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Old 10-24-2017, 12:01 AM   #1
brianp01
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Proper drivetrain angles?

Hey guys my name is Brian, I'm currently restoring a '59 pickup. This past weekend I installed a 5.3L and 4L60 transmission. Its a stock frame with a CPP mustang II kit with 2" drop spindles, and a flipped rear end. I have been following others builds here and other sites along with using articles from HotRod and Classic Trucks for reference. This is my first time installing a motor and transmission, so I just want to make sure before I go any further that I'm on the right track.

Here's what I did:

- leveled the frame, supported it with jack stands in order to get clearance for the engine dolly.

- fit the motor, centered it between the frame rails, with clearance for the PS rack, firewall and proper clearance for the oil pan. Leveled the motor left to right. Supported the transmission with blocks. At this point the drive train was pitching back about 3 degrees.

- fit and welded LS200 motor mounts kit from WelderSeries.com, these worked out well, really nice kit.

- began to fit CPP transmission cross member, removed the support blocks form earlier. To get the cross member to fit correctly with the frame rail and on the transmission everything needed to tilt down quite a bit. In doing this the motor and tranny pitched a bit more, actually a lot more, now the motor is pitched backwards about 5-6 degrees. I have not welded the cross member in yet, I was thinking I may shim it somehow or modify it to get the original motor/trans 3 degree tilt back, but I want to double check things here, get others advice before I proceed forward.

- I have the rear end's pinion angle tilting 3 degrees upward, but haven't welded the perches to the axle tubes yet, once again waiting to confirm I have things right before I go any further

The pictures show some of the steps I took. The second side view showing the motor/tranny 3 degree pitch when I had the transmission supported and the third side view showing the latest 5-6 degree pitch with the transmission cross member mocked up.

Is the 5-6 degree pitch too much? Should I go back to the 3 degrees?

Thanks for any and all help, advice and tips, it's all greatly appreciated!
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Old 10-24-2017, 12:10 AM   #2
iowaboynca
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Re: Proper drivetrain angles?

all i've seen is go to 3 degrees...

also to help:
https://www.youtube.com/watch?v=Idk3BVDVHq4

(man i love this video)
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Old 10-24-2017, 01:21 AM   #3
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Re: Proper drivetrain angles?

you may need to install the engine a bit offset to the pass side in order to get a clear shot from the steering column to the steering rack.

you may need to reconfigure the trans cross member or make a trans mount spacer in order to get the trans at that magical 3 deg mark. the engine is made to run at that angle so try to keep it there if possible. match the diff angle to be opposite to the engine angle so you don't get vibration. 3 deg down on the engine and 3 deg up on the diff, at ride height.

you may need to use a set of exh manifolds from a camaro in order to fit between the rails. or a set if headers I guess.

you may need to c notch the rear frame to clear the diff. you need at least 3 inches above the diff at ride height. also may want to consider incorporating a suspension snubber like the newer trucks have. they are beehive shaped and absorb the shock well before the axle hits the frame

you may need a firewall mod to clear the engine especially on the driver's side.


what engine did you go with, car , truck?
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Old 10-24-2017, 02:08 AM   #4
joedoh
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Re: Proper drivetrain angles?

I measured the stock angle on a couple of the 4.3 trucks I have done and they were both 4 degrees down. pinion between 3 and 5 degrees up.

are you using a carrier bearing? or a one piece shaft

if one piece, you dont want the two angles to be exact, zero angle on the u joints is bad. also leaf springs tend to let the axle go down under acceleration
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Old 10-24-2017, 07:45 AM   #5
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Re: Proper drivetrain angles?

Hey guys thanks, I appreciate it.

Raven- I ended up going with the truck motor, I have a c notch kit for the rear just haven't put it in yet. I think right now there is about 3" or more clearance between the axle and frame, but I'll double check. I was thinking I might need to do that trans spacer to get the angle correct, will do. I will need to go with headers or camaro manifolds because the stock ones weren't fitting between the rails.

Iowa- Thanks for the video, great to see, makes it easier to understand what and why, cool video.

Joe- Not sure on the carrier bearing or one piece, I think previously it was setup as a one piece, is their advantages one way vs. the other?
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Old 10-24-2017, 09:59 AM   #6
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Re: Proper drivetrain angles?

