what size lift to fit 35" on a 71 GMC 3/4

[Brewski*]

Yes, I am going to lift the Red Rocket. But I have a million questions about what to do and how to do it. I think I need 4" lift minimum to clear 34" tires. Correct? What about rear springs: Do they make a great difference or just cost more money? My 3/4 ton is pretty stiff back there already. I know the blocks look crappy but who is really going to look besides me?
The Rocky Mountain suspension page Rocky Mountain says this:


quote:
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To correctly lift a solid axle General Motors vehicle, it is important to achieve the correct drag link angle. Most vehicles can be lifted 2" and maintain the correct angle. Lifts over 2" increase the distance between the link’s two attaching points causing the vehicle to "wander". These adverse angles also can cause premature wear on other steering components shortening their life expectancy. There are several options for correcting this angle, however, they all require an open knuckle, 3-bolt steering box. Prior to 1973, most vehicles are not so equipped. The best option is to upgrade the steering box to a 1973 style open knuckle type in order for the various dropped steering components to fit. No steering correction is made for the earlier version steering box. Once updated, the options for steering correction include steering arm, pitman arm, adjustable drag link or steering blocks.
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IS ALL THIS NECESSARY? Has anyone here ever done this steering box change out? I don't want my truck to wander or tear up the stearing parts. What have you all done to your trucks to make them ride right? Any help much appreciated~!

[Destructo]

4" at the minimum. 6" is really preffered for 35's, but you can probably clear 35's with a 4". I think you can clear a little bit bigger tires with a 67-72 rather than the 73-87 trucks.

[Pont]

What size wheel and tire combo are you going to run? How wide will the 35's be and how wide will the wheels be with what offset or backspacing? This will make a difference on the rub factor. If there is any doubt and you think you might want something with some width to it, run at least 6".

[Brewski*]

The wheels and tires are the ones off the H2 Hummers the size is:
Wheels: 17x8.5Jx18.0
Tires: BR Goodrich, All Terrain, KO, 315/70R/17, 34" tall, 10" tread width 12" wide at widest point. I was told the 2.5 inch lift would work for 34" tires with no steering box replacement needed. Anyone know for sure? I would much rather do the 4" lift just to be safe and allow more travel.

[BladeX]

35x10.50x15RLT

I got 4 inches suspension and 2 inches body.


So 6 inches in all.

[72Bob]

I would go 6". Here is mine 1969 3/4 ton with 4" lift and 35"12.5 16.5 hit the front of the front fenders when the body flexes.

[barraza]

Originally posted by Brewski*
The wheels and tires are the ones off the H2 Hummers the size is:
Wheels: 17x8.5Jx18.0
Tires: BR Goodrich, All Terrain, KO, 315/70R/17, 34" tall, 10" tread width 12" wide at widest point. I was told the 2.5 inch lift would work for 34" tires with no steering box replacement needed. Anyone know for sure? I would much rather do the 4" lift just to be safe and allow more travel.

Those hummer h2 wheels have a lot of backspacing, I would think you won't have any problem with 4inches. Wheel offset and width can make huge differences in how wide an arc the front wheel swings when turned, and thats where your clearance problems will be, at the front and rear of the front wheelwell. Be aware that most 4" lifts will actually bring the front of your truck up over 5". My 4" skyjacker raised my 72 over 5". I had 33x12.5's on 8 1/2" rims with 3.5" backspace (I think) and they fit fine with no lift.

[72SWB4X4]

for the size tire and wide and offset of the rim I would go with 4" and the steering thing is sometimes a concern but try the lift then if needed change out the steering parts I think it will be fine

I have 32 x 10.5 on a 15 x 8 rim and it is all good no lift I am thinking of going to the 35 or 36 x 11.5 and a 6" lift

[rockwe11]

No, it is not necessary to change the steering box.... You can change the steering arm on the axle itself as opposed to a dropped pitman arm on the steering box. they are not that expensive, probably 75$ The only trouble is it is usually hard to change the arm because it becomes seized on the tapered cones on the three mounting studs.. I just torched mine off with the oxy acetylene torch..

