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Discussion Starter · #1 ·
Ok so I I matted the trans to engine and proceeded to try to set the pinion angle. (I am really hoping that my logic/measuring is flawed).
I put my digital angel gauge against the nut on the yoke of the axle and got .7 tilting up (my car has dropped spindles and smaller front tires).
So I proceeded to jack up the trans until I got a .7 tilting down.
This puts my trans yoke into the floor.
The trans cross bar was used before with the same T56 Magnum when it was behind a SBC. I was figuring that the trans bar my need to be moved forward a bit maybe up 1/2 inch, but the way I measured the pinion angel, it was having transmission sit 2 inches higher than where it sat before.

Is my logic of setting proper pinion angle flawed? (I hope so).

So I am trying to get a reference of where other peoples engine sit.
I am using the Holly 302-1 replica oil pan... The bottom of the pan sits level with the steering linkage (with the wheel straight), and I would say is just a little higher than the cross member.
Can someone tell me where their Holly 302-1 (or replica) oil pan sits in relating to the steering linkage or bottom of the front cross member.
Also height of the crank pulley bolt from the center hole in the cross member.
(I would post mine but I pulled the engine out.)


Idea of my front clearance (I pounded down part of the front cross member to get more clearance.)
337630


Trans cross bar in original location with trans sitting at my measured proper pinion angle.
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Steering linkage sitting with wheels fully turned. It's close but it clears. I can still move the engine backwards 1/2 inch with the adaptor plates.
337633


Then add further frustration, my $300 HF trans jack blew a seal and leaked hydraulic fluid all over my leg and the floor.
 

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Here's what you need to do.

The Holley pan should clear the front crossmember but not by much if the engine is at the correct height. I have seen a measurement posted on this forum for the height of a small block or LS above the crossmember but frankly I couldn't tell you how to find that. If you didn't hammer the crossmember much I wouldn't worry about that part.

Next you need to place the transmission mount so that the engine/transmission crankshaft and transmission mainshaft are 4° down in back relative to a level frame. After that you put the rear axle pinion shaft parallel to the engine/transmission - meaning it's 4° up. That angle should be when the car is being used as intended, so you may want to allow for a little spring wrap if you still have the leaf springs.
 

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Here's what you need to do.

The Holley pan should clear the front crossmember but not by much if the engine is at the correct height. I have seen a measurement posted on this forum for the height of a small block or LS above the crossmember but frankly I couldn't tell you how to find that. If you didn't hammer the crossmember much I wouldn't worry about that part.

Next you need to place the transmission mount so that the engine/transmission crankshaft and transmission mainshaft are 4° down in back relative to a level frame. After that you put the rear axle pinion shaft parallel to the engine/transmission - meaning it's 4° up. That angle should be when the car is being used as intended, so you may want to allow for a little spring wrap if you still have the leaf springs.
What Rick said is correct.
 

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Discussion Starter · #5 ·
Perhaps
Next you need to place the transmission mount so that the engine/transmission crankshaft and transmission mainshaft are 4° down in back relative to a level frame. After that you put the rear axle pinion shaft parallel to the engine/transmission - meaning it's 4° up. That angle should be when the car is being used as intended, so you may want to allow for a little spring wrap if you still have the leaf springs.
I have 2" inch drop spindles/smaller tires in front. The car has to 2° rake to to the front.
So let's walk through this
So basically the engine should be tilted 6°down to offset the 2° of the forward rake, and then another 4° to achieve the original backwards tilt.

Once this is set. I then need to match the pinion angle of the to that of the engine/trans which will be 6° tilted up (adjusting for the 2° rake and the 4 backwards tilt) correct?
 

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So basically the engine should be tilted 6°down to offset the 2° of the forward rake, and then another 4° to achieve the original backwards tilt.
In this description, you've done the needed 4° down twice. Same for the rear, you've done it twice.
 

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Discussion Starter · #7 ·
Ok, I see my explanation was not clear..
The car has a 2° rake forward because of drop spindles.... To compensate for this, with a desired 4° downward tilt on the engine/trans (if the frame was level)...
The engine/trans should have a 6° downward tilt, and the axle pinion for have a upward tilt of 6°. Correct?
 

