6" Skyjacker Lift with 35" tires? Fitment Good?

[Jason Reed]

On my 1977 GMC 1/2 ton restoration, I was thinking about Skyjacker's 6" suspension lift with 35x12.50x20 on 20x12 wheels. Any cutting or rubbing issues. Thanks for the help.

* Also, while on this topic, what is the preferred or liked/best ride 6" suspension lift for the 1973-1987?

Jason-

 

[Jason Reed]

Also- any issues with having to extend the drivelines with the 6" lift? Or am I good to go?

Jason-

 

[PrairieDrifter]

You’re gonna have to get extended driveshafts and mess with the pinion angles. As for the wheels it depends on what offset and backspacing they’ll have. And also what kind of driving you’re doing, on the street it should be ok

 

[Jason Reed]

Yes- I’m actually building a show/street truck 4x4. Should I be safe and go 8” lift? Is the ride signifigantly different from 6” to 8”? What brand is preferred?

Jason-

 

[PrairieDrifter]

In my opinion I would just go a with a six inch as long as you don’t go bigger than 35’s with that wheel combo you should be fine on the street. I would say any kind of decent flex it would rub slightly with a deep dish rim.

Others might have different opinions. I’ve never messed with big wide rims so I don’t know much about fitment for them.

 

[PrairieDrifter]

As for the brand, off-road design has custom leafs that people say ride pretty nice. You could do their shackle flip in the rear instead of full leaf lift and that would help the ride also. I think EZ ride is another decent brand, and I believe skyjacker is decent as well. 8 inch would definitely ride stiffer than a 6 inch. Probably pretty noticeably, there’s a lot of people with lifted squares on here with all sorts of different brands and lift heights. You can do a site search and find quite a few threads with ride quality info and such

 

[Jason Reed]

Thanks Reaper.. Appreciate it.

Jason-

 

[mavtricks71]

On my 1977 GMC 1/2 ton restoration, I was thinking about Skyjacker's 6" suspension lift with 35x12.50x20 on 20x12 wheels. Any cutting or rubbing issues. Thanks for the help.

* Also, while on this topic, what is the preferred or liked/best ride 6" suspension lift for the 1973-1987?

Jason-

Im doing Skyjacker soft ride leaf springs 8 inch lift right now....I haven't driven the truck yet ....weird thing is my driveshaft "rear" only moved about quarter inch ....I don't think im gona need to mess with it...but im gona put it on the ground and see in a couple weeks.

 

[theblindchicken]

35's will easily fit on a 6" lift. You clearances will definitely be determined based on your offset/backspacing of the wheels. Stock backspacing is right around 4-4.5" if I remember correctly. Smaller backspacing and you'll push the wheels out and make the front and rear of the wheel well easier to hit. Too large of backspacing and you may contact the frame and/or shocks.

I'm only around a 4" lift and some, but running the EZ Ride springs up front and they're pretty comfy compared to the stock springs. Rear end went with a shackle flip and much more comfortable than the stock rear end.

You'll definitely need to put some attention into the steering with probably a brace as well as needing a raised steering arm, potentially with a dropped pitman arm as well. At my height, only a dropped pitman arm isn't enough to correct the steering.


Look up the spring rates on the various kits. You may not be able to find it if you only look at the kit, but find the individual spring part numbers and compare them to each other. The lower the spring rate, the softer the ride, but it will also lower you hauling/towing capacity.

You'll also need to look into getting extended brake lines as well as the parking brake cable.

The axles will have to be shimmed to adjust the pinion angles. Rear driveshaft may be long enough depending on whether you have a long bed or short bed. Front driveshaft will most likely need to be extended.

Hope that helps.

 

[shiftpro]

35's will easily fit on a 6" lift. You clearances will definitely be determined based on your offset/backspacing of the wheels. Stock backspacing is right around 4-4.5" if I remember correctly. Smaller backspacing and you'll push the wheels out and make the front and rear of the wheel well easier to hit. Too large of backspacing and you may contact the frame and/or shocks.

I'm only around a 4" lift and some, but running the EZ Ride springs up front and they're pretty comfy compared to the stock springs. Rear end went with a shackle flip and much more comfortable than the stock rear end.

You'll definitely need to put some attention into the steering with probably a brace as well as needing a raised steering arm, potentially with a dropped pitman arm as well. At my height, only a dropped pitman arm isn't enough to correct the steering.


Look up the spring rates on the various kits. You may not be able to find it if you only look at the kit, but find the individual spring part numbers and compare them to each other. The lower the spring rate, the softer the ride, but it will also lower you hauling/towing capacity.

