My headache

[cstmwgn]

... It still has the driveline vibration, so I'm guessing pinion angle... I was warned the pinion angle may be off.

Typically on a leaf spring car you change pinion angle with tapered shims that go between the leaf spring and rear end. There probably are other ways to get there that I am not aware of.

As to measuring pinion angle - I am very much a "shade tree" mechanic - so here is what I do. Lift the car up enough to be able to get under it. You could put the car on jackstands with the rear stands under the rear axle so that the rear end is sitting at ride height.
I prefer to have the car sitting on the tires - not jack stands so I built wooden blocks to do this.
Others use a bunch of 2 x 4s

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiHv-rn6JLqAhUORzABHT8RAP0QwqsBMAB6BAgJEAQ&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DaCqfHligDSQ&usg=AOvVaw1D4BCNVIZbGSLj2qc10Xu7

Once the car is up, you need a level that measures in degrees (10ths or better) to measure stuff.
First, I measure the angle on the driveshaft.
Next you have to measure the pinion itself. This can be complicated and varies greatly depending on your car.
On my junk, I tend to remove the driveshaft from the rear yoke and measure the angle of the yoke by placing a flat plate across the face and then using the level to measure that angle. IF you use this method, you then need to subtract that number from 90* so that you have a comparable number to the driveshaft. I have heard stories of people finding flat spots on the rear housing or yoke that is parallel/perpendicular to the pinion shaft and use that as a measuring point.

I hope I have totally confused you with this convoluted explanation.

[brotherGood]

Whether Im using stands, I'll need both nose and tail level correct?

Is an angle finder something sold at places such as Autozone? Maybe Im overthinking it, but its all pretty new to me. I know that taking the isolater/leaf spring pads out, it raised the rear about a half an inch, and took out about an inch or so of bushing material (maybe more). Is there a simple way to math it out, or is it more complicated than that?

It looks like once this is sorted, Im left with needing new tires and figuring out how to mount the grant adapter so my wheel doesnt knock the car out of gear. Then, I've just gotta force myself to leave the new truck at home and take the car so I can see what else I'll need to fix before running it at the track.

[cstmwgn]

Strictly speaking, they don't have to both be level as you are comparing angles of the driveshaft and the pinion shaft.
With that said, I like to sit the car on the wheels at ride height so that I don't get too confused.
Digital levels can be found at hardware stores (Ace, Home Depot, Lowes, ...) as well as the internet and auto part stores.

Are you sure it is pinion angle and not something else - driveshaft balance or bad u-joint or ????
I would not have thought that raising the rear end 1/2" would change the pinion angle noticeably. If the rear end bolts to the springs (using u-bolts) and the isolator that fit between the spring and the rear end was the same thickness (front to rear) then again, that doesn't seem like it should be a problem BUT I have no personal experience with Mopar stuff and have never had a car with isolators.

Also, I didn't mention it in my first response, but if you want to do the job correctly, you need to check the angle between the transmission output shaft and the drive shaft AND the angle between the driveshaft and the pinion shaft.

[DanStokes]

Strictly speaking, they don't have to both be level as you are comparing angles of the driveshaft and the pinion shaft.
With that said, I like to sit the car on the wheels at ride height so that I don't get too confused.
Digital levels can be found at hardware stores (Ace, Home Depot, Lowes, ...) as well as the internet and auto part stores.

Are you sure it is pinion angle and not something else - driveshaft balance or bad u-joint or ????
I would not have thought that raising the rear end 1/2" would change the pinion angle noticeably. If the rear end bolts to the springs (using u-bolts) and the isolator that fit between the spring and the rear end was the same thickness (front to rear) then again, that doesn't seem like it should be a problem BUT I have no personal experience with Mopar stuff and have never had a car with isolators.

Also, I didn't mention it in my first response, but if you want to do the job correctly, you need to check the angle between the transmission output shaft and the drive shaft AND the angle between the driveshaft and the pinion shaft.

What he said! That's how I set up Mutt - it's in my build thread if it would be useful to go thru it to find it. I don't know how to scan for something like "set up driveshaft". Anyhow, it works fine and even at 136.22 MPH there's no noticeable driveline shake even with my locally-built driveshaft.

BTW - I put Mutt up on the hoist and used tall jackstands to compress the rear to more or less running height.

Dan

[brotherGood]

Okay, I think I've got (at least) a basic idea on it.

Now, to talk myself up to removing the drives haft, and unbolting the springs

[brotherGood]

So, I went and downloaded the Tremec app and measured everything up this morning, heres what I show..

