How much should I extend my bumpstops?

[Chris]

Here's how to properly measure your bumpstop on your Wrangler.

1. Measure the distance between the bumpstop and the point where it contacts the axle.
2. Measure the amount of up-travel you have in your shocks before they bottom out.
3. Measure the distance between your tire and where it will contact the fender.

If #2 or #3 is less than than #1, you need to extend your bumpstops.

Take the smaller of measurement #2 or #3. This is a good starting point for how far your bumpstop should be from the point where it contacts the axle. Then subtract another 1/2" to allow for compression of the rubber bumpstop. I say good starting point because you'll have to do some fine tuning to account for turning and possible other areas where the tiremay rub.

Maybe adding some hypothetical numbers to this would help clear it up.

#1 = 6"
#2 = 4"
#3 = 5"

In this scenario, you need to extend your bumpstop at least 2". Its currently allowing 6" of uptravel but your shocks only have 4".

 

[weldedcambolt]

do you just push the bump stocks up into the cup or can you glue them up in there so they dont fall out, like mine did?

 

[Chris]

do you just push the bump stocks up into the cup or can you glue them up in there so they dont fall out, like mine did?

They should be bolted in. Good bump stops (at least for the front springs) are actually bolted into the lower front spring perches. This requires you to drill and tap a hole for a bolt. Adding bump stops to the top of the front spring perches (where the jounce bumpers are on a stock TJ) isn't recommended, as they'll likely contact the springs themselves as oppose to the lower spring perch like they should.

For this reason it's suggested you keep the stock jounce bumpers in the front and add the bump stop puck to the lower spring perches.

 

[weldedcambolt]

I am gonna sleep on that one to try to understand it, be back tommorow had to much fun on here today

 

[JMT]

I am gonna sleep on that one to try to understand it, be back tommorow had to much fun on here today

X2 to Chris ^^^.
The squishy thing in the cup is not a bumpstop. It’s called the jounce bumper. The extended bumpstop is usually a poly cylinder with a hole through it for a bolt to pass through. Some companies send these with a budget boost kit and instructions to add them to the upper column, above the cup. However, as @Chris said, this is not a good place (in the front) since the extension will likely cause the edge of the cup to rub on your spring. The correct way is to remove your spring and tap into the lower spring perch (5/16” or 3/8” is fine). Then add your extended bumpstop there with a new grade 8 bolt the proper length. I’ll post some pics when I get out of bed

 

[weldedcambolt]

so the jounce bumper fell out of the extended bumpstop in the rear in this pic?

 

[weldedcambolt]

an this is the front, an your saying, it should be switched to the bottom? instead of bolted from the top, or remove this, an put on the bottom, something completely different, inside the spring?

 

[Drizit]

In this scenario, you need to extend your bumpstop at least 2". Its currently allowing 6" of uptravel but your shocks only have 4".

2.5" you forgot the extra for compression.

If you are using stock jounces you should acctualy measure right to the metal lip of the cup as the jounces can compress all the way down in a hard enough hit.

Personally I run an extended jounce from daystar and then also an extended pad on the bottom

—
There must have been a time
when we could have said no.

 

[Drizit]

an this is the front, an your saying, it should be switched to the bottom? instead of bolted from the top, or remove this, an put on the bottom, something completely different, inside the spring?View attachment 35443

In an ideal world yes, but at least make sure that your spring doesn't touch it at any point in its travel arc

—
There must have been a time
when we could have said no.

 

[tomtaylz]

X2 to Chris ^^^.
The squishy thing in the cup is not a bumpstop. It’s called the jounce bumper. The extended bumpstop is usually a poly cylinder with a hole through it for a bolt to pass through. Some companies send these with a budget boost kit and instructions to add them to the upper column, above the cup. However, as @Chris said, this is not a good place (in the front) since the extension will likely cause the edge of the cup to rub on your spring. The correct way is to remove your spring and tap into the lower spring perch (5/16” or 3/8” is fine). Then add your extended bumpstop there with a new grade 8 bolt the proper length. I’ll post some pics when I get out of bed

As I just did this recently thought I’d beat you to a pic. The bumpstop are those two hockey puck looking things on the bottom.

