Alignment- Measuring Caster

[OX1]

Since I got the 70 roadworthy, it just hasn't been much fun to drive.
It is all over the road. Since the entire front end and steering are new,
track bar and drag link angles are parallel, I was hoping there was no
caster in the front axle.

Anyway, I've had this camber/caster guage since about 92,

but never used it to measure caster before. Picked up a new
toy to help out. Rand alignment plates.

Specs here.
http://sherice.hortencia19.com/rand...blespadstie-rod-adjustment-set-of-2-big-sale/

They come with small ramps to drive up on, but the first time I tried
the ramps and plates just skidded down the lift runway.
Ended up cutting 2x6's to keep them put.

So I figured I'd try a supposed known quantity first, 14 stang
with 850 miles on it. Stang specs are

-.75 degree camber and 6.35 to 7.85 degrees caster (disturbing that
ford allows 1.5 degrees cross caster in this day and age, keeps them
from having to fix anything that is out, I guess %)). So the stang
goes up first.

Went to measure camber just for S&G, and realized I bought this guage
in a time when 17's were unheard of, let alone 18's. Had to add a
little extension.

It was dead on @ -.75, both sides.

Industry standard for steering wheel angle when measuring caster
is supposed to be 20 degrees. For some reason (maybe due to the
electric power steering), this thing just will not stay put when you shut
it off with the steering off center (on the plates anyway). So I went
out to the first lock on the steering column, which ended up about
18 degrees (close enough).

Results were

Drivers, left +2-1/8, right -2-3/16
Pass, left +2-1/2, right -2-1/4

Your supposed to add a negative to postive, and multiply by 1.5

So that gives me 6.46 caster drivers, 7.125 caster pass. close enough to make me think this might work.

So up goes the bronc.

Results

Camber, +1/2, both sides (can live with that)
Caster Drivers, Left-1/4, Right -2-3/8
Pass, Left, -1/4, Right -2-1/4

So pretty even at 3.2 degrees drivers and 3 degrees pass. Not the
zero or one degree I was hoping for, but room for improvement on a
rig with a 3.5 lift (using 7 degree bushings) and 33's I guess. About
what one would expect on a stock 77 axle since ford supposedly
added some caster in the later years.

You could do this on a relatively level floor without the plates or lift
too. I used level out a spot on any garage floor using newspaper,
a level and a long straight edge. Instructions show you can just make
marks on the floor for the caster part. A real cheap caster/camber
here.

http://www.toyheadauto.com/CasterCamberGauge.html

 

[siderbox]

Very nice set up.
Where did you come up with wanting zero or one degree?
-5 to -7 would give a better drive down the road.

I would like to see a comparison between the results you got with your set up and the using the BC caster adapter and then a digital level on the flat part of the upper 'C'.

 

[siderbox]

Some pics to go with my honorably ask question.

digtial level on the flat part of the 'C'

using the BC adapter and digital level

These pics were taken with the axle at full drop.

 

[OX1]

Very nice set up.
Where did you come up with wanting zero or one degree?
-5 to -7 would give a better drive down the road.

I would like to see a comparison between the results you got with your set up and the using the BC caster adapter and then a digital level on the flat part of the upper 'C'.

Not wanting, but hoping, so the correction to 5 or 8 would be more dramatic.

Just looked up that tool. Awsome idea for $10.
May just grab one to see how it compares.
I assume it would work on 78/79's too??

 

[siderbox]

So if I read your results correctly you ended up with -3.2 and
-3.0.
That should be manageable.

From what I have found putting the level on top of the 'C' gives the same results at the BC tool.

I would still like to see the level numbers compared to your numbers.

 

[bmc69]

From what I have found putting the level on top of the 'C' gives the same results at the BC tool.

Me too. That's what I always use. When I'm building an EB, I shoot for about 6 degrees of caster as the "design target". I'm thinking that will be what I go for when I put the Duff long arms and D60 under my '78 Bronc soon too...

 

[broncokak]

You can always have the C's turned. Makes a huge difference going down the road.

 

[OX1]

Me too. That's what I always use. When I'm building an EB, I shoot for about 6 degrees of caster as the "design target". I'm thinking that will be what I go for when I put the Duff long arms and D60 under my '78 Bronc soon too...

