Adjustable control arm lengths for various lift heights?

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AOR

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This question is on the minds of most 4x4 enthusiasts who are building their rig themselves. What adjustable control arms length do I need for my lift height? Which is a great question. Most mfg go +/- 1" depending on the lift height. For short arm lifts that is.

This question is really more focused @mrblaine . I would like to pick your brain Sir. Since you have the technical knowledge, and real world application of designing products for market. What say you to the following?

Can you have a single arm length for a JK and lift heights of 2.5-4" ? Same question for TJ/LJs. What would that be over stock length. The reason I ask is, the new mfg I picked up has three lengths spec'd for lift heights to 6" ( less then 4", 4-6", and 6" plus). This has me puzzled. They are using JJs for their highest level product.

I have possed the question to them, but have yet to get an answer.

Thank you for your or anyone else's imput.

Allen
 
I'm curious about this as well. I know the lengths Currie specifies with their 4" lift control arms and they are mostly accurate.

I know @David Kishpaugh likely has a good answer to this as well.
 
AOR said:
Also, above 4" lift height, wouldn't you want to go long arms anyway?
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I'll let an expert chime in, but I was always under the impression that the rule of thumb was they anything over 4" should be long arm.
 
Chris said:
Yep! I've never seen a company make a lift over 4" that didn't use long arms.

Does such a product exist?
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Not to my knowledge. Btw, I will be in and out today. So, please don't take offense if I don't participate a lot this morning in this thread. Have to get the bare root Raspberries and Blueberries in the beds.
 
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AOR said:
This question is on the minds of most 4x4 enthusiasts who are building their rig themselves. What adjustable control arms length do I need for my lift height? Which is a great question. Most mfg go +/- 1" depending on the lift height. For short arm lifts that is.

This question is really more focused @mrblaine . I would like to pick your brain Sir. Since you have the technical knowledge, and real world application of designing products for market. What say you to the following?

Can you have a single arm length for a JK and lift heights of 2.5-4" ? Same question for TJ/LJs. What would that be over stock length. The reason I ask is, the new mfg I picked up has three lengths spec'd for lift heights to 6" ( less then 4", 4-6", and 6" plus). This has me puzzled. They are using JJs for their highest level product.

I have possed the question to them, but have yet to get an answer.

Thank you for your or anyone else's imput.

Allen
Click to expand...


There is enough adjustability in a JJ shank to accommodate those lift heights but as a company, you want to avoid the internet BS of nitpicking every single aspect of a product to death which includes how much shank is showing at a specific lift height.

It sounds like what they have done is pick the max thread showing and altered the length of the non adjustable section to make that work.
 
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Teraflex has a TJ alignment 3 part video on YouTube, it explains general adjustments for a long arm for a rubicon because with a rear CV joint ,driveshaft angle will be different than a all unjointed driveshaft it has a lot of good info.
 
mrblaine said:
There is enough adjustability in a JJ shank to accommodate those lift heights but as a company, you want to avoid the internet BS of nitpicking every single aspect of a product to death which includes how much shank is showing at a specific lift height.

It sounds like what they have done is pick the max thread showing and altered the length of the non adjustable section to make that work.
Click to expand...

Okay. So you are saying that they probably have way too much shank still in the arm? Also, that they could get away with one length of arm? Or, they are using one length of arm and are using it as a marketing ploy.

TF example below for the front lower Sport Flex Arms (fixed and just one example). They only have increased the arm length by 3/16" for up to 3". Granted, you will get approximately 4.3-4.5 deg caster with 3" lift and approximately 4.8 deg with a 2.5" lift (other factors considered). Given you want to be on the upper side of 5 deg, I understand the adjustability part. Wouldn't you just need one arm factory length or slightly long with a JJ?

Factory Length= 22-5/8”
Sport Length= 22-13/16”
 
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Synergy fixed front LCA for JK (again example), is only .25" longer the stock and is for 3" lift. Below are some numbers they have for caster results and lift heights. http://www.synergymfg.com/Synergy-J...ed-Front-Lower-Control-Arms-Pair-p-29225.html

Lift/Caster Measurements
Stock 6.5 Degrees
2" Lift 5.5 Degrees
3" Lift 5.0 Degrees
4.5" Lift 4.5 Degrees

Just try to understand if there is really a need for multiple lengths of the fixed portion in an adjustable arm(s). Sounds like, as long as you do not exceed the "4x4 communities" definition of too much thread showing, you could get away with one length arm. Is this the gist of it?
 
