Im doing the jump from 3" to 4.5-5". I got new lower arms from RC when I got my lift. They measure 16.5". And I have stock Uppers. I have this chart that gives you a good starting point but how accurate is it? Can I do the jump With the arms I got? I havent shimmed the lowers so i know i can shim them if needed. Im getting an SYE and shims. Longer brake lines, But i dont know if i need arms.

Lift...........Lower Control Arms/Upper Control Arms
********Decimal**Fraction**Decimal**Fraction
Stock........15.75.......15 ¾........15.00.......15
2”.............15.92.......16............14.88.... ...15
3”.............16.09.......16............14.92.... ...15
4”.............16.33.......16 3/8......15.03.......15
4.5”..........16.47.......16 ½........15.11.......15
5”.............16.62.......16 5/8......15.21.......15 ¼
6”.............16.97.......17............15.44.... ...15 ½
7”.............17.36.......17 3/8......15.74.......15 ¾
8”.............17.81.......17 ¾........16.09.......16
9”.............18.30.......18 ¼........16.50.......16 ½
10”...........18.82.......18 ¾........16.96.......17

 

Its accurate. your good

 

Thats what i thought. hopefully other will chime in

 

its correct, i have seen it used on pirate for references and they say its right

 

The chart is accurate, but here is the issue. With stock uppers, your caster angle will be off. This is especially true with any lift over 4".

 

I've used the measurements before and had to give it another inch for the uca & lca so there not 100% correct atleast from my experience.

 

Exactly true. Thats the problem I am currently facing. Over 4in with no adjustable uppers your caster and pinion driveshaft angle sucks. My driveshaft vibrates now because of the pinion angle. I am at 4.75 but I dont want to spend money on more shortarms. I am waiting to get longarms so for now I drive with no front driveshaft.

 

I'd have to take a minute to do the math, but I can't imagine a 10" lift w/ 19" long lower arms (amd matching uppers) wouldn't be over 45*! Not to mention the front axle would swing like a pendelum!

To your point, going another 1.5" in lift, I would think you'd create more negatives than positives by swapping your lower arms. Adding .5" to the lower wouldn't do much for locating your front axle further forward, maybe 1/4" - 3/8"? It would negatively affect your caster and pinion angles as already mentioned.

 

So to do it right i need new arms. i should get uppers???

 

You should be ok without uppers. Rc sells the 4.5 kit with just the extended lowers so it should work. The adjustable uppers are so that you could extend them to rotate the axle forward to adjust the angle of the driveshaft going into the pinion. Your angle will be off. I think the magic number for as much as a stock setup could take is 4.5. Literally at 4.75 I developed problems.

 

Also, RC sells the same lower arms for their 3.5 and 4.5 in lifts. So you are good there.

 

Yea well Im at 3" im adding 1.75 coil spacers and 1.5"-2" Shackles. So if i need them i need them tell me. But do i need lowers to or will 16.5" lowers work shimmed? If i can have solid lowers and adjustable uppers i would like it.

Also does it sound like i covered my bases on what i need to lift??

 

16.5 will be ok. It depends on you also, If you like the ride after the lift and stuff like that. i have seen people use stock control arms on 6in lifts. Im sure their ride sucks but somehow they are doing it. Install the spacers and see how you like it, if it wobbles etc. and go from there. I mean, thats what I did at least. If your driveshaft shakes you need adjustable uppers to rotate the axle. If you get death wobble, you need an adjustable track bar, and align your track bar with the steering.

 

I got a IRO tracbar I'm trying to install now. I want to stay on short arms. Even if it means Drop brackets welded on. The ride sucks now i think but its lifted whats it suppose to ride like???
I got 3 friends that own the same caddy. I dont want it to ride like that. Its a Lifted Jeep.
I want it to be solid on 5" and 33s, so if it wobbles Its getting replaced. I feel i can keep the lowers and buy uppers for now. Then later after i got the lift set and i know what length lowers i need ill buy solid lowers at the right length.

 

Well if you are planning on going with drop brackets than the arm lenght changes. You have to find a chart for that. I think rocky-road.com has a chart for their drop brackets, which by the way are awesome. So if you intend to ever get those, either keep your stock control arms or get both sets adjustable. At 4.5 with drop brackets the control arm lenght goes back to stock I think.