Looking to run 40s or 37s! Setup advice.


Most Wanted 21

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Well, where do I start? I am a complete noob to YJ's but have a background in building S chassis drift/track cars. I am looking to lift my 87 YJ Laredo and run 37s or possibly 40s preferably without a coilover setup (at least for now). I find it so difficult to find a reputable shop in my area LA/San Pedro and I've scoured the internet for setup advice but it's all over the place.

What would be recommended to get this setup complete without breaking the bank (leaf spring for now...)?

Currently, it's only driven locally and a few times a week as I am a Software Engineer and spend my days behind the computer screen at home.

Hope to do trails in the future if time permits, not much available here in my local region though. But for now, I just want it to have a mean stance sitting high on big tires as I get tired of staring at it sitting on the stock setup.

So far, I've ordered a custom tan hardtop, upgraded the battery to an Optima blue top, installed a new radiator, thermostat, and hoses. I will be doing a custom audio install in the next few weeks (any advice here is appreciated as well).

Any and all advice / recommendation is greatly appreciated! All critique is welcome! :cool:

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jeepjoe43

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Dec 4, 2020
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Black Canyon City, AZ 85324
Get out your wallet.
First, throw away the stock axles, neither of them will withstand tires of that size. 35" ABSOLUTE MAX, and that is questionable.
Whatever you replace the axles with will have to be re-geared, somewhere in the 4.88-5.89 range.
Next you're looking at a serious suspension/body lift and ALL the complications (and expenses) that come with them.
And you Will have them. Like a Slip Yoke Eliminator and CV driveshafts so you can actually drive it more than 40mph.
You're essentially turning a "Car" into a monster, not impossible, but it's going to be expensive.
Don't know what your budget is, but just be prepared.
 
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OP
Most Wanted 21

Most Wanted 21

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Get out your wallet.
First, throw away the stock axles, neither of them will withstand tires of that size. 35" ABSOLUTE MAX, and that is questionable.
Whatever you replace the axles with will have to be re-geared, somewhere in the 4.88-5.89 range.
Next you're looking at a serious suspension/body lift and ALL the complications (and expenses) that come with them.
And you Will have them. Like a Slip Yoke Eliminator and CV driveshafts so you can actually drive it more than 40mph.
You're essentially turning a "Car" into a monster, not impossible, but it's going to be expensive.
Don't know what your budget is, but just be prepared.
Thanks for the 'hole in my pocket' warning!
I figured this wasn't going to be an easy task or at least if I want it done right...
Where could I search for better and beefier axles? Is it typically a junkyard or online? How do I know which ones to look for? Do they sell new sets or is it just not worth the price?

For the lift kit, I prefer to go with the leaf spring route since coilover setup is looking like $10K++! Which brand of kits are the best? Also, thinking SOA setup might be better?
I'd say a 5K budget is reasonable for now. I do plan on an engine swap for the near future and maybe coilovers one day if I actually get into crawling and trailing it.
 

jeepjoe43

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For the axles, that is subjective. Probably best to do the junk-yard scrounge for some truck axles.
You've got some homework to do.
You'll hear a lot of different opinions on which are the best, what will fit, what won't, etc.
And opinions are like ass-holes, everyone has one and nobody wants to hear it.
Try to find someone you can talk to face to face who's actually done it. Not just bought it that way.
I figured you were headed SOA, but with the YJs long tranny/t-case assembly the rear drive shaft is very short.
I don't know if you can even get your Wrangler high enough to do what you want.

Mine was bone stock, clean, rust free and unmolested when I bought it, this was 3 years ago.
I started out with a $5000 budget to accomplish this plan;
2-1/2" Rough Country lift SUA
32"-11.50 TSLs
10" white spokes
Lunch-box lockers
Fabbed front cage
Seats and restraints
Tool box
Tuffy center console for radios and accessory switches (which came out WAY bitchin' BTW)

Done, Go wheelin'.
Nope....
Couldn't go more than 45mph without it sounding like missed a shift. Had to buy a SYE and driveshafts, just recently installed.
3 months after the lift on a local trail a Gremlin showed up. Cutting out on every bump in the road.
Now I can't trust the jeep to wheel to my buddies shop for the SYE install.
Spent a lot of money chasing it and it was a broken, or breaking, wire at the plug for the coil, just found that.
2-1/2 years later I finally get it to my buddies shop to do the SYE after deciding to just call a wrecker.
I find I bent the D35 on that very first trip, the lunch-box won't unlock on one side.
$3400 later I have a moose of a custom D489 on a pallet, re-geared to 4.88, OX and 35 spline chromos.
Have to re-gear the 30 and upgrade it to match, probably another $2500.
Now I can do the only swap I wanted, but couldn't because of the stock axles.
Granny box!
You see where this is going?
My original $5000 budget has turned into a Continuing Resolution and I've spent closer to $15000 so far.
 