You'll also need to look into getting extended brake lines as well as the parking brake cable.

The axles will have to be shimmed to adjust the pinion angles. Rear driveshaft may be long enough depending on whether you have a long bed or short bed. Front driveshaft will most likely need to be extended.

Hope that helps.

For the OP's intended use you are correct 6" is enough for 35s. But for true off-roading no way. Under flex and twisting there will be all kind of rubber to metal contact.
You're correct stock backspacing is 4.5. 35" tires can comfortably fit on a 16x8.5 rim.

 

[shiftpro]

On my 1977 GMC 1/2 ton restoration, I was thinking about Skyjacker's 6" suspension lift with 35x12.50x20 on 20x12 wheels. Any cutting or rubbing issues. Thanks for the help.

* Also, while on this topic, what is the preferred or liked/best ride 6" suspension lift for the 1973-1987?

Jason-

Your wishes of 20x12 rims will cause great discomfort when you turn the steering wheel. You can run 35s on 16x8.5(.75) rims with a 6" lift pretty safe on the street, but if you go off-road and twist it up you will have cut tires and bent metal... and an ulcer.

If you need big rims consider 17s. IMO (and many others I promise) 20" rims look like stupid azz on a squarebody.

 

[shiftpro]

Yes- I’m actually building a show/street truck 4x4. Should I be safe and go 8” lift? Is the ride signifigantly different from 6” to 8”? What brand is preferred?

Jason-

Not a lot of hard core drivers use 6" springs anymore, they use 4" and cut the fenders. The arc on a 6" is so much it just reduces flex. 8" are totally worse, they can barely flex. Ride like **** to the point of being dangerous.

 

[theblindchicken]

For the OP's intended use you are correct 6" is enough for 35s. But for true off-roading no way. Under flex and twisting there will be all kind of rubber to metal contact.
You're correct stock backspacing is 4.5. 35" tires can comfortably fit on a 16x8.5 rim.

I was under the impression that it was
33's: 2" street, 4" offroad.
35's: 4" street, 6" offroad.

Or is it more like 5"/7"?

Running about 5-6" on my truck with a 2" body on top now. Pretty sure I won't be rubbing much of anywhere.

Also, OP you'll wanna get a steering box brace kit since our frames like to crack at the steering box with big tires. Should check that to begin with too.

 

[Craig 85]

This is my old '77 K5 (circa 1992). It had 6" Skyjacker springs all around. I had 15.5/36R16.5 Dick Cepek Fun Countrys on 16.5x9.75 wheels. They had 4.75" of backspacing. I added the Bushwacker cutout flares due to some rust issues behind the rear wheel wells. Go figure it was a California truck. In this configuration, it did not rub, but would have if I didn't do some trimming in the front.

It road better than a Rancho kit I had on an '87 K20, but was a little bouncey. It could have been due to the 36" radials I was running as they were load range "C" or the springs. After this truck I decided I would never run a 6" lift again. A 4" lift rides a lot better. My last K15 had a Tuff Country 4" soft ride and my '85 K30 has 3" Tuff Country HD springs due to the fact I have a 454. Both right better than the K5 or the K20.

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[shiftpro]

I was under the impression that it was
33's: 2" street, 4" offroad.
35's: 4" street, 6" offroad.

Or is it more like 5"/7"?

Running about 5-6" on my truck with a 2" body on top now. Pretty sure I won't be rubbing much of anywhere.

Also, OP you'll wanna get a steering box brace kit since our frames like to crack at the steering box with big tires. Should check that to begin with too.

You know Christian it's all relative. Some guys live in the flatlands and to them 4x4 = a muddy road. Some guys use their trucks in ways that
are unimaginable to mere mortals.
Some guys (ME!) can destroy an aluminum rad from gravel roads. Like try driving 80mph down a logging road drifting and sliding on gravel,
the gravel sprays up under the engine compartment and stones make it up to the fan and 'bing' there's a pin hole in that aluminum rad.
Everyone had a different idea and location specific mods are pretty normal.
Some guys just want to rip up deep mud, and articulation is not so important and can actually cause drama in deep mud pits.

Here is my tire/lift formula that works for my general off road intensity...
Based on 35" tires...
4" springs, Tough Country at least or ORD custom multi leaf flexy buggers.
1" EZ Inch or Zero Rate (ORD again) moving the axle forward.
Make sure cab is as far back as it will move on the mounts.
8.5 or .75" rim width by 16". 4.5" (stock) backspacing.
1" body lift.
trim front fender from the side marker light down.

I can still put rubber to metal with this setup if I try, but for most of my needs I'm good to go.