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Discussion Starter #1
Getting ready to mount my Fox 2.0x 2" bump stops on my rig and had a question on material thickness. I'm using the standard pinch style cans from Poly Performance, but was wondering about the material to mount the cans to the frame.

I haven't started designing the details, but the thought was basically three pieces of material - two wings - one on each side, and a top portion - here's a rough sketch:



I was assuming that the wings would intersect the can close to the center line so that there's still ability for the can to compress as the bolts are tightened to pinch the bump stop.

The material thickness is what I'm wondering about. Originally I was thinking 3/16" or 1/4" for the three pieces, but I saw that Poly uses 1/8" on their similar generic mounting kit. It seems like there would be the ideal thickness where you would trade off strength vs. ability to flex enough to pinch the can enough to hold it in place.

This is my first time mounting bumps, so any experiences/suggestions on what people have used in the past with regards to can mount material thickness would be appreciated!
 

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I cut my wings from 3/16". Stay slightly less than 1/2 the can diameter and slug the can with 2" tubing with the bolts loose or left off. Afterwards if you want to get really fancy, clean them out with a 2-1/8" 240grit ball hone.

If mounting to tubing try to design your plates to hit 1/2 the tubing diameter at least. That's what I would do differently.

I chose 3/16" because mine will be beat and flown through the air. 1/4" is probably excessive with no benefit. 1/8" is just fine for recreation or cone dodging.
 

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Discussion Starter #4
Perfect! Thanks for the inputs, I'll probably use 3/16". I was thinking about machining a dummy slug about 0.020-0.30" oversize to accommodate any shrinkage from welding. The hone sounds like a nice way to clean up the inside.
 

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That'd be great if you can machine something oversize but beware it will tough to drive out if the metal pinches bad. Be conscious of how you can remove it/clean up the can bore.
 

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Discussion Starter #6
Yep, that would definitely suck. I may see if I have a large expansion reamer or something that could be expanded and then loosened to release easier.
 

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10 GA dimple die'd is what I'm using to mount my cans.
 

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I used 1/8". Hole saw works great to clean the cans and much faster if you get them too hot.
Tried the hole saw today on a can that was stubborn. Wasn't too bad since I was using a hole saw from Roark Supply that isn't seam welded and ghetto like a Holedozer. It didn't gawl up the can near as bad as I imagined but I still honed it because I'm OCD.
 

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Don't use a continuous round piece. Look toward the ones shown above and TMR. My LJ came with tubes and I had to carefully grind a slot all the way down to get the bump out. You want the bump top to be accessible for gas and to drain mud, etc. Cutting at the angle on top easily solves a lot of potential problems.

Most bumps have a flange on the bottom so you don't need a bunch of pinching.
 

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Discussion Starter #13
I had forgotten about this thread, ended up using 3/16". When I welded them I put a piece of 2" x .250 wall DOM in the can and left the bolts loose. It tighten up some, but was able to drive it out and then just drove it through a couple more times and the bumps fit just fine. Didn't end up having to do any cleanup inside the cans.



 

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Don't use a continuous round piece. Look toward the ones shown above and TMR. My LJ came with tubes and I had to carefully grind a slot all the way down to get the bump out. You want the bump top to be accessible for gas and to drain mud, etc. Cutting at the angle on top easily solves a lot of potential problems.

Most bumps have a flange on the bottom so you don't need a bunch of pinching.
My bumps will just be poly type bumps mounted to a tube. But trying to not buy bump can mounts.
 

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What size bolts are we looking at for these? I have the material to use a 7/16" or even 1/2" bolt.
 

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Discussion Starter #17
I was going to say I think the standard ones are around 3/8" or 5/16", but didn't have one in front of me, but you can tell by the pics they aren't anywhere near 7/16" or 1/2". All they have to do is keep the bump from slipping out of the can, which doesn't require much given how snugly they normally fit. The shoulder on the bump which is in contact with the bottom edge of the can takes all of the load when the bump gets compressed.
 

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I realize that, I am making mine tube inside of tube, with a GM bump stop. I have tubing that is 1/2" or 7/16 ID and just wanted to make sure that was sufficient, as mine will be relying on the clamping pressure, unless i eventually weld in a shoulder.
 

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I realize that, I am making mine tube inside of tube, with a GM bump stop. I have tubing that is 1/2" or 7/16 ID and just wanted to make sure that was sufficient, as mine will be relying on the clamping pressure, unless i eventually weld in a shoulder.
I would do a shoulder, wouldn't want to rely on the clamping pressure of the can to stop the crashing of metal on metal bump out. Lots of expensive collateral damage if the clamping slips. Imho.

Matt
 

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I have the Poly bump cans in mine, with their modified can mounts. It's 1/8 thick. Can comes with 3/8 bolts. They are barely enough to hold a piece of 2x0.25 DOM. I had it slip once. I'd do 7/16 if you planned on not running shouldered air bumps.

 
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