Like I said, sometimes it's better to use the KISS method and just stick with measuring where the TRUE caster angle is located. Glad you figured it out though.Jeremy
CASTOR Adjustment ? (was camber)
- Thread starter nspctr1
- Start date
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Like I said, sometimes it's better to use the KISS method and just stick with measuring where the TRUE caster angle is located. Glad you figured it out though.Jeremy
The easiest and most accurate way to measure caster is on an alignment machine. Trust me, spend a few bucks and take it to an alignment shop. You will have a good baseline to work from. You can then determine the exact thickness of the wedge that you will need. From the pics, it looks like you should be prepared to purchase new u bolts that are longer to accommodate the wedge. You should also take into account your driveline angle when determining wedge thickness.
inkpot
SILVER Star
Howdy! A lot of alignment shops refuse to to 4x4 rigs, especially if they are lifted and/or have much bigger tires. They call it "modified" and say they won't accept the liabilty. So I just tell them I do not want any adjustments, just the computer readouts with all the good numbers on it. That way they are not liable for anything. Usually less than $50. Some equipment will not mount to tires larger than 35". BTDT. Usually they will adjust the toe in for a couple of extra $$, once they get it on the machine. I changed my springs and shackles, and after I got the readings from them, I added shims and now it steers like a dream down the freeway at speed. John
That axle does not look cut and turned to me. With the exception of dgangle, I have never heard of people cutting and turning axles in SUA configuration. I think his issue is simply extended shackles that have given him negative caster and I still believe it can be easily resolved with probably 4deg shims looking at the length of his shackles. nspctr1, Either slap some stock shackles on there or install some 4 deg shims and report back. I bet your scary steering disappears.
That looks like a stock axle to me. The pinion is rotated up due to the longer front shackles. Maybe adds 4-5 degrees of pinion rotation up.
Can you put your wheels straight and measure the top of the steering arms? Then measure the floor to see what angle it is. Then measure the pinion flange.
Can you put your wheels straight and measure the top of the steering arms? Then measure the floor to see what angle it is. Then measure the pinion flange.
dgangle
total rice
I did my C&T because
1. the V8 moved everything forward making the front driveshaft shorter
2. the engine/trans/TC is angled downward in the rear effectively tilting upward the front output flange at the TC
3. 4" lift
with the lift the front DS u-joints bound at any extension and it vibrated so bad at anything over a crawl I thought it would self destruct.
C&T solved everything.
With that pinion angle, if that axle has not been C&T'd then the caster has got to be at least -10* and would surely explain the bad steering characteristics.
We can hypothesize all we want but until he gets a realistic number by either himself or paying someone else, all of this is just conjecture.
1. the V8 moved everything forward making the front driveshaft shorter
2. the engine/trans/TC is angled downward in the rear effectively tilting upward the front output flange at the TC
3. 4" lift
with the lift the front DS u-joints bound at any extension and it vibrated so bad at anything over a crawl I thought it would self destruct.
C&T solved everything.
With that pinion angle, if that axle has not been C&T'd then the caster has got to be at least -10* and would surely explain the bad steering characteristics.
We can hypothesize all we want but until he gets a realistic number by either himself or paying someone else, all of this is just conjecture.
- Thread starter
- #27
I will fire it up and take it to an alignment shop and report back. It seems none of my buddies know how to check the caster angle either.
We look forward to hearing the results. My guess, looking at those shackles again, is you will be at -3 deg or worse.
- Thread starter
- #29
I decided to re-check a couple of spots before taking it to the shop which will be later this week. I checked the angle at the bottom of the wiper plate and it shows approx 8*, from the knuckle studs it shows the same. I put a level on the lower knuckle studs and the forward studs are a 1/4" lower to the ground than the rearward ones. If these are supposed to be level or near level they certainly are not.
dgangle
total rice
8* + or -????
Sounds like 8*+. If so, that sucks. Wonder why someone would C&T the opposite way?
Jeremy
Jeremy
dgangle
total rice
"opposite way"?????
You WANT positive caster, maybe just not that much
You WANT positive caster, maybe just not that much
How long are those shackles from pin to pin? Stock is around 2-3/4".
- Thread starter
- #34
My bad, I meant it looks like 8*-.
