Setting torsion bar preload?
#1
Setting torsion bar preload?
I have a set of Sway-A-Way torsion bars on order and should have them soon.
I’m installing them on a 89 Xtra Cab V6 4WD. It has a 4” bracket lift, shock hoops, custom valved Bilsteins and 265x75-16 Nittos.
The truck has cranked torsion bars from the PO but now that I have added 110 lbs of winch and heavy tube bumper it really needs the stiffer torsion bars.
Back in my dirt bike riding days I would set the droop of the rear suspension to about 1/3 total suspension travel. Would this also work well for the truck?
Say the IFS have 7” of travel. So I’ll make a measurement with the front wheels off the ground. Then make a measurement with the weight of the vehicle on the tires. I’ll adjust the preload to get about 2.3” droop.
Does this sound okay? Any other ways of setting preload? The method in the FSM doesn’t seem to apply because of the lift and bigger tires.
Thanks
I’m installing them on a 89 Xtra Cab V6 4WD. It has a 4” bracket lift, shock hoops, custom valved Bilsteins and 265x75-16 Nittos.
The truck has cranked torsion bars from the PO but now that I have added 110 lbs of winch and heavy tube bumper it really needs the stiffer torsion bars.
Back in my dirt bike riding days I would set the droop of the rear suspension to about 1/3 total suspension travel. Would this also work well for the truck?
Say the IFS have 7” of travel. So I’ll make a measurement with the front wheels off the ground. Then make a measurement with the weight of the vehicle on the tires. I’ll adjust the preload to get about 2.3” droop.
Does this sound okay? Any other ways of setting preload? The method in the FSM doesn’t seem to apply because of the lift and bigger tires.
Thanks
#2
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When I was IFS, I was more concerned with tires rubbing when compressed and wheels turned. With your bracket lift that is prolly not as big of a concern. So your logic sounds good to me. Just make sure front is level. I marked a spot on fender and measured off of rim. Then wheel it to try set up out.
I removed my sway bar years ago and never looked back.
I removed my sway bar years ago and never looked back.
#3
Thanks for the reply Muddpigg...I appreciate the advice.
I have long thought about removing my sway bar also. But I live at least 100 miles from any trail that needs 4WD. A trail that causes articulation problems are even rarer. If I knew someone with a fork lift I'd do some measuring with and with out the sway bar. Did you notice any difference in twisty mountain roads with out the sway bar?
I did remove the rear overload leaf spring which did get me some extra articulation.
I have long thought about removing my sway bar also. But I live at least 100 miles from any trail that needs 4WD. A trail that causes articulation problems are even rarer. If I knew someone with a fork lift I'd do some measuring with and with out the sway bar. Did you notice any difference in twisty mountain roads with out the sway bar?
I did remove the rear overload leaf spring which did get me some extra articulation.
#4
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Of course I could tell that the sway bar wasn't there both on and off road. I kept the thing for years just in case and eventually recycled it. But I don't drive my lifted truck like a sports car and I don't off road my turbo passat.
The sway bar doesn't apply much preload except for body roll. The torsion bars carry the vehicle weight and have preload. You can remove the two brackets and bolts of sway bar and it will just fall off.
I have seen guys that ran quick releases on sway bar to disconnect for off road and reconnect for road.
The sway bar doesn't apply much preload except for body roll. The torsion bars carry the vehicle weight and have preload. You can remove the two brackets and bolts of sway bar and it will just fall off.
I have seen guys that ran quick releases on sway bar to disconnect for off road and reconnect for road.
#5
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i think setting the tbars on your rig is also a personal preference of ride quality and how you plan to use the rig. for example, i'd want to set extra preload if I planned to bottom out my suspension frequently via jumping or high-speed stuff. rule of thump for IFS trucks is to make sure all moving parts are within their operating angles - so CV axles and ball joints are the two that are most effected by the front lift. you do have the option to add diff drop and lessen a few degrees of angle on the CVs. last year (i think) there was a thread that included some good pics of different IFS setups and max operating angles of the different components - it was a good posting that I hadn't seen before (at least not with pics). i think it was blazen8 from blazeland that posted this thread.
i too have not used a swaybar on my truck for several years, but I have fresh/stiffer leaf springs + shocks, and I do not have a bracket lift either. you can try it out and put it back on if you don't like it, or you can make quick disconnects.
i too have not used a swaybar on my truck for several years, but I have fresh/stiffer leaf springs + shocks, and I do not have a bracket lift either. you can try it out and put it back on if you don't like it, or you can make quick disconnects.
