3.5" Poly Rear Bumpstops (DIY thread)

[Starboard M]

did a little digging and found these too just in case someone wants options.
http://www.pirate4x4.com/forum/showthread.php?t=347598&highlight=timbren

Those are interesting.



They give load capacities on their bumps, which I assume is the max weight that will bottom out the bumpstop.

Assuming a normal built XJ weighs somewhere between 4200 and 5k, what weight rating should you get for the bumpstop?

If there is a 50-50 weight bias front and rear, do you get one that is between 2100 and 2500? Or will the force of a jump make that weight too light and require one that is heavier?

 

[slcpunk74]

Those are interesting.



They give load capacities on their bumps, which I assume is the max weight that will bottom out the bumpstop.

Assuming a normal built XJ weighs somewhere between 4200 and 5k, what weight rating should you get for the bumpstop?

If there is a 50-50 weight bias front and rear, do you get one that is between 2100 and 2500? Or will the force of a jump make that weight too light and require one that is heavier?

I have no idea on any of those questions but I just wanted to quote so someone who knows would not miss it after I posted.

I tried my front and rear polys yesterday and I really like the way they felt. Very soft and they still kept my tires and shocks happy:yelclap:

 

[dakineJ]

Those are interesting.



They give load capacities on their bumps, which I assume is the max weight that will bottom out the bumpstop.

Assuming a normal built XJ weighs somewhere between 4200 and 5k, what weight rating should you get for the bumpstop?

If there is a 50-50 weight bias front and rear, do you get one that is between 2100 and 2500? Or will the force of a jump make that weight too light and require one that is heavier?

Excellent question. Maybe a Tech at one of the shock manufacturers that makes air bumps would have info on compression forces.

 

[XJLI]

Assuming a normal built XJ weighs somewhere between 4200 and 5k, what weight rating should you get for the bumpstop?

holy crap i dont think so. mine was 3875 with some gear and me in it- weighed it right after i put the 33s on.

 

[srimes]

Those are interesting.



They give load capacities on their bumps, which I assume is the max weight that will bottom out the bumpstop.

Assuming a normal built XJ weighs somewhere between 4200 and 5k, what weight rating should you get for the bumpstop?

If there is a 50-50 weight bias front and rear, do you get one that is between 2100 and 2500? Or will the force of a jump make that weight too light and require one that is heavier?

I don't speak from experience, but from a physics standpoint it's pretty complicated. If it was just the bumpstop you could calculate it for a given jump height and jeep weight. But you also have the main springs, which you could account for if you know the spring rate and travel, but more importantly there's the shocks, which vary widely and their resistance depends on velocity.

How about this: take high-speed video of a big jump to measure downward velocity as the suspension bottoms out. We could then pick a good bumpstop size to use after fixing whatever broke.

v=at, d=.5at^2
a = 32 ft/s*s


I'll take a SWAG and say 2-3 g's at full compression. Stiffer with less travel, softer with more.

 

[JeepFreak21]

These are similar to what I got, but I got the energy suspensions ones but red

You don't have a part number on those do you? I contacted Energy Suspensions and they claim to not have a 3.5" tall bump in the style you have. (The guy was less than helpful).

I've got $40 in credit to use at VatoZone, so I was hoping to pick them up there

EDIT:

called fourwheel parts looking for the pro comp3.5" and they said it was not avail so they could only find a 4.5" and a 2.5" so I went with the 2.5" for space reasons. They are made by energy suspension part# 9.9109g vato zone might be able to get them for you. http://www.energysuspension.com/pages/bsp2.html

Have you tried out the 2.5" bumps yet? How do you like them?
Thanks,
Billy

 

[slcpunk74]

You don't have a part number on those do you? I contacted Energy Suspensions and they claim to not have a 3.5" tall bump in the style you have. (The guy was less than helpful).

I've got $40 in credit to use at VatoZone, so I was hoping to pick them up there
I would check out the ones that I am using if you want to go the vato zone way. I bet that you can get energy polys at the "zone".


Have you tried out the 2.5" bumps yet? How do you like them?
Thanks,
Billy

I love them. I hit some whoops yesterday goin about 50-55 pretty gnarly. I did pop off one of my back flares but I guess that just means I need to trim a bit more.

 

[XJLI]

got mine in today. welded some steel to them so I could mount them to the stock location since I already have DPG bumpstop plates. So far they work great on road lol.