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I don't have the frame level or compensate for it not being level. Or reference the frame at all.

I just use the pinion and trans angles, at the end of the day it is the relationship between these two that is important. It doesn't matter if they are both 4 degrees, 12 degrees, or 40 degrees, as long as they both match, or are close.

An easy way if the driveshaft has been installed is to use an appropriately sized socket on the front and rear universal 'cups' check the levels, and compare them. Obviously the cups need to be horizontal when measuring. An iPhone angle app is ideal for this.
 

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Discussion Starter · #9 ·
Re-thinking my logic to compensate for the rake of the car which pitches... The engine/trans needs to be tilting downward 2°...
That again puts my trans yoke pretty high right by the floor board....
Oh man this is driving me crazy...
 

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I suspect that this is being overthought.

It is only the relationship between the pinion and trans angles that is important, nothing else matters. Get these two the same, or close and call it done.

The rake of the car is irrelevant.
 

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Discussion Starter · #11 ·
Ok so a rehash. If I have the engine sitting at the 4 degree tilt. The trans yoke is hitting the trans tunnel. (Plus the rubber trans mount is 2 inches higher on the trans cross member to achieve this degree. (I had the T56 Magnum install previously behind a SBC and the tilt was 4 degrees.
Per Earl Williams on the trans cross member install, the welder brackets should be 1" below the top of the frame which they are.
To have the trans sit on the trans cross member would require it the engine to be tilted back ~7.5 degrees. This then would require me shimming the axle 3 to 4 degrees.

Options it seems are:
1 - lower the engine which means notching the cross member (although from what everyone has told me on a seamless frame I should not have to do).
* then I am concerned that the oil pan may sit too low)
2 - have the engine sit at ~7.5 degrees and shim the axle 3 degrees (although I think this is too extreme of pitches (not sure))
3 - have the rise the trans tunnel up quite a bit (to the point where it's hitting bech seat).
From what everyone has told me, I should not be hitting this issues.

What I really need to some comparisons of where other peoples engine sit.
I am using the Holly 302-1 replica oil pan... The bottom of the pan sits level with the steering linkage (with the wheel straight), and I would say is just a little higher than the cross member.
Can someone tell me where their Holly 302-1 (or replica) oil pan sits in relating to the steering linkage or bottom of the front cross member.
And Or - height of the crank pulley bolt from the center hole in the cross member.

(I put the engine back in and the bottom of the pully is 1.75 inches from the cross member)
 

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Let's see if I can go through this and make it clearer to you. We're going to assume that the 2° rake is really there as you reported.

The engine/transmission should be at 4° down in back relative to a level frame. If your frame is 2° down in front, then the engine/transmission angle to the ground should be 2° down in back. Then your pinion should be 2° up in front when the suspension is loaded as you intend to drive the car.

Place the front of the engine at the same height as a stock installation. It appears from your photo and original description that you have this correct.

If you do the above, a T56 transmission is NOT going to clear the transmission tunnel. But most other GM transmissions are going to fit in the tunnel nicely.

Remember too that the transmission mount location on the T56 is not in the same location either lengthwise or heightwise as most other GM transmissions.
 

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Discussion Starter · #13 ·
Thanks Rick,
Assume that the 2° rake is really there as you reported. Yes
The engine/transmission should be at 4° down in back relative to a level frame. If your frame is 2° down in front, then the engine/transmission angle to the ground should be 2° down in back. Correct, the engine has a 2° pitch when the car is sitting on all 4 wheels
Then your pinion should be 2° up in front when the suspension is loaded as you intend to drive the car. The .7 is probably b/c the the car is not fully weighted or b/c the leafs are slightly worn.

Place the front of the engine at the same height as a stock installation. It appears from your photo and original description that you have this correct.

