School me on torsion bar lifts

[Rezarf]

So I am looking at lifting the 100 series. I was under yesterday pulling the running boards and noticed the torsion bars have been replaced with factory Toyota units relatively recently, as at least they looked newer than everything else by a long shot.

That said, I know that the OME is a popular kit but I am having a hard time figuring out if I actually NEED new torsion bars? Am I correct that the factory bars can be cranked up and adjusted like the OME bars. It seems like it is an indexing thing verses a spring rate change.

Am I missing something? I would assume the TB from OME or aftermarket is simply a different spring rate for the rotational force to help with the added weight of a bumper/winch etc. That the aftermarket TB's are tuned for the suspension as a whole, to work with the load, shocks ect.

I guess what I am asking if there is not plans for a front bumper/winch on my 100, is there a reason I shouldn't see what kind of lift I can safely get out of the OEM TBs?

Maybe I am missing something very obvious but this is my first IFS anything I've wanted to modify.

I know I'll need rear springs, diff drop, and shocks all around, but I am more curious than anything on how this all works.

 

[AimCOTaco]

You are correct, OEM bars will handle the stock weight just fine and you can tune the ride height with index or adjusters. Just move the adjusters when the truck is in the air, not on the ground. With a lot of extra weight the stockers will be overloaded but with stock or close to stock weight you can crank them up. I ran a couple years that way...

I've also been running a moderate front height without a diff drop and while not recommended due to boot wear, my boots have handled a couple years like that.. recall that you're still using Toyotas range, just the neutral position is more aggressive if that makes any sense.

For a poor mans lift; crank up the front and put some urethane spacers on the rear springs and you'll gain height but not load capacity.. stock shocks can remain as well.

 

[Rezarf]

Andy, how much height did you actually gain? I am looking at stuffing some 315/75-16 up under it and I think I'll need at least 3" of real lift maybe some body lift ~1" or so as well.

 

[DaveInDenver]

The spring rate remains the same with cranked torsions but you are increasing the pre-load of them when you lift and slightly changing the angle of the force applied to them, so the travel reduces. It's a cheap way to lift but not ideal. If you install larger diameter torsion bars (thus increase spring rate), you will lift the truck without pre-loading them. I had to back off the adjusting bolt completely and I still had some lift with 25mm Sway-A-Way in place of 22.5mm stock on my truck. However the wheel travel still reduces because now there's not enough weight to fully cycle the suspension. Both ways generally will need an alignment to keep from wearing out tires.

There is no perfect way to lift IFS and keep the same wheel travel and spring rate without adding brackets and longer spindles (which I don't think is an option with 100, right?), so you have to balance which compromise you want. If you intend to ever add a bumper or winch, then replacing the torsion bars will ride a little less stiff in my experience with a mini truck. Cranked torsions equaled bone rattling until I added a bumper. I now run 25mm bars with an ARB and winch and didn't have to dial in much adjustment to lift about an inch.

The total lift you can get is only whatever the down travel of the suspension is right now in theory, but that is not really possible because doing that would make it ride absolutely intolerable and it would 'wheel like a mini truck.

For torsion lifts mini truck actually do have better ways. SDORI/Roger Brown have ball joint spacers that give you 1.5" of lift without changing down travel. Those actually open up the window of wheel travel by almost 1.5" and let you keep stock torsions so the up travel is the same.

BTW, realize too that if you do crank up a lot of lift you put the CV axles near their maximum angle, so you have to be careful. With hub locks and part time 4WD this is only an issue off road but with full time 4WD this can be really bad for them.

 

[AimCOTaco]

I don't think it's the suspension lift that is going to affect your wheel/tire fit. You won't be moving or changing the front bump stops so full stuff won't change. The body lift will give you an extra 1" of fender clearance at the top which I expect you will need for 35's. I'm running 1.5-2" over stock in the front.

I personally would not extend the front bump stops because we have so precious little front travel to begin with so body lift and pinch weld hammering and/or wheel spacers are the ticket.

Are you going to re-gear for 35's? I feel like the '99 would need gears to push more tire on the highway and for decent crawl control on the trail.

 

[Rezarf]

Yes, I'm planning on regearing as funds allow.

 

[AxleIke]

The spring rate remains the same with cranked torsions but you are increasing the pre-load of them when you lift and slightly changing the angle of the force applied to them, so the travel reduces. It's a cheap way to lift but not ideal. If you install larger diameter torsion bars (thus increase spring rate), you will lift the truck without pre-loading them. I had to back off the adjusting bolt completely and I still had some lift with 25mm Sway-A-Way in place of 22.5mm stock on my truck. However the wheel travel still reduces because now there's not enough weight to fully cycle the suspension. Both ways generally will need an alignment to keep from wearing out tires.

