Tunnel extension support brackets

snow guy

snow guy

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Joined
Mar 10, 2004
Messages
146
Location
Fairbanks, AK
I'm stretching my 05 Mt. Viper from 144 to 151 and with a used Mt. Performance kit I got a while ago. While getting ready to put it on I got concerned that there was no support brackets under the tunnel extension to stiffen it up. I'm concerned about lifting from the back and it flexing. I called Mt. Perf and they said they don't use one with their 151 kit. I looked at Hartman and he has some bumper support brackets that say they do what I'm looking for. Does anyone have any experience with this?
 
Same thing with my 2004 MNT Viper with a 156". I just recently purchased it but the previous owner installed the tunnel & rail extension kit from MPI, but he got the re-inforced brackets from Hartman after the fact.
 
I have a 121 to 151 hartman extension and it came with the bumper support brackets. They are essentially a 1" x 1/8" thick aluminum flat that runs from the old bumper bolt holes on the tunnell to the new bumper mounting location on the extension. Basically if you are pulling something hooked to your bumper the load is transferred to the tunnell and not pulling on the extension. I am constantly pulling people with a sno-bungee and have not had a problem with mine.
 
A K MtnViper....so neither of you used any extra bracing or the Hartman bumper support bracket? I'm a little concerned with using a bumper lift and/or tugging on the back end when stuck so I'm probably going to add something just for peace of mind.
 
I use a Hartman 144 ext. I tried to lift the back of the sled without these two supports and the extension did in fact flex up. Not good. The two support brakets takes almost all of the stress from the rivets. I would just fab up some out of 1-1.12 X .250" aluminum flat stock and not have to worry about it. It's really easy to do, so why not?

1CS
 
That's what I figured, I just got back from Home Depot with some 1 X 1/8 flat stock that I'm going to use plus I've got some support brackets from a 136 extension that I might use too, more is better right!
 
Here's what I ended up doing for support. Before I put the brackets on the tunnel it actually felt pretty solid and I probably could have gotten by without them but it is very solid now. I used stainless washers as backers as you can see for some extra bite and something solid to for the rivets to squish up against. I didn't use any extra support for the bumper as it too was good by just using the existing bolts and mounts. All and all I'm pleased with how it turned out.
 

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Very nice job. That will work. I'm thinking, tho. ( LOL ) With your bumper, as long as the bolt holes have no play, I would think you will be fine. If there is any play, I fear that the bolt will make the holes oblong over time. Something to think about.

What is that bumper from? I like the little cross bar on the bottom.

-1CS
 
The bumper is the stock unit, the holes were nice and tight in fact I had to do some grinding on the bumper to get the holes to line up vs. drilling out the holes to avoid future problems like you suggested.
 
snow guy said:
The bumper is the stock unit, the holes were nice and tight in fact I had to do some grinding on the bumper to get the holes to line up vs. drilling out the holes to avoid future problems like you suggested.
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Awesome. Sounds like your issues are all taken care of. Glad when a plan comes together.

-1CS
 
Well not exactly, I just went to put on the rear cooling hoses that came with the MPI kit to find out that they are 3/4" ID and the stock coolers need a 1" ID hose, now I'm off to the parts store to buy some 1" hose, there's always something, it's never over til it's over!
 
snow guy said:
Well not exactly, I just went to put on the rear cooling hoses that came with the MPI kit to find out that they are 3/4" ID and the stock coolers need a 1" ID hose, now I'm off to the parts store to buy some 1" hose, there's always something, it's never over til it's over!
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LOL....Maybe a couple reducers will help.
Yeah, I'm having some issues with my rear bumper from Hartman on my project. I need some bumper ideas. Click on the link below, see if you can give me an idea. You are correct, it's always something. lol Gotta love these machines.

-1CS
 
snow guy said:
I don't see any of the pictures on the link under your posts, did you post pictures?
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Yeah, You have to be logged in to view pictures. Just like here, I think. You must not be registered on the 4 stroke side.

-1CS
 
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