#6
Registered User
The torsion bar adjustment is just a ride-height adjuster to level out the truck from the factory to compensate for slight manufacturing variations. It doesn't change the stiffness of the bar, it just re-clocks it to provide a higher or lower ride height. Which is a good thing. "Pre-load" is a misleading term (as I too once thought) because it gets you thinking about loads and weight and not ride height.
Yeah, but the ride is stiffer once the bars are "cranked" a lot of people claim. That's because of the changed geometry -- the front tires now scrub much more laterally, side-to-side, through their travel arc than when at factory ride height. Good you're getting heavier bars. I'd start at the factory setting +4" and fine-tune the ride height from there. I have the '94 FSM in the garage and can tell you the ride-height measuring points if you'd like.
Yeah, but the ride is stiffer once the bars are "cranked" a lot of people claim. That's because of the changed geometry -- the front tires now scrub much more laterally, side-to-side, through their travel arc than when at factory ride height. Good you're getting heavier bars. I'd start at the factory setting +4" and fine-tune the ride height from there. I have the '94 FSM in the garage and can tell you the ride-height measuring points if you'd like.
#7
Okay, you guys got me thinking about taking the sway bar off. Next off road trip I'll take it off and put it in the back of the truck. I'll wheel half the day with out the sway bar. Reinstall during lunch and finish the day. That should help me decide.
I pretty much agree with truckmikes26 advice. Like on motorcycles, the springs just holds the bike up. The dampening rates control bottoming, topping out and ride quality.
I've reconsidered using the FSM and have come up with these calculations.
My truck came stock with 225/75x15 tire. I calculated this to be a 28.3" diameter tire. My 265/75x16 are worn to 30.5" diameter. That's a 1.1" difference in radius. My FSM says the front should have a ride height of 11.1". I'll just add 1.1" for a setting of 12.2" and should be at good starting point.
As a side topic, I suspect the torsion bar adjusting bolts are hard to remove. The punched hole in the bottom of the cab right above the bolt tells me the PO had a hell of a time. Do you guys thinks a 600 ft/lb impact wrench will be enough persuasion? I'm going to start soaking the bolts with Kroil tomorrow.
I pretty much agree with truckmikes26 advice. Like on motorcycles, the springs just holds the bike up. The dampening rates control bottoming, topping out and ride quality.
I've reconsidered using the FSM and have come up with these calculations.
My truck came stock with 225/75x15 tire. I calculated this to be a 28.3" diameter tire. My 265/75x16 are worn to 30.5" diameter. That's a 1.1" difference in radius. My FSM says the front should have a ride height of 11.1". I'll just add 1.1" for a setting of 12.2" and should be at good starting point.
As a side topic, I suspect the torsion bar adjusting bolts are hard to remove. The punched hole in the bottom of the cab right above the bolt tells me the PO had a hell of a time. Do you guys thinks a 600 ft/lb impact wrench will be enough persuasion? I'm going to start soaking the bolts with Kroil tomorrow.
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#9
Registered User
And once you find the torsion bar sweet spot you're happy with, you can fine tune the upper and lower bump stops to keep your travel range where you want it.
Also, years ago I took my sway bar off when one of the links broke and I figured, hey, I don't need that POS anyway 'cause it hurts my articulation (I was a hard-core dude back in the day). So the bar hung in my garage for 15 years. I recently reinstalled it with new links from Rock Auto ($30) and man, the Toyota chassis engineers are, I admit, much smarter than me. Sure some articulation is sacrificed, but the truck handles, tracks and steers so much better on road and off. I'm planning to put a Lock-Right in the front so that'll make up for the lost articulation (I replaced the drive flanges with Aisin hubs).
