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thiokol 1404 imp springs

Alan K

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Does anybody know what the arch measurement is or how to tell if they are weak I am new at this.:smile: have tracks off and checking things out, thanks
 

turbinator62

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My cat is at our cabin so I can't measure it but check out the "Snowcat Restoration and Modifications forum http://www.forumsforums.com/3_9/forumdisplay.php?f=88 and look for pictures of 1404s or 1402s to see how much arch there is. I'm sure most of them are worn out. I had one break last year and spent 160 bucks to have two custom made to a sample. Then I found these http://www.sdtrucksprings.com/index.php?main_page=product_info&products_id=331 They are the right length, but are 1/4 inch thick as opposed to 3/16" and have quite a bit more arch. I bought two to check out. I think if you disassembled them and used the original back up leaves and just the main spring they would be ok. You would have to machine new bushings of the proper ID as the supplied ones are too big. I would make the bushings out of UHMW plastic. I may replace all of mine next year. You could do the whole cat for about $170 plus freight.

A higher arch will also tighten up your tracks, so make sure you have some adjustment. It will also give you more ground clearance, but may cause the cat to pitch more on rough ground.

Post pictures when you can. We all like to see other peoples projects.
 
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hansoni

Member
This is a drawing of the IMP springs I just had 8 made.
 

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rodre

Member
My Imps springs tend to "walk" side to side. I was going to get some "bend over keepers" like in the drawing above installed to stop this from happening. I was told by a spring shop that if the U-bolt were tight enough that they shouldn't walk. I think part of the problem is that the U-bolts I had made, by 2 different shops, are a hair wider than the originals. I started looking at pictures of Imps and a few that I looked at had the "keepers" and a rivet at each end of the springs. So I figured I would just get them put on, but then I measured the space between an original tire and the spring and it is less then 1/4 inch. Do you other Imp owners have the keepers/clips? If so how thick are they? How wide are your springs? How close to the tires? My springs also only have 4 leafs, not 5 like in the drawing, it is a wide track. I am perplexed...
 

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turbinator62

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My 1402 originally had 3 leaves. I added a 12" leaf to the top of each pack due to the increased weight of my cab. The leaves are 3/16" thick. I do not have the clips and have not had a problem with them getting out of alignment. My u bolts are a pretty tight fit and limit how far they can move. My tires are also very close to the springs.
 

rodre

Member
Looking at the Imp manual the drawing of the spring shows 4 leafs and no clip on the ends. The part number 1405028 is also different then the one in the drawing above. I wonder where Hansoni got that drawing from?
 

turbinator62

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The drawing looks like 1450 springs. They are much heavier. Check out post "1450 Wt New To me" from BearGap. (About #17 on the resto`mod page) He has some good pictures of them. Your springs sound correct, you just need some closer u bolts.
 

turbinator62

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The first picture is of my 1402 springs. I added a 4th 12" leaf and arched them to 3-3/4" sitting on the the bench to the top of the upper leaf. You could go to 4" but if you go too high the tire guides on the upper track will hit the axles. The second picture is of BearGap's 1450. The springs look like the drawing above.
 

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