4" lift vs 6" lift

[rayclarkiv57]

im trying to decide on a 4" lift or a 6" lift for my 79 k10. i do not want to lengthen my drive shafts and i am going to run 35s. im getting a rough country lift. i dont do any serious off roading mostly on the road and occasional mud nothing crazy and maybe drive through a ditch here and there mostly a pavement pounder. cutting fenders is not an option. will the 35s rub on a 4? and how bad? how about driveshafts with both of these? thanks for any help. the truck is a 1979 k10  with a 350 sm465 and np205. also how about gearing? what gears do i need for best gas mileage with 35s. i have 32s now with stock gears (i dont know the ratio) and going down the highway i have no power cant pass unless i have a mile. 1st and 2nd are fine but 3rd is awful. the 32s do not rub at all and ill include pics of front fender with them for reference. and ill also attach pics of driveshaft and slip yoke. thanks yall. oh i also want 15x10 rims with 3.6" backspacing.

[ehjorten]

I say you will need 6" to run 35's if you want your suspension to move at all and you are not going to trim the body.  You will also need to lengthen your drive shafts.  That is just my opinion and I am sure someone will tell you 4" will work just fine.

[Don5]

^ What he says. I have a 79 gmc with a 6 inch lift. I have a 350, 465 transmission and 205 transfer case in the truck. I run stock rally wheels with 35's and I have no trouble with the body rubbing. I had to lengthen driveshafts and replace the front and rear ends. I put a set with 3:73 gears in it. It seems to do well. If I could have put 4.10s in it, I would have. I think the 3.73s put the truck back to stock gearing with the tall tires. Another think with a 6 inch lift, you will have to use either a dropped drag link or a raised steering arm. Personally I think the truck has the right stance with a 6 inch lift and 35s myself.   

[rayclarkiv57]

^ What he says. I have a 79 gmc with a 6 inch lift. I have a 350, 465 transmission and 205 transfer case in the truck. I run stock rally wheels with 35's and I have no trouble with the body rubbing. I had to lengthen driveshafts and replace the front and rear ends. I put a set with 3:73 gears in it. It seems to do well. If I could have put 4.10s in it, I would have. I think the 3.73s put the truck back to stock gearing with the tall tires. Another think with a 6 inch lift, you will have to use either a dropped drag link or a raised steering arm. Personally I think the truck has the right stance with a 6 inch lift and 35s myself.   

what kind of fuel mileage are you getting? thanks!

[Don5]

Ahh- I didn't build the truck with gas mileage in mind. The truck is currently in the garage waiting on us to redo the cab and bed. I did most of my driving in the city also.

 I remember when I first got the truck I checked the gas mileage. This was back in 1985 when it was stock with an auto trans, stock 350 motor, 308 gears, full time frontend, 10.50 tires, 43000 miles and no lift. I am thinking that 10 mpg was the number around town if I remember correctly. If I had to guess now I bet it gets 8 mpg.

I do know this, my 15 year old son is wanting to drive it to school really bad next year. I told him that it won't hardly pass a gas station and to get ready to go to work to put gas in it. LOL.... BTW- It now has a 375 hp 350 with a big Crane cam in it.       

[roundhouse]

With 35s
I'd say 4.56 gears or 4.11 would be right


Ive run 35s on my bronco with 4.11 axle gears and it's just about right.  But I also have a NV3550 5 speed trans in it

We also recently swapped in a NV3500 5 speed from a 2006 silverrado into our 76 K-10 shortbed stepside that my 16 year old drives

That's something you might  want to consider
It's a great trans.   The gear ratios are perfect
There is no huge gap between the gears like with the 435

And since it has OD and you're going to need to regear the axles anyway. You could gear them a little lower to take advantage of the overdrive 5th gear


You'll get variable answers because each truck is different

We have zero lift and 33s fit fine on stock rally wheels
No rubbing at all even in a twist


