Possibly got the wrong Rancho shocks


TJim

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So, I did a 2.5" SL. As suggested in this forum I chose Rancho RS5000X shocks. I think almost anyone in this forum suggest RS55128 vs RS55239 front shocks for this kind of lifts.

Today I took some measurements.

Front Shocks have around 5.7" up travel. Ranchos RS55128 have compressed length of 13.05". That means that my shock length at ride height is 18.75".

RS55128 - Extended length: 21.03"
That means that I have 21.03" - 18.75" = 2.28" DOWN TRAVEL
UP TRAVEL
is at 5.7" as mentioned above.

On the other hand!
RS55239 (Compressed length: 14.43", Extended length: 23.84")
Which means,
Up travel = 4.32"
Down Travel = 5.09"


It seems that RS55239 would be a better choice for a 2.5" SL. Am I right or wrong? Do you find any flaws in my thinking? Please correct me if I am wrong.

Do you have any other suggestions for me? I just installed RS55128, and I don't know what to do!
 

Gollywomper

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So, I did a 2.5" SL. As suggested in this forum I chose Rancho RS5000X shocks. I think almost anyone in this forum suggest RS55128 vs RS55239 front shocks for this kind of lifts.

Today I took some measurements.

Front Shocks have around 5.7" up travel. Ranchos RS55128 have compressed length of 13.05". That means that my shock length at ride height is 18.75".

RS55128 - Extended length: 21.03"
That means that I have 21.03" - 18.75" = 2.28" DOWN TRAVEL
UP TRAVEL
is at 5.7" as mentioned above.

On the other hand!
RS55239 (Compressed length: 14.43", Extended length: 23.84")
Which means,
Up travel = 4.32"
Down Travel = 5.09"


It seems that RS55239 would be a better choice for a 2.5" SL. Am I right or wrong? Do you find any flaws in my thinking? Please correct me if I am wrong.

Do you have any other suggestions for me? I just installed RS55128, and I don't know what to do!
Looks better. Without custom shock mounts we usually have compromise somewhere near the 50-50 range.
 
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Hoboscratch

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I have a winch/plate and stock bumper and have the same problem. I don’t plan to put a new bumper on anytime soon but my RS55128 shocks are also too short, similar measurements to what you got.

I just ordered the 239’s to replace these which will put me at close to a 50/50 bias. Same with the rears, I’m changing the 240’s for 241’s. Every application is different.
 
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TJim

TJim

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I have a winch/plate and stock bumper and have the same problem. I don’t plan to put a new bumper on anytime soon but my RS55128 shocks are also too short, similar measurements to what you got.

I just ordered the 239’s to replace these which will put me at close to a 50/50 bias. Same with the rears, I’m changing the 240’s for 241’s. Every application is different.
To be honest I cannot see how every application is different. 2.5" SL = 2.5" SL.

The ride height for every TJ that would be lifted 2.5" over stock would be the same no matter what (I am talking about final lift height, and not advertised). Which means up travel and down travel would be exactly the same in each application.

The only case that this shock would be okay would be if the advertised 2.5" springs turned out to give you 1.5" or lower lift.

So, that leads me into the conclusion that RS55128 should NOT be suggested to people for 2-3" lifts.
 
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Hoboscratch

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Well, if you have a big heavy bumper and a big winch etc, it will lower your overall height gained from the lift. Mine lowered .5” when I put the winch and plate on. So yeah, the goalposts do move depending on what you end up doing with it.

I would say the fix for this would be not to have folks recommend length but instead recommend measuring first then buying shocks. Which is what I did not do unfortunately.
 
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TJim

TJim

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Well, if you have a big heavy bumper and a big winch etc, it will lower your overall height gained from the lift. Mine lowered .5” when I put the winch and plate on. So yeah, the goalposts do move depending on what you end up doing with it.

I would say the fix for this would be not to have folks recommend length but instead recommend measuring first then buying shocks. Which is what I did not do unfortunately.
This is what I did not do too unfortunately. Mostly because it is my daily driver and didn't have the luxury to leave it jacked for days.

This also leaves a hole in my pocket since I am trying to build my TJ in a very limited budget.
 

Hoboscratch

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I know brother, same here. I put off buying my new ones for 500 miles or so but I have a few wheeling trips planned so had to bite the bullet. Hopefully I can sell them on here or locally to recoup some losses
 

Mike_H

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This is what I did not do too unfortunately. Mostly because it is my daily driver and didn't have the luxury to leave it jacked for days.

