Ride height adj. explain loaded vs unloaded specs please (1 Viewer)

[MoCoNative]

I'm trying to dial in my 1996 T100 Extra Cab, yes I know wrong forum, but that one does not get much traffic, and the front end is the same as the minitrucks.

I've been fighting alignment issues on this truck for years, about a year ago I replaced all front suspension bushings, spindles, bearings and torsion bars. The alignment just won't dial in. What I'm stumped on is the ride height adjustment, as it vastly affects the ability of the lower control arm cams to set caster and camber. This is a stock truck, so trying to establish stock baseline.

In the FSM in the alignment section it starts off with a section of text:

HINT:
For the vehicle height of non−loaded vehicles for each model
and alignment standard values, refer to page SA−XXX

It then continues on with this information:

1. MEASURE VEHICLE HEIGHT
Vehicle height:
Front: A − B = 58.0 mm (2.283 in.)
Rear: C − D = STD cab: 23.0 mm (0.906 in.)
Extra cab: 28.0 mm (1.102 in.)
Measuring points:
A: Drive shaft height measured at its center on the
outer edge.
B: Lower suspension arm front adjusting bolt height
measured at its center.
C: Rear leaf spring front bushing height measured at
its center.
D: Rear axle shaft height measured at its center.
NOTICE:
Before inspecting the wheel alignment, adjust the vehicle
height to specification.
If the vehicle height is not standard, try to adjust it by pushing
down on or lifting the body.

I have seen this information in the FSM for the other trucks and 4runners too. In my actual paper copy of the 1996 T100 FSM there are specs at the end of the axle section that give ride heights for unloaded vehicles. Toyota uses the terms "non-loaded vehicle condition" and "standard loaded vehicle condition."

What do these two terms actually define????????

The non-loaded height specs are 32.3mm for the front end measurement and 79mm for the rear end, for my model, caster and camber are defined too. Sitting in the garage, the rear end with no extra weight in the truck is right around the 79 mark. If I set the front end to the 32mm difference, my camber becomes very negative without really maxing out the front cam. Now perhaps my assumptions are incorrect, but I imagine Toyota envisioned the adjustment cams to ride around the 0 mark or neutral in there adjustment range if all the suspension was in correct shape. If I set the cams to 0, caster and camber are nowhere close to right. On the alignment adjustment chart the negative camber is not even on the chart. I lowered the front end a tad, by letting the torsion bars off, to about the middle of this range. This of course increases the rake of the truck, but camber is beginning to come back into spec with less cam manipulation. Ride improved too.

I noticed in one of the pickup FSM's it explains loaded and non-loaded a little more, by saying in the loaded condition, regardless of the model variation of the truck, as weight is added alignment values are all the same or as the FSM puts it, approach the "standard value". But spring rate differences for different trucks would alter the unloaded specs. The only way I could hit the loaded spec above for the rear axle on my T100 would be with significant weight in the rear end of the truck. To properly distribute that weight would require weight in all the seats and such to load the vehicle equally to GVWR. Obviously they wouldn't do that at the shop.

I'm playing with this at home, very controlled environment. All wheels leveled, I have slip plates and I made brackets to hold a Longacre bubble caster/camber tool properly on the rim, so I can play with this and get things pretty close to a real alignment. This truck has been on the rack many, many times and they never seem to get it just right, so I'm trying to figure out what is wrong. I really thought after replacing pretty much the whole front end it would just fall into spec, but it did not. Didn't replace control arms, but look good, OEM ball joints have about 55,000 miles on them.

So what do we set the front height at. I found some info on Yotatech, that just said stock adjustment is 58mm, period, to ignore the non-loaded spec, but as I said, that does not jive with the rear end. So again, what did Toyota want done.

 

[gnob]

Afair the ride height is set via a measure on the torsion bar adjuster.

What exactly is the alignment issue and what exactly is nit happening or not possible with your current setup?

 

[MoCoNative]

Its a long story. Yes, ride height is set by tightening or loosening the torsion bar adjuster, the FSM demonstrates measuring from the front outer axle/hub face to the ground and then measuring the front adjusting cam bolt. The difference will set ride height to stock.

