i have a 98 f150 with an extra cab. i just got a pro comp 4 inch suspension lift installed and it has 33x12.50 pro comp tires. i wanted to get a little more clearence so i was looking at puting in some truxxx torsion keys in for the front orr just cranking the torsion bars with no aftermarket keys. for the rear i would just use blocks. how much more clearence will i be able to get by cranking the tortions? when you crank the torsions so you have to move your bump stop? i offroad alot so will cranking the t bars make it have less travel or make the suspension stiffer? thanks

 

Stay away from the aftermarket keys. Just crank up your torsion bars with the oem keys. You can probably get around 2 more inches of lift. This will make the initial portion of your suspension's travel slightly stiffer. You don't need to trim the bumpstops. Your suspension travel will remain the same, it will just ride a little higher in the stroke. In other words you will have more down travel than up travel.

 

Won't you have more up travel available than down travel after the torsion bars are cranked? As you crank the t-bars the truck raises, so the shock gets extended leaving you with less down travel.

Also, I don't agree with the "initial" comment regarding the suspension stiffness. The torsion bars are basically springs. As springs are compressed they continue to require more force to compress them. So if the t-bars are cranked it's going to make them stiffer throughout the entire suspension cycle, not only at the beginning of their cycle.

 

is more down travel and less up travel bad for offroading? i am mostly doing rock crawling to get to the beach so i need good travel.

 

I think wandell made a typo about the up/down travel.

Think of it this way. Your truck has 8" of total front suspension travel stock. Let's just say 4" for upward travel and 4" for downward travel. When you crank the torsion bars you're going to maintain that same 8" of travel... you're just going to change the resting position (4" up/4" down) of the cycle. So if you crank the torsion bars to achieve 2" of suspension lift, you've just changed your 4" up and 4" down to 6"up and 2" down.

Those numbers aren't the actual suspension travel numbers of a 1998 F-150... I just used them as an example, but they're probably pretty close.

Typically you want more upward travel than downward travel. Upward travel is for when you hit bumps... downward travel is for when you hit potholes. You just don't want to have too little downward travel to the point where your tires are coming off the ground at speed over rough terrain.

Personally I wouldn't crank my torsion bars a full 2". I had a 1998 F-150 and I didn't care for the ride quality or the lack of downward suspension travel on the crappy roads in my area.

 

Yep, my bad. That was a typo about the up travel and down travel.