[StevieBB54]

I can use an opinion if what I have is correct, I am not the greatest mathematician when it comes to geometry and compound angles.
To make a long story short, I just installed a TKX in my lowered 68. The angles I have are:
Crankshaft/output shaft is at .4* down
Pinion angle is 8.5* down

Is it correct to say I need an 8* shim to get correct working angles?
Thanks in advance

 

[69-er]

To raise the pinion angle to match the trans centerline, you would need 12.5 degrees. Someone with more experience could chip on this but I believe if you plan on drag racing the car you would want the pinion a degree? or two down to compensate for axle wrap. So maybe only 10 degrees would be needed.

That pinion sure is down a bunch. When I lowered mine it was down maybe half that. I thought that the Moser's perches were welded in the wrong position. I still have a vibration after getting them close.

 

[StevieBB54]

Ok this is where I am dumb. Theoretically it is only down 8.1*, not sure where 12* would come in? I was told the operating angles between the two locations can be between 0-1.5*. Its only a street car.

 

[Worn Out Welder]

They would be ideally parallel.
Equal but opposite….
I’d go with shims under the trans to bring it up to
3 degrees and reduce the amount of shim to 4 degrees on the rear.
8 degrees on the rear only would be close to 3/4”
That would be too thick for me.

 

[RifRaf]

Crankshaft/output shaft is at .4* down
Pinion angle is 8.5* down

When stating driveline angles, it is always helpful that the same reference point is being used for all of the angles that are listed... Example: All angles are referenced from the front of the car to the back of the car.
I have seen many posts were people say the pinion angle is pointed up because they are looking at the direction the pinion yoke is pointing... but in reality, the pinion is angled down (when viewing/referencing the front of the pinion (yoke) to the rear of the pinion (gear). Just need to clarify the reference point for viewing the 8.5° pinion angle.

We would also need to know the driveshaft angle... referenced from the front of the car (trans) to the back of the car (rear). The driveshaft angle will provide the "working angles" of both U-joints.

• It is my opinion that getting the front and rear u-joint working angles to match should be the goal (no greater then a 1° difference between the front and rear u-joint working angles). NOTE: The working angle of each u-joint should be between .5° and 3°. It is not necessary for the trans angle and the pinion angle to be "parallel" to each other to achieve a vibration free ride.

 

[StevieBB54]

Angles were recorded at front vibration dampener and rear machined surface where diff cover bolts to.

 

[SoCal805]

OP

do as post 4 notes. Raise trans as much as you can with shims. take new measurements to confirm wtf the trans and pinon angles are. Typically the rear end on lowered cars will need a 2-to-4-degree shim.

I raised my trans 1/2" and used 2 degree shim on rear end to get mine in the zone.

 

[StevieBB54]

Ok ill give this a try. One thing i didnt mention is: I had to raise the back of the trans1”. Reason being is the Holly/Tremec conversion x member was a lot lower than the Muncie one, so much so the header was hitting the steering box and the dist. cap wouldnt fit and the wire trough had to be raised so I could attach two plug wires. Right now were in a major storm here and the power is out, but I will try adjusting the trans up some more.

 

[Melmount]

Did the op state he measured rear pinion angle at the cover? Need to do it at yoke, if it’s flat at front of pinion.
What rear end is in it? 8 down is a lot. Does car have leaf springs?
Don’t see how it’s 8 unless maybe perches welded wrong?

 

[Worn Out Welder]

I suppose I should rephrase “ ideally “
No it is not imperative.
It is not a bad idea though
…but if your going to spend time to correct this relationship, why not target between 2&3 degrees on both.
Yes to post 9…unless it’s a bad reference.

 

[Worn Out Welder]

Here’s another opinion.

Driveshaft Tech - Mark Williams Enterprises, Inc

Mark Williams Enterprises is an industry leading manufacturer of drag race axles, drive shafts, brakes, modular rears, rear end housings, thirdmembers, and chassis components.

www.markwilliams.com

 

[SoCal805]

Angles were recorded at front vibration dampener and rear machined surface where diff cover bolts to.

while using the flat front damper surface to measure engine/trans angle is OK....you really want to measure the pinon form the flat surface of the pinon yoke.

 

[Larry Madsen]

I may have missed it, but for the sake of clarity.

Is the differential angled up toward the floor of the car.

or

Down toward the ground?

Generally (as RifRaf stated) the yoke pointed up toward the floor of the car is referred to as a “downward” driveline angle.

If this point was clarified by the OP please excuse my missing it.

Either way that does seem like an unusually big angle.

 

[StevieBB54]

Its pointing slightly towards the ground. Im going by what was suggested by a well respected suspension friend told me. Apparently on a 8.5” 10 bolt the machined rear cover flange is the same as pinion angle. Same as crank and trans output shaft are the same angle. I suppose the saddles could be wrong, the guy I bought the car from said he used this diff that was built for another car. The numbers are missing as the housing is powder coated. I guess I could scrape paint off to get the model code. The future plan is to run this one for a while until I get a 9”.

 

[StevieBB54]

I may have missed it, but for the sake of clarity.

Is the differential angled up toward the floor of the car.

or

I may have missed it, but for the sake of clarity.

Is the differential angled up toward the floor of the car.

or

Down toward the ground?

Generally (as RifRaf stated) the yoke pointed up toward the floor of the car is referred to as a “downward” driveline angle.

If this point was clarified by the OP please excuse my missing it.

Either way that does seem like an unusually big angle.

Down toward the ground?

Generally (as RifRaf stated) the yoke pointed up toward the floor of the car is referred to as a “downward” driveline angle.

