Pinion angle on tranz

[Garagely5150]

Anyone know how I can squeeze a couple more degrees of pinion angle on my tranz.. I have a gen 1 pb drop xmember and my pinion angle right now is 7* I was under the impression that as long as the pinion angle on the rear and was 180 opposite I'd be in good shape. But now after talking to expirienced builders I learned it should be 3* .... but I can't jack up my tranz with out putting stress on my motor mounts 7* was the most I could get out of it with out having the bushing squished on the motor mount. And just to get it at 7* I had to shave my steering rack down bc it was hitting my oil pan. And I had to roll the edge of my oil pan too. Any one ever hear of this? It's pb I wouldn't think I'd have this problem.

[andyh1956]

Your COMBINED crank / trans angle PLUS the PINION angle DIVIDED by TWO should be under 3 degrees for optimum performance.
Example- if the trans is 4 deg & pinion is 3 deg then 4 + 3 = 7 / 2 = 3.5 degrees.

[Garagely5150]

Just a pic to go along with the post

[Keith Seymore]

Do you have the chassis set to the intended ride height?

These angles need to be measured as though it is a fully assembled vehicle with the full weight on the wheels. That could potentially "raise" the rear axle relative to the frame and flatten your driveshaft/trans tailshaft working angle out.

K

[Garagely5150]

Yea it's set up at ride height. Frame is level....

[SCOTI]

Originally Posted by Garagely5150

Anyone know how I can squeeze a couple more degrees of pinion angle on my tranz.. I have a gen 1 pb drop xmember and my pinion angle right now is 7* I was under the impression that as long as the pinion angle on the rear and was 180 opposite I'd be in good shape. But now after talking to expirienced builders I learned it should be 3* .... but I can't jack up my tranz with out putting stress on my motor mounts 7* was the most I could get out of it with out having the bushing squished on the motor mount. And just to get it at 7* I had to shave my steering rack down bc it was hitting my oil pan. And I had to roll the edge of my oil pan too. Any one ever hear of this? It's pb I wouldn't think I'd have this problem.

I have an early ('07?) PBDM in my 64 (68 frame) & didn't have issues w/binding @ the motor mounts. PB recommended 5° @ the trans output shaft but I made a spacer to put mine closer to the traditional 3° angle. No interference up front either w/the R&P & motor (sbc w/a 700r4). Your set-up has me scratching my head. Any more details you can provide?

[Garagely5150]

I bought the whole assy used I'm not 100% sure the motor mounts are the right ones bc my engine is on a wicked slant. I wish I had more for u... u have to Chang ur oil pan buy any chance ?

[SCOTI]

Originally Posted by Garagely5150

I bought the whole assy used I'm not 100% sure the motor mounts are the right ones bc my engine is on a wicked slant. I wish I had more for u... u have to Chang ur oil pan buy any chance ?

Stock stamped steel 5qt pan.

[Garagely5150]

Pb recommends 5* tho huh I wonder if that goes for mine too? I was talking to pb about this problem via email but they left me hanging

[Garagely5150]

I thought about heating the motor mounts up with the torch and jacking up the tranz. Or possibly pie cut them

[tinydb84]

Do you have better pictures of all the interference points? Granted I cant really see what you are working with but I would look at redoing the bottom tabs where the motor mount attaches to the cross member.

You could cut new tabs and raise the engine just enough to clear the rack at the same time as correcting the trans angle.

[SCOTI]

Originally Posted by Garagely5150

Pb recommends 5* tho huh I wonder if that goes for mine too? I was talking to pb about this problem via email but they left me hanging

He does recommend the 5° set-up angle. I talked w/him @ length about this.

Porterbuilt might be more eloquent w/his explanation but here's my summary.... Extreme drops come w/the caveat of compromise. His standard method is the 5° angle & a 2pc driveline. Given that usually works well for most apps, I chose a different path but needed to better understand the 'Why' in his recommendation. I felt that going through the expense of a 2pc driveline & it still possibly being a greater than desired compromise would be a roll of the dice (I experienced this 1st hand in someone's truck). The fix? Adding in a Double Cardan/CV joint.

I opted to do 3° & a 1pc driveline as it's more common w/hot-rod builds & is a standard. I could save money using the 1pc & avoid the added complexity. If there's an issue w/vibration, I can still swap to that same Double Cardan/CV joint. To me, the cost difference & 'dumbing things down' was worth cutting up some of the bottom of my cab.

[Garagely5150]

What's a cardon cv joint and it requires cutting up the cab? Drive line = drive shaft ?

[SCOTI]

Originally Posted by Garagely5150

What's a cardon cv joint and it requires cutting up the cab? Drive line = drive shaft ?

Yes.... Driveline = motor/trans/driveshaft to pinion.
Double Cardan/CV joints are popular w/trucks that have serious lift. Google them.

[wilkin250r]

A double-cardan joint (also called a CV joint) can handle more angle than a universal joint, BUT operates a little different. With a double-cardan, you align the axle pinion directly inline with the driveline, you do NOT match the transmission angle.

[El Dorado Jim]

Originally Posted by wilkin250r

A double-cardan joint (also called a CV joint) can handle more angle than a universal joint, BUT operates a little different. With a double-cardan, you align the axle pinion directly inline with the driveline, you do NOT match the transmission angle.

x2

[andyh1956]

This is what we went with on our K5 Blazer w/ 4" lift. NO vibes!

[Garagely5150]

I don't don't know about doing a cv joint I just wanna get my tranz angle to 3*

[SCOTI]

Originally Posted by Garagely5150

I don't don't know about doing a cv joint I just wanna get my tranz angle to 3*

How low are you going? You may need to know & understand the parts. I never had issues w/my other trucks (other than the differential hitting the bed floor) & that was w/stock frame. Add a different/aftermarket front xmember + other alterations and especially if you run an OD trans..... it could be very necessary.

[Garagely5150]

It's gonna lay frame

[Garagely5150]

What goes into changing to cv joint style drive shaft. What does it cost

[SCOTI]

Originally Posted by Garagely5150

What goes into changing to cv joint style drive shaft. What does it cost

A CV joint set-up was about $150 last time I checked (2013?) when I had my 1pc shaft built. I had my 1pc shaft built by cutting down a longer unit & then balanced for ~ $125.

When I priced a balanced 2pc set-up w/a poly/billet carrier bearing @ the same place it was about $650 (that was w/everything new as I never had any C10's w/a 2pc set-up to have used parts as my starting point).