 

[weldedcambolt]

In an ideal world yes, but at least make sure that your spring doesn't touch it at any point in its travel arc

—
There must have been a time
when we could have said no.

okay,
i havent seen it or heard it rubber yet in the front, but aint be rough with it yet, till, i get it all secure to be rough with it. I will pay attention to it. Now the back jounce that fell out on each side. do those jounces, just get pushed up into the cup, and held on with internal pressure of the cup being smaller? an can you get em in without taking the spring off, an if the spring has to come off, might as well, replace the cup? An having the cup, upside down, will it lead to water getting in there an corroding the cup an lower spring perch?

 

[tomtaylz]

okay,
i havent seen it or heard it rubber yet in the front, but aint be rough with it yet, till, i get it all secure to be rough with it. I will pay attention to it. Now the back jounce that fell out on each side. do those jounces, just get pushed up into the cup, and held on with internal pressure of the cup being smaller? an can you get em in without taking the spring off, an if the spring has to come off, might as well, replace the cup? An having the cup, upside down, will it lead to water getting in there an corroding the cup an lower spring perch?

1. Yes the jounces are on just by pressure
2. Not 100% if you could get them in with the spring still on, maybe if you the axle droop
3. The cup doesn’t actually go upside down. You just add the new components to the bottom

 

[weldedcambolt]

As I just did this recently thought I’d beat you to a pic. The bumpstop are those two hockey puck looking things on the bottom.

Okay, so you got the bump stop, on the bottom of the spring perch, an you go the jounce bumper on the bottom of the upper spring perch, an you use them in combination. an this article was to understand how to measure the right size bump stop an jounce bumper, so you dont blow your fender out? does that sound correct

an for the front, you can put the jounce bumper an cup on the bottom, an the bump stop on the top inside the spring, or just the jounce bumper on the bottom.

 

[weldedcambolt]

1. Yes the jounces are on just by pressure
2. Not 100% if you could get them in with the spring still on, maybe if you the axle droop
3. The cup doesn’t actually go upside down. You just add the new components to the bottom

ok, but the cup always stays on the top hanging down like a cup bat, with both the front an the back, or just the rear.

 

[Chris]

ok, but the cup always stays on the top hanging down like a cup bat, with both the front an the back, or just the rear.

Both the front and rear.

 

[weldedcambolt]

okay, i was getting confused between the term bumpstocks an the jounce bumper. along with the not good part, with the front putting the bump stops in on top, when i was thinking you were saying to not put the jounce bumper on top in the front, but were saying to not put the bump stops up top in the front. now were good. so in my pictures, are those small bump stops on the bottom.

 

[bobthetj03]

Here is an example of why you don't want to add more bump stop to the front upper cup. At droop, the jounce bumper comes close to hitting the spring as it arcs when extended.

This isn't as much of a problem for the rear springs because of the ballon like shape of the spring, so you can add more bumpstop to the rear upper spring cup. The front needs the added bumpstop to the lower perch.

 

[bobthetj03]

okay, i was getting confused between the term bumpstocks an the jounce bumper. along with the not good part, with the front putting the bump stops in on top, when i was thinking you were saying to not put the jounce bumper on top in the front, but were saying to not put the bump stops up top in the front. now were good. so in my pictures, are those small bump stops on the bottom.

This is a jounce bumper,

Rear jounce bumper,

They are a soft cushion that swedges into the steel spring cut and held into the cup under pressure.

 

[Drizit]

Yep that's it exactly

By the way the setup shown above with the hockey pucks is not ideal strictly from point of view of the bolt holding it in. You want to recess the bolt as with the head sticking up like that it will destroy the jounces in short order.

Like this

—
There must have been a time
when we could have said no.

 

[Serbonze]

Yes, you can get the jounce bumpers in without removing the springs. Just let the axle go to full droop.