78 Liquifire rebuild!

[400brian]

Here we go again!

I purchased this sled in 2009. It shows 875 miles on the odometer. I had done some work on it, the sled was largely stripped down to a bare tunnel years ago. The engine was re-sealed, a rewound stator installed, a NOS cdi box, a new thermostat, and the sport seat was re-covered.

10 years ago I found most of a Cross Country suspension at the Round Up in St Germain, and I have acquired a couple of rubber tracks. The goal is to build the sled as a Cross Country clone aesthetically, but I am perfectly happy with the 440 engine.

Clean up starts now.

[ihengineer76]

Are your tracks the Deere Yokohamas, or one of the Cat tracks that work for this?

[400brian]

The Cat tracks. I had a line on a complete CC track and suspension kit once, but I didn't get it.

[400brian]

When I begin a sled project, I generally start with the engine, it just seems like the logical place to me. On this 78 Liquifire, I re-sealed the engine, and swapped the ignition system some years ago. So as I restart the build, I am going to concentrate on the suspension and track, because this looks like a big project.

Ten years ago, I got lucky at a swap meet and found most of a 78 Cross Country suspension. When I spotted it laying on the grass, it stopped me dead in my tracks. It had what appeared to be 80 LF arms on it, but it had 3 aluminum center idler wheels at the rear. I looked at it for a moment, then realized it had teardrop shaped aluminum extrusions that the track adjusters pushed against. That identified it as a Cross Country suspension ( more or less ).

I honestly couldn’t believe what I was seeing! At that moment Joe Rainville walks up beside me and asks me what I am looking at so intently? I nonchalantly ask him what this skid is out of? He is pointing out notable features, then suddenly says to me quietly; “if you don’t buy this I am”.

I ask the young man what he wants for this junk skid? His reply is $25. I hand him the cash and thank him. I had an 80 LF skid at home that I had bought to put under the 78, so when I got home I set them side by side and compared them.

The 78 rails are slightly longer due to the 121” track vs the 116” used in ‘80. The 78 CC had the upper idlers on a separate shaft bolted into the tunnel, where the 80 had the mounted to the rear arm. It appears that the 78 CC suspension is the prototype for the 80 production suspension.

Shortly after I got this CC suspension, a close look revealed one rail to be worn badly on one edge. Either the sled it had been under had been circled track raced, or the track had been run wildly out of alignment. I took it down to the local machine shop and asked if they had anyone good enough welding aluminum to fix this? The owner looked at it, and asked what it was? I replied; it is a race sled suspension rail, and that it was made out of UNOBTAINIUM. He understood, and opined that they could fix it. A couple of weeks later I picked it up, I think it cost me $100, and it looked great. I have no idea how the welder did it.

So now I am digging all the parts out and taking stock. Everything is seized or rusted solid.
The adjusters are solid, I managed to remove one hyfax retainer, but the other wants to twist off. Working on the forward arm, the short aluminum shaft is going to require heat. While I was pounding a bit on the short shaft, the long one ( which is steel ) rattled out a bit, and I got it out.

So heat and patience is going to be required to get this thing apart, and I am guessing I will be making all new shafts.

[400brian]

Still learning about what I have here. Tom Rehberg was showing me a restored CC skid, and it had 2 sets of wheels inside the rails. I took a look at my rails, and I have the same brackets bolted onto mine. The auxiliary wheel closest to the outside wheel was an option, and while they used the same wheels, the brackets are different. These are 5" diameter wheels with a machined aluminum center, and were used on the CC and Dator lite suspensions.

The skid only came with one set of wheels installed, and I hadn't really thought much about the brackets. You can see by the wear pattern on the hyfax that the second set they hadn't been there for a while.

Tom opined that this skid must have come from a raced machine, who else would have bought the aux wheel kit? I dunno. If it could only speak...

Including a pic from Tom to show what I am shooting for.

[400brian]

Getting ready to pull the stuck shafts out of the suspension arms. Both are aluminum of course, on the short one the cap screws had turned out, but the rear main shaft had both bolts twisted off in the holes. I did get a hole drilled and tapped into one end, so I am going to get the puller wound up tight on it, heat then quench it, to see if I can break the bond.

As a warm up, I put some heat to the adjuster bolts and got them out successfully. Then I put some heat to the hyfax retaining bolt, and got that out without damaging the aluminum retainer.

[ihengineer76]

Looks like yours had the added support plate on the rear tensioner bracket that was called out in the racing tech tips.