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AOR said:
Synergy fixed front LCA for JK (again example), is only .25" longer the stock and is for 3" lift. Below are some numbers they have for caster results and lift heights. http://www.synergymfg.com/Synergy-J...ed-Front-Lower-Control-Arms-Pair-p-29225.html

Lift/Caster Measurements
Stock 6.5 Degrees
2" Lift 5.5 Degrees
3" Lift 5.0 Degrees
4.5" Lift 4.5 Degrees

Just try to understand if there is really a need for multiple lengths of the fixed portion in an adjustable arm(s). Sounds like, as long as you do not exceed the "4x4 communities" definition of too much thread showing, you could get away with one length arm. Is this the jist of it?
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Pretty much the gist of it.

Jeep boards by and large are a funny place. They get very wound up over stuff that is bizarre and just plain wrong.

How dare you offer a control arm that adjusts shorter than stock? I'm upgrading, my stuff needs to be longer than stock.

Well, when you raise a TJ, the pinion has to rotate up and due to the little fact that you can't rotate the pinion without moving the axle fore or aft, one set of arms may well be shorter than stock and the other set a bit longer.

They also don't understand that the tires have to center in the wheel well at full stuff and hit the bump stops nicely. That means with 35's, the axle is going to look slightly forward at ride height because the axle moves back slightly as it moves up to hit the bump stops.

Just a few days ago, I saw it reported yet again that you use the uppers for pinion angle and the lowers for wheelbase. Unfortunately, you can't shorten or lengthen either set without changing both the wheelbase and the pinion angle.
 
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mrblaine said:
Pretty much the gist of it.

Jeep boards by and large are a funny place. They get very wound up over stuff that is bizarre and just plain wrong.

How dare you offer a control arm that adjusts shorter than stock? I'm upgrading, my stuff needs to be longer than stock.

Well, when you raise a TJ, the pinion has to rotate up and due to the little fact that you can't rotate the pinion without moving the axle fore or aft, one set of arms may well be shorter than stock and the other set a bit longer.

They also don't understand that the tires have to center in the wheel well at full stuff and hit the bump stops nicely. That means with 35's, the axle is going to look slightly forward at ride height because the axle moves back slightly as it moves up to hit the bump stops.

Just a few days ago, I saw it reported yet again that you use the uppers for pinion angle and the lowers for wheelbase. Unfortunately, you can't shorten or lengthen either set without changing both the wheelbase and the pinion angle.
Click to expand...

Thank you for your participation.

Allen
 
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AOR said:
Totally understood the direction that was aimed.
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Thank you. We've been battling the lack of understanding for years and it has been an uphill fight all the way. Very few seem to be able to understand that 1" less wheelbase won't prevent you from making an obstacle and 1" more won't make you a hero that goes places no one else can.

One of the more egregious misunderstandings is the marketing of stretch kits with shorter fuel tanks and longer control arms for the rear. They advertise them as a 5" stretch because the mount for the tank moves the tank back 5" from stock. That leads the end user to believe that his stock 94" wheelbase will now be 99" but he overlooks that his lifted TJ on 35's is at 92 so he paid a whole bunch of money for an effective 3 more inches of wheelbase which never really makes that much difference. Generally that works out to about a thousand bucks an inch if you're paying someone to do the work.

We wheel in difficult terrain and I build rigs quite frequently that retain the lifted wheelbase of a TJ on 35's that out wheel the crap out of stretched rigs simply due to good geometry, good clearance, and excellent handling.
 
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mrblaine said:
Thank you. We've been battling the lack of understanding for years and it has been an uphill fight all the way. Very few seem to be able to understand that 1" less wheelbase won't prevent you from making an obstacle and 1" more won't make you a hero that goes places no one else can.

One of the more egregious misunderstandings is the marketing of stretch kits with shorter fuel tanks and longer control arms for the rear. They advertise them as a 5" stretch because the mount for the tank moves the tank back 5" from stock. That leads the end user to believe that his stock 94" wheelbase will now be 99" but he overlooks that his lifted TJ on 35's is at 92 so he paid a whole bunch of money for an effective 3 more inches of wheelbase which never really makes that much difference. Generally that works out to about a thousand bucks an inch if you're paying someone to do the work.

We wheel in difficult terrain and I build rigs quite frequently that retain the lifted wheelbase of a TJ on 35's that out wheel the crap out of stretched rigs simply due to good geometry, good clearance, and excellent handling.
Click to expand...

Makes total sense to me. Those last three should be the target of all builds. But then again, half the shops and half of most mfg's inventory would disappear. Maybe a good thing really.
 
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mrblaine said:
<snip>

We wheel in difficult terrain and I build rigs quite frequently that retain the lifted wheelbase of a TJ on 35's that out wheel the crap out of stretched rigs simply due to good geometry, good clearance, and excellent handling.
Click to expand...

I'm an amateur at all of this and will probably remain so. So, how do we set up our suspensions to get good geometry, good clearance and excellent handling? What are we looking for, in other words, and how do we go about it? I have clear design goals, but no idea what parts to look for and how to arrange them.
 
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