Im thinking of ordering a 6° shim to start. My worry is that it may not be enough for when I run it at National Trail in August. Old springs have me worried..haha

Side note, adding a Grant wheel and can to this car has been a nightmare. Anyone have any tips on Grant wheel installs? With it being an 80s tilt Mopar column, theyre pretty much the same as the GM of the time.

[cstmwgn]

More questions than answers.
Did you measure the transmission to driveshaft or just the driveshaft to rear end?
From true horizontal, is the driveshaft pointing down as it connects to the rear end?
From true horizontal, is the pinion pointing up as it connects to the rear end?

IF (IIIIFFFFFF) those last two questions are yes, then I think you would want something more like 2* - 3*.
The pinion is going to move up as you put load on the tires, so you want the pinion angle to be less than the driveshaft angle.

IF the answers are different in regards to true horizontal, then it would help me to understand the angles as they are associated with horizontal.

[brotherGood]

Measured parallel to the output shaft, then on a flat part of the drive shaft, then parallel to the pinion per the tremec app instructions.

Angle 1 would show trans to driveshaft angle, angle 2 would be pinion to driveshaft angle showing the difference.

Since the trans didn't change, but the rear did..that signals to me the adjustment needs to be outback.

I didnt think to get a solid visual on the rear-to-driveshaft angle, but I think both were down.

[cstmwgn]

OK, so I believe I misunderstood your data. I had thought the two angles you gave was for the driveshaft and pinion.
Does this picture represent what you have?



IF so,a 6* wedge should be OK. I certainly wouldn't go more than 7*
If you move the pinion down 6* then the difference between your two angles should be 1.6*

Yes, you might have a little bit of spring wrap but how often are you going drag racing and how hard does your car hook?

[brotherGood]

Correct.

its only going to make the occasional pass..maybe once or twice in its lifetime. Beyond that, stoplight drags at most.

As far as how hard it hooks? We'll see when I get some confidence back in it (along with tires)

[brotherGood]

Holy cow..its been a while since I've been on here.

To catch up, I'm still not certain the angle is correct. It occurred to me as I reread this just now that my garage floor isn't level, so it may have effected the reading.

I sold the car to Dad around September last year. He had full intentions of working on it, yet I'm fairly certain it's not been touched since January. He said it still has a shake to it, so it may need a different degree of shim, and I know it needs new lifters and pushrods from sitting. The shifter debacle was finally fixed prior to selling it, so it's a couple adjustments away from being a serious contender.

Myself, I picked up something they used to write magazine articles about.......

[Dan Barlow]

As cool as cop cars are , yeah no comparison. One of my favorite body styles of the 70s .

[brotherGood]

Quick little update on the Diplomat...

It sounds sound I may have gotten Pops back interested in it. I finally convinced him to bring it to the garage yesterday and we changed out the 6° shims for 4° shims and the shake is darn near gone. I say darn near, as the rest of it may be related to motor mounts.

It sure was nice seeing it out driving around yesterday though, and has me that much more motivated (and confident) in wrenching on the Olds to get it done..once the engine shows up

[brotherGood]

Little update:

Dad sent me a text this afternoon saying the car is (finally) going in for a trans rebuild. In addition to the rebuild, they're going to check pinion angle, replace the trans mount, add a shift kit and also put a new, higher stall converter in it. Based on what he (the mechanic) was saying, it sounds like the drive ability issues that have plagued the car for the last 5 years or so are heavily influenced by the lack of converter in there currently.

After the car gets back, it's getting a new cam/lifter/pushrod setup, followed by a new interior fixing my inexperienced hackery.

Even though it's not mine, I'm still not only hands on with the planning, but also the execution..and can't wait to see the end result.

Stay tuned.....

[brotherGood]

Well..we almost made it a year, but the car finally went into the trans shop. New converter went in, trans was fully rebuilt, come to find out the shake that I thought went away ended up being a U joint that was incorrect (long story) and due to it being bad for so long, it also cooked the trans mount.

It came back last Thursday and I got in it on Friday. Dad said the brakes were still non-existent though, but the mechanic seemed to think that was due to a leak on the line that runs to the PS front. Drove it up and down the lane and Holy Smokes. I forgot how rowdy that thing was, especially after adding big pipes and headers (granted, this is still a stock bottom end 318). Add to the fact the firewall is pretty much non-existent as is the dash and half the interior..it was a far cry from the luxury muscle car I'd been driving the last few months. Brakes are there after about 90% pedal travel, so I got out and looked for a leak only to find there was nothing in the master cylinder.

Once the Olds goes in for body work, the Dodge is coming over for a new interior and to find the brake leak. We also ordered a new cam/lifter/pushrod set as the old ones are junk from sitting (and improper break in..another long story)

Definitely excited to see this thing start getting the attention its deserved for years.