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Ideal seems to be the face of the diff by the yoke, and the face of the trans by yoke. And side of driveshaft itself.
In car some creativity is required..
Driveshaft removal possibly.
Measure from flat end of yokes.
Or use 90 degree carpenters angle on trans face so you can use a flat surface under trans, etc.
And yes digital angle finders use the earth's magnetism for vertical, and there may be a slight effect around iron.
Sounds like you already measured that effect.
+/- .15* still seems accurate enough.
Do some research on here, about C3 driveline angles.
The "Normally" suggested "ideal" "parallel" angle seems not to work on our cars.
IIRC what is important is to keep the angles low, like 1-3*.
There is an app somewhere for either computer or smartphone.
Last edited by leigh1322; Jan 19, 2025 at 11:35 AM.
Wow you can measure angles to .015 accuracy - that is amazing !
And .15 degree variation is basically bugger all !
Here is how a low tech analog man (me) does it.
I run on an orginal flip phone - no apps LOL
This is a Calgano type "tool" LOL
The "T" adapter clamps into the yoke in place of the U-joint.
Then I have a length of perfect sized tubing that I slide into the tranny - with NO PLAY to determine the transmission angle
The "angle finder" is fitted with magnets at both ends and is zero calibrated by turning 180 degrees
This way I get the actual angle of the pinion shaft and transmission mainshaft
Here is OCB's thread with a TKX install: https://www.corvetteforum.com/forums...roject-55.html
He had 3.0* down on engine/trans, and 2.8* up on the diff.
Closer to 1.0* is better if you can get it.
The rollers need at least 1/2* so they move grease around.
Some owners report 0* on the diff if stock parts.
Also the engine motor mounts are about 1" to the pass side which tilts the engine u-joint laterally as well.
So that u-joint movement is always there.
Here is OCB's thread with a TKX install: https://www.corvetteforum.com/forums...roject-55.html
He had 3.0* down on engine/trans, and 2.8* up on the diff.
Closer to 1.0* is better if you can get it.
The rollers need at least 1/2* so they move grease around.
Some owners report 0* on the diff if stock parts.
Also the engine motor mounts are about 1" to the pass side which tilts the engine u-joint laterally as well.
So that u-joint movement is always there.
The angle I’m trying to re-measure seem similar. This time I want to revisit and be ultra-sure.
There’s is definitely a 1-inch offset to the passenger side.
I have an additional differential bracket on the way. My plan is possibly to make an adjustable bracket.
Ideal seems to be the face of the diff by the yoke, and the face of the trans by yoke. And side of driveshaft itself.
In car some creativity is required..
Driveshaft removal possibly.
Measure from flat end of yokes.
Or use 90 degree carpenters angle on trans face so you can use a flat surface under trans, etc.
And yes digital angle finders use the earth's magnetism for vertical, and there may be a slight effect around iron.
Sounds like you already measured that effect.
+/- .15* still seems accurate enough.
Do some research on here, about C3 driveline angles.
The "Normally" suggested "ideal" "parallel" angle seems not to work on our cars.
IIRC what is important is to keep the angles low, like 1-3*.
There is an app somewhere for either computer or smartphone.
Super interesting !!
I probably am going to try to bring the differential to go 1 degree down instead of .5 degrees up (if I recall correctly).
When I installed my TKO many years ago, I put some shims under the trans crossmember. The first time I drove it it kind of had some vibration, so I took out a 1/4" shim and it was all good. When I measured my drive line angles it looked like it was just right when the trans was up against the tunnel. Since that wouldn't work I lowered it as little as I could and left it there. Then on the test drive lowered it another 1/4".as said above. It started out a precision measurement, and ended up a "let's try this". Been that way ever since.
Here is OCB's thread with a TKX install: https://www.corvetteforum.com/forums...roject-55.html
He had 3.0* down on engine/trans, and 2.8* up on the diff.
Closer to 1.0* is better if you can get it.
The rollers need at least 1/2* so they move grease around.
Some owners report 0* on the diff if stock parts.
Also the engine motor mounts are about 1" to the pass side which tilts the engine u-joint laterally as well.
So that u-joint movement is always there.
.
This is so true. Typical driveline angles don't apply as the driveline is all fixed in our C3. They are 'basically' stright, but a small amount of offset to keep the U joints alive.
Don't over think this.
Ok. I guess I was indeed overthinking this. It’s seemed fine at speed, but I wanted the smoothness of my old Chevelle.
I am getting the sense that angle adjustments will be an exercise of “see what sticks” in terms of vibrations, rather than getting within spec.
I may put this one back in the cooler and first get the exhaust and rear suspension done (there’s no adjustment left on stut rods)… test drive… and reconsider.
It will be hard to get it to ride like a solid axle car! The smoothest Corvette ride is in a C4 as it rides like a regular vehicle but handles like a Corvette.
It sounds like you are building quite a Corvette there Dorian!
Here is a link to the thread I started regarding drive line angles.
I ended up with 2.2 degrees of up and down angle at both the transmission yoke and the pinion yoke using the W angles between the transmission and differential.
Read my thread, it explains it.
Keep in mind that you’re measuring the up angle at the pinion yoke and the down angle at the transmission yoke.
There is a lot of very technical information in the thread posted by other forum members, but you’ll pick up the basics through the common language that I tried to keep it at.
I tried using a digital angle finder but it measured all over the place and I ended up getting a magnetic analog one from Harbor Freight, but not their cheapest one.
I measured using the pinion yoke, the transmission yoke, then checked at the transmission housing tail shaft and the face of the front crank harmonic balancer just to back up my readings.
You gotta watch those type of angle finders - some of them have sticktion problems - repeatability is the essence of quality measurement.
Nothing like driving yourself crazy LOL
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Drive angle reading: frustrating !!!!
