Ok, I'm kinda confused here. I have been looking at several lift kits for my 11' FX4. I see that Rancho makes a 4" and clears 35's with nice room still left. The 6" lifts on the market appear to do the same thing and have the same amount of clearance as a 4". Anybody have any experience with the Rancho 4 inch lift kit? Also any opinions would be great since I am confused and need to get this lift ordered this week. The top pic is the Rancho 4'' and the bottom is the Fabtech 6". Thanks in advance

 

I had the 4-inch Rancho system (it is actually closer to a 5-inch lift up front); and yes it will clear 35s but you have to be careful about offset and backspacing. My BFG KM2s were 34.8 inches tall, but mounted on 18x9 wheels with -11mm offset wheels with 4.5 inches of BS I would still rub at full lock. The 6-inch system would give you more room for a true +35-inch tall tire and wider wheel.

 

Ok, thanks. I'm really torn between what system to go with. I was thinking of running 35/12.50/17's. What ya think about that setup? Thanks for your help!

 

Before you settle on any suspension lift kit, determine first what rim and tire you want to use as each of the different kits out there may limit your wheel selection.

Rancho 4": Recommends up to 35x12.5 tires on an 18" diameter or more, 9" wide rim with 4.5" backspacing.

Fabtech 6": Recommends up to 35x13.5 tire on an 18" diameter or more, 9" wide rim with 5" backspacing.

BDS 6": Recommends up to 37x13.5 tire on an 18" diameter or more, 9" wide rim with up 5.5" backspacing.

Pro Comp 6": Recommends up to 35x13.5 tire on a minimum 20" rim up to 9" wide and as much as 5.5" backspacing.

Skyjacker 4-6": Only specifies minimum 20" rim, but I would assume at least comparable to Fabtech, depending upon which lift height is selected.

As you can see, 17" rims will NOT fit these kits. And keep in mind that most of the 20" rims for F150's have backspacing more than 4.5".

Personally, I would not select the Fabtech as it requires the most cutting of OEM parts, to include removing one mounting eyelet off the front differential. But if you don't mind that much cutting, then it should work for you just fine if the rim you select has no more than 5" backspacing.

If largest diameter tire is your thing or want the most compatibility with wheels, then BDS is your lift.

Otherwise, if you are springing for 20" rims, Pro Comp should work as well, and along with BDS, offer a lifetime guarantee.

 

Augster,

Thanks a ton for that post and info, that cleared it up for me....BIG TIME! Thats just the info I needed. I was unaware that these kits weren't compatable with 17" rims, why is that? I am leaning towards the Rancho kit at this point and guess I'll go with 18" rims. Thanks again and if you can answer why they don't fit 17" rims that would be great. I don't want my tires sticking out to far, will a 9" rim do that?

 

All these kits use a custom made steering knuckle/arm which offsets the wheel hub lower on the arm. This is how they accomplish the actual lift itself. The position of the lower control arms need to be relocated as well (via custom crossmember), and possibly due to geometry issues depending upon kit manufacture and design to induce or maintain camber changes throughout the full wheel travel, this may place them closer to the rims, requiring at least an 18" or even 20" diameter rim to ensure there is sufficient clearance.

And no, a 9" should just be right with at least a 5", if not 5.5" backspacing.

 

This is why I love this site, learning this kinda stuff. Thanks again, you saved me a ton of headache and $$$$. I woulda bought the 17" rims and tires and had to ship them back. I nominate you for "F150online.com Member of The Month"

 

I had to go through each of the kits myself when I was trying to determine which one would be right for me as I would be the one doing the installation, hence I already had this knowledge on hand.

 

Well, thanks again!

 

what is the backspacing on the factory 20" rims, and will they work with any of these lifts?

 

Great question! Will 35/12.50's fit on the stock 11' FX4 rims?

 

i dont know the actually BS number of the stiock 20's but i so kwow for a fact tht the stock 18's with stock tires fit with my 6 inch BDS. It looks corny though since the tire and wheel look "tucked" in to much. thats why I opted for a negative offset and fender flares...to give the truck a wider stance as well as raising it up

 

OEM 20's have a backspacing of 6". Width is 8.5".

@4thf150: Although it's possible to squeeze a 12.5" wide tire onto an 8.5" rim, would you really want to do that? Besides, with a stock 20 and their large backspacing, that "overhanging" wide tire will rub on the upper control arm so the answer is it won't work.

OEM 17 and 18's have a backspacing of 5.5" and a width of 7.5".

 

Augster,

Rancho is not sure if a 5" backspace will work with their lift since they have only tested a 4.5" backspace, any opinion on that? Also what does a 1/2 backspace due to the apperance of the wheels, does it make them stick out or tuck them under the well a 1/2?

 

Manufacturer knows best, so unless you have a "test" wheel package with 5" backspacing you can try on to check clearances under your actual driving conditions, I would not tempt fate. Otherwise, it may be a very expensive short ride of folly.

Regarding that extra 1/2" of protrusion (yes, it will stick out farther than a 5" backspacing), I doubt you would notice it at all. However, with only 4.5" of backspacing, you have to be careful on the tire size, including width as it's the diagonal cross-section of the tire that you need to be concerned about in regards to whether the corners of the tire will rub at full lock.