Also, years ago I took my sway bar off when one of the links broke and I figured, hey, I don't need that POS anyway 'cause it hurts my articulation (I was a hard-core dude back in the day). So the bar hung in my garage for 15 years. I recently reinstalled it with new links from Rock Auto ($30) and man, the Toyota chassis engineers are, I admit, much smarter than me. Sure some articulation is sacrificed, but the truck handles, tracks and steers so much better on road and off. I'm planning to put a Lock-Right in the front so that'll make up for the lost articulation (I replaced the drive flanges with Aisin hubs).
#10
A quick update
Well this turned out to be a long drawn out project. I was unable to get the Sway A Way torsion bars because of a long back order.
I was able to find a set of used Rancho torsion bars off a 88 4Runner. They were free if I just swapped the bars between trucks. I was a little worried because of some of the stories I've read about breaking loose the adjuster bolts. Luckily my truck and the donor had plenty greased adjuster bolts so installation was easy.
During my first road test, I had the preload set for 11.5" of tire to fender clearance...this was way too stiff. I next adjusted the bolts 8 turns softer. This gave 9.5" of clearance...this was way too mushy. After more testing I ended up with a tire to fender clearance of 10.25". Exactly were it was before the winch and tube bumper was installed.
I'm quite happy with the result. The weight of the winch no longer feels like there is a snow plow on the truck. Very steep rocky down hills are more sure footed. On faster dirt roads the body stays more level. Before the front end would kinda mush through a rut and then the rear would kick up by the rut. Now the front and rear have about the same feel.
Next mod is a set of Trail Gear 4" rear leafs so I can get rid of those dumb lift blocks.
Anyways, thanks for the input, it helped.
I was able to find a set of used Rancho torsion bars off a 88 4Runner. They were free if I just swapped the bars between trucks. I was a little worried because of some of the stories I've read about breaking loose the adjuster bolts. Luckily my truck and the donor had plenty greased adjuster bolts so installation was easy.
During my first road test, I had the preload set for 11.5" of tire to fender clearance...this was way too stiff. I next adjusted the bolts 8 turns softer. This gave 9.5" of clearance...this was way too mushy. After more testing I ended up with a tire to fender clearance of 10.25". Exactly were it was before the winch and tube bumper was installed.
I'm quite happy with the result. The weight of the winch no longer feels like there is a snow plow on the truck. Very steep rocky down hills are more sure footed. On faster dirt roads the body stays more level. Before the front end would kinda mush through a rut and then the rear would kick up by the rut. Now the front and rear have about the same feel.
Next mod is a set of Trail Gear 4" rear leafs so I can get rid of those dumb lift blocks.
Anyways, thanks for the input, it helped.
#11
just seen this post. I just purchased a 94 extra cab 4x4. Has 31 10.50 on it. Tires are rubbing in the turns, mainly dut to the american racing aftermarket rims. How do you adjust the torsion bars and might this work for my situation. Thanks in advance.
#12
IMO it is best to change the tires and wheels and not adjust the torsion bars.
When I first purchased my truck it had 10.5 wide rims. Off roading was poor because they that many more surface rocks and the steering wheel got bumped around more. But on the freeway during rain they were outright dangerous. Any standing water over 50 MPH was a guaranteed hydroplane and these were still good tires.
Also there just messy.
When I first purchased my truck it had 10.5 wide rims. Off roading was poor because they that many more surface rocks and the steering wheel got bumped around more. But on the freeway during rain they were outright dangerous. Any standing water over 50 MPH was a guaranteed hydroplane and these were still good tires.
Also there just messy.
#13
thanks for the reply. Thats an awesome looking truck, ecspecially for the age. Would like to do some of these mods myself, in time. This truck is new to me, so I'm still learning about it. Want to do what ever is best for the long term. Have you ever had any trouble with the 3.0? I've only put on 800 miles so far. Getting new parts in the front end to tighten it up. Service the tranny cause I'm not sure when it was done. Going to change the timing belt, waterpump and the front seals. Don't have any ideas on the real condition. Had thought about saving alittle more and having the head resurfaced and a new head gasket. Info I was told on the tires is these are factory size tires. I think the rims are 8 inch. American racing rims are off set, causing problems, at least what I was told. thought about getting a backset rims to tuck back under the fender wheels. Just don't want to spend in the wrong direction. I'm a fifty year old, so I want to build it maturel, properly. Plus my 16 year old will be driving it, so safty is a factor. Thankls again.