This also leaves a hole in my pocket since I am trying to build my TJ in a very limited budget.
It won't be the end of the world, running them out of balance. I ran that way for 3 years. No ill effects.
 
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TJim

TJim

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It won't be the end of the world, running them out of balance. I ran that way for 3 years. No ill effects.
The main disadvantage that concerns is very limited down travel.

Even with disconnected sway bar my articulation would be very limited. Am I wrong on that?
 

JMT

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To be honest I cannot see how every application is different. 2.5" SL = 2.5" SL.

The ride height for every TJ that would be lifted 2.5" over stock would be the same no matter what (I am talking about final lift height, and not advertised). Which means up travel and down travel would be exactly the same in each application.

The only case that this shock would be okay would be if the advertised 2.5" springs turned out to give you 1.5" or lower lift.

So, that leads me into the conclusion that RS55128 should NOT be suggested to people for 2-3" lifts.
FWIW, I always recommend 55239 and 55241 for 2.5" SL. It's also what I run with 3.5" SL, and at that lift height, it's darn near 50:50 travel.
 
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JMT

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This is what I did not do too unfortunately. Mostly because it is my daily driver and didn't have the luxury to leave it jacked for days.

This also leaves a hole in my pocket since I am trying to build my TJ in a very limited budget.
Can you return the shocks?
 
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TJim

TJim

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FWIW, I always recommend 55239 and 55241 for 2.5" SL. It's also what I run with 3.5" SL, and at that lift height, it's darn near 50:50 travel.
I wish I had seen your recommendation before buying! haha

I am going to try to find the time to jack it up tomorrow to take some better measurements. I just learned that a friend has a spare set of 55239/55241. I might at least borrow it later to compare them.
 
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TJim

TJim

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Can you return the shocks?
Unfortunately no. I might consider selling them.

I am mostly concerned about articulation, and not ride quality. I am not very picky TBH, since I haven't had any major problems with their ride quality the past month.

EDIT: I haven't been off road yet though
 
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JMT

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Unfortunately no. I might consider selling them.

I am mostly concerned about articulation, and not ride quality. I am not very picky TBH, since I haven't had any major problems with their ride quality the past month.

EDIT: I haven't been off road yet though
Yeah, I know, just aiming to get the travel 50:50, which is a noble goal.
 
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TJim

TJim

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Yeah, I know, just aiming to get the travel 50:50, which is a noble goal.
BTW, with some quick maths I calculated that with 55239/55241 I would have around 4.3" up travel and 5.1" down travel. Are those close to your results?
 

JMT

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BTW, with some quick maths I calculated that with 55239/55241 I would have around 4.3" up travel and 5.1" down travel. Are those close to your results?
Yes, but I'm at 3.5" SL, so I think my up is closer to 5 and down is 4.4 (true measurements)
 
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Mike_H

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The main disadvantage that concerns is very limited down travel.

Even with disconnected sway bar my articulation would be very limited. Am I wrong on that?
1620157579641.png


It works. Its not ideal. Just means you'll pull a tire off the ground a bit sooner and the jeep won't stay as level. You still have the travel, its just biased toward up travel vs down travel. If you're going to have a bias in travel, up travel is WAY better than down travel.
 
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TJim

TJim

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View attachment 249889

It works. Its not ideal. Just means you'll pull a tire off the ground a bit sooner and the jeep won't stay as level. You still have the travel, its just biased toward up travel vs down travel. If you're going to have a bias in travel, up travel is WAY better than down travel.
Is this RS55128/RS55240 with 2.5" SL?

If you do it all over again (with Rancho shocks), would you prefer RS55128/RS55240 or RS55239/RS55241?
 

Mike_H

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Is this RS55128/RS55240 with 2.5" SL?

If you do it all over again (with Rancho shocks), would you prefer RS55128/RS55240 or RS55239/RS55241?
Its OME Springs 2" with Bilstein 5100 shocks. Not exactly what you're running, but close enough. I had about 5" up and 3" down, the Bilsteins are an 8" travel shock, meant for 0-2" of lift (basically stock replacement).

I'm currently adding a 3/4" spacer to my springs and putting the 239/241's in. I'm planning to be pretty close, travelwise, to what @JMT posted above.
 
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