There is no perfect way to lift IFS and keep the same wheel travel and spring rate without adding brackets and longer spindles (which I don't think is an option with 100, right?), so you have to balance which compromise you want. If you intend to ever add a bumper or winch, then replacing the torsion bars will ride a little less stiff in my experience with a mini truck. Cranked torsions equaled bone rattling until I added a bumper. I now run 25mm bars with an ARB and winch and didn't have to dial in much adjustment to lift about an inch.

The total lift you can get is only whatever the down travel of the suspension is right now in theory, but that is not really possible because doing that would make it ride absolutely intolerable and it would 'wheel like a mini truck.

For torsion lifts mini truck actually do have better ways. SDORI/Roger Brown have ball joint spacers that give you 1.5" of lift without changing down travel. Those actually open up the window of wheel travel by almost 1.5" and let you keep stock torsions so the up travel is the same.

BTW, realize too that if you do crank up a lot of lift you put the CV axles near their maximum angle, so you have to be careful. With hub locks and part time 4WD this is only an issue off road but with full time 4WD this can be really bad for them.

That's a pretty good summary of what's going on in the front end. However, the ride will likely be a bit different from the mini truck world. I always found the early mini truck IFS to be over sprung for what it was. The trucks weigh nothing so cranking the bars or aftermarket spring rate bars are a very bad ride.

A 100, on the other hand, is essentially a 60 foot pleasure yacht with wheels . So even with aftermarket bars, it still rides [Borat Voice] a-very niice [/Borat Voice]. My brothers 100 had a. 2-2.5" OME lift on it and it rides better than my 4Runner on coil overs, though I have a very crappy lift, and they are bilstein shocks which also ride like crap in general.

That said, with big tires, and as I said on the phone, with IFS, I am a major proponent of surgery to fit the tires. A bit of lift is fine, but as your front end angles increase, you have more and more issues. When you lift the ifs, your camber gets out of whack, so an alignment is needed. However, the higher you go, the less adjustment you have, and your caster adjustment can be affected. As I said on the phone, mine was bad enough that my caster ended up near zero trying to zero my camber, which necessitated aftermarket upper arms to get back to around -2 deg.

I put 35s on my old 4Runner with no lift at all. And that had small fenders designed for 27-28" tires from the factory. The 100s have much bigger wells. Stick the tires on and see where there are/may be issues. Crank the bars a little if needed and massage the back of the fender a bit with a hammer. You'll be surprised how much room you have, I think. Don't drive yourself crazy worrying about what all you need to do before you start.

Oh, and pull your kick panels before you start hammering. Make sure you aren't going to pinch/smash any of the 100 billion wires that run through that area on a 100. When we took my brothers apart, I couldn't believe the number of wires on those trucks.

 

[DaveInDenver]

Yeah, I assume a 100 would ride like the Cadillac of cars even with torsion bars!

I had to flatten my fender pinch seams as well, I think that may be pretty universal.

 

[DouglasVB]

For torsion lifts mini truck actually do have better ways. SDORI/Roger Brown have ball joint spacers that give you 1.5" of lift without changing down travel. Those actually open up the window of wheel travel by almost 1.5" and let you keep stock torsions so the up travel is the same.

The siren song of the mini truck!

 

[AxleIke]

Yeah, I assume a 100 would ride like the Cadillac of cars even with torsion bars!

I had to flatten my fender pinch seams as well, I think that may be pretty universal.

The other thing I wonder about is the 100 series are attached to the lower control arms, whereas the mini trucks had them on the upper arms. Hard to package a V8 and exhaust manifolds around those bars they way they had them on the early mini's.

I cannot exactly remember the dimensions but, if I remember correctly, the upper arms are shorter on the early mini's (they definitely are on my 99), which gives a shorter lever, meaning a greater force is required to twist the bar a given number of degrees. The lower arms, which are longer, give you a longer lever, meaning less force for a given number of degrees.

More leverage=nicer ride

 

[DaveInDenver]

I think most torsion IFS has them on the lower arms, pretty sure GM and Dodge are that way at least. The ride notwithstanding, they always seem so vulnerable on the lower arms and lot of junk hanging way below the frame. That I assume is why they were placed up high by Toyota back when they still had to justify IFS to the market as being as rugged as solid axles.