Bump stop extensions

[IOPort51]

Ok so I did not eve think of this.

I have a 2 1/2" lift and I never did anything with the bump stops. I guess here in Dallas Co. there was not much for me to bottom out the shocks on. BUT after the trip to the mountains and the roughest terrain that the CJ or I have ever traveled, I am finding signs that I may have exceeded the range of the shocks a few times. The bottom mounts are bent downward a couple of degrees.

I am not finding a lot of information on dropping the bump stops or a lot of options from suppliers.

If anybody has any comments, hopefully with pictures, before I go off on a journey of spontaneous creativity?? I would appreciate the input.

 

[Old Dog]

When I got my jeep it had the stock bump stops on the front but nothing in the rear.
I just flexed it to see what I needed to keep the shocks from bottoming out. I ended up adding a .75 shim between the front bump stop and the frame and in the rear I had to weld a peice of tube to the frame to bolt the stop to.
You can also either buy bigger stops or shop the junkyard for bigger ones.
My rear ones came off a dodge pick-up truck.

 

[alpha6]

Hey IO, thanks for bringing this to my attention...never really thought about it. I did some searching and found this forum discussion (it's jeep but not jeep-ch). There is some pretty good info and links to buy bump stops.
Who drives without bump stops? - JeepForum.com

And also found this short article by the Jeep Guru about them.
Replacing Bumps stops on the Jeep Cherokee | The Jeep Guru

Now I gotta get under my jeep and see what condition mine are in.

 

[Old Dog]

I'd also use rubber bumps and not the polly one, you want something
that absorbs the shock here.

 

[IOPort51]

the shots of the broken /dented oil pan must be with no stops at all.

OK I think a plan is forming. cant say I am all that impressed with the available extensions. I can't see where welding an extension on the axle tube is a good thing.

I think I would prefer the tires rubbing to the shocks bottoming out. I am going to start running 33s off road but I think the stops are a good idea.

 

[BusaDave9]

I believe in having the maximum wheel travel. But you still don't want the tires to damage the fenders. Or vise versa.
I did measurements similar to what Old Dog is talking about. But first I checked to make sure I didn't have shocks that would limit my travel. I removed my shocks. Then I drove into a ditch to compress the opposite corners of my jeep like this:

​

DISCLAIMER: Driving a jeep on the highway without shocks can cause instability, especially when hitting a bump while going around a curve.
The writer of this post bears no responsibility if you die following my instructions.
​

Then with the jeep sitting like the above picture and 2 wheels just coming off the ground I measured how long the shocks should be at fully extended and fully compressed.
Then with the correct shocks I made the same measurements to see how high the tires went up into the wheel wells. I ended up cutting the fenders for clearance and I realize that's something you may not want to do. But still measure where the tires start to hit the fenders. Then with the jeep secured so it won't roll I measured how far the axle had to go to hit the OEM bump stops. I then bought polyurethane bumpstops to limit the travel where the tires were about to get in trouble.
Here's what I ended up with:

Maximum articulation without the tires ramming into the fenders.

 

[IOPort51]

As far as I can see, with a 2-2 1/2" lift, the options are a bit Limited as far as to the stroke. With 10"+ being about the max.

some things I learned, the original springs/shocks allowed about 1" of upward travel and approximately 6" downward.

With the 2-2 1/2" lift and a 13.71min, X 22.58max shock (Skyjacker H7023) there will be 1.75"+ before the shock bottoms out and 3" for it to bottom out in. So, I am thinking that a 1.75" spacer between the bump stop and frame should give me about 1.5" of upward travel and close to 8" downward to full extend. The center to center when parked on all four wheels, flat is 15.5 front and 17.5 rear.

Dave I would really like to know what your wheel up and wheel down measurements were, the 4" lift does have the advantage of allowing 4" longer shocks for longer min and max dimensions. And Bilstein does not really make an off road shock for my jeep and lift.

Item #H7023 / Skyjacker Suspensions

 

[BusaDave9]

Dave I would really like to know what your wheel up and wheel down measurements were, the 4" lift does have the advantage of allowing 4" longer shocks for longer min and max dimensions.

Sorry for the delay Larry.
You have to keep in mind I have build my front shock mounts with ford shock towers.