OP
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Geez!

This is exactly why I want to do it right the first time even if I have to go over budget or sacrifice tire size initially in order to take the right steps and step up to 40s eventually.

I'm talking to a local shop with a decent rep right now, waiting on the guy to get back to me with some options.

Ahhh! Maybe I should just sell it clean stock and save the headache. Lol.
 

jeepjoe43

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Black Canyon City, AZ 85324
Geez!

This is exactly why I want to do it right the first time even if I have to go over budget or sacrifice tire size initially in order to take the right steps and step up to 40s eventually.

I'm talking to a local shop with a decent rep right now, waiting on the guy to get back to me with some options.

Ahhh! Maybe I should just sell it clean stock and save the headache. Lol.
That is a Very Nice looking Laredo! Way cleaner than mine!
IMHO, I think she would look Sweet with a 2-1/2" lift sitting on 32s. Classic Jeep.
I know that's not what you're looking for, just saying...
But you could do it without becoming undrivable.
1-1/2" spring lift, 1 to 1-1/4" body lift and a transfer case lowering kit. Easy and cheap.

I just hate to see you end up with something you can't drive, or drive for a long time.
Or worse, not be able to finish.
Been there, done that on another Jeep project that I got too ambitious with.
Now it's a flower pot and it deprived me of 20 years of wheeling.
 

Fouledplugs

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South Carolina
I am looking to lift my 87 YJ Laredo and run 37s or possibly 40s preferably without a coilover setup (at least for now).
You’ll need one ton axles, or something equivalent, to support that tire size as well as much more wheelbase. With leafs, 37’s or 38’s would be a good goal to shoot for.

I was going this same exact route up until a month ago or so. 37’s-40’s on leafs. I was going to keep the gas tank under the tub instead of the popular, “in the tub,” mod. I was going to use a Genright stretch tank paired with a Motobilt stretch kit which allows the use of XJ springs in a spring over setup, gaining 6” of rear stretch.

On the front I was planning on using either XJ springs or front waggy springs to gain the stretch from the offset centerpin and hang the springs as far foward as I could while still keeping a steering box under it.

I scrapped this build plan and went the direction of coilovers and links instead of leafs recently. Using coilovers, I can place my axles exactly where I want them and not be restricted by leaf spring center pins determining my wheelbase.

if I were you, I’d stick with a 2 inch spring and 31’s. Put lockers in it, upgrade the shafts, maybe do an axle swap and get your feet wet before diving into a one ton build on 40’s. You mentioned it yourself, there are not a lot of trails where you live, so who cares? Let the trails tell you what you need.

If you want something road worthy, says Jeep on it, and can handle 40’s, get a JLU or JKU on tons. Going about this YJ build for $5k is a bit unrealistic if done right.
 

Fouledplugs

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The only shop I know of in Cali is WFO Concepts in Auburn, CA. They could absolutley build a SOAYJ on 40’s and get you the axles you need under it as well. WFO is prob about 7 hours away from you, but would be my go-to for something like this.
 
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jeepjoe43

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You’ll need one ton axles, or something equivalent, to support that tire size as well as much more wheelbase. With leafs, 37’s or 38’s would be a good goal to shoot for.

I was going this same exact route up until a month ago or so. 37’s-40’s on leafs. I was going to keep the gas tank under the tub instead of the popular, “in the tub,” mod. I was going to use a Genright stretch tank paired with a Motobilt stretch kit which allows the use of XJ springs in a spring over setup, gaining 6” of rear stretch.

On the front I was planning on using either XJ springs or front waggy springs to gain the stretch from the offset centerpin and hang the springs as far foward as I could while still keeping a steering box under it.

I scrapped this build plan and went the direction of coilovers and links instead of leafs recently. Using coilovers, I can place my axles exactly where I want them and not be restricted by leaf spring center pins determining my wheelbase.

if I were you, I’d stick with a 2 inch spring and 31’s. Put lockers in it, upgrade the shafts, maybe do an axle swap and get your feet wet before diving into a one ton build on 40’s. You mentioned it yourself, there are not a lot of trails where you live, so who cares? Let the trails tell you what you need.

If you want something road worthy, says Jeep on it, and can handle 40’s, get a JLU or JKU on tons. Going about this YJ build for $5k is a bit unrealistic if done right.
Kind of my thoughts, too!
Small steps first.
 
