spartanv8

iTrader: (4)

In more than one place, I've read that the engine/trans needs to be tipped back at 1 to 5 degrees. Even my LS1 swap book says it, but doesn't say why.

I've heard arguments about lining up the driveline to the differential pinion, about getting the oil back to the sump of the pan, about making the front of the motor the high point so that air bubbles can get to the water pump and get vented to the radiator/reservoir, and I understand the steam lines as well.
-For what its worth, I'm going to run steam lines on all four corners of the motor.

So, I challenge anyone to tell me why I can't mount my motor horizontal, flat, front to back....

gofastwclass

iTrader: (2)

You CAN mount the engine and transmission any way you want but to eliminate drive line harmonics (usually around 70 mph), wear on u-joints and other bits, somewhere between 1 - 5 degrees is the best. The pinion angle needs to be set this way as well but if you aren't changing rear ends it already is.

All factory setups are in that neighborhood and are designed to be at that angle. The engine being lower than the radiator is optimum but on many new cars some cooling lines on the engine sit higher at some point so there are air bleeds in them.

spartanv8

iTrader: (4)

I don't have my T56 yet, so I don't know exactly what height the output shaft is at, relative to the engine's crank centerline.... but, so far it looks like they line up pretty well, if anything, the diff pinion flange is slightly HIGHER than the trans output shaft.

Thanks though, I will make sure that they line up into that range.

Any other reasons?

gofastwclass

iTrader: (2)

You really need the transmission you are going to use (or a good mockup of it) to get accurate measurements. Your angles are going to be dictated by engine and transