So I finally took the plunge and cut out the trans tunnel tonight, fit the motor and trans in and I run into this.

At 3*, the driveline is basically inside the car. I imagine that this is being caused by the 1/2" worth of plate I have underneath the engine mounts to raise the engine in order to clear the crossmember.

Well, in order to create more room to maneuver the motor and trans in, I ended up notching/cutting out the aft section of the cross member anyway, so that clearance is basically a non issue now.

My guess is I should remove the 1/2" worth of spacers and put the mounts back down on the frame. I just don't know if that's going to be enough to get the driveline back underneath the car. But how much lower should it really go? that shifter platform is way up inside the car.

What am I missing here?

 

Wow.. I have never seen a driveline issue as you have with the output of the trans being that High before.

I would take out them spacers... If you notch the cross member... the engine should really sit down now. what oil pan are you using ?... Looks like a CTS-V ??? If you notched the cross member.. you should be able to use a F-Body pan now. I highly recommend the Holley 302-2 pan. It also has clearance for the steering ends for a A-Body,.

BC

 

I would remove those plates and get the motor down in there. What oil pan are you using? My F body pan worked great after I notched the rear of my crossmember. I'm sure it's an illusion from the floor, but it almost looks like the motor is 3* up in that first pic. Is the car sitting on it's own weight?

 

Thanks for the responses guys.

That is the CTS-V oil pan.

I think you're right that I need to remove the spacers and even consider the Holley pan to hopefully just make it all easier.

The car is sitting on its own weight.

Of all the builds I've read about I've never seen this issue.

 

I believe you want a 3° down difference to the vehicle frame angle. Looks like you are doing 3° angle to the parallel to the ground and not the vehicle rake.

 

Your not the first to question how I'm measuring my angle. I assumed that I could take the angle measurement off any flat surface that's on an equal plane as the output shaft. Is this incorrect?

 

Don't get overly fixated on the engine inclination angle as it's just a point of reference as to how it affects the U-joint working angles, which is what you are really trying to optimize through all your efforts. The engine and transmission will operate just fine at angles that will destroy your U-joints. You should be measuring the actual working angles of your front and rear U-joints so that you can determine what amount of difference, if any, exists between them. You want to end up with no more than 3 degrees of U-joint working angle (not to be confused with engine inclination angle) and a minimum of 1/2 a degree to keep the U-joint needle bearings from brinneling the u-joint trunions. There should also be no more than 1/2 a degree difference between the angle of the front and rear joints on any car equipped with a non leaf spring suspension. Leaf spring suspensions will typically be set-up with a couple of degress of extra pinion down angle to compensate for axle wrap on acceleration. All your measurements and adjustments need to be carried out with your car sitting at its intended final ride height...in other words, don't set your U-joints up and then lower your car and change your wheel/tire package.

 

Todd, with that being said, would you suggest I lower my transmission to an acceptable location/height where I have good driveshaft clearance in relation to the floor then just take my angle comparisons from there?

So for example, if I lower the trans to let's say an angle of 8* down. Then I measure my axle pinion angle and its 5* up for a difference of 3*. That's acceptable?

But if I measure my trans pinion angle at 8* down and the axle pinion is at 8* up...that's bad and would cause driveline vibrations issues?

 

What Todd said!.
I was going to state don't worry what the angles are in relationship to the body/frame, if you did, it would still not be optimal.. The Frame and body could be jacked up all different ways (good old California Rack ! LOL), as long as the driveline angle are setup within tolerance you will be good, that being ythe trans output shaft, drive shaft and rear pinion.

BC

 

The angle of the trans in relation to the ground doesn't matter. What matters is the angle of the driveshaft w.r.t. the trans and w.r.t. the diff. The driveshaft should be 2-3° raked down from the trans, then 2-3° up to the diff.

