2WDoffroadx

Tell me if I'm correct. I am guessing that a solid axle (SAS) doesn't have individual control arms. It is just one straight bar across such as the white 4runner in this

https://www.yotatech.com/forums/f100/first-run-since-my-sas-113354/


While an IFS has control arms like in 2wd trucks such as
http://i2.photobucket.com/albums/y39...rucks/sam7.jpg


?

Am I correct?

drguitarum2005

you are mainly correct. IFS has a control arm (or two) per side. the differential stays bolted to the frame and the wheels move independently of each other and of the differential. the CV axle gives power to the wheel and is comprised of several moving parts and joints that allow it to articulate from the stationary differential to the mobile wheels.

solid axle is one long axle tube (just like what you have in the rear) where the differential is an integral part of the axle and it moves when the axle moves. there are no CVs and no individual controls arms so to speak. the power goes from the differential, down the axle, to the wheel

and just for reference, SAS stands for Solid Axle Swap, while IFS stands for Independent Front Suspension. A SASed rig has a front axle just like the rear...only with added steering components and whatnot

MudHippy

Lookin' to SAS your 2wd? Not happenin'. Does that answer your ?

2WDoffroadx

Im not looking to SAS my pup. I was just curious to know EXACTLY the difference.
Thanks Dr.

Another Guess about SA & IFS
SA is better for crawling and fat crevises because the up-travel that it allows the wheels.
IFS is better for jumping because the wheels usually land at two different times.

Is this guess correct?

Would my rear axle be able to lean all the way up into the wheel wells like I see in 4x4 crawling pictures like in the link in my first post?
I have Edelbrock Performer IAS shocks all around

Elvota

Replace your word "lean" with the word "flex".

There are a lot of factors that dictate flex. Generally, a straight axle will allow for more wheel travel (flex) than IFS.

You'll see on YT and on the web that many IFS trucks flex like mad in the rear due to the rear straight axle. Limitations on flex basically come from spring arch and shock length.

Of course, an infinite amount of combinations are out there to help improve flex.

Your rear springs will flatten until they hit the bump stops or the tires start binding in the fender openings. You'd want to make sure the tires are not responsible for stopping your travel.

ewong

The SHORT answer is that IFS is not good for rock crawling becuase when the front wheels are "crossed up" (one wheel in the air on a rock, the other on the ground) the differential is LOWER
On a solid axle truck - when one wheel goes up - the differntial goes UP too...

So in crawling circumstances - the SA will have more clearance under the diff.


IFS tends to work better for high speed running (baja) becuase the wheels are independent. One wheel hits a rock, the wheel goes UP but the truck stays LEVEL...

Adam F

Just to clarify, there are "CV's" in a solid front axle. They are referred to as "birfields"

Rcross

I wouldn't say that IFS isn't good for rock crawling, I do it regularly with my 91. I would agree that it is more challenging at times. I can go anywhere a friend with his 85 Toy can go, and sometimes more places with my longer wheelbase, its just the 21 points turns start being a pain .

AxleIke

yes, but that is a relatively minor reason. Throw a skid plate under the IFS diff, and its no longer a problem.

The main reasons are for tire fitment, flex, and strength. You can put larger tires under a sa rig, the flex, as you mentioned is better. And a properly built front axle can be nearly unbreakable. Not very many are built properly to be that strong, but even stock housings and axles will handle slightly heavier loading.

AxleIke

very true. stock to stock, there is very little difference. The difference is that the 85 can be built to go further than the IFS

Rcross

My friends 85 is built up fairly well, 4in suspension and a 3in body lift, locked in the rear with a limited slip in the front. My truck has minimal lift, locked in the rear and we both run 35's. I occasionally lift a front tire, but with ball joint spacers and the T-bars relaxed the front flexes enough to keep the tires on the ground most of the time.

Sorry I just get tired of hearing IFS is crap and is bad for crawling. I have never wheeled a solid axle Yota, but have witnessed several and so far have kept up with my bad IFS. I got an idea instead of people saying you cant wheel with IFS, how about wheeling with a solid axle, its so easy a caveman can do it.

drguitarum2005

now youre just being too particular. we all know when i and everyone else on here refers to CVs, we're referring to the half-shafts on our IFS...no need to confuse anyone by bringing birfields into this

AxleIke

I wheel an IFS yota. Haven't gotten to a trail i can't do yet. I also agree that IFS is great for most people. Even with ARB's, a 4.7 case, sliders, bumpers and plenty of belly armor, i'm not rock crawling. I got up hard trails, but you can't build IFS to handle this:



I'm not bashing IFS. I too hate it when people say "oh, ive broken one CV, time to SAS". IFS is just fine. I think it will go much farther than most people think. I felt that the question asked was about the benifits one way or another of IFS to SAS. As i said, you can build a live axle to handle 44's, and extreme crawling, you can't do that with the IFS that is on these trucks.

Elvota

Did anyone else notice that rock jammed in the slider of the rig climbing the waterfall posted above? Aggressive. I think it's in mid air... but still...

The problem with IFS is that it ultimately has limitations, no matter how deep your pockets. It's true a solid axle does as well, but the ceiling is much, much higher (and pockets need to be much, much deeper )

No one can really tell another what level they should build their rigs. The definition of "rockcrawling" is very general after all.

AxleIke

Agreed.

Just so we are clear Rcross, i'm not saying you're wrong, nor am i attacking your IFS, or anything. Just was clarifying my position.

JamesD

I see you have a lifted 2wd. I had an 87 with the Ivan Dan kit. I would never do that again!

I agree their is nothing wrong with IFS. If plan on doing extreme rock crawling like the pic above then you have to go solid axle.

James

Rcross

AxleIke I wasn't saying you were attacking my IFS. I had quoted you and gave just a few specs comparing my truck, other than a locker and 35's it is mostly stock, and my friends, which is fairly built. With his built a good bit more than mine, he has yet to go up a trail I haven't been able to follow.

My second paragraph above was directed at the crowd who scream IFS is crap, not at you. Sorry for the misunderstanding I was just making a generalized statement.

BruceTS

I wheel IFS and rockcrawl too.......

Thr real problem is when you want to run tires larger than 35's, that's when the front drivetrain breaks. 35's are marginal, expect to break on the tougher trails. I've gone up a trail that a SFA rig couldn't, simply because his diff got hung up on a boulder that my skid plate allowed me to clear.

The advantage to SFA, it allows you to run bigger tires and more lift, which gives you more breakover clearance.

Rcross

Yeah I have seen my share of carnage due to the 35's, thats the main reason I am going to SAS my runner. I really dont want to lock the front axle and run 37-39's on the front IFS.

Im not too terribly worried about break over angles. Usually when I lift a front tire on my truck that side is resting on my sliders. As long as I have 1 tire in the back on the ground with traction I usually keep moving forward