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Author Topic: 75 340 Z track conversion for drag racing  (Read 2369 times)

RMK800

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75 340 Z track conversion for drag racing
« on: August 03, 2019, 06:30:06 pm »
I plan to drag race (Stock events) my Z that I have not raced or even hardly driven since I purchased it. Our rules in Saskatchewan state max 3/4" lug track allowed. I have purchased a very good condition used Arctco rubber track for the job. Thought I would post the conversion as this is fairly extensive to do converting from a unique cleated 3.29" pitch x 112" to a 2.52" pitch x 121". The skid will need to be totally modified by widening the rails spacing from 7.5" to 8.875" c/c and lengthening them 4.5". I have acquired used Z rails and other parts to do the mods. Needed the upper return rollers on the rear swing arm and now have a good used set. A bit worn in the bores. The rear swing arm looks to be a custom steel replacement and I do not have the aluminum swing arms for this. If anyone reading this can help out with locating the aluminum swing arms I would be grateful. I will start out by posting pics of the rails. Needed straightening on a press first and then 4.5" rail extensions prepared. As I cannot find original antistab parts for the rail nose I purchased an aftermarket antistab plastic part that fits the rail profile excellent with minor rail modification to accept them. More to come as I progress.
First photo shows rail extensions ready to be welded.
Last photo shows the original worn out antistab on (upper right). Rails both modified to accept the new antistab (lower right)
« Last Edit: August 03, 2019, 06:35:45 pm by RMK800 »
79 TX 340
78 el Tigre 5000
76 TX 440
75 Sno Twister 440
75 340 Z
74 el Tigre 295
74 TX 440

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    RMK800

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    Re: 75 340 Z track conversion for drag racing
    « Reply #1 on: August 03, 2019, 06:34:26 pm »
    Rear swing arm in steel. Would love to find the original aluminum swing arms. Shafts are seized in the arms right now.
    79 TX 340
    78 el Tigre 5000
    76 TX 440
    75 Sno Twister 440
    75 340 Z
    74 el Tigre 295
    74 TX 440

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    Re: 75 340 Z track conversion for drag racing
    « Reply #2 on: August 05, 2019, 02:40:50 am »
    Man someone spent some time making up those rear arms.  To bad they didn't  spend that time finding the OEM parts.

    RMK800

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    Re: 75 340 Z track conversion for drag racing
    « Reply #3 on: August 08, 2019, 04:46:42 am »
    Actually is very good workmanship. If I cannot get aluminum ones I will lighten these up a lot. Sled will be used for drags so no severe side loading on the parts.
    79 TX 340
    78 el Tigre 5000
    76 TX 440
    75 Sno Twister 440
    75 340 Z
    74 el Tigre 295
    74 TX 440

    RMK800

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    Re: 75 340 Z track conversion for drag racing
    « Reply #4 on: August 27, 2019, 04:51:39 am »
    A little more progress. Working on the rear swing arm and almost complete. Also working on the final drive. As I am installing a 121 x 3/4" lug track with 2.52 pitch I needed to totally change the final drive with the proper sprockets. The original final drive is the first pic. It's shaft is worn bad where the bearing mounts opposite the spline side so will use a used spare I have that is good and the proper length also. Yes it is not bent at all as determined with a dial indicator. Cleaned the shaft in the sand blaster first. Then measured the lug spacing on the track and referencing the original drive to establish the center of the track location to set up the drive sprockets. Trick was to get enough sprockets that match and they do differ between sled years. Not sure what sleds the final drives I had came from but out of 3 complete drive assemblies I was able to put together properly timed sprockets that were in very good condition. I decided to go with 4 sprockets instead of 2 for better track support and drive efficiency. Outer sprockets required the shaft to be drilled for the split pin to secure them. Exisitng holes shown were not correct. Also I had the outer sprocket on the side opposite the spline machined to remove the boss flush to the sprocket as there was not much room for the bearing securing eccentric collar. Plastic gears do not offer much for rotating mass concerns. Will complete the rear swing arm shortly and post. Rails are also ready with extensions welded. Pics to come.
    « Last Edit: August 27, 2019, 04:57:01 am by RMK800 »
    79 TX 340
    78 el Tigre 5000
    76 TX 440
    75 Sno Twister 440
    75 340 Z
    74 el Tigre 295
    74 TX 440