I think that the 3 degree was more important in carbed engines, most all gm carb manifolds are set to have a level carb base when the crank is at 3 degrees so as not to cause cylinder washout of front or back cylinders. On the EFI I've had them in at 5*. The more important degree relationship is the drive shaft to flange angles. you may have a 5* up on the pinion a 3* down on the crank and still end up spot on for the shaft angles. You don't want more that 3* between angles but could have more than 3* crank or pinion angle.

Tremec has a angle app for the smartphones that can help you get lined up and turns your phone into an angle finder. it show angle 1, angle 2 and driveline operating angle. press the ? in the app window and it explains the function.

And as mentioned above don't be afraid to off set the motor is you need clearance
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Old 10-24-2017, 10:09 AM   #7
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Re: Proper drivetrain angles?

if you have fab skills then just make a trans cross member that works for you once you get the engine where you want it. modify the cross that you have to make it work. don't forget to slip the cab back on periodically to ensure other stuff, like the trans tunnel, firewall clearance, accel pedal, room for exhaust and under cab brake booster (if you go that route) will still fit in there. keep the engine low and back for good center of gravity. try to build stuff that can easily be made to work with other items if the build changes down the road somewhere, like you decide to go with big power upgrade and need to swap in a bigger trans etc.
are you using the camaro oil pan kit a s well? the truck pan hangs down a lot right?
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Old 10-24-2017, 10:28 AM   #8
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Re: Proper drivetrain angles?

also, try to get the suspension set at ride height and the rake angle you want when you are mocking stuff up. sometimes you forget the diff will be stuffed into the frame and then there will be no room for exhaust when you factor in shocks and other stuff. you can use threaded rod in place of the shocks to keep the suspension set at the correct ride height. on my original frame with the TCI mustangII front end I used some plumbing pipe cut to length with a flange on one end. the flange can be screwed in or out some to dial in the exact length required. then threaded rod can be run up the inside of the pipe to bolt the pipe in place of the shock and that keeps everything exactly where you place it. on my frame swap I fabbed up some lengths of square tube that replace the shocks and that keeps the suspension at ride height and rake angle. it can't move as I install or remove stuff plus I know where the suspension parts will be when the truck is done. it helps fit other things into the plan like steering shaft, exhaust, potential under cab master cyl mounting, length of rear shocks required etc etc
just some thoughts

hey, post up a few more pics of your [project, you have tweaked my curiosity now to see how you have assembled stuff. I may see something that I had a challenge with and it could save you some time with yours. ya never know
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Old 10-24-2017, 12:52 PM   #9
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Re: Proper drivetrain angles?

IMO: before you start anything throw the cab on and move the motor as far back as you can
tf trucks and old trucks in general had the motor too far over the front axle
not much we can do about it other than to not move the motor any further forward

hot rod mag had a good article on driveline angles a few months back
http://www.hotrod.com/articles/understanding-driveline-alignment
from that article "If your car must have drive line angles from a design standpoint, the angle of the drive shaft to both the transmission output shaft and the pinion shaft should be equal and also opposite."

Quote:
- began to fit CPP transmission cross member, removed the support blocks form earlier. To get the cross member to fit correctly with the frame rail and on the transmission everything needed to tilt down quite a bit.
cross members are the easiest and cheapest fabrication projects to build: motor or trans mounts
to modify your motor angle to ''fit'' a prefab x-member doesn't make sense to me
pitch it or modify the mount to get back to the 3* angle
either way the trans mount needs to be removable to service the trans or pull the motor

task force trucks were the first gm trucks to come with factory v8 motors
you should not need to offset the motor to fit the steering with the right exhaust manifolds
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Old 10-24-2017, 02:19 PM   #10
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Re: Proper drivetrain angles?

here are a couple pics of the camaro manifolds inside the stock frame that has been boxed. another shows the engine in the bay. it is a little tight on the a/c belt tensioner but that could have a work around easily by changing the fitting on the rack
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Old 10-24-2017, 06:38 PM   #11
brianp01
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Thanks for the help guys. My plan is to modify the trans member to get the angle back to around 3, then I’ll get the cab back on and Ogre I’ll keep in mind getting the motor back as far as I can. Also downloaded the tremec app, I’ll put that to good use too. I will post some pictures this weekend with updates. Thanks again guys!
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Old 10-24-2017, 07:24 PM   #12
dsraven
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Re: Proper drivetrain angles?

when you are fabbing the trans cross member try to keep the weight of the trans on the mock up part so it will include the squish on the trans mount. when I did mine I had a short piece fabbed for the center so it woild fit on the trans mount, then had that installed and held the trans up with the jack unmder that new part, then added pieces to the sides to get a complete cross member. tacking parts together as I went. then when done it was at the same angle as when I mocked it up.
just my thoughts
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Old 10-24-2017, 07:44 PM   #13
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Re: Proper drivetrain angles?