You can always have the C's turned. Makes a huge difference going down the road.

Bronc is still sitting on the plates, so I could grab a cheap digital angle guage and do the top of C. One thing I didn't account for was the front tires are on the plates, the rears are not. Comes in right around 1/2 a degree, so true current caster is probably closer to 2.5ish.

and yup, that is the plan on turning C's, was just curious what I was starting with.

 

[OX1]

These pics were taken with the axle at full drop.

BTW, your @ almost 9 degrees at full drop/droop??

 

[broncnaz]

You want good numbers at ride height full drop is irrelevant to handling.
There are lots of factor that affect the wandering issue you have. toe in is one of the biggest since your caster is not that bad. the standard you qoute of 20 degrees is good for stock tires on a new car but thats not what you have. yes the numbers should be close but they will be different. Also you may want to change the tire pressure as it affects handling as well.

 

[OX1]

You want good numbers at ride height full drop is irrelevant to handling.
There are lots of factor that affect the wandering issue you have. toe in is one of the biggest since your caster is not that bad. the standard you qoute of 20 degrees is good for stock tires on a new car but thats not what you have. yes the numbers should be close but they will be different. Also you may want to change the tire pressure as it affects handling as well.

I'll check toe again. Pretty sure I set it around a 1/16 in. Tire pressure I have had from 15 (when I had went on a snow run one time and then drove home with no way to add air), to 35. No difference really.

Agree on the angle. I checked caster on the stang for fun, putting it as close to full lock as I could get, and camber was still 2ish in one direction, but upwards of 5 in the other direction (forget which was which). Do the new alignment machines take this into account and/or is there any kind of standard with oversize tires? (add, subtract 3 or 5 degrees when turning tires for camber measurement??)

The only things left that I can think of are
1. Caster (maybe)
2. 78 steering box setup like it goes on a 78, not reverse, but Bill has that setup on his crawler with 38's and has said in the past his drives fine.
http://luxjo.supermotors.net/70 EB SPORT/STEERING/78 STEERING BOX/DCP02913.JPG
3. Ball joints (felt tight, but only front end part not new).
4. Fairly overboosted steering with sag from a HB lincoln and the 78 box (upping caster should actually help with that).

Parts that should be OK.

1. Tight 78 man trans steering column.
2. 70's F350 steering shaft with the small CV, no rag joint. Very small side to side angle @ box, no angle up-down.
http://luxjo.supermotors.net/70 EB SPORT/STEERING/78 STEERING BOX/DCP02824.JPG
http://luxjo.supermotors.net/70 EB SPORT/STEERING/78 STEERING BOX/DCP02826.JPG.
3. New chevy tie rods and drag link (DOM). Riser to set track bar parallel.
http://luxjo.supermotors.net/70 EB ... LINK/CHEBBIE TIE RODS_DOM LINKS/DCP04573.jpg
4. 7 degree rad arm C-bushings and new rubber radius arm rear bushings.
5. New track bar with upper end a rod end.
6. New front wheel bearings.
7. New deaver 11 pack rear leaf springs.
8. Rear end completely rebuilt, all new wheel bearings.

I'm leaning towards changing the caster first, then maybe moving the box and switching it to a rear facing pitman. The pitman/drag link should affect bump steer more I would think. This problem happens even on perfectly flat, good condition roads @ moderate speeds, say 40 MPH with suspension not cycling.

 

[bmc69]

2. 78 steering box setup like it goes on a 78, not reverse, but Bill has that setup on his crawler with 38's and has said in the past his drives fine.
.

I did that on a '72 and it drove fine...but it only had 32" swampers on it and only 2.5" lift. If you think about it, any offset front to back does not change what the vertical motion does to the steering linkage and bump steer effects. Different plane and one with almost no relative motion (a little from the rotation of the radius arms).

 

[mlake01]

I'll check toe again. Pretty sure I set it around a 1/16 in. Tire pressure I have had from 15 (when I had went on a snow run one time and then drove home with no way to add air), to 35. No difference really.

