorrect one. The measurement was taken from the end of the tapered bore to the outer edge of the bore. The difference in the insertion lengths equates to 0.38"! That's a significant difference! The clutch bore tapers must have different angles too since the incorrect clutch slides down the end of the crankshaft further even though it has a shorter insertion depth.

Correct Clutch Insertion Depth

Incorrect Clutch Insertion Depth

The incorrect clutch is physically in better shape with less signs of wear and corrosion than the correct clutch. I am considering of swapping all the parts off the incorrect clutch, with exception of the fixed face sheave, onto the correct clutch and replacing anything else required. The correct clutch works and engaged at around 3,600 RPM's or so. As always any suggestions are appreciated.

Hec

[Hec In Omaha]

Update:

I decided to purchase a brand new Comet 208306A 102C clutch. It has the negative 0.20" offset. According to Comet this is the clutch I need for my 1981 Trailfire 440. I got it on Ebay for $166 shipped! I couldn't pass it up at that price! It is supposed to arrive on Monday. I know this clutch does not come with weights or a spring but does come with a bolt kit to mount the weights. So no more roll pins! I hope that it comes with the 2 washers between the movable and fixed sheave. There is no way to tell if they are there without further disassembling the clutch. I downloaded the instructions for the clutch and there is no mention of the washers and that only weights and springs are needed to calibrate it.
Today I removed the clutch cover on the incorrect clutch (Flush mount) and removed the spring and weights. This clutch is in super shape. The correct clutch (Neg. Offset) that I have on the sled now isn't in good shape. Someone beat on it and tried to pry it off a crankshaft as there are beat and pry marks all over it. I also inspected the correct clutch and it had a lot of wobble on the clutch cover and movable sheave. So the bushings are worn out. That's why I didn't think it was a good idea to try to rebuild it.

Plan:

Take the "U" Weights and spring from the incorrect clutch and install it on my new 208306A 102C clutch. I may also use the clutch cover off the incorrect clutch on the 208306A 102C Clutch as it has the John Deere Stampings on it. I will compare the fit of the Clutch Cover bushing against the brand new one and decide if its usable.

That's all for now

Hec