I just went through this last weekend. set your frame at final rake, not level, then set engine and rear axle angle. inland empire driveline has a how to on there website
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Old 10-24-2017, 09:35 PM   #14
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Re: Proper drivetrain angles?

Quote:
Originally Posted by dwcsr View Post
I think that the 3 degree was more important in carbed engines, most all gm carb manifolds are set to have a level carb base when the crank is at 3 degrees so as not to cause cylinder washout of front or back cylinders. On the EFI I've had them in at 5*. The more important degree relationship is the drive shaft to flange angles. you may have a 5* up on the pinion a 3* down on the crank and still end up spot on for the shaft angles. You don't want more that 3* between angles but could have more than 3* crank or pinion angle.

And as mentioned above don't be afraid to off set the motor is you need clearance
Correctamudo
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Old 10-26-2017, 01:06 AM   #15
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Re: Proper drivetrain angles?

it was set up for the carbs but also for a little more trans and driveshaft clearance on the floors. automatic transmissions were set up for this too and its amazing how long things like that hang around in engineering circles, there is a GM engineer on this forum and he will attest to the "thats the way we always did it" mantra in legacy engineering. I remember when I was building my 65, I used the 98 floor pan and the holes for the cab lifting pins on the assembly line were the same size and in the same spot on trucks built 33 years apart.

what I am saying is that changing something like that isnt really thought of because SO MANY things you dont even think about are affected by that kind of change and well, engineers have better things to do than update thousands of drawings and make a BC/AD kind of change in thinking, interiors engineers are used to that kind of room, driveline engineers are used to those angles, and on and on.

its also why you can easily put later engines in earlier chassis.
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Old 10-27-2017, 10:56 PM   #16
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Re: Proper drivetrain angles?

here is my home made cross member. it sits on flat bar welded to the lower frame rail and is long enough to be slid forward or back to enable a different powertrain option. it isn't finished yet as I plan on gusseting it to the top rail for added strength.
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Old 10-28-2017, 10:35 PM   #17
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Re: Proper drivetrain angles?

I set my truck up with 2 degrees nose down for the pinion angle. Meaning, the centerline of the output shaft and the centerline of the pinion were made parallel then the nose of the pinion was rotated downward 2 degrees before welding the spring perches, on the tires and sitting at final ride height. . Different suspension types may require a different setting but for leaf springs the slightly nose down setting seems to work well for me. My Mopar is set up with 3 or 4 degrees nose down but it's a high horsepower car with sticky tires and steep gears.
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Old 10-31-2017, 11:54 AM   #18
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Re: Proper drivetrain angles?

Quote:
Originally Posted by Black_Sheep View Post
I set my truck up with 2 degrees nose down for the pinion angle. Meaning, the centerline of the output shaft and the centerline of the pinion were made parallel then the nose of the pinion was rotated downward 2 degrees before welding the spring perches, on the tires and sitting at final ride height. . Different suspension types may require a different setting but for leaf springs the slightly nose down setting seems to work well for me. My Mopar is set up with 3 or 4 degrees nose down but it's a high horsepower car with sticky tires and steep gears.
A few degrees nose down is very common with race applications so that the angle is correct when under severe load when the pinion noses up such as the 1/4 mile
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Old 10-31-2017, 12:48 PM   #19
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Re: Proper drivetrain angles?

Quote:
Originally Posted by dsraven View Post
here is my home made cross member. it sits on flat bar welded to the lower frame rail and is long enough to be slid forward or back to enable a different powertrain option. it isn't finished yet as I plan on gusseting it to the top rail for added strength.
That looks a far sight more solid than mine. I'm still kind of worried about my abilities to have made something strong enough. I jumped up and down on it, so that's about as scientific a test as I have haha. I set my angle to 5 degrees as I have an edelbrock carburetor and that seemed to be the consensus to help the float bowl stay flat.

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Old 10-31-2017, 02:08 PM   #20
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Re: Proper drivetrain angles?

one thing to keep in mind is serviceability as in removal of the trans
and that the oem trans support also supported the cab mounts and braced the frame

ogre's trans mount is pretty basic fabrication and reinforces the frame in xy&z axis's
lower angle iron holds the trans mount and is removable if trans needs to be removed
tubing braces tie into the cab supports to keep the cab mounts from flexing
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