Jeremy
Jeremy
I don't know that the surfaces you used are accurate indicators of caster. The one I trust is the machined surfaces at the top and bottom of the knuckle where the bearing reetainer and steering arm mount. You also have to take into account the ambient angle of the surface on which the truck is sitting and if it is reasonably flat. You need to subtract the ambient angle from the angle measured with a magnetic angle finder.
- Thread starter
- #37
That is kinda what I was implying earlier. I checked the concrete floor surrounding the wheels and it is level per indication of a 3' level. from that I measured across the knuckle studs and the flat part of the felt retainer ring which measure equally using the angle finder. I'm reading approx -8*. I know it's not set in stone due to too many variables but to get a reading of -8* could possibly mean it is out at - 4 to 6* , right?
- Thread starter
- #38
OK, while doing more research I found this in a article on caster angles.
"Single-Cardan Measurements:
Assuming you have a single cardan driveshaft and want to check if the transfer case output and pinion flanges are close to parallel, just measure the distance between the top and bottom of each flange.
If the dimensions are equal, the two flanges are parallel.
If they are not equal, then each 1/16" difference is equal to 0.9° across the ~4" diameter of the flange (which is the size Toyota uses)
If 0.9° is too confusing for you, call it 1°, that is probably close enough for small differences.
Other makes may use different size flanges and some may not use flanges at all,
If no flanges are uses, then an angle finder must be employed to measure the angles
Ideally, you would like the upper measurement to be 1/16-1/8" less than the lower measurement for a bit of static "down-angle". Then, as the axle (and pinion) tilt up under load, the angles will approach parallel. While this measurement can be done with the driveshaft in place, it may be easier to do with it off, in order to get more accurate measurements: "
That said, I measured the distance between the top and bottom yokes and there appears to be between a 1/4" to 5/16" difference between the two. This coincides with the measurement on the wiper plate by the way. Not sure if there is any significance to that but thought I would mention it. Anyway, with this geometry it shows I have a negative caster of approx. 5* if my math is correct.
Does this sound more in line? I know it should be closer to 1* positive but at least it's a starting point. BTW, I did have a guy in the neighborhood look at it, another shade tree mechanic if you will and he says the yoke or axle should face either level or just 1* towards the ground and that way when you encounter obstacles you have a little more flex or room for your drive shaft to manuver before binding.
"Single-Cardan Measurements:
Assuming you have a single cardan driveshaft and want to check if the transfer case output and pinion flanges are close to parallel, just measure the distance between the top and bottom of each flange.
If the dimensions are equal, the two flanges are parallel.
If they are not equal, then each 1/16" difference is equal to 0.9° across the ~4" diameter of the flange (which is the size Toyota uses)
If 0.9° is too confusing for you, call it 1°, that is probably close enough for small differences.
Other makes may use different size flanges and some may not use flanges at all,
If no flanges are uses, then an angle finder must be employed to measure the angles
Ideally, you would like the upper measurement to be 1/16-1/8" less than the lower measurement for a bit of static "down-angle". Then, as the axle (and pinion) tilt up under load, the angles will approach parallel. While this measurement can be done with the driveshaft in place, it may be easier to do with it off, in order to get more accurate measurements: "
That said, I measured the distance between the top and bottom yokes and there appears to be between a 1/4" to 5/16" difference between the two. This coincides with the measurement on the wiper plate by the way. Not sure if there is any significance to that but thought I would mention it. Anyway, with this geometry it shows I have a negative caster of approx. 5* if my math is correct.
Does this sound more in line? I know it should be closer to 1* positive but at least it's a starting point. BTW, I did have a guy in the neighborhood look at it, another shade tree mechanic if you will and he says the yoke or axle should face either level or just 1* towards the ground and that way when you encounter obstacles you have a little more flex or room for your drive shaft to manuver before binding.
- Thread starter
- #39
I doubt that your caster measurements are accurate.
What is accurate is that you have a longer shackle in front, by about 2.75 inches. The longer shackle would make your caster more negative by nearly 4 degrees. The odds are overwhelming that you have a stock axle housing. If you put in 4 degree caster correction shims (with the fat end toward the shackle), the caster should return to stock. 5-6 degree shims might be good for a little extra caster.
What is accurate is that you have a longer shackle in front, by about 2.75 inches. The longer shackle would make your caster more negative by nearly 4 degrees. The odds are overwhelming that you have a stock axle housing. If you put in 4 degree caster correction shims (with the fat end toward the shackle), the caster should return to stock. 5-6 degree shims might be good for a little extra caster.
