How to Properly Adjust 1st Gen IFS Torsion Bars to Factory Specs (Via the SM)
#1
How to Properly Adjust 1st Gen IFS Torsion Bars to Factory Specs (Via the SM)
I decided to create this write up to assist with those of us replacing torsion bars, repairing or restoring a front end.
There has been a ton of mixed information floating around the 1st Gen 4Runner community regarding the factory height of the IFS 1st Gen 4Runners of 1986-1989. This forum as well as competing forums have thread after thread of tape measure measurements from the ground to the fender, hub to the fender, hub to the frame, etc. Every post produces wildly different numbers.
The information was gathered from one of these…
Information on ride height and alignment correction are pieced together from a few pages.
Page "FA-3" instructs the technician that before alignment of the front end, the ride height needs to be confirmed as standard and correct, and it is shown where to measure for this here:
Next to this photo are these instructions:
This clarifies the correct spot to measure from, which is the "center of the lower suspension arm front mounting bolt" as pictured above.
These instructions also state to reference page "A-35" for the correct chassis ground clearance.
Page A-35 can be seen here:
Confirming your model will give you the measurement down to the one thousanth, but that is impossible to adjust to. Adjusting to the tenth is possible, and extremely accurate.
1. Remember: This is for factory tire size and wheels. ***The chassis ground clearance numbers found on a-35 above is for 225/75 R15***. If you are running 31x10.5, which were a factory option, you must do the math for the additional sidewall lift.
That is a 1.35" difference, so for 31x10.5 tires, the technician would have to add 1.35" to the chassis ground clearance numbers found on page A-35. This applies to new tires, and not all tires are perfectly the same in size. To minimize error, do this with brand new tires only, properly inflated to specifications (26psi in the front for the 225/75 R15s).
2. Remember when adjusting you need to be on a perfectly level surface, say a leveled porch, or shop floor, garage. You cannot do this well on a seemingly flat parking lot, as the independent front suspension is, well, independent, and will not read correctly, leaving you with a leaning truck in the end.
3. Remember, you CAN adjust ride height on the ground, but you will need to drive in reverse and forward apply heavy brake pressure to rock the suspension to the actual height you adjusted to each time you turn the torsion bolts. Once the vehicle is close to the correct measurements, take it for a five minute drive, come back, check to see if there is change, and adjust and drive as necessary.
I hope this information helps those of you replacing torsion bars, repairing a front end from damage, or trying to compensate for heavy accessories. Sometimes the bars just sag unevenly after 25+ years. This is how they are properly corrected.
Good Luck!
There has been a ton of mixed information floating around the 1st Gen 4Runner community regarding the factory height of the IFS 1st Gen 4Runners of 1986-1989. This forum as well as competing forums have thread after thread of tape measure measurements from the ground to the fender, hub to the fender, hub to the frame, etc. Every post produces wildly different numbers.
The information was gathered from one of these…
Information on ride height and alignment correction are pieced together from a few pages.
Page "FA-3" instructs the technician that before alignment of the front end, the ride height needs to be confirmed as standard and correct, and it is shown where to measure for this here:
Next to this photo are these instructions:
This clarifies the correct spot to measure from, which is the "center of the lower suspension arm front mounting bolt" as pictured above.
These instructions also state to reference page "A-35" for the correct chassis ground clearance.
Page A-35 can be seen here:
Confirming your model will give you the measurement down to the one thousanth, but that is impossible to adjust to. Adjusting to the tenth is possible, and extremely accurate.
1. Remember: This is for factory tire size and wheels. ***The chassis ground clearance numbers found on a-35 above is for 225/75 R15***. If you are running 31x10.5, which were a factory option, you must do the math for the additional sidewall lift.
That is a 1.35" difference, so for 31x10.5 tires, the technician would have to add 1.35" to the chassis ground clearance numbers found on page A-35. This applies to new tires, and not all tires are perfectly the same in size. To minimize error, do this with brand new tires only, properly inflated to specifications (26psi in the front for the 225/75 R15s).
2. Remember when adjusting you need to be on a perfectly level surface, say a leveled porch, or shop floor, garage. You cannot do this well on a seemingly flat parking lot, as the independent front suspension is, well, independent, and will not read correctly, leaving you with a leaning truck in the end.
3. Remember, you CAN adjust ride height on the ground, but you will need to drive in reverse and forward apply heavy brake pressure to rock the suspension to the actual height you adjusted to each time you turn the torsion bolts. Once the vehicle is close to the correct measurements, take it for a five minute drive, come back, check to see if there is change, and adjust and drive as necessary.
I hope this information helps those of you replacing torsion bars, repairing a front end from damage, or trying to compensate for heavy accessories. Sometimes the bars just sag unevenly after 25+ years. This is how they are properly corrected.
Good Luck!
#2
#4
Very late to update this post, but here are all the numbers in relation to the correct way to adjust old/ install new T-Bars on IFS:
Remember, this is for the above explained 1986 to 1989 body style IFS 4Runner (it most likely applies to 86-88 IFS 4x4 Pickup too).
Tires:
225/75R15
Factory height -
(at lower control arm) ground to middle of mounting bolt: 11.2"
from 15" rim to bottom of fender lip: 13.5"
31x10.5R15
Factory height-
(at lower control arm) ground to mounting bolt 12.55"
from 15" rim to bottom of fender lip 13.5"
So for those of you who just want the shortcut answer, it is 13.5" from top of a 15" rim (factory size) to the bottom of the front fender lip. This is the best way to measure, it takes the tires out of the equation.
It is worth noting that I have worked on some 1st gen 4runners that measured 13.75" from the top of the 15" rim to the bottom of the front fender lip. This could be because the rear sagged, and changed the height of the front end - but if you are replacing bars or adjusting bars to stock then 13.5" to 13.75" is pretty much perfect - unlike the misinformation floating around the web stating "14 to 15 inches". That is far from stock on a rather limited IFS system.
Hope this helps everyone looking to restore a 1st Gen!
Remember, this is for the above explained 1986 to 1989 body style IFS 4Runner (it most likely applies to 86-88 IFS 4x4 Pickup too).
Tires:
225/75R15
Factory height -
(at lower control arm) ground to middle of mounting bolt: 11.2"
from 15" rim to bottom of fender lip: 13.5"
31x10.5R15
Factory height-
(at lower control arm) ground to mounting bolt 12.55"
from 15" rim to bottom of fender lip 13.5"
So for those of you who just want the shortcut answer, it is 13.5" from top of a 15" rim (factory size) to the bottom of the front fender lip. This is the best way to measure, it takes the tires out of the equation.
It is worth noting that I have worked on some 1st gen 4runners that measured 13.75" from the top of the 15" rim to the bottom of the front fender lip. This could be because the rear sagged, and changed the height of the front end - but if you are replacing bars or adjusting bars to stock then 13.5" to 13.75" is pretty much perfect - unlike the misinformation floating around the web stating "14 to 15 inches". That is far from stock on a rather limited IFS system.
Hope this helps everyone looking to restore a 1st Gen!
Last edited by 89fourrunner; 02-17-2016 at 06:55 AM.
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