#14
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cheapest solution i would say is to buy some used wheels or some stock wheel/tire takeoffs from a newer 4wd toyota. all the 6lug toyota wheels should fit just fine as long as you don't try to change tire size for larger, which is when you run into more clearance issues. most toyotas past 95 came with a 31" tire vs the older 28", so stock take-offs should be fine.
good luck. if you have questions about specific wheels/tires you find, search here and then ask - very likely someone's tried it in the past.
#15
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31x10.50's were stock on many '94 4runners (mine included), so with stock wheels you should be fine. I never had rubbing with 31's. I get just a bit with my 33's, but mostly just on plastic parts during tight turns. Not enough to worry about.
Your door sticker may call for P225 tires, or something like that. My understanding is that was just a gimmick to get around higher import taxes. Toyota shipped the vehicles with the smaller tires to get in the lower tax bracket, but geared and otherwise configured for the bigger ones. The dealers then installed the proper sized 31's when the vehicles got to their lot.
Your door sticker may call for P225 tires, or something like that. My understanding is that was just a gimmick to get around higher import taxes. Toyota shipped the vehicles with the smaller tires to get in the lower tax bracket, but geared and otherwise configured for the bigger ones. The dealers then installed the proper sized 31's when the vehicles got to their lot.
#17
torsion bars?
Was getting some front end work done the the truck. Asked the mechanics if they could adjust the torsion bars to try and stop the rubbing. They adjusted them until the bolts hit the bottom of the cab. still rubbing. Found some factory toyota rims, 200 miles away. bought them and put them on. doesn't rub as much, but still rubs. Was wondering if something might be wrong with the torsion springs.
#18
Registered User
Well this turned out to be a long drawn out project. I was unable to get the Sway A Way torsion bars because of a long back order.
I was able to find a set of used Rancho torsion bars off a 88 4Runner. They were free if I just swapped the bars between trucks. I was a little worried because of some of the stories I've read about breaking loose the adjuster bolts. Luckily my truck and the donor had plenty greased adjuster bolts so installation was easy.
During my first road test, I had the preload set for 11.5" of tire to fender clearance...this was way too stiff. I next adjusted the bolts 8 turns softer. This gave 9.5" of clearance...this was way too mushy. After more testing I ended up with a tire to fender clearance of 10.25". Exactly were it was before the winch and tube bumper was installed.
I'm quite happy with the result. The weight of the winch no longer feels like there is a snow plow on the truck. Very steep rocky down hills are more sure footed. On faster dirt roads the body stays more level. Before the front end would kinda mush through a rut and then the rear would kick up by the rut. Now the front and rear have about the same feel.
Next mod is a set of Trail Gear 4" rear leafs so I can get rid of those dumb lift blocks.
Anyways, thanks for the input, it helped.
I was able to find a set of used Rancho torsion bars off a 88 4Runner. They were free if I just swapped the bars between trucks. I was a little worried because of some of the stories I've read about breaking loose the adjuster bolts. Luckily my truck and the donor had plenty greased adjuster bolts so installation was easy.
During my first road test, I had the preload set for 11.5" of tire to fender clearance...this was way too stiff. I next adjusted the bolts 8 turns softer. This gave 9.5" of clearance...this was way too mushy. After more testing I ended up with a tire to fender clearance of 10.25". Exactly were it was before the winch and tube bumper was installed.
I'm quite happy with the result. The weight of the winch no longer feels like there is a snow plow on the truck. Very steep rocky down hills are more sure footed. On faster dirt roads the body stays more level. Before the front end would kinda mush through a rut and then the rear would kick up by the rut. Now the front and rear have about the same feel.
Next mod is a set of Trail Gear 4" rear leafs so I can get rid of those dumb lift blocks.
Anyways, thanks for the input, it helped.
#19
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Was getting some front end work done the the truck. Asked the mechanics if they could adjust the torsion bars to try and stop the rubbing. They adjusted them until the bolts hit the bottom of the cab. still rubbing. Found some factory toyota rims, 200 miles away. bought them and put them on. doesn't rub as much, but still rubs. Was wondering if something might be wrong with the torsion springs.