[400brian]

I wasn't aware of that Tom. I had noted that the welding on that tab didn't look particularly factory. Also, the parts book shows three bolts per side, 2 1/4", and one 3/16", so I really hadn't suspected anything.

[400brian]

I found the discussion we had about this suspension back in 2013: viewtopic.php?t=15471&fbclid=IwAR0bAxWf ... fIreP3jT2I


And the delivery photo back in May of '09, Joe Rainville on the left, Nick Freatman on the right.

[ihengineer76]

Here are all the ‘78 CC race bulletins.
http://www.vintagesnow.com/John_Deere_f ... LLETIN.pdf

[400brian]

I was hoping a couple of hours would have the two stuck aluminum shafts out of the suspension arms. Yeah, aluminum and steel just don't play nice together. I started with the 16" main shaft in the rear arm. I wound the puller up tight, warmed the tube up nicely, then quenched it. I have had the experience where I could actually hear the ping of the shaft letting go in the tube...not this time. I worked on it for most of an hour, and I moved it less than 1/4". I set it aside for the moment.

I went to work on the forward arm where the stuck shaft is only 6 3/4" long. I used the same method, again no ping. With the puller turned tight I wacked a bolt I had threaded into the opposite end. Eventually I saw slight movement. I tried using an air hammer on the bolt after it started moving, but it was not magic. I sprayed lube into the tube, I heated it, I pounded it, I cranked on the puller,, and finally it started moving with just the puller. Probably it came hard the first 3 or 4 inches. I will clean the rust out of the tubes with a 3/4" dingleberry hone, and these arms will need sand blasting.
I plan to replace all the shafts.

Next; back on the uncooperative rear arm.

[400brian]

We have run into this issue with Vintage Snow before. This one works for me. Thanks to Tom for making me aware that the 78 bulletins were there.



https://vintagesnow.com/John_Deere_file ... LLETIN.pdf

[400brian]

Had help in the garage today! Grandson wanted to hang with Grandpa, note he has his Snowmobile Hall of Fame cap on.

So we went to work on that long aluminum shaft stuck in the rear arm. I stood it on end last night and filled the tube with penetrating oil. Today I put the air hammer to a bolt screwed into the hole I had the puller in yesterday, Thus pushing the shaft the opposite direction that I had managed to move it ¼” yesterday. It moved in this direction nicely!

A longer bolt was installed and I drove the shaft out about 4”. I decided that rather than try to drive the shaft out with a big bolt ( and mushroom the end ), I would cut the exposed shaft off, drill and tap it, and continue pulling it with the puller.

So the Grandson got to see the drilling and tapping operation, then we installed the puller and cranked it for effect! The shaft was walking out nicely, but the more we got out, the harder it was going. I backed everything off and took stock of the situation, and decided that the corroded shaft was jamming in the puller tube. So, we took the puller off, cleaned the crud off the shaft with a file and then sandpaper, greased it up and reassembled the puller. Now we could crank the nut on the puller easily, and in just a minute later the shaft was out!

[400brian]

A little progress on the 78 LF project. The graphics are pretty decent on this sled, so I am going to try to rattle can the top of the tunnel and the lower sides and foot boards without messing them up. I had to remove 40 year old registration numbers, and they came off with the paint despite warming them up. The top of the tunnel is corroded, not sure why, the seat was in very nice condition when I took it off.

The snow flap was not perfect, but most of the yellow leaping deer is still there, so it will probably be reused. The tail light is your typical mess, hope it can be salvaged.

It's going to take a lot of paper towels and solvent to get the black goo off the inside of the pan and under the fuel tank.

BTW, anyone want the super neato custom rear hitch?

[400brian]

On the 78 LF re-fresh; tonight I re-visited a project I had started over 10 years ago. The pivots of both skis were rusted solid, and I had tried and failed once before to get things apart. The first ski I put in the vise had the bolt rusted solid in the steel bushing, but was loose in the spindle. I have a good hacksaw, and there was room between the spindle and the saddle, so I started sawing. I had to cut both sides, but then it was out! The cotter pins came out of the pins, they tapped out, and the first ski was disassembled.

The second ski had the pivot bolt completely intact, but on this side the bolt was rusted into the bushing, and the bushing was solidly rusted in the spindle, which means the bolt was turning in the saddle. This one was a bit tighter, but I got the blade in there and again cut both sides. These pins also came out of the springs, so the job was mostly complete.

All that is left, is to get the bushing and bolt out of the spindle. The fire wrench will come out for that soon.
The skis are pretty straight, but the sled had apparently sat on dirt. The track cleats were badly rusty on one half, and the pictured ski is rusted through in several places. The plastic skis are ordered.