Some people bolt these shock towers to the frame. That works great if you have extra wide axles. But I thought they would stick out a little too much. so I cut them down and had a friend weld them on. This setup allows for longer shocks and hence longer travel. It's good to raise the top shock mount for this reason.
The top of my shock mount is now 5 inches above the top of my frame.
Here is my measurements:
Front shock extended (as shown in the ditch above) 26.25 inches fully extended. 18.25 inches compressed. and 23 inches sitting still.
That works out to 8 inches of travel in front.
These measurements are for my suspension travel. (If I remove the shocks, the shocks themselves could extend and compress further.)

Now for the rear.
21 inches extended, 16 inches compressed
That works out to 5 inches of travel in the rear.

Bilstein does not really make an off road shock for my jeep and lift.

A word of advice: do not look up specs for a manufacturer to see what shocks work for your jeep with such and such a lift. Instead ask for shocks that have the length you need extended and the correct length compressed. I used to have shocks the manufacturer said were for a CJ with my lift. But they would bottom out and they had several inches more travel than my CJ could allow. Go by your own measurements for extended and compressed length. I think this is very important to get the best shocks for your Jeep!

 

[IOPort51]

OK Dave, this is something you and I will have to set down with a couple shots of the Irish and a paper and pencil but if the math is right I actually have more possible travel in my suspension than you do. With 9.5 inches front and back.You have 8 front and 5 rear?

 

[BusaDave9]

Wow 9 inches. That's great. I'll have to remeasure my travel.
I get great travel and articulation in front but my rear only gets 5 inches of travel. I thought my shocks were limiting my travel so I took them off as a test and didn't get any more travel in the rear.

I drove my jeep into a ditch without shocks like in the above picture and measured shock mount to shock mount. When I twist my suspension the wheels get more travel than that because of the angle of the axle and the fact that the wheel is farther outboard than the shock.

 

[IOPort51]

Keep in mind that I said "possible" travel. the distance the shock will allow the bottom shock mount to travel in a vertical direction. I think the trick is to position the shock to allow the necessary upward travel and the maximum downward travel. this would, I think in most cases require a drop in the height of the shock tower after a spring lift. As is now the shock on my jeep is centered in the stroke at "park" which will allow more upward travel than is necessary and may run out of stroke before the suspension runs out of downward travel. I guess the best way to put this is that when you have bottomed out on the bump stop do you still have shock travel left, How much?

I hope this makes some sense, it's Saturday AM and I am just now drinking coffee.

Wow 9 inches. That's great. I'll have to remeasure my travel.
I get great travel and articulation in front but my rear only gets 5 inches of travel. I thought my shocks were limiting my travel so I took them off as a test and didn't get any more travel in the rear.

I drove my jeep into a ditch without shocks like in the above picture and measured shock mount to shock mount. When I twist my suspension the wheels get more travel than that because of the angle of the axle and the fact that the wheel is farther outboard than the shock.

 

[BC CJ]

Interesting question IO. I'll be interested in the answers of others. In my Jeep it's very close, the bump stop may not take all of the force before the shock bottoms out but will at least cusion it which I think is OK for a trail crawling Jeep (as oppossed to a baja racer). This way I have maximum down travel but I've found the leaf springs dont flex quite that much anyhow so I'm not really able to utilize all that droop anyhow.

My bump stop spacers were simple and free. I used scrap pieces of 2x3 box tube, drilled some holes and mounted the original rubber stops on the bottom. Very simple and cheap... but I like BusaDaves alot more

 

[BusaDave9]

I think the trick is to position the shock to allow the necessary upward travel and the maximum downward travel.

I agree with you so far.

this would, I think in most cases require a drop in the height of the shock tower after a spring lift.

I would agree with you here IF you wanted to keep the OEM shocks after installing the lift. To maximize the suspension travel you are better off getting longer shocks. The longer shocks can extend further. But of course the longer shocks don't compress as far.
So now if you wanted to get the maximum travel you would get extra long shocks. Shocks that have 12 inches of travel would not restrict the travel of most CJs. But those shocks would be about 20 inches compressed. If the suspension was completely bottomed out there would not be enough room for such a long shock to be installed without raising the top shock mount by installing a tall shock tower.

The higher you raise the shock tower the longer the shock that can be installed. and hence the more travel you could get.