A lot is going to depend on wheels.
I think you could run 35s on stock rally's with no lift with just a little trim of the inside lip of the corners of the front fenders    Something that wouldn't even be noticeable

And with a 6" lift 35s and a teen driver I doubt it will ever see above 7~8 MPG
Probably gonna be around 5 ,  about the same as a loaded 18 wheeler


MPG shouldnt be of any concern

A good rule of thumb is for every 2"you raise the truck you're gonna lose 1 MPG

So whatever mpg you get now, if you do a 6" suspension lift
And if you go from 32's to 35's that will raise your truck another 1.5 inches    For a total of 7.5"

You're will lose ~4 MPG , maybe less.  But probably more

My bronco had 30s. And got 16-17
I did a 3.5 lift and 33s and it now gets 11-12 
The other thing is I'd suggest not to  use lift blocks
That tall.   A 2" block in the back is ok but anything taller causes problems

A 4 or especially 6 lift is gonna need
new longer brake lines
New steering arms
New driveshafts
New shocks
New speedometer gear or recalabration 

Brakes will be marginal with 35s
And that's with everything working properly
That's a lot of rotating mass to bring to a halt

Your son will  just have to remember it ain't a sports car
The stoping distance will be double that of his friends that have riced up Honda with fart pipes.

And I'm sure I'm forgetting something

Gonna easily be $2000 in parts alone

Another $1000 or so to regear the axles
$1000 for the tires
$500 for the rims


BDS is the best suspension but priced accordingly
Several places have flip kits for the rear axle shackles so you don't need such a tall spring or block

A steering box brace on the frame will also be needed
You frame is probably already cracked around the box
    Get someone to turn the steering wheel back and forth with the engine running
While you look closely at the frame with a bright light
    Especially viewed from above looking streigt down on the frame and box

You will see the top of the box where the shaft from the steering wheel  comes in move side to side

Also check the right passenger rear shock mount at the frame closely
   Bet you have some tiny spider cracks there too

[ehjorten]

Loaded 18 wheelers are getting 8 MPG now! LOL

[roundhouse]

Loaded 18 wheelers are getting 8 MPG now! LOL

Been a while since I owned one

Mine got 4.6 mpg

I briefly owned a newer one that got better mpg.but it had a computerised engine that broke down a lot

I ditched it and went back to older trucks with mechanical injection.    Way more reliable ,

[Irish_Alley]

i have a 79 ¾ton 350 sm465/205 38s and 4.10 ran a 6" lift the front drive shaft is the problem you dont "need" a new shaft but it wont last with the amount of splines that are left. but i got 8 mpgs with with 38x16x16 super swampers. took them off for some military tires 37.5x12.5x16.5 and picked up about 2 mpgs.

i wouldnt worry about ratios unless youre mudding then just kick her in low. just try it and see how it feels might have to use 1st (granny) to get moving but just try it

[Gusgusa1]

4" lift for 35" tires

[dylan.hodges.92]

Did you like your super swampers? I need a new set and have been considering them. How much trimming did you have to do to fit the 37's, I'll be running 36/14.5/16.5. Sorry if I hijacked your post.


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[Irish_Alley]

I hate swampers. The only thing good about them is the sound they make on the road. They wear too fast they're too soft IMO.

[dylan.hodges.92]

Who else makes good 36/14.5/16.5 mud tires?


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[Irish_Alley]

I like ground hawgs but some years ago super swampers bought them out

[frotosride]

35" won't rub with the 4' RC lift. I put the 4" RC lift on my truck almost two years ago and have been running 35x12.5's with absolutely no problem. Just remember that the ride will be rough especially up front. I always hated the reverse arch spring but thee are days that i wish I still had them.  Either way I wouldn't change the lift. I got the transfercase drop just incase but never installed it because there isn't a lot of runout from the tranny tail shaft so there are no drive shaft issues. The only thing I wish I had done when I rebuilt the axels was taller gears front and rear...4.11 should do nicely. Either way the truck will spin the little 35's front and rear once the limited slip kicks in.