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Old 12-01-2019, 11:42 PM
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Default Setting pinion angle.

I hope to get my transmission out of layaway if not with my Christmas money then shortly there after. My question is the kit from American Powertrain comes with a driveshaft once you provide them the measurements and I know how to measure for that but if my pinion angle is off how do I correct it? With a shorter or taller trans mount or what? My suspension in the rear is UMI non adjustable. Rear end is a ford 9 inch. I am using the stock crossmember

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1964 Tempest Custom
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Built a custom roller cammed 467 all forged internals. TKO 600 trans with Ford 9 inch from Quick Performance with 3.70 geared aluminum thru bolt center section with billet pinion support with an Eaton tru trac. Plans are for car to be Silver Mist Gray with Dark Blue Interior. Keeping bench seat and adding air conditioning.
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Old 12-02-2019, 12:23 AM
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Adjustable upper control arms.

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Old 12-02-2019, 10:16 PM
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Originally Posted by b-man View Post
Adjustable upper control arms.
x2

But if the angle needs to change at the trans, you can make some shims to have the mount sit higher. Just be careful you dont run out of stud on the mount.

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Old 12-02-2019, 10:31 PM
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Floor pan clearance to the driveshaft u-joint is tight on these cars, shimming the trans mount isn’t likely an option.

Honestly you’re going to have to throw some cash at making your adjustments happen in the upper control arms.

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Old 12-02-2019, 11:36 PM
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Well American Powertrain swears that their transmission mount will work with stock crossmember and should check out fine. The 9 inch bolted right into place beautifully and is centered in the tunnel. The the control arms bolted up perfectly too so is there a chance of everything coming together without me having to do anything?

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1964 Tempest Custom
Original 326 Auto with power steering, brake, and dealer installed non working AC.
Built a custom roller cammed 467 all forged internals. TKO 600 trans with Ford 9 inch from Quick Performance with 3.70 geared aluminum thru bolt center section with billet pinion support with an Eaton tru trac. Plans are for car to be Silver Mist Gray with Dark Blue Interior. Keeping bench seat and adding air conditioning.
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Old 12-03-2019, 12:11 AM
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Quote:
Originally Posted by 64speed View Post
... so is there a chance of everything coming together without me having to do anything?
You won't know until it's all together, so there's no point fretting about it until then.

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Old 12-03-2019, 06:14 AM
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I have a set of these and they are really nice for the price.
https://www.spohn.net/shop/1964-1967...djustable.html

As far as the chance that the pinion angle will be right with all of the mods you’ve done that’s probably not going to happen. Just changing rear ride height with all stock parts usually requires some adjustment.

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68 GTO,3860#
Stock Original 400/M-20 Muncie,3.55’s
13.86 @ 100
Old combo:
462 10.75 CR,,SD 330CFM Round Port E's,Old Faithful cam,Jim Hand Continental,3.42's.
1968 Pontiac GTO : 11.114 @ 120.130 MPH

New combo:
517 MR-1,10.8 CR,SD 350CFM E's,QFT 950/Northwind,Road Paver,9.5” 4000 stall,3.42's
636HP/654TQ

1968 Pontiac GTO : 10.706 @ 124.440 MPH
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Old 12-03-2019, 08:36 AM
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Yeah, chances are pretty slim the angles would be right, have to understand that with a longer trans, and a shorter driveshaft, the angle change.

Shims are available, and pre-cut to fit, several people make them, and are inexpensive. But as others pointed out, you have limited room to make any big adjustments.

Adjustable uppers is probably the best approach, but it may, and probably will take a combo of adjustments to get it acceptable.

Keep in mind too that driveshaft diameter and material impacts driveline 'harmonics'. If it still has vibration after the angle are in an acceptable range, you may have to switch to a different diameter/material driveshaft.

Another factor often overlooked is that the pinion angle is actually a 'range', because it changes with suspension travel. You may for example cruising on the highway at a particular RPM find that it vibrates, even if you at rest have acceptable angles. Choosing something more 'in the middle' of the range may or may not correct that. You might have to actually go outside of an acceptable range at rest to get the optimum in-use results.

The car will settle some too, and since it's a new build, you may have to check it a couple times in the first like 5-10k of miles.

Tremec has a phone app for smart phones to check driveline angles, it's not bad, and I have used it a number of times.

http://www.tremec.com/menu/tremec-toolbox-app/

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Old 12-03-2019, 08:42 AM
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Here's an example of crossmember/trans mount shims:

https://www.crossmembers.com/product...ions-set-of-4/

Some make them in different thicknesses, but it's really not that exact of a science.

If you run out of room on your floorboards, you can always jack the car up slightly by using a floor jack with a 8x8 piece of wood or other material of choice, on the floor pan above the trans mount, and jack it up some. You can open a door and jump on the door sill if it's not cooperating. Many cars over time have the floor pans sag, very common issue.

One way to check for floor pan sag is if the car has bucket seats, the headrests tip towards each other, towards the center of the car.

If it's a bench seat, or at the moment no seats, you can use a level across the seat bracket on each side of the tunnel.

EDIT: You can also in a pinch add washers to the body mounts, but that will cause a ripple effect where you have to re-align panels.

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Old 12-03-2019, 08:55 AM
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I have fixed rear arms.

Just looking underneath at normal stance, the pinion ought be SLIGHTLY below level for Street-Strip, maybe at level for Street.

Then (when nobody is around to bother ya) floor-jack the pinion and see how the pinion attitude doesn't change. Only the rear system rises.

Then consider the front end height when running the 1/4 mile. Set the front end with blocks under the Engine cradle, and redo the pinion raise with floor jack. I think a Urethane bushed rear system will barely show a change in pinion angle. You just might have the correct angle as-is. I sure do, with stock arms, boxed lowers, and the Straps for frame stiffning.