    AHood

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    Re: 75 340 Z track conversion for drag racing
    « Reply #5 on: August 29, 2019, 01:07:13 am »
    Good stuff. You probably could have used a 116 track and just moved the rear idler brackets back one hole though.. just a thought.
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    RMK800

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    Re: 75 340 Z track conversion for drag racing
    « Reply #6 on: September 02, 2019, 01:03:03 am »
    Yea a 116 would be less work. Did not find one but then I did not really scour the country for one that is 116 x 3/4" lug either. Little lazy on my part. Rubber track conversion will still require widening the rails would it not? Anyway we are committed now. :-)
    79 TX 340
    78 el Tigre 5000
    76 TX 440
    75 Sno Twister 440
    75 340 Z
    74 el Tigre 295
    74 TX 440

    RMK800

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    Re: 75 340 Z track conversion for drag racing
    « Reply #7 on: September 02, 2019, 01:10:12 am »
    Onward we go. Widening front and rear rails cross braces. Self explanatory I think. Set up a rail jig with wood to space the rails and position them for fitting the cross braces.
    Mount the parts and clamp them for welding for perfect fit. Mig time.
    79 TX 340
    78 el Tigre 5000
    76 TX 440
    75 Sno Twister 440
    75 340 Z
    74 el Tigre 295
    74 TX 440

    RMK800

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    Re: 75 340 Z track conversion for drag racing
    « Reply #8 on: September 02, 2019, 01:13:01 am »
    Next I needed to widen the front swing arm where it attaches to the rails. Laid out the front swing arm and used positioning blocks to hold the position of the pivot tube from moving I measured the new location of the lower pivot tubes. Look close and you can see the zip disc cut marks to allow bending the arms to position and then mig weld er.
    « Last Edit: September 02, 2019, 01:16:37 am by RMK800 »
    79 TX 340
    78 el Tigre 5000
    76 TX 440
    75 Sno Twister 440
    75 340 Z
    74 el Tigre 295
    74 TX 440

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    Re: 75 340 Z track conversion for drag racing
    « Reply #9 on: September 12, 2019, 04:32:58 pm »
    Thought you had to keep stock length ?
    twisters are it

    RMK800

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    Re: 75 340 Z track conversion for drag racing
    « Reply #10 on: September 13, 2019, 02:09:53 am »
    Track just has to stay inside the tunnel.
    79 TX 340
    78 el Tigre 5000
    76 TX 440
    75 Sno Twister 440
    75 340 Z
    74 el Tigre 295
    74 TX 440

    AHood

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    Re: 75 340 Z track conversion for drag racing
    « Reply #11 on: September 20, 2019, 01:15:49 am »
    Yeah you obviously had to widen the skid. Best 116 would have been a phazer track. Still available new I believe or plenty of used ones.
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    RMK800

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    Re: 75 340 Z track conversion for drag racing
    « Reply #12 on: September 25, 2019, 04:39:56 am »
    Camso makes a 116 x .72 full block track. I put one on my 75 twister. It already had the original Merc rubber track on it so no need to widen rails. Just pushed the rear axle bracket back a few inches. Tunnel rear bulkhead was also moded to accommodate clearance. Did not want to spend the money on another new track for the Z. $500 Canadian but still have to lengthen skid or install another skid. I also love the challenge to modify to accommodate.
    79 TX 340
    78 el Tigre 5000
    76 TX 440
    75 Sno Twister 440
    75 340 Z
    74 el Tigre 295
    74 TX 440

    RMK800

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    Re: 75 340 Z track conversion for drag racing
    « Reply #13 on: September 25, 2019, 04:43:48 am »
    Thought you had to keep stock length ?
    Twisters are it I agree. Love my 75. Tough to beat it in snow drags.
    79 TX 340
    78 el Tigre 5000
    76 TX 440
    75 Sno Twister 440
    75 340 Z
    74 el Tigre 295
    74 TX 440

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    Re: 75 340 Z track conversion for drag racing
    « Reply #14 on: April 14, 2020, 06:08:35 pm »
    Arctic Cat has a 116 that fits the cleated track rail center to center.