I purchased this truck with 119K miles in 2007. Very clean, decent maintenance, no collisions or evidence of any. It had recently had a thrust angle alignment. It drove okay then. However, after many years and now 285K total miles I've witnessed alot of tire wearing and seat time. The truck consistently wore the shoulders off the front tires, mainly the insides to the point they would get really bad, more on one side than the other. I just installed my fifth set of tires on this truck. For the past 6-7 years it has had a consistent left hand pull, like brace your elbow and just hold the wheel about 1/8 to 1/4 turn at times to hold your lane. Sometimes it would wane, but always come back. Different techs, different shops, put it all to spec, would still pull after a couple months. Part of this is the tires would always be worn funny, so I think it would just settle back into it over time.

I had to replace the front control arm bushings once several years ago, cause the adjuster bolts were seized, had to cut them all out. Went back with non OE bushings, they crushed out quickly, that and the mechanic insisted his book calls for 250lbs torque on those, so that didn't help them. So over the last couple years I decided something must be whack. Thought maybe the endplay in the rear end was excessive, put in all new rear bearings. Thought maybe the fretting on the front spindles was letting the something fall out of spec, replaced both front spindles, new bearings, all new front suspension bushings, new torsion bars.

The truck always indicated a thrust angle of 28-32 degrees in the rear end. Figured up the angle the the right rear spring perch needed to move to correct that and altered the hole to rotate the axle to straight. Finally figured out the thrust angle alignment many years ago had put the tie rods in an unequal state and they had moved the steering wheel back to straight. I often questioned the techs why the tire rods were not equal lengths. The FSM directly states they should be equal length, and no more than 1mm difference. If they had been altered, and the tech blocks the steering wheel at center, then he will always adjust according the read out, and not re-equal them. I learned that if the tie rods are not equal in length it throws off Ackerman's angle when turning the wheel. So every corner, every slight course correction turns the wheels in an unequal arc to each other, guess what, it produces tire shoulder wear similar to a camber or toe problem.

So about a year ago, I re-did this whole front end, had it aligned, he had it on the rack 5 times and still could not completely cure the left hand pull. I went home and figured out this unequal tie rod issue. I bought the tools and realigned everything my self. It improved, but the tire wear was pretty bad, so some pull returned. Even cross rotated the tires and listened to wheel lug drone for thousands of miles now trying to re-wear them the other way. Skip to a a couple weeks ago, I damaged a tire beyond repair, so bought a new set of tires.

Now it pulls to the right. It figured maybe a radial pull, swapped fronts, no help. Has a little shimmy while correcting down the highway, might have a wheel out of balance, too busy working to get back to the tire shop at the moment. But decided to check alignment over the weekend. Thought maybe hanging on the wheel to the left, pulled the right wheel toe out, or loosened a wheel bearing. No loose bearings, got toe all back in check and I'm revisiting the fact the cams just seem out of whack when you try to dial in about 1/2 degree camber and 1.5 degrees of caster. Tracked much better today, but camber is not equal at the moment, more positive on the left front, didn't want to adjust again till I figure out ride height definitively.

Ride height is the last variable I'm unsure of compared to factory spec. Front left cam is maxed out, short, to achieve 1/2 degree camber, caster is around 1.5, rear cam is in long 4 marks. Right side is about 0 camber with front cam short 4 marks, rear cam close to center. I didn't adjust it, as it was better than what I found on the left side, but found lowering ride help helped.

 

[gnob]

Are you shooting this on a laser machine or with a tape measure?
Id be curious to the actual printout.

I typically run these as close to zero camber as possible while keeping caster as even as possible.

Make sure your steering box is actually centered in relation to the rest of the steering system as well.

 

[MoCoNative]

I'm using my best tape measure skills, trying to center toe measurements with laser down centerline of vehicle. Using a Longacre bubble gauge for the caster/camber. The steering is centered now, it was not before last summer. It is not a perfect setup, but my measurements were very, very close to what it left with the last time it was on a rack when I initially set everything up last summer. I felt some confidence that I was getting accurate measurements. I'm going to fool with it some more, but probably have to break down and take it in, just been very disappointed in the last many attempts at the shops. May be better this time on fresh tires and properly aligned steering box and tie rods. I'm not knocking it out either. I almost always mark the cams after alignments, because of the issues I've had, and not once has one come loose or spun. Its just a daily driver most the time.

 

[gnob]

As much as I hate to say/admit this. There is a super high percentage of people who are "mechanics" who simply aren't car guys. They dont give two shyts other than the paycheck.
There gets to be a "just slam it" mentality and on to the next $$.
Find a shop that specializes in suspension and alignment, not just a general with a rack.

