Suspension lift

Hi,
I'm new to this forum and had a few ? about suspension lifts. I'm thinking of doing a 3 inch black diamond lift and was wondering about pitman arm and driveshaft length. I currently have a 258, t-18, and what I believe is a dana 20 transfer case. Do I need a dropped pitman arm for this amount of lift??? How about longer rear driveshaft???? And one more that I just thought of, do I need a transfercase lowering kit???
Any help would be appreciated, I plan on these mods in the spring.
Oh and by the way, it's a 1975 CJ5.
Thanks
High5

 

Howdy High5, and welcome from another '75 owner from southwestern Pennsylvania. Where are you from? Got any pics of yer rig?

With a 2.5" kit, you definately don't need the pitman arm, the shims, driveshafts, etc... With the 4+" kit, you need a pitman arm and shims, but I don't believe you need the other stuff. With a 3" kit, you're gonna have to see. May or may not need shims, but since they're cheap, I'd use them. The pitman arm can be had for around $80 and will definatley help - know that there is a difference between the manual steering arm and the power steering arm, but I'm not sure what the difference is.

As for the driveshaft, you should be OK, unless you plan other extreme stuff or super articulation - where you may risk over extending the slip part of the shaft...

 

Welcome High5. I'm "resto-modding" a '74 CJ5 right now for some friends. It has the 258, T-18, and Dana 20. I used the Black Diamond 3" kit, along with 8* shims for the rear axle. The kit doesn't come with shims, nor does it mention needing them - I was a little ticked at that b/c if a novice had been working on it, he/she wouldn't have known to ask about the shims. The rear drive shaft is really short behind the T-18, but it did hook back up just fine with only the shims in place. I didn't lower the t-case either.

I don't have it on the road just yet, so I can't speak about vibration, but it looks okay to me.

BTW: I'm not going to add a dropped pitman arm either, unless it turns out to be a big problem.

 

Thanks for the welcome guys!!
I live in Ottumwa, IA which is in Southeastern Iowa. I don't have any pics of the Jeep on my digital camera yet, but I sure will get some. I had no idea about the shims. Where did you pick them up at??? I'm also going to be putting a new power steering box in as well as some ignition and carb work. My dad and I built this when I was in high school and we were on quite a budget then. Now I am going to sell my Ranger and make this a daily driver. It definitely needs suspension work, it has the 10 leafs all the way around. Rides like a lumber wagon!! Plus, right now I have a clifford intake and a carb that is too big on there. It also has headers and glasspacks. Sounds like a stock car I like it, but it is a little loud.
Thanks for the advice
High5

 

I am going to put a 4" lift on 74 cj. I will get it this weekend.


Jerry

 

One more thing since this has been answered so well. This lift will surely improve the ride since it currently rides on 10 leaf springs, right?????
Now, I swear you can't push down on the front end and move it any. I'm 220 pounds and can't move it an inch. It's always been that way. Was this an option for a plow and V8???? I can't understand why else Jeep would offer it.

Thanks in advance
High5 :stout:

 

Welcome from Eastern Washington. I can't give any advice as I've only had my 75 cj5 for about a year and a half and have a lot to learn. This is the site to learn from. I have the 304 with only the five pack leaf springs and it rides fairly good. Good luck.

 

I did not find the stock HD springs in my '73 or '75 to be rough riding. A lot of that "lumber wagon" ride depends on your tire pressure and the sidewall stiffness of your tires. If you have some narrow stiff tires way with a load rating much higher than the weight of a Jeep, and you're running the 45 psi listed on the sidewall, the ride will be very harsh.

Running a soft tire will smooth out the jiggles greatly. Drop the pressure to 15 psi and see how the ride changes. Radial tires smooth out the ride a lot too - I know that the heavy bias ply mudders are popular, but you pay a daily price in ride quality for all that sidewall stiffness.

 

Because of the frame design in a CJ, the springs are mounted way inboard of the tires. This means that a soft spring will allow a lot of body lean; stiff springs resist body lean and transfer more weight to the inside side of the suspension on curves. It's all a compromise ... later models changed the frame to move the rear springs further outward. However, with a live axle suspension and leaf springs, there aren't a lot of modifications possible.

You can outboard the rear springs (and use softer rear springs) if you accept having the rear spring hangers stick out beyond the rear body corners. Look at the rear suspension of a Commando for ideas.

Another problem is with lift. To me, the world has gone "lift crazy." On the CJ, you can't change the length of the springs symmetrically because the mounting points are already at the extreme ends of the vehicle. To get a lot of lift, you need higher spring rates and more arch - both of which will make the ride stiffness worse.

So, you have to decide where you will compromise. If you aren't going to drive your Jeep on the street, you can make a lot of changes. IMO you can't really have a "soft" spring rate, minimal body lean, really big tires and stock spring length/location at the same time. The stock configuration is a good compromise that provides acceptable ride, sufficient clearance, and pretty good roll-over resistance with reasonable width tires.

 

Thanks for the help. The Jeep currently rides on 33inch Mud King tires. They are a big, heavy, truck tire. I usually run about 20 pounds of pressure in them. This will mostly be a street rig, but I still want to lift it some so it willl perform off road when the time comes. I'm sure that having a glass body on it, 6 cylinder, and a soft top makes it pretty light and that probably affects the ride too.
Thanks again, I really need to get some pics posted
High5

 

Hope I don't sound like an old fart here, but most times IMO, lift is done for appearance or ego. If it were mine, I'd bring make all the systems reliable, get some softer tires (like Wrangler MT/R?), and wheel the bejesus out of it. So much depends on the skill of the driver that, until you are really familiar with the vehicle, you won't know whether you're getting some benefit from your mods (lift or whatever) until you've driven it a while. Drive first, then mod.

JMHO. Be sure to have fun, whatever you do. Cheers :stout:

 

BTW the 258/T18 combo is great - customers really liked it. What axle ratio do you have? Do you have the rear Trac-Lock? If so, it's probably worn out - not a very agressive posi to begin with. You can rebuild it, or replace it with a locker. That'll help your off-road capability a lot.

 

I really like the engine and trans combination as well. Everyone that has popped the hood is amazed that a straight 6 can sound that good. Problem is, we have had a hell of a time getting it to run good. I think it is going to take a new ignition and carb to fix the problems. Still running the old ignition components and like I said before, a carb that is too big. I need a holley 390, or if I had the cash fuel injection.
It currently has 3.73 gears and open diffs. The gearing is pretty good, I never have any problem cuttin' em loose in first or second. I love that low first gear and the basically straight pipe exhaust. I can't wait for Spring so I can start with the mods we have talked about. It's like 10 below zero here in Iowa and I don't have a heated garage, yet.
Thanks for your advice

High5