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Post by rupper on Feb 1, 2016 15:17:59 GMT -6
Looking at converting my 75 rupp fa to a jackshaft. What year rupp parts can I use and what do I need to look out for when I measure and install. I am sure someone has already done this on this site so I am looking to the experts to make my conversion relatively painless. Thanks in advance for your responses and insights. Jim
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Post by 400nitro on Feb 1, 2016 21:05:06 GMT -6
if anyone has pictures of sam sessions kalamazoo rupps with the Kawasaki 650 in it had a jackshaft.
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Post by kronnikracing on Feb 2, 2016 7:51:27 GMT -6
That would be a pretty tough change wouldn't it? Chaincase would have to be moved to the other side and im not sure you would be able to use a rupp fa chaincase, you would have to retro fit a 76 nitro setup onto the 75 chassis. Then hope that your pipes would still fit, unless you are changing to mod pipes. Good luck and post pics as you go.
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Post by StingerSS427 on Feb 2, 2016 8:41:17 GMT -6
Are you thinking of doing this for stability? Would there be steering and fuel tank issues by doing this? If it is a stability issue, I have heard of the old racers making a longer shaft like a jack shaft. They would fab a bearing bracket for the right side and the long shaft offers stability to the driven and the chain case. Just a thought if you were looking for stability.
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Post by rupper on Feb 2, 2016 12:35:34 GMT -6
I want to make this change as i never did like the tower chaincase. I was thinking the later nitro or magnums 1976 and up, used a jackshaft, so unless the tunnel width changed, i dont see why those parts wouldn't work. I am saying that only because i believe those later sleds used the same width track, it was just shorter. Can you guys confirm that for me as i dont have a sled near by to measure.
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Post by Hoots on Feb 2, 2016 12:50:59 GMT -6
Pretty easy change over really if you have a 76 nitro donor sled like I had. I did see a 76 nitro, chassis only, on VS in the last week, do a search on their classified. You'll need, the steering post, chain case, jack shaft, pto side bearing and plate bolt right on (same size tunnel), drive shaft and I believe that I just went down and bought a couple bearing holder plates at the local hardware store for pto side drive shaft bearing plate. Only tricky part is getting the hole for that bearing plate, in the tunnel. I measured, remeasured, over and over before placing this bearing. Must have f'ed it up as my rear axle adjusters are a little lopsided. Been racing it this way for 3-4 years but embarrassing as a few guys have noticed and believe this sled would be unstoppable if thing were lined up better! LOL! It does usually finish no worse than second and has won Waconia most years Reason why I did it is this little 340 Kohler mod motor, loves to be launched at around 7g. Pretty hard on the tower, same side chain case. PS, I believe you wouldn't be able to use stock exh. Cans if you do this. Works great with my pipes though. My pic's are too large, I'll resize and post in a bit.
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Post by Hoots on Feb 2, 2016 13:22:03 GMT -6
Crap, its not my pic's, the forum is maxed again. Oh well, if you want I can email but they just show what looks like a F/A motor in a liquid chassis.
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Post by rupper on Feb 2, 2016 13:25:40 GMT -6
Hi Hoots, to clarify, 1976 nitro parts should do the trick for what i am about to do....Oh, I forgot to mention that i am putting the jackshaft THRU the chassis and will be laying down the chaincase. I know that will mean i have to move the track drivers and suspension back but that shouldn't be too hard..just alot of labour.b
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Post by rupper on Feb 2, 2016 13:27:10 GMT -6
hoots..my email address is rupperj@hotmail.com..you can send any pics you want to share there...thanks...Jim
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Post by upmagnum on Feb 2, 2016 17:27:18 GMT -6
I built a 76 Super Brut mod on a 75 FA chassis once so yes, what you want to do can be done. Pretty sure you will have to relocate the front motor plate mounts and use the 76 plate to get the motor over far enough to run a jackshaft but not positive on that. Have also seen the jackshaft run through the tunnel on a 75 FA also so know that can be done also. Ended up running a 106" track on that one.
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Post by rupper on Feb 2, 2016 18:02:57 GMT -6
Good point on the motor mount upmagnum. Do you recall where they put the disc brake on that setup? I don't really want to cut a hole in the chassis to fit it...I was thinking of mounting in on the driveshaft (on the clutch side of the chassis)
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Post by mrmotors on Feb 2, 2016 20:51:54 GMT -6
I have a liguid Nitro chaincase, don't recall if it has guts. I believe I have a jackshaft as well. I also have a set of modified F/A pipes where the stingers drop down and out holes if front of the foot rests, not the stock holes. It will be a couple weeks before I can look at the stuff again. If you have interest, let me know.
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Post by Hoots on Feb 2, 2016 21:41:29 GMT -6
Oh yes, forgot to mention the 76 motor plate works great also. I just set the motor and drilled the plate for same offset and center to center as my liquid Magnum, that way I use the same belt. I trimmed the webbing in hood opening a little for more air to pto cylinder. As far as laying down the 76 chain case, you're on your own.
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Post by upmagnum on Feb 3, 2016 6:30:23 GMT -6
The case wasn't laying all the way down. A bracket was added to top of tunnel to catch the top bolt for case. If I remember right that location was added to the case. Brake rotor ran between case and tunnel. Pretty tight there but it worked. Don't believe it was the stock 76 chain case as the tensioner was completely different unless it had been modified. Don't know, never asked. I do know when it was all done the primary was higher than the secondary.
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Post by rupper on Feb 4, 2016 15:02:00 GMT -6
Thanks for all the info guys. Will the same parts from a 1977 nitro work too?
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Post by upmagnum on Feb 4, 2016 18:06:35 GMT -6
Yes
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Post by rupper on Mar 9, 2016 19:47:12 GMT -6
Hi Guys, Found all the parts i need to perform the build.Thanks for everyone's input. Whenever i get it done i will try and post some pics of the before and after...Jim...
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Post by snosnake on Mar 11, 2016 13:11:09 GMT -6
To put the 76 Rupp Jackshaft on a 75 F/A is pretty much a bolt on job. Nothing to it.
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Post by rupper on Mar 11, 2016 13:52:22 GMT -6
Hi Rick, Thats what i am counting on...I have some other challenges before i get to it though as i have a bare tunnel that i will need to repair and then connect to the front bulk head first. Is anyone repopping the original size F/A fuel tank.
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