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Author Topic: 74 Lynx 292 HD tilly  (Read 723 times)

2manyprojects

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74 Lynx 292 HD tilly
« on: December 26, 2020, 05:41:30 pm »
Hi I'm new here but have been lurking reading a bunch of the resurrection and restoration topics.

I have a few late 70's polaris sleds but nothing special or one of a kind. I took the last 10 months or so and customized my 79 TX-L into a stock oval sled (started with a chassis so I've done a lot of parts hunting) I've always been interested in the older single cylinder sleds though I think they are pretty cool but after trying to find a decent chassis over the last few years to redo my 78 SS 340 Polaris I've kind of given up on the steel chassis sleds. Also Polaris never really had a decent single for a race sled. I did a 488 clyinder conversion on a 244 gemini single which was cool but anyways.

This intro is super long sorry but the want/need for a aluminim chassis single led me to Arctic cat which I've always liked the early 70's Cats anyways. I don't dislike Yamaha but never had an interest in any Yamaha sled old or new.

So yeah I found this sad sack 1974 Lynx 292 kawi that has what appears to be a factory or atleast decently installed Tilotson HD13A carb on it (I have no idea but the conversion block looks manufactured). The condition of the sled is arguably scrap condition which I figured was perfect for modifying into an oval sled.

Didn't actually take any pictures of the sled when it was together just as I disassembled it which sucks. Anyways the top end is cooked and I will get the crank checked and rebearinged anyways if I can find top end parts.

What I'm starting with is the cleated to rubber conversion. I did a bunch of reading about this conversion at least as much as is available.

What I have

-NOS kimpex round drive shaft 2.52 8 tooth drivers with a 6" diameter. (The kimpex notes on them were for a 2.52 rubber conversion back when)
-1975 or 1976 lynx skid mounting brackets that "bubble" into the tunnel the 3/4" per side I'm going to need (17 3/4" cross shaft to 16 1/4" cross shaft)
-1983 Polaris Star skid (108" discontinued 2" pitch track with 3" diameter drivers)
-1979 or 80 Polaris TX 440 skid (114" cleated track)

What I'm likely to do is buy a new 116" 2.52 camoplast track with .53 lugs. The Camso R tracks at 116" only come in .7X lug (afaik) with 3/8" stud beyond would put me into over an inch of protrusion theoretically. This likely wont fit the tunnel and I'm not into drop and rolls as its beyond my fabrication skills or what I want to get into.

Further info:
Star skid
- bolt to bolt is ~23"
- forward mounting bolt to driveshaft center ~13.5"
- forward mounting bolt to tip of skid rails 8.5"

TX skid
- bolt to bolt is ~24"
- forward mounting bolt to driveshaft center ~16"
- forward mounting bolt to tip of skid rails ~11"

Lynx
- bolt to bolt is ~24"
- forward mounting bolt to driveshaft center ~11"
- Driver diameter is 6 1/8"

I'd like to hack up the tunnel as little as possible drilling holes and moving mounting plates etc. I can use the star skid parts to widen the rail centers for the tx skid if that's what I go with.

By my rough figuring I'd have to move the star skid back 5" and the TX skid probably wont work without modifying the rails irreversibly. A lot of comments I read were saying to use a sport/cutlass/ss skid for the conversion which afaik is the same as the star and also direct drive 2" pitch track sleds only difference being the 340s and 440s had a bit larger track drivers.

Anyone that's actually done something similar have any input on this am I out to lunch? Appreciate any input thanks.

Vintagesleds.com

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    motorman45

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    Re: 74 Lynx 292 HD tilly
    « Reply #1 on: December 28, 2020, 03:57:02 pm »
     if the rail spacing on the 116 track is the same as the TX skid i think it would be best as it had a 114" track and will fit better than using the star's 108" skid. I would take good measurements of the tx skid installed in its chassis especially the mounting bolts to ground or bottom of the skid as well as the ones you already took of how far back and up they are from the drive shaft center.

     the TX skid is taller and you may get away with drilling a new hole in the stock lynx front mounting plate, the rear plate will need to move forward most likely. ride height is something to look at.

     The lynx  obviously used a shorter track than 116" but i have looked at doing exactly this to a 72 Puma chassis ( same as your 74 lynx) i have and it seems it will fit, the track will be back a little and nearly flush with the end if the chassis but it looks ok.
    72 Cheetah 440 sachs
    72 Cheetah 303 custom
    71 Puma 303 mod
    71 lynx 303 mod

    chris r

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    Re: 74 Lynx 292 HD tilly
    « Reply #2 on: December 30, 2020, 01:28:55 pm »
    Sounds like you've done a lot of homework on this. I'm sure the answers will come as you move forward.

    Though I don't have experience with this swap, I find that if I make a print of what I need it often helps me find my answers. It takes time but for something like this, I'd put some lines, circles, and arrows down on paper and start crunching the numbers.

     :)
    If you can't look back on your younger self and realize you were an idiot, you're probably still an idiot.

    motorman45

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    Re: 74 Lynx 292 HD tilly
    « Reply #3 on: December 30, 2020, 11:21:37 pm »
    I agree with putting on paper. I used my Cad program to layout both sled chassis and figure out where the mounting points would need to be, but you can do the same on paper.
    72 Cheetah 440 sachs
    72 Cheetah 303 custom
    71 Puma 303 mod
    71 lynx 303 mod

    2manyprojects

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    Re: 74 Lynx 292 HD tilly
    « Reply #4 on: January 02, 2021, 01:16:59 am »
    That's a good idea would be far better to hash it out that way than juggling numbers in my head. The hitch that was thrown into this plan is I bought a really nice 70 panther with a ruined 399 Kohler in it for some parts but it's in far better shape than the lynx chassis AND the dimensions seem to make more sense for a polaris skid 121 swap. However, the cleated track is good and the old cat steel bird cage skid still has about 70% of the original paint on it which I've never seen. So I'm juggling with the idea of rubber swapping it and putting the 292 in it atm. 399 panther wasnt a rare sled 14000+ made in 1970 I think but still complete and original including original seat.

    Lumpy59

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    Re: 74 Lynx 292 HD tilly
    « Reply #5 on: January 15, 2021, 01:17:37 pm »
    The cat photo attached is a sled I built , it has a Polaris Star skid , 121 modern track , and a panther tunnel that was shorten and boxed after the install. I will get better pictures of the skid if anyone is interested. The slide rails are modified ( home built big wheel kit concept) with Cat 9 rear wheels and axle .

    Remember your mounting location can only be transferred when the front drivers are the same size.

    It was interesting on this project I did , how much of the track length was absorbed with larger drivers vs the Star sled, and adding the larger rear wheels.

    The sled was built to oval , the skid was modified to look and attack like the mid 70s Z skid. The 15 skid required the wider axles to fit the wide tunnel, and tube spacers are added to center the skid .
    As others have said , pre-planning is key , if all wheel size remains the same it is a simple exchange, hole location from front axle back to mounting holes , also height of hole location from running board TOP edge Not bottom edge .
    Tunnels vary in thickness and track clearance is from mounting hole to top of tunnel .
    Best of luck ! Cant wait to see the results !
    50 years of sledding, proud to have served as a National  Judge.