And I fit 35-12.50-16 Super swampers, on a 4 inch lift with only minor rubbing on the tip of the front fenders, I think the only reason I could do that was because I had previously replaced The body mounts with new polyurethane ones..

[Dean]

4" Skyjacker Softride with 35" BFG A/Ts.

[D.PASSMORE]

I put a 4 ''Skyjacker softride on my 3/4 T 4x4. Iam running 33 x12.50x16.5's. Plenty of room under the front wheel wheels. I think 35x12.50x16's would fit but what would determine the rubbing of the tires on the front would be the offset of the rims. If you stick the tires to far out, they will rub on the front of fenders when turning. Skyjacker includes a lifted steering arm with a complete (front and back springs) 4'' lift kit for around 750. to 900. dallors. Make sure the bushings are included and buy new bolts. Have fun....

[Chris_T]

I run a Skyjacker softride kit on my Blazer - 6" front springs, 8" rear springs (for the Blazer butt-sag) with 35" BFG MTs. I've trimmed the 'fang' at the front of the fender, but can still get the tires to hit the rear of the front wheelwells, but usually only when the wheel is stuffed and turned out.

In the rear the front of the wheelwell will still catch on a particularly hard compression, but this will also depend on the shackle length and the rearward movement of your axle. You can always offset the axle back a bit.

Keep in mind that my rubbing is only ever on particularly twisty trail sections. It also differed with my wheel width and offset. I think it was better when I ran 15x8's with 3.5" than my current 15x10 with 4" bs. On the street or mild wheeling it never comes close. I would think 6" is the way to go. With a 4" lift I was hitting on all four corners if I ventured offroad.

With a 4" raised steering arm I have minimal bump steer - of course once I flex the front end the steering pretty much goes away, so I'm swithcing to crossover.

[Stocker]

I'm running 33/12.50-16.5s on 9.75 rims, with 2" Softride springs in front and a single add-a-leaf in each rear pack. Before I got the front springs, I had sagging OEM springs with add-a-leafs up front. No problems, but many years ago I notched the leading inner fender corners. I think you'll be able to run 35s with a 4" lift. Just a thought - can you use a flip-kit instead of blocks in the rear?

[IoWnZa]

I have 32x11.50R15's with no lift on the Blazer, but for what you are talking about, I would say 4" would work...

[bigger=better]

Brewski,

Let us know how it goes. I am getting ready to do the same with my '68 sub. H2 wheels and 34" MT/Rs. Goodyear tho. I, like you, am wondering how this is gonna go, especially since I already bought the wheels and tires and can't afford a lift kit. Anybody know a good place to buy blocks?

[Brewski*]

Put a Skyjacker 4" lift on my truck with H2 Wheels and tires. The wheels and tires are way cool they look fantastic, and I get compliments on them everywhere. BUT.... I hate the lift. The truck rides like crap>>>> bounces all over the place and does not steer correctly thanks to Skyjackers crap steering arm that is NOT the right size for our trucks. They say to adjust the drag link but that only candy coats the problem and actually makes the truck understeer. I really have to turn the wheel way farther than necessary to get it to turn. I have adjusted the air pressure and found 40 to be the best handeling and riding. I am changing out the shocks back to the Edelbrock to see if that helps also. They are large enough to work in the back. The stance of the truck looks nice but the front and back are the same height now. I think the front can drop about an inch or 2 and it would look better and still clear the tires. The front Edelbrock shocks are slightly smaller than the Skyjacker ones so I may try them to see if they bring it down and inch or 2.

[Dean]

Sorry to hear of all your problems with the Softride system. I've put it on five trucks so far with no issues. Used the 4" and the steering arm also. I however do not recommend their Nitro shocks do to the ride. Those are on my blue K20 and it rides much worse. I use the Hydro shocks now. Let me know if you need any close up pictures of how mine is adjusted and etc.

[bigger=better]

Oh yes, pictures we likesss

you too Brewski

[RICHARD MORGAN]

I HAVE A 1972. IT HAS A 6" SUPERLIFT WITH 35" TIRES. I STILL HAVE 2 OR 3 INCHES TO CLEAR BIGGER TIRES. HERES SOME PICS.

http://67-72chevytrucks.com/vboard/s...hlight=RICHARD