70ssclone

so my 70 use to have a 454 with a th400 , I swapped in a lq4 with the original th400 , I noticed that when weight is on the axle the DS will only move into the tranny 3/8 before bottoming out however with the suspension at droop you cannot get the DS out so where do I go from here to find out how much the shaft needs shortened ?

Project GatTagO

iTrader: (7)

Usually, with the rear axle at full droop, there is more clearance for the driveshaft for installation than with the car at ride height. Also, keep in mind that pinion angle relative to the driveshaft will effect the driveshaft length.

I'd be curious to know the angle of the engine, driveshaft and pinion gear with the car at ride height. I would also be curious to know what engine swap components you are using. All this matters...

Andrew

70ssclone

I will have to measure the angles , I'm using dirty dingo solid mounts they are slotted to move the powertrain back , forward and up or down , I need to move the engine up some because my tie rods hit the holley pan

70ssclone

Andrew I've also heard that what your saying about full droop is opposite on a body coil spring cars , I've read that at full droop the shaft is in the Trans further then if it was compressed

Project GatTagO

iTrader: (7)

There is no general for this and a lot depends on your rear ride height, and the angle of the pinion, which is why I asked for the angles. If you rotate the pinion down, that will pull the driveshaft out of the trans, presuming there is a shallow V angle between the driveshaft and the pinion.

The absolute shortest distance between the trans and the pinion gear is when everything is in a straight line, meaning the front and rear operating angles are zero. Every other combination will pull the pinion out of the transmission.

Stock ride cars were set-up so that the engine angles down slightly, say 3 degrees, the driveshaft angles down a little more, say 5 degrees, this makes the operating angle -2 degrees. In there rear, the driveshaft is still 5 degrees, and the pinion might be set for 1 degree up, but under power, the pinion moves up, the angles get equalized, and the driveshaft pushes into the trans. Also when the suspension hits a bump, the shaft goes inside the trans.

However, once you start doing engine swaps, different transmissions, and lowering the rear ride height all that goes out the window!

I highly recommend not moving the engine up, because it will make your driveline angles even worse, as I suspect you already have issues.

Andrew

garys 68

iTrader: (1)

Andrew hit the nail on the head. On my 72, I ended up with trans down, driveshaft down, diff up, all at almost the same angle. There's only about 1/2" before the yoke bottomed out. When I cycled the rear suspension, the reality was that there was almost no in/out movement. Been driving that way for years.

70ssclone

Sitting here in my garage on its wheels and tires the pinion is 7 degrees the middle of driveshaft is 0 and the Trans yoke is up 4 degrees because engine and Trans are pointing down toward driveshaft , I'm afraid I have no choice but to raise my engine some because of steering clearance , tierods hit it and draglink damn near touches all I can think would be to shim the crossmember to bring the Trans up to

Project GatTagO

iTrader: (7)

So it looks something line this?

\_/ exaggerated of course...

70ssclone

Pinion points toward floor 7 degrees according to pumpkin, driveshaft at the back by the pinion is 2 degrees lower ( I remeasured its 5 degrees ) driveshaft by the slip yoke is 0 degrees , slip yoke coming out of Trans is pointing toward the ground 4 degrees. Only thing I can think to correct is shim the Trans mount

70ssclone

So more like /-/

Toddoky

Are you using the Holley 302-1 pan, or the 302-2? What engine mounting brackets are you using?

Project GatTagO

iTrader: (7)

The driveshaft at the pinion and at the transmission should have exactly the same measurement, unless there is something really wrong with the driveshaft!

Andrew

70ssclone

I'm using the 302-1 pan, I will figure all this bs out someway or another

Project GatTagO

iTrader: (7)

The 302-2 pan offers the clearance that you need for the tie rods. This isn't "BS" and is very important to having a car that goes down the road smoothly. I promise that raising the engine is a very bad idea. The LS swaps already suffer poor drivelines with LS swaps, and the issue gets even worse when you start jacking up the engine. Besides, what's that going to do to your header clearance, etc...?

Is your car lowered in the back from stock?

Andrew

70ssclone

I bought that pan in 2013 never knew that they made a better one Unfortunatley im not going to blow another 350 on that better pan, I guess all I can do is slide the motor as far back as possible and see what to do from there . The car isnt lowered has stock springs , front sits up high because I haven't taken the bbc springs out yet

70ssclone

Actually looking at it now even if I move it back I only have an inch or so before the firewall so really have no choice at all besides raising the motor just a hair and shimming the Trans crossmember to get the yoke up , u have plenty of header room

Toddoky

If you are firm on sticking with the 302-1 pan, you have two viable options I see that will allow you to achieve desirable U-joint operating angles.

One would be to cut/rebuild the tunnel to allow you to raise the engine/trans together to clear your tie rod ends AND allow you to achieve an engine inclination angle between 2-3 degrees.

The other would be to just raise your engine as needed to clear your inner tie rod ends, max out the trans tailshaft height with shims and install a CV driveshaft.

Project GatTagO

iTrader: (7)

Here is my suggestion, and please take it as simply an opinion, and we all know how opinions go....

Sell the 302-1 pan. There are applications where that pan is desirable. Get yourself the 302-2 pan and get the Holley mounts while you are at it. This combination of parts will give you the best bet for achieving acceptable driveline angles, especially with a stock ride height car, and will clear the inner tie rods. I know this doesn't sound like fun, but it is less money that a CV driveshaft. I did my swap in 2008 and used whatever parts were available, and I had to use a CV driveshaft, which I can tell you is not cheap.....

Anyone that has done an A-body LS swap "back in the day" that tells you that it runs vibration smooth at 70+ mph is just lying...It's impossible...

Andrew