Fun fact: in the 1980s i has a 68 GTO Street car where the upper Arm Frame Crossmember mount holes had 3-holes per side. Had to be factory piercings: it was too neat. Thought that some engine option caused that. Never saw such a pinion-angle selection again.

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Old 12-03-2019, 11:44 AM
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I have the Spohn Del Sphere adjustable rear control arms. Well worth it! Made a big difference in how my el Camino handles, rides and pulls out, I have a standard 2:87 with a 454.. Getting it not to spin used to be such a challenge now that I had everything set with a four wheel alignment, it takes off like a missile..

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Old 12-03-2019, 12:22 PM
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When I installed a 9 inch Ford Rear into my Mid American Stock car Metric chassis, I fixed the pinion angle by enlarging the front holes on the upper trailing arms and and welding 7/16 washers. They were a couple thou over 1/2 inch. I put he rear where it was at ride height then using an angle finder set it where it needed to be and tacked them in.Then I took them off and welded around Try it out,

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Old 12-03-2019, 03:25 PM
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Quote:
Originally Posted by Half-Inch Stud View Post
I have fixed rear arms.

Just looking underneath at normal stance, the pinion ought be SLIGHTLY below level for Street-Strip, maybe at level for Street.

Then (when nobody is around to bother ya) floor-jack the pinion and see how the pinion attitude doesn't change. Only the rear system rises.

Then consider the front end height when running the 1/4 mile. Set the front end with blocks under the Engine cradle, and redo the pinion raise with floor jack. I think a Urethane bushed rear system will barely show a change in pinion angle. You just might have the correct angle as-is. I sure do, with stock arms, boxed lowers, and the Straps for frame stiffning.

Fun fact: in the 1980s i has a 68 GTO Street car where the upper Arm Frame Crossmember mount holes had 3-holes per side. Had to be factory piercings: it was too neat. Thought that some engine option caused that. Never saw such a pinion-angle selection again.
When the trans is longer than stock, the driveshaft becomes shorter, which in turn changes the operating angles. I would seriously doubt the pinion angle is correct without adjustment.

The only way to know for sure is to measure and calculate the operating angles.

.

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Old 12-03-2019, 11:34 PM
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All this is over my head. I will let my alignment shop handle it if I have to install adjustables

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1964 Tempest Custom
Original 326 Auto with power steering, brake, and dealer installed non working AC.
Built a custom roller cammed 467 all forged internals. TKO 600 trans with Ford 9 inch from Quick Performance with 3.70 geared aluminum thru bolt center section with billet pinion support with an Eaton tru trac. Plans are for car to be Silver Mist Gray with Dark Blue Interior. Keeping bench seat and adding air conditioning.
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Old 12-04-2019, 04:18 PM
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You do realize that an alignment shop doesn't do chassis work usually, yes? Pinion angle work is usually done by a chassis shop.

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Old 12-04-2019, 05:09 PM
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What do you guys set your pinion angle at? Just set it equal and opposite of the transmission? A few degrees down to compensate for pinion rising under acceleration? Trial and error?

Just curious, as I have been trying to get rid of a second order vibration that I get around 65-75mph.

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Old 12-04-2019, 06:19 PM
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Quote:
Originally Posted by ID67goat View Post
What do you guys set your pinion angle at? Just set it equal and opposite of the transmission? A few degrees down to compensate for pinion rising under acceleration? Trial and error?

Just curious, as I have been trying to get rid of a second order vibration that I get around 65-75mph.
Yes, the proper way is to set the trans tail shaft parallel to the pinion, minus a degree or so like you said to compensate for the pinion rising under acceleration. Don’t be surprised if the pinion ends up pointing upward, especially on an A-body. Fixed a pesky vibration on my car by doing it that way.
The vibration you are experiencing could also be from operating the driveshaft at 1/2 of its critical speed. There are calculators online that can give you the shafts critical speed where it becomes unstable. The only way to change that is to change the driveshafts’ diameter, wall thickness and or material.

__________________
68 GTO,3860#
Stock Original 400/M-20 Muncie,3.55’s
13.86 @ 100
Old combo:
462 10.75 CR,,SD 330CFM Round Port E's,Old Faithful cam,Jim Hand Continental,3.42's.
1968 Pontiac GTO : 11.114 @ 120.130 MPH

New combo:
517 MR-1,10.8 CR,SD 350CFM E's,QFT 950/Northwind,Road Paver,9.5” 4000 stall,3.42's
636HP/654TQ

1968 Pontiac GTO : 10.706 @ 124.440 MPH
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Old 12-04-2019, 08:35 PM
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Quote:
Originally Posted by HWYSTR455 View Post
When the trans is longer than stock, the driveshaft becomes shorter, which in turn changes the operating angles. I would seriously doubt the pinion angle is correct without adjustment.

The only way to know for sure is to measure and calculate the operating angles..
Yez, is why the Tail Mount & XMBR ends are a key item to adjust the driveline attitude. Mine is excellent.

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Old 12-04-2019, 10:10 PM
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Quote:
Originally Posted by TCSGTO View Post
I have a set of these and they are really nice for the price.
https://www.spohn.net/shop/1964-1967...djustable.html

As far as the chance that the pinion angle will be right with all of the mods you’ve done that’s probably not going to happen. Just changing rear ride height with all stock parts usually requires some adjustment.
I ordered those Spohns for mine and they are nice. Spohn sets them to the stock specs so if that works you're gold. Otherwise get out your angle finder and go to work. (Spohn is located in PA and their tech assistance is great.)

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Old 12-05-2019, 12:14 AM
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My alignment shop is full service speed shop they do all kinds of stuff

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