LS engine angle problems

[Bihili]

A few facts first:
Completely stripped down 57
I have about 250 pounds in trunk to simulate a gas tank, bumpers & misc
The current pinion angle is between 2.5 and 3 degrees on the stock rear end.

While test fitting the LS 5.3 & 4L60E the angle at tail shaft is 5 degrees.

I cannot get less engine angle because the top of the tail shaft is hitting transmission tunnel.



I had not planned on modifying the tunnel for this project. Am I missing something?

[NickP]

What engine mount are you using? Pics, brand, manufacturer etc.

[chevynut]

Why not just leave the engine at 5 degrees and set the pinion appropriately? We typically set our engines at 5.5 degrees and the C4 IRS at 5 degrees. That's because of rack clearance. Is your engine sitting higher than stock?

[Bihili]

Nick, the motors mounts were welded in place by the former owner who died.
Nick, years ago you posted the factory pinion angle was 4 degrees to match the engine angle of 4 degrees and it had something to do with the float on carburetors.
This car is stripped down but my pinion angle is only 2.5 to 3.0 degrees. Do you think it will change that much when at full body weight?

I don't think the engine is sitting higher.

I notched the crossmember to make room for the factory AC compressor and removed original motor mount humps from crossmember to give additional clearance to oil pan.

What is factory engine angle for a LS engine?

[NickP]

3° , 4°, 5° or 5.4978345°; As Laszlow is alluding to, the main function to consider, for me is to keep the pinion center-line and the power-plant center-line parallel or as close as possible, say (arguments to ensue) +/-.25° We all strive for perfection for the most part but I feel as hot rodders in the new technological era, we tend to overthink and shy away from allowances and tolerances given. Sure, it's cool to converse to the highest degree about some exponentially wonderus feature of the front gizmo that's attached to the turbocharged thin-a-ma-jig but for me, the expense doesn't outweigh the aggravation of the train ride.

As to the question, angle for stock LS, I have never measured any of my present vehicles so am unable to give direct feedback/numbers on that but with an LS (fuel injected) the float level is no longer an issue really.

Not being an engineer, I know there are specifics relative to a minimum/maximum angle of operation on universal joints but I can't expound upon specifics, just generalities.

[chevynut]

Like you said Nick, the EFI doesn't care what angle the engine is at and oil flowback isn't going to matter if it's different by a couple of degrees. The car probably has a slight rake anyhow. You want the crank and pinion centerlines to be parallel while under a constant load so the u-joint angles and their resulting acceleration cancel each other. I think they recommend to have them within 1 degree or less of each other. I set my pinion 1/2 degree below engine angle to account for any flexing of the mounts, etc. If you ever look at a leaf spring vehicle while driving, the pinion goes all over the place.

From what I've read the maximum recommended u-joint angle is usually around 3-4 degrees but I don't know where the limit really is. That's the angle between the driveshaft and crank, and between the driveshaft and pinion.

[WagonCrazy]

pinion angle_sm.jpg

[chevynut]

Paul, any idea what they mean by "strain"? Some of those diagrams and comments make no sense to me. Having shafts in perfect alignment is NOT good, as the u-joint bearings don't move and don't get lubed properly causing brinnelling. That's why the C4 IRS knuckles are set back from the differential yokes...to ensure the u-joints are always moving.

Vibration can be caused by out-of-balance, or by the acceleration of the shaft as the u-joints turn. If the ends are at the correct angles (same u-joint angles), the acceleration is cancelled out, eliminating vibration. You can get the same u-joint angles if you do #2 AND #4. I see no reason for #4 to have, "rediculous vibe" any more than #1 or #2. Pinion lubrication might be a problem depending on how the case is designed. I don't see why a Dana 44 would have any lubrication issues as there's a passage for oil thrown from the ring gear to the front pinion bearing. I imagine most cases are designed that way.

[55 Rescue Dog]

So does 5.5 degrees work or not, if 3-4 degrees is considered max? Or is kinda close good enough at 100mph?

[chevynut]

So does 5.5 degrees work or not, if 3-4 degrees is considered max?

Re-read what's been posted.