Ls swap and driveline angle

[Ghost's68]

Hello everyone.

I want to start off by saying I am not a mechanic and have very little knowledge of building cars or swapping motors. I’m learning as I go and do research and learn how to do things before attempting. This is my first major engine job I’ve done and frankly this truck has taught me a lot about working cars. I just throuroughly enjoy working on my own clunker as I get major satisfaction knowing I did this or that to my truck.

So onto my question I just dropped my LS/4l80e into my 68 SWB today and will be tackling setting drive line angles. From what I have read, LS’s should have about a 3-4* down at trans. Now what about centering the engine? Doesn’t it sort of self level itself when engine mounts are tightened down? Should I center the trans output shaft to the frame rails?

Any help you guys offer is HIGHLY appreciated. I will continue to read on this topic but I sometimes have question I can’t ask a article, hence when I posted this thread. Lol.

Here’s a pic of what I got going on.

Thanks in advance

[mongocanfly]

your engine and trans can be off center to the frame...but keep your driveline centerline running parallel to the frame...as far as the angle question..you need to check your axle yoke angle and match that angle number with your trans....one will be postive angle one will be negative angle....so if your axle is up 3 degrees..the trans needs to be down 3 degrees...

[mongocanfly]

here's a good video explaining driveshaft phasing...
https://m.youtube.com/watch?v=Idk3BVDVHq4

[Ghost's68]

Originally Posted by mongocanfly

your engine and trans can be off center to the frame...but keep your driveline centerline running parallel to the frame...as far as the angle question..you need to check your axle yoke angle and match that angle number with your trans....one will be postive angle one will be negative angle....so if your axle is up 3 degrees..the trans needs to be down 3 degrees...

Originally Posted by mongocanfly

here's a good video explaining driveshaft phasing...
https://m.youtube.com/watch?v=Idk3BVDVHq4

I think I got you when your talking about keeping the engine trans parallel to the frame. I would have to verify the engine and trans center line the same how it sits in the Frame. Ex. Center of crank pulley sits at 20” in the rail and the trans tailhousing also sits at 20”. Is my understanding correct?

Is having the pinion yoke and transmission yoke offset ok?

Also, I have a Ford 9” if that matters. A buddy at work had mentioned the pinion angle should be down since under torque it moves up. Does that sound right?

That vid sure was educational and very informative. Thanks

[mongocanfly]

Center of crank pulley sits at 20” in the rail and the trans tailhousing also sits at 20”. Is my understanding correct?
[yes] as long as your frame rails run parallel to each other, you want to keep centerline of engine/trans running parallel to center line of rear differential from side to side..being offset is ok

Is having the pinion yoke and transmission yoke offset ok?
[yes]

I have a Ford 9” if that matters
[some furds have a offset pinion anyway]

A buddy at work had mentioned the pinion angle should be down since under torque it moves up
[done mostly in drag car]

from curries website
[ According to Currie, the average car crafter should strive for between 1 and 3 degrees between the tailshaft of the transmission and driveshaft, and 1 to 3 degrees between the driveshaft and pinion. Furthermore, the two angles should be nearly equal (between 1 and 3 degrees), but always opposite]
[With a leaf spring–equipped car, the differential movement isn’t nearly as controlled as that of a four-link suspension, so more angle may be needed to prevent the U-joint from hyperextending beyond zero degrees under load. Sometimes people increase the pinion angle to increase dragstrip bite, but Currie does not recommend this approach for a street car]

[NC_John]

The drawing showing inline as perfect (as I understand it), is wrong. You need the u-joints at an angle (a degree or two) otherwise they won't lubricate properly and they will not last.

[truckdude239]

I dont know the answer but i just droped mine in motor looked level i have a 2 peice drive shaft didn't center anything sofar i have around 2k miles on swap and havent noticed any nosies or vibrations

[Ghost's68]

Guys, thanks so much for all the help and info so far. Today I went out and bought a digital and analog angle gauge.

I’m currently trying to get my crossmember moved back since I slid the motor back as far as I could using the DD sliders. Once I get it in place and bolts in I’ll try and get it parallel.

If I find center of rail in the front and somewhere near the middle I can use plumb bob line as a refence. Then see how far off the center of the crank and tail shaft are to that reference and then make needed adjustments to have them equal correct? Ex. Front of crank is right of centere 1” then I should have tailhousing center right of center 1” as well . Does that sound right?

[mongocanfly]

"Ex. Front of crank is right of centere 1” then I should have tailhousing center right of center 1” as well . Does that sound right?"
correct

[stexag]

Ghost,

Are your engine stands bolted into the front or rear set of holes? thx.

ETA, I'm asking for my own benefit, I am exactly where you are right now and even though I haven't had time to get more done on the truck - I'm planning my next move.

[Ghost's68]

Originally Posted by mongocanfly

"Ex. Front of crank is right of centere 1” then I should have tailhousing center right of center 1” as well . Does that sound right?"
correct

Sweet! I’ll try and tackle that here shortly! Thanks mango.

Originally Posted by stexag

Ghost,

Are your engine stands bolted into the front or rear set of holes? thx.

ETA, I'm asking for my own benefit, I am exactly where you are right now and even though I haven't had time to get more done on the truck - I'm planning my next move.

Stex,

You can sort of see on the pic I posted if you zoom in, but I did use the front holes for my CPP perches. Whatever I can help with let me know.