If this point was clarified by the OP please excuse my missing it.

Either way that does seem like an unusually big angle.

Even the place I bought the trans from cant believe I had to put a 1” spacer under trans ridesdirt here is doing this same install and has to drop his trans 1” so it would fit. 🥴

 

[Worn Out Welder]

I had to supplement 1” to the Holley cross member
to get a 2.75 down angle at the trans. It was at 4 degrees.
Along with the “ required spacer on top of the poly mount.
( which was shorter than the old mount I replaced)
Then used a 3 degree wedge at the rear , which was zero ( read level with the surface reference)
All with the car at the loaded stance for service.
Just a passing thought on my RS
RS stands for “rally screwed up” 😆

 

[Melmount]

I understand some cars the trans points to floor by few degrees. Why would u make it this way if didn’t have to? Perfect world the trans is up a couple degrees and the front pinion is down to ground a couple. That gives u the parallel lines. Then hopefully the driveshaft working angle is just like a 1.5 angle or something.
on my 69 the trans was down like 4. The 9” pinion is also going down like 2.
technically I should raise pinion angle some to get parallel. But raising a pinion loses forward bite. So you do best u can. Then fix further if it vibrates. If not, leave it alone.
some cases raising trans up gets u parallel but then increases the working angle. Some tones, most often, u can’t lower the motor to fix the working angle.

 

[schmeling99]

A lot of good comments are coming through really fast on this subject, impressive! StevieBB54, for clarity I suggest searching YouTube. There must be dozens of posts on this subject and some have pretty good visuals to help understand the subject. I spent a good hour watching postings. Most of them were fine with using the harmonic balancer to measure the engine angle. The vast majority measured the drive shaft angle and used the front of the u-joint mount for the pinion/rear end. There was also a vast number of postings that mentioned using the TREMEC TOOL BOX "app". The first function on the app. is for calculating the Driveline angle using your smartphone as the angle finder. Must See TV for this topic. I just started studying this and the impression I got was you're shooting for equal, yet opposite angles between the front u-joint and pinion shaft angles with no more than 3 degrees total. The reason I am pursuing correcting my pinion angle is the fact that like many cars out there, mine starts vibrating around 60 mph and just gets worse as speed increases. Good Luck everyone.
Life is short, Drive a Hot Rod Camaro

 

[RifRaf]

What is your driveshaft angle?... as this info would be needed to calculate your u-joint working angles.

When you measured the trans angle, you used your engine's vibration damper and stated it was pointed down... To help clarify, was the top of the vibration damper further away from the radiator then the bottom of the damper?... or the opposite?

Also... was the car's weight on all 4 tires (as normally sitting at ride height) when the driveline angles were taken?

• I agree with other members that an 8.5° pinion angle (up or down) seems excessive for a Camaro.

As a side note: I have a 3rd gen Nova (stock rear leaf spring suspension - same as the 1st gen Camaro). The trans angle on my Nova is 3.3° down (front to back), the driveshaft angle is 1.8° down (front to back), and my pinion angle is 0.7° down (front to back). My trans and pinion angle are not parallel... but my trans u-joint working angle is 1.5° and my pinion u-joint angle is 1.1°, so the difference between the trans and pinion working angle is 0.4° (well within max of 1°).
I have driven/cruised my car at several different speeds (up to 90 mph) and I have absolutely no drivetrain vibration at all.

Below is a link that goes into more details of how I set-up my driveline angles and the reason why my "mis-matched" trans/pinion angles works better for me... especially while aggressively accelerating and the differential is being torqued up during load (pinion yoke angles up towards floor of car).

Some New Thoughts on "Driveline Angles"

After completing a rear end upgrade to my Nova, I’ve come to a new understanding of calculating and adjusting the correct “Driveline Angles” for my vehicle. I wrote-up my new thoughts below... but it's a little lengthy. My prior thinking was you would match the transmission yoke angle to the...

www.camaros.net

 

[ridesdirt]

Check the pinion angle in relation to the spring perch angle. This will confirm if there is an issue with the rear end. That is a big number you are reading. I can get you the numbers I read on my rearend, Side note, I checked my pinion angle off the face of the pinion yoke and the machined cover surface while the cover was off - I got the same reading. I also checked that again off the back of my cover (Moser rear cover and has a small flat machined surface) again the measurement was the same. These measurements were on my rear, but my gut is telling me if you measured your angle off the machined cover surface you should be good. However, since you are getting such a large measurement, maybe drop the driveshaft and measure off the pinion yoke and see what you get. The crank/trans centerline seems to be a good number to me, anything between 0 and about 3 degrees is what most people find (from my reading) and is what I believe manufacturers design to.

@StevieBB54 I initially thought I needed to lower the back of my trans, it just seemed like the shifter was way too high, like in my face! In reality it isn't. My issues are a little different from yours. After checking some driveline angles, then looking at distributor clearance, fan location in the shroud as compared to where they were before my trans swap, I think I may end up spacing the rear of the trans up a small amount, maybe 1/4". I still need to check driveshaft angle, but my pinion and trans/crank are within a 1 to 1.5 degrees of parallel, a small spacer should bring it to something under 1 degree. Right now I measure my trans centerline at 2.5 down. Or, if my research is correct, I may consider swapping to the 69 307/327 engine stands. I believe these stands with correct mounts move the engine 0.7" forward and about 1/4" down. Lowering the engine or raising the trans effectively gains me the same goal for my situation. That forward movement would help me with a distributor clearance concern I have.

This is a good diagram to explain the working angles in the driveline.