OP
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You’ll need one ton axles, or something equivalent, to support that tire size as well as much more wheelbase. With leafs, 37’s or 38’s would be a good goal to shoot for.

I was going this same exact route up until a month ago or so. 37’s-40’s on leafs. I was going to keep the gas tank under the tub instead of the popular, “in the tub,” mod. I was going to use a Genright stretch tank paired with a Motobilt stretch kit which allows the use of XJ springs in a spring over setup, gaining 6” of rear stretch.

On the front I was planning on using either XJ springs or front waggy springs to gain the stretch from the offset centerpin and hang the springs as far foward as I could while still keeping a steering box under it.

I scrapped this build plan and went the direction of coilovers and links instead of leafs recently. Using coilovers, I can place my axles exactly where I want them and not be restricted by leaf spring center pins determining my wheelbase.

if I were you, I’d stick with a 2 inch spring and 31’s. Put lockers in it, upgrade the shafts, maybe do an axle swap and get your feet wet before diving into a one ton build on 40’s. You mentioned it yourself, there are not a lot of trails where you live, so who cares? Let the trails tell you what you need.

If you want something road worthy, says Jeep on it, and can handle 40’s, get a JLU or JKU on tons. Going about this YJ build for $5k is a bit unrealistic if done right.
Good advice, I'll keep this in mind.
 
OP
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The only shop I know of in Cali is WFO Concepts in Auburn, CA. They could absolutley build a SOAYJ on 40’s and get you the axles you need under it as well. WFO is prob about 7 hours away from you, but would be my go-to for something like this.
Thanks! I will check them out. Currently waiting on T&J Performance to get back to me but we'll see how that goes.
What's your budget for the coilover setup if you don't mind me asking?
 

jeepjoe43

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I kinda want to agree but I feel like it'll be a waste knowing how I am and see myself wanting to go bigger anyways which will lead to ditching the setup with 31's and spending more to go bigger still...
You're a noob, you need to learn the vehicle a step at a time. Mod by mod.
jumping into a full blown beast can be down-right dangerous if you don't know what you're doing.
I know you want the "Look", I have couple of neighbors with CJ5s, one on 37s, the other on 40s.
Personally, I think they both look ridiculous. And they both both bought them that way.
 

smgager

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It is a cool episode, but I see around $20k if not more to have a shop do what they did to that jeep and I'm low-balling. Everything past the transmission is replaced and there is a lot of fab work. That is 2.5 to 3 times my jeep's cost and I have a lot of fun in mine as it sits.
 
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smgager

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You're a noob, you need to learn the vehicle a step at a time. Mod by mod.
jumping into a full blown beast can be down-right dangerous if you don't know what you're doing.
I know you want the "Look", I have couple of neighbors with CJ5s, one on 37s, the other on 40s.
Personally, I think they both look ridiculous. And they both both bought them that way.
I would think that 40s would come close to rubbing each other in the middle on a CJ5. Please post a picture of that.
 

smgager

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Messages
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Wilmington, NC
Well, where do I start? I am a complete noob to YJ's but have a background in building S chassis drift/track cars. I am looking to lift my 87 YJ Laredo and run 37s or possibly 40s preferably without a coilover setup (at least for now). I find it so difficult to find a reputable shop in my area LA/San Pedro and I've scoured the internet for setup advice but it's all over the place.

What would be recommended to get this setup complete without breaking the bank (leaf spring for now...)?

Currently, it's only driven locally and a few times a week as I am a Software Engineer and spend my days behind the computer screen at home.

Hope to do trails in the future if time permits, not much available here in my local region though. But for now, I just want it to have a mean stance sitting high on big tires as I get tired of staring at it sitting on the stock setup.

So far, I've ordered a custom tan hardtop, upgraded the battery to an Optima blue top, installed a new radiator, thermostat, and hoses. I will be doing a custom audio install in the next few weeks (any advice here is appreciated as well).

Any and all advice / recommendation is greatly appreciated! All critique is welcome! :cool:

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BTW That Jeep looks like it is in great shape. My advice would be a cheap winch, 31s or 33s, re-gear appropriately for the tire size, selectable locker in the front and rear, 2.5 in spring lift, and a slip yoke eliminator. Can be done for $5k if you do most/all of the work.
 
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jeepjoe43

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Black Canyon City, AZ 85324
BTW That Jeep looks like it is in great shape. My advice would be a cheap winch, 31s or 33s, re-gear appropriately for the tire size, selectable locker in the front and rear, 2.5 in spring lift, and a slip yoke eliminator. Can be done for $5k if you do most/all of the work.
They're both stretched, one the front the other the rear.
I don't have one of those smart phone thingies, so pics are a problem for me. Sorry.