Agree on the angle. I checked caster on the stang for fun, putting it as close to full lock as I could get, and camber was still 2ish in one direction, but upwards of 5 in the other direction (forget which was which). Do the new alignment machines take this into account and/or is there any kind of standard with oversize tires? (add, subtract 3 or 5 degrees when turning tires for camber measurement??)

The only things left that I can think of are
1. Caster (maybe)
2. 78 steering box setup like it goes on a 78, not reverse, but Bill has that setup on his crawler with 38's and has said in the past his drives fine.
http://luxjo.supermotors.net/70 EB SPORT/STEERING/78 STEERING BOX/DCP02913.JPG
3. Ball joints (felt tight, but only front end part not new).
4. Fairly overboosted steering with sag from a HB lincoln and the 78 box (upping caster should actually help with that).

Parts that should be OK.

1. Tight 78 man trans steering column.
2. 70's F350 steering shaft with the small CV, no rag joint. Very small side to side angle @ box, no angle up-down.
http://luxjo.supermotors.net/70 EB SPORT/STEERING/78 STEERING BOX/DCP02824.JPG
http://luxjo.supermotors.net/70 EB SPORT/STEERING/78 STEERING BOX/DCP02826.JPG.
3. New chevy tie rods and drag link (DOM). Riser to set track bar parallel.
http://luxjo.supermotors.net/70 EB ... LINK/CHEBBIE TIE RODS_DOM LINKS/DCP04573.jpg
4. 7 degree rad arm C-bushings and new rubber radius arm rear bushings.
5. New track bar with upper end a rod end.
6. New front wheel bearings.
7. New deaver 11 pack rear leaf springs.
8. Rear end completely rebuilt, all new wheel bearings.

I'm leaning towards changing the caster first, then maybe moving the box and switching it to a rear facing pitman. The pitman/drag link should affect bump steer more I would think. This problem happens even on perfectly flat, good condition roads @ moderate speeds, say 40 MPH with suspension not cycling.

Bump your toe-in to 3/16" and give it a quick little test drive.

 

[OX1]

So I cleaned up the upper C, put a small straight edge on it and it
read 4 degrees with an analog angle finder. Will try to get a digital
later today.

Also re-measured toe and it is between 3/32 and 1/8, closer to 1/8 in.

For the heck of it, measured my 79 with 2" springs, no caster
correction (no suspension geometry corrrection in any way).
It was 5, maybe 5.5 caster. It has original looking rad arm
bushings (both ends), orig steering, possibly ball joints. Has
original rear springs/bushings on 35 AT's and it goes down
the road just fine.

Even this disaster back in the day when NJ allowed 44 boggers
on the street, 7" lift (and 2" body), 4 degree bushings, 4" rad arm
drops with 7" springs, no track bar drop or riser, went down the
road pretty good.

Very frustrating

 

[OX1]

Bump your toe-in to 3/16" and give it a quick little test drive.

Will give it a shot after I get a digital angle finder. Don't want to move it until I measure that, for comparison sake.

 

[bmc69]

Bump your toe-in to 3/16" and give it a quick little test drive.

That. Heck, I run 1/4" on some of mine.

 

[OX1]

That. Heck, I run 1/4" on some of mine.

OK, pretty soon I'm going to have to break out the yardstick........

 

[broncnaz]

After the toe changes if it doesnt improve much. Id still play around with the tire pressures. Some tires have a sweet spot. going from 15 to 35 and seeing little differance means little. as usually low tire pressure and high tire pressure have similar effects on handling. you may have to find your sweet spot.

 

[OX1]

Digital angle guage said 3.6 drivers, 3.7 passenger (off top of "C").
Reset toe to 9/32.

 

[siderbox]

Digital angle guage said 3.6 drivers, 3.7 passenger (off top of "C").
Reset toe to 9/32.

Thanks for those numbers. I'm assuming those are (negative) angles.

BTW, your @ almost 9 degrees at full drop/droop??

I'm in the process of narrowing the d44 and at the same time I'm going to rotate the 'C'.
Shooting for 59" wms, stock bushings, ideal pinion angle, and -5 to -7 degree caster.

It has + 4.5 at ride height now.