EDIT: if you take this idea to the extreme and look at the competition jeeps that have the shock tower that extends through a hole in the hood. You could follow that approach. If you had shock towers that extended above the hood then you could install shocks 2 or 3 feet long. Those shocks would be mounted so high they would never bottom out. These shocks could extend so far they would never hyper extend. That would give you the maximum travel but it would be overkill. There are some off-roaders that do this and then say they have 18 inches of wheel travel. They only have shocks that have that much travel. It doesn't mean the suspension can actually move that far.

 

[Old Dog]

I guess the best way to put this is that when you have bottomed out on the bump stop do you still have shock travel left, How much?

I set mine so I had about 1" of up travel left just incase I hit a big bump going to fast.
Keep in mind that I also have the Ford shock towers and longer than stock shocks, so they never extend beyond their travel lenght.
I still need to find a good way to extend my rear shocks though.

 

[tarry99]

Keep in mind that I said "possible" travel. the distance the shock will allow the bottom shock mount to travel in a vertical direction. I think the trick is to position the shock to allow the necessary upward travel and the maximum downward travel. this would, I think in most cases require a drop in the height of the shock tower after a spring lift. As is now the shock on my jeep is centered in the stroke at "park" which will allow more upward travel than is necessary and may run out of stroke before the suspension runs out of downward travel. I guess the best way to put this is that when you have bottomed out on the bump stop do you still have shock travel left, How much?

I hope this makes some sense, it's Saturday AM and I am just now drinking coffee.

IO , Have another cup of coffee.............

I like to take the bottom shock mount and relocate it to the axle tube via a formed bracket. This will allow the shock to be near bottom when compressed against the bumps and still allow ample extension during articulation. Most times a near stock shock lenth will get you where you need to be even with a 3-4" lift. I hope I explanied that correctly.

 

[IOPort51]

@ tarry: exactly, the upward travel is Limited by the proximity of the fender to the tire. There is no reason for it to travel higher than that, and the distance between the axle tube and the frame, stock 1" mine 3"+, Dave I am guessing 5+ with your 4" lift. It is not possible for it to go higher than than the lesser of these two.

Bottom line: I think I understand the dynamics of the shock absorber and its positioning a lot better now. and think I will be able to maximize my lift and available articulation when I do get around to replacing the shocks. It should be pretty easy to keep from bending the shock mounts any more than they are now.

IO , Have another cup of coffee.............

I like to take the bottom shock mount and relocate it to the axle tube via a formed bracket. This will allow the shock to be near bottom when compressed against the bumps and still allow ample extension during articulation. Most times a near stock shock lenth will get you where you need to be even with a 3-4" lift. I hope I explanied that correctly.

 

[tarry99]

@ tarry: exactly, the upward travel is Limited by the proximity of the fender to the tire. There is no reason for it to travel higher than that, and the distance between the axle tube and the frame, stock 1" mine 3"+, Dave I am guessing 5+ with your 4" lift. It is not possible for it to go higher than than the lesser of these two.

Bottom line: I think I understand the dynamics of the shock absorber and its positioning a lot better now. and think I will be able to maximize my lift and available articulation when I do get around to replacing the shocks. It should be pretty easy to keep from bending the shock mounts any more than they are now.

IO,

Yep..........the shock really doesn't know where it's mounted it just knows it's limit of travel......moving the bottom mount I've found to be a better solution. Just my Opinion!

 

[IOPort51]

A good idea with a SOA but mine is already as low as it can be on a SUA.

IO,

Yep..........the shock really doesn't know where it's mounted it just knows it's limit of travel......moving the bottom mount I've found to be a better solution. Just my Opinion!

 

[Kilo19]

IO,

Yep..........the shock really doesn't know where it's mounted it just knows it's limit of travel......moving the bottom mount I've found to be a better solution. Just my Opinion!

In your picture tarry99, ( excuse my lack of knowledge) are springs perches the formed metal on the bottom of the axle, where the leafs are under and then bolted on? If so in a SOA do you remove those perches and make new ones to go on top or is there a reputable place that has SOA perches.

Thx


Sent from my iPhone using Tapatalk

 

[tarry99]

In your picture tarry99, ( excuse my lack of knowledge) are springs perches the formed metal on the bottom of the axle, where the leafs are under and then bolted on? If so in a SOA do you remove those perches and make new ones to go on top or is there a reputable place that has SOA perches.

Thx

Kilo, Yes those are spring perches that are welded to the axle tube that locates the springs...............all of the 4-wheel guys that manufacure & sell suspension parts have them...........get on the internet and look around. Just make sure the part they sell fits your springs & axle radius size.