See here: https://www.drivelinesnw.com/part-tr...ngle-problems/

 

If you have a smartphone Tremec has a free app that figures all of this out for you.
http://www.hotrod.com/how-to/additio...le-finder-app/
http://www.tremec.com/menu.php?m=154

 

Good advice here, so far.
Also, are you sure that flat pad on the trans is actually parallel to the engine crankshaft (and trans output shaft)?
I put the angle finder on the harmonic balancer to determine engine / trans angle. (use a straightedge or a plate which covers the diameter of the harmonic balancer. Worth double checking, that, too.

 

I measured my axle pinion and it's pretty much 1* up...nearly perfectly flat.

I lowered the trans to below the floor where I thought it "looked" clear. This position measured about 8-9* down at both the yoke and the flat plate on top of trans for a difference of about 7-8*.

That seems like a ton to overcome.

 

First off, I can tell you that you're never going to get acceptable angles with the 1/2" plates in there; All A-body swaps are challenging to achieve something close to acceptable U-joint angles due to the constraints imposed by the high height of the steering center link/inner tie rod ends up front, and the low height of the tunnel sheet metal in the middle of the car.

Get rid of the plates and get the front of the engine as low as possible in your car(the Holley 302-2 pan is going to give you about the most clearance you are going to find) and then get the rear of the trans as close to the floor as practically possible and use that as your baseline position to take your initial measurements. The down angle of the engine/trans only matters how it relates to the measured angles taken off of the driveshaft and pinion; the measured angles of the trans output shaft and driveshaft determine the working angle of the front U-joint and the measured angles of the driveshaft and pinion determine the working angle of the rear U-joint. The working angles of both joints need to be more than 1/2 a degree, less than 3 degrees and be within half a degree of being the same but opposite of each other on a non leaf spring car. It should be becoming apparent to you that a high eng/trans down angle works against getting your U-joints under 3 degrees of working angle since you have to tip up the rear pinion to the same but opposite degree...lowering your car just makes things worse and requires even more floor cutting.

Your referenced 8 degree down trans and 8 degree up pinion does not give enough information to be able to determine what the U-joint angles are; you are missing the measured driveshaft angle that needs to be factored in to reach a determination. The same 8 degree trans down/8 degree pinion up angle measurements could provide both optimized or horrendous U-joint working angles depending on the ride height of the vehicle in question (i.e. a 4 wheel drive truck compared to a lowered muscle car). You can't do the exercise correctly if you don't have a driveshaft installed so as to be able to take measurements off of it.

 

I posted this on Chevelles.com also for you to read Steve. http://www.roadkillcustoms.com/hot-r...#axzz3QoXWWa33

 

I removed the 1/2" spacers and set the motor back about 3/4" from original mounting holes.

It dropped the trans quite a bit but still not close to where I should be. Plus, of course the tie rod ends make contact with the pan about half turn.

This put my trans about about 5* down but the yoke is up against the floor board at this angle. Reminder that my axle pinion angle is at 1* up.

What's next? Why haven't I seen this issue in other builds? This seems fairly severe.

 

These issues with A-body swaps is quite well known and guys either take the time to work through it like you are doing or are from the "screw-it" camp and just bolt everthing in the car without checking any angles to see if things are as they should be. The next step for you if you want to see improved angles is to use a pan with a lower front end height.

 

So the lower profile oil pan will possibly solve my tie rod end clearance issue, but my biggest concern right now is the angle of the transmission and where it puts the output shaft.

Am I not doing this right? The hard part also is that I don't have the correct length driveshaft yet. I need to get everything set where it's going to go so I can measure the correct length and get my driveshaft cut down. I feel like I'm kind of stuck.

 

Well at some point I'll have to join the "screw it" camp because the setup has to get installed. The driveline has to be "under" the car as opposed to "inside" the car.

 

If you have to have your driveshaft shortened anyway, cut the front yoke off yourself and shorten the shaft enough to allow you to install it in your car for use as as mock-up tool. Use tape or a hose clamp to hold the yoke to the shaft temporarily. Once you get everything figured out you can then send the shaft out to be welded back together.