 

[toyotaboy80]

119 to 285k miles is 166k miles. 4 sets of tires. 41.5k miles on a set. Thats pretty fair.

How often do you do a rotation front left tire to rear right front right tire to rear left and rears straight to the front? Thats how you keep tires square. Id say every 3k miles to keep the wear in check, square, quiet, and minimal. The rear axle only goes straight and squares up the uneven tread from the variable angles introduced to the steering tires.

Toe wear will scrub the tire across the tread. Toe in will scrub the tire outside to inside and toe out will scrub the tire inside to outside. Ideally you want 1/16" toe in static and under load on the highway that will produce 0 toe. You dont really need toe except for in high performance applications altered toe can introduce specificly looked for stability characteristics. I.e rear toe in when doing high speed straights or a specific toe in or out to produce under/over steer. That doesnt apply here. Toe finds its own center. Thats why the tire scrubs when toe isnt set right. Also why you ideally want 0 toe while cruising so the tires dont scrub. The steering box will find its own center. With the box centered, the toe is set then the drag link is set to center the steering wheel. If the drag link isnt adjustable(not sure on your truck) then you would want to set the toe square to both rear wheels with the steering wheel straight.

Camber will wear an angle into the tire. It adds stability to the steering. This manufactured inside edge tire wear is why you would rotate to the opposite rear to square the tread up.

Caster at 1.5 seems low. Doesnt really produce tire wear unless you consider low caster as a result of the tire not returning to center or staying center by its own inertia.

Do your brakes function properly? That can introduce pulls. Especially sticky brakes.

Your miles to tire replacement doesnt seem odd to me. Your pull does seem odd but could be from lack of tire rotation. Your specs seem OK. Whats your tire rotation schedule?

Edit: I think the 96 truck uses a rack and pinion. So no drag link. Youd want to set the toe with the steering wheel straight and then the toe at spec while front wheels are square to rear wheels.

 

[MoCoNative]

T100 uses the same steering arrangement as the the IFS pickups and 4runners, traditional steering box, draglink, idler arm and tireods. Steering is centered, then tierods set for toe and centered steering. You can't bring the wheel back to center with any other adjustment. I can't really get much more caster without losing camber, by lowering the front end, some more adjustability seems to be available. The tirewear I was consistently getting for many years wasn't just camber wear, but severe cupping on the edges, as I mentioned above, unequal tireods were likely the problem.

Alignment specs from FSM, there are other similar specs noted for each model with unique ride height measurements in the unloaded vehicle condition pages. Mine is the Extra Cab, it does not call for much caster.

INSPECT CAMBER, CASTER AND STEERING AXIS
INCLINATION
STD cab
Camber 0°45’ ± 45’ (0.75° ± 0.75°)
Left−right error 45’ (0.75°) or less

Caster 1°30’ ± 45’ (1.5° ± 0.75°)
Left−right error 45’ (0.75°) or less

Steering axis inclination 11°50’ ± 45’ (11.83° ± 0.75°)
Left−right error 45’ (0.75°) or less

Extra cab
Camber 0°45’ ± 45’ (0.75° ± 0.75°)
Left−right error 45’ (0.75°) or less

Caster 1°20’ ± 45’ (1.33° ± 0.75°)
Left−right error 45’ (0.75°) or less

Steering axis inclination 11°50’ ± 45’ (11.83° ± 0.75°)
Left−right error 45’ (0.75°) or less

Still looking for an explanation/definition of the "non-loaded" vs "standard loaded" vehicle height, anyone???? Otherwise I'm going to reset at the standard height and re-align, hopefully this weekend. Takes a while to get it all done, haven't had time, but wanted to know on the height question.

 

[toyotaboy80]

Not really sure in FSM terms but it would make sense values change depending on vehicle weight.

I.e a truck in bone stock form with a full tank of gas and the driver might be unloaded.

Set it up for the majority of driving conditions and call it a day. Driving down the road at a nominal spec caster camber toe is about all you can do. If its a work truck and you drive around 99% of the time on the rear bump stops, youd want to dial in more caster camber and toe.... if its set up for work truck weight in the box and you remove 2k lbs out of the box and start dailying it empty, youd ideally readjust. factory specs appease a range of conditions.

Cupped tires is a shock or spring issue, i.e tire bouncing on the ground.