If you do the above, a T56 transmission is NOT going to clear the transmission tunnel. But most other GM transmissions are going to fit in the tunnel nicely.
Regardless what transmission is used, the yoke would still be a ~ inch a away from the trans tunnel as maintaining the pitch "normal" 4° pitch, crankshaft/trans shaft will be in a straight line. I understand that the t56 may require some widening of the trans tunnel. That should be all up front... Plus my

Remember too that the transmission mount location on the T56 is not in the same location either lengthwise or height wise as most other GM transmissions.
Under stood, BUT this same trans/trans cross member was in the car before behind a SBC. I would have expected it needing to be moved forward/backward, not up or down (well maybe but not beyond a inch)
Rick I answered your questions in Red in the quote above.
Hopefully someone with a LS engine installed can give me a idea where their oil pan sits in relation the steering linkage or bottom of the cross member.
I am in a dreadful situation where something is amiss and I do not know how to proceed. :cry:
 

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"Regardless what transmission is used, the yoke would still be a ~ inch a away from the trans tunnel as maintaining the pitch "normal" 4° pitch, crankshaft/trans shaft will be in a straight line. I understand that the t56 may require some widening of the trans tunnel."

The T56 only requires raising the trans tunnel, it does not need to be widened.

"Under stood, BUT this same trans/trans cross member was in the car before behind a SBC. I would have expected it needing to be moved forward/backward, not up or down (well maybe but not beyond a inch)"

That is all correct. If the SBC/T56 was installed correctly, you should have already had to raise the trans tunnel. And you're right you should be able to use the crossmember at the height it already has if you are using the same transmission.

What is the engine/transmission angle if you mount the trans on the crossmember "as is"?
 

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You could try jacking the front of the car up to get the frame level for a starting point if that would help you simplify things. It cuts out some of the calculations and brain twisting. As stated above though, the way the car sits is irrelevant compared to the driveline.

And many here who have done it before have said before that the trans tunnel needs to get modified to run that tranny.
 

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I certainly had to raise the tunnel when I switched from a Ls with 4l65e to a T56 not that big a deal to do oil pan is very close to crossmember.
 

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Discussion Starter · #17 ·
Rick / 56ls408 , I meant "raising" the trans tunnel not widening. , but from what I have read that seems for the front of the trans and the shifter area, not needed to accommodate the yoke.

If the SBC/T56 was installed correctly, you should have already had to raise the trans tunnel. I had to bend over the pinch welds and open up the floor for the shifter. That is common for the T56 Magnum install. I never heard of someone saying the yoke hit the floor board.

What is the engine/transmission angle if you mount the trans on the crossmember "as is"? (I believe 5.5 degrees (having the car level it would have been 7.5) the numbers in my head are starting to swirl. The engine is in right now but the trans is not (my trans jack blew a gasket so I need to get a new one in the next couple of days)

nad427
, I already did that.. having both sets of numbers in my head made things worse...

56ls408, I have .5 inch to from oil pan to cross member in front. Cross member dimpled.

Let's step back and instead of focusing on the angles, can someone post any of the following:
  • Height from the bottom of the crank to top of the cross member?
  • Where the steering linkage sits in relation to the oil. Right now the bottom of the oil pan sits about even with bottom of the steering linkage (wheels straight)?
  • How far back oil pan sits from the steering linkage?
 

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Mine also had to be raised 1"from the front seam to the rear for the rear shifter cover to clear the floor although my shifter was in the most forward position for my bench seat. The yoke was close to but not hitting the uncut floor area directly above the yoke. If doing it now I would raise it past where the yoke could possibly hit the floor If needed to obtain your 4* down angle. I had no problem with a original one piece carpet fitting & the bench seat cleared the raised floor fine.
 

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[nad427[/B], I already did that.. having both sets of numbers in my head made things worse...
If your car isn’t wired yet wait til you get to THAT one. That’s where I’m at now, and building a custom wiring setup. Makes the head spin like an axle.
 

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This is interesting having two threads on the same subject....................

Hopefully this helps.

337830
337831
337832


Height from crossmember to balancer bolt is 135mm (we use metric in Australia = 5.3149").
 
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