Help !! What lift do I need

[Tina Thomas]

Hello,
I am fixing my fathers 78 k5 blazer for my sons 16th bday..what lift do I need for 37x13.5 on 20 x12

Also what gear ratio should we use for rear end

 

[Craig 85]

Here's my old K5 circa 1992. 6" Skyjacker all spring lift with 36"x 15" wide radials. The front would have rubbed if I did not use the cut out flares. My rims were 9.75" wide with about 4.75" backspacing. My truck had 4.10 gears and was fine with a stock 400 SBC. Brakes are going to be an issue if you're keeping the stock axle. I did a 3/4 ton axle swap on this one to get biggers gears and brakes.

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[HotRodPC]

Yep, 6in lift at least for 37's at bare minimum. If it's not quite enough, then maybe add a 1in Hockey Puck body lift later on.

 

[CSFJ]

You'll also need to address steering geometry, and drive shaft length.

 

[Old77]

I moved this to the proper subforum for you

 

[hirschdalechevy]

What you are going to do with your blazer ? Street truck or off road ? If it's street mainly you can get away with less lift with big rubber , off road not the case.

Your 12 inch wide wheels hang the tire's out a lot more than say an 8 inch wheel , which leads to fender cutting with a lower lift for off road and sometime's on the street as well. Going to larger lift's cost's a lot more money and modifications to get it right for wide wheels with big rubber. Narrow wheels you can get away with less lift and trimming of the body even with tall tire's. Back spacing of your wheels come's into play as well.

With that said , (street truck with 12 wide wheels) , I would go 6 inch, (soft ride) lift spring's and then take those and put a 1 inch 0 rate block under them, (front and rear) with a new center pin , then you would be a clean 7 inch lift. Then for steering I would go a 2 inch drop pitman on the box and a 6 inch raised steering arm on the axle. Then I would chuck the sway bar in the trash, (not needed, imo). Then brake lines , (longer) , e-brake cable's , (longer) , drive line's , (longer). Then check everything out for clearance ,(should be good). If you need a little more lift then do the 1 inch body lift like , (hot rod pc) said.

12 wide wheels are the hang up for needing more lift , so for the street you need 7 inches of lift with 37's on 12 wide's to keep from cutting you front fender's and you could still do mild off road stuff as well but make sure you have some room at the front and rear of your front fender's when turning.

Off road is a whole different deal , you will need more lift and cross over steering and more modifications for your k-5 to be done right.

My k-5 has 9 inches of lift , t-case drop , cross over steering , etc... with 10 inch wide wheels and 38x14.50 tire's , with cut front fender's and it still rub's off road a bit , but it does not hit doing mild off road and street driving and thats with only 10 inch wide wheels.

Here is a pic of my blazer , (I wheel this rig all the time and it's great on the hwy.)

Hope this helps you out.

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[Dish]

6 inch if pavement queen
8 inch if going to 4 wheel
And it's for your son it will most likely be off road at some point I would say a 8 and would go springs front and back and also put a shackle flip on rear of rear springs that way you can use a small of block as possible in rear and would run a crossover steering in front to take pressure off the frame at steering box

 

[roundhouse]

Id start with 33s and no lift and drive t a while
You didn’t provide much info about the truck, it’s condition and modifications ,

If it’s been sitting for a while you’re gonna most likely going to be dealing with cleaning or replacing TJ fuel tank and pump and rubber lines
Carburetor replacement or rebuild
Radiator rebuild or replacement , hoses , probably water pump etc

You might consider if trim the wheelwells a little and depending on the wheel offset and width you can probably use 35s with no lift and 37s with a 3 or 4 inch lift


Gonna need 4.56 or 4.88 gears
That’s going to be pricy ,
And worth it
Setting up gears is the automotive equivalent of brain surgery , and has to be done by some grey haired guy with a lot of experience , or it won’t last

But if you have stock axles , they won’t last Very long with 37s
Especially with a teenage driver

The rear 10 or 12 bolt is not even strong enough for 29” stock tires
It won’t last much over a week with 37s

You’re gonna Need 14 bolt rear axle

Might get by with a Dana 44 front , but then you’ll need the 3/4 ton spindles rotors and brakes to handle the giant tires .

Might be easier and cheaper to pick up a army CUCV K30 for the Dana 60 front and 14 bolt which should be 4.56 ratio

And as the others mentioned
Gonna need longer brake lines ,
Longer driveshafts , about $300 each
$1000 for leaf springs , $500 for shocks , bumpstops, etc

Any lift over 4” is going to need steering upgrades
Frame bracing, dropped pitman arm
Maybe a crossover tie rod

Might need to switch from vacuum booster to hydro boost for the large tires

It’s a lot of $$ , easily $2000 in parts plus whatever the tires and rims cost , another $2k ?
And that’s not counting labor , that’s assuming you’re doing it yourself

A lot of work and money for something that won’t be a daily driver since it will get 7 MPG

 

[roundhouse]

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Above pic is with no lift and 33s on stock 6 lug rally wheels
got onto a calendar with this picture

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Above pic is a before and after
29” stock tires no lift
And with a 4” lift and 35” tires

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35 tires , 8 lug 15” slot mags 4” lift with 1” hockey puck body lift

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This nighttime pic got selected for some actual wall art