Pinion Angle Question

[zimmstoy]

Hi everyone,

I have been working some bugs out of my new to me 67 Coronet R/T. The previous owner (who unfortunately has passed away) had the rear leaf springs relocated inboard to allow for a little bit larger tire. My question is; "When this is done, what should be pinon angle be and what is the best way to measure it?".

Additionally, is there any information out there on there on these spring relocation kits -why they are done, impact to suspension, exhaust alternatives, etc?

Thanks,
Scott

 

[RustyRatRod]

Generally, for a street you want no more that 5* nose down. I like using a direct read angle finder, like this:

http://www.harborfreight.com/dial-gauge-angle-finder-34214.html

Supershafts is real sharp and he runs a driveline shop. He may have some different/better advice. PM him if he does not reply soon. He's always a big help.

 

[zimmstoy]

Thanks RustyRatRod - I have that exact gauge. I am pretty sure my angle is way off. I will keep an eye out for Supershafts. You both have been a huge help to me through my diagnosis on the car. I want to make sure I measure and adjust correctly.

 

[RustyRatRod]

Just remember if you want to get an accurate DIRECT reading, you'll need to level up the car first. You can measure the drive shaft angle and then the pinion angle and find the difference without leveling the car. But as I said, Supershafts may have more useful information.

 

[benno440]

sorry for hijacking but might also be useful, Rusty so if you have a 4 link where there is no diff twist on a hard launch you can run your pinion at 0* or level with the driveshaft?

 

[RustyRatRod]

No. There has to be a working angle between the drive shaft and the pinion center line. If not, the U joints will wear out in short order. Supershafts will chime in I am sure. He hawks for driveline threads...he's real good at this stuff. He can splain it a lot better than I can I am sure.

 

[Cornpatch MO]

I thought the center line of the tranny should be parrallel with the center line of the differential. I think that would make both u joints equal in degree of angle? Please correct me if I'm wrong. I will soon be setting my pinion angle...................MO

 

[RustyRatRod]

That's correct, but that will not make the angle "zero".

 

[tallhair]

No. There has to be a working angle between the drive shaft and the pinion center line. If not, the U joints will wear out in short order. Supershafts will chime in I am sure. He hawks for driveline threads...he's real good at this stuff. He can splain it a lot better than I can I am sure.

why is that rusty?

 

[RustyRatRod]

Ok, let me make myself clearer. I am talking strictly about the pinion angle. The optimal drive shaft working angle IS zero. To get there, the pinion angle must be nose down X number of degrees and the drive shaft angle must be up the same number of degrees. Does that help?

And get this.....to make matters WORSE, as usual, the Mopar Performance book calls it "pinion nose down" when it is really nose up. They are referring to the pinion angle in relation to the drive shaft....which when looked at that way IS nose down. As if it were not confusing enough already.

 

[68 HEMI GTS]

usually with leafs you run 4-6 degrees pinion down. "easiest way" to do it is put the angle finder on your damper first (engine and trans installed) then set it across the flats of the rear end yoke with it pointed vertical. just set it up so its the correct degrees down vs damper reading. im sure someone will say this is absolutely wrong, but this is how i was told to do it from calvert and its worked fine for me on a few cars.

 

[RustyRatRod]

Nope, that's basically the same way I am talkin about. It's right. The problem is not everybody calls everything the same. lol

 

[shorty64]

PM sent.

 

[snakeoil24]

usually with leafs you run 4-6 degrees pinion down. "easiest way" to do it is put the angle finder on your damper first (engine and trans installed) then set it across the flats of the rear end yoke with it pointed vertical. just set it up so its the correct degrees down vs damper reading. im sure someone will say this is absolutely wrong, but this is how i was told to do it from calvert and its worked fine for me on a few cars.

68 hemi you are correct damper face and pinion to check your self then drive shaft

 

[bm02tj]

Depending on your springs add a little for axle wrap like a couple of degrees so at highway speed your ujoint angle will be the same or equal