4in lift with 35s, anything additional I should buy

[Dylan44]

Hi everyone, I'm going to be putting on a 4in lift on my 86 gmc 3/4. Is there anything I should install along with this lift? My uncle recommended replacing the u joints since they're probably original and I'm gonna take the drop pitman arm off his truck (this is also where I'm getting the kift from). I plan on running 35s since I am in need of need of new tires for the winter.

Thank you in advance.

 

[shiftpro]

Console...

 

[John Lenahan]

Just a recommendation. On the transfer case cross member, there is usually a small metal collar/spacer like deal, that should be on the bolt below the cross member, if you take that collar off and drop the cross member and put it between the frame and the cross member, it'll drop it down about 1" and reduce some of the stress on the u-joints.
if you go that route i'd replace it with grade 8 7/16 hardware

 

[Craig 85]

Few things I'd recommend. The ORD swaybar correction/disconnect kit. It frees up the spring from any bind the fixed sway bar causes. I've installed them on the last two trucks and they make a big difference in ride quality. If you have a weight sensing proportioning valve at the rear axle, bypass it (photo #2). I had a '87 K20 in the early 90's and didn't raise the valve enough and had basically no rear brakes. Lastly, a Sawall. You're probably going to have to trim the front fenders. I had to on my old '87 even with a 4" lift on 33's.

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[shiftpro]

Everything Craig said above ^^^.

You will absolutely have rubber meet metal even if you don't get it twisted up off road. First place will be where your driveway meets the road! If you insist on running 35s there are a few other things that will help, such as ORD's Zero-rate blocks. This is a 1" block that installs inside your spring pack. You will have the option to move the axle forward an inch also and this is critical to get clearance at the rear of the tire to the rear of the front fender opening. Also, if your running 10" rims this will make the metal to rubber drama worse.
You might also consider a 1" body lift.

You may also need to lengthen your brake lines. If you do like Craig suggested, pulling the anti-swaybar, you may need longer lines up front. At this point, your shock length will determine your wheel droop. Run longer shocks (with modified upper mount) and you will achieve more travel. (this is a good thing)
And... will your gear set handle the tall tires?

 

[K201979]

I've got 4" of lift with 315/70/17 tires on 17x9" wheels with no trimming or rubbing. Ive not flexed it hard but never has rubbed under normal road conditions. Im not sure of the back spacing but this might be an easyer option for u since 315/70's are a little smaller than most 35x12.50's. Last set of tires measured 34.5". Just put new on havnt measured yet but i think they may be a little smaller. First is old set. Second is new.

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[K201979]

only issue i had going up 4" was my exhaust. 3" y that crossed under the front driveshaft had to b cut and flex piped lower to clear. Leaks like a ****** But ill fix that someday. I wanna go to duels. Front brake lines i just dropped with brackets that came with the lift. E brake cables are probly pretty stretched when the rear droops but hasnt caused a problem yet. Both driveshafts worked but the front was a little more stretched than i liked and wore out so i bought one a couple inces longer. I used a zone(company name) 4" front springs rear block lift with shocks included and ive not done the swaybar disconnect yet but i want to. Instructions said to leave the swaybar off but it was bein a b*tch to get off and it went together with it in place so i left it. If i can help at all, just ask.

 

[bucket]

Just ditch the sway bar. Unless you are running some super flexy springs or toting a slide-in camper, it's really not needed at all. I was not a believer in this theory untill I actually tried it for myself. There is zero ill effects on handling even at interstate speeds.

Also, with just a 4 inch lift, there is no need to lower the t-case.

 

[K201979]

X2 on the tcase drop. Ive heard it can actually make angles and vibrations worse.

 

[Dylan44]

Thank you for all of the replies! I will take everything into account. I have 33s on the truck now and I've always thought the ratio with lifts is 4in you go with 35s, 6in 37s, ect. I have 410s for gearing, will that be an issue?

 

[Dylan44]

Also, I'll probably take the brake lines off my uncles chassis since they're probably a longer set made for a lifted system. He said I can take anything I need off of it since his plans are a bigger lift and some other custom fab things so he'll probably end up needing different parts than he has now.

 

[dcameron787]

I have a 4” Lift, running 35’s on 20”x9” rims with no rubbing. I did have to purchase longer front brake lines lines. Skyjacker has them for the 3/4 tons. Not case drop as well. I also ended up going to a 2” lift in the rear as the 4” gave it a big rake and I was not a fan. With the 4/2 it sits pretty level.

 

[4WDKC]

Longer flexible brake hoses...unless his are fairly new I would just buy new ones. To do it correctly you should add heavier duty brakes to the truck to stop correctly with the additional weight of bigger tires. You will also need to readjust your headlights so they dont blind other drivers..hate when people dont do this.

 

[Ilgy84]

I have a 4 inch lift and 315/70-17 on my k30 cucv. If you're gonna get rid of the sway bar I would suggest crossover steering. You can't run the sway bar with crossover steering. My drivers side tire hits the drop pitman arm a little before full right right steering lock. I'm not sure if your k20 will have the same issue but it's something to keep in the back of your mind. Also, the ord steering box brace is a great idea with bigger tires to keep from cracking the frame at the steering gear

 

[K201979]

Im no expert but i think 410s are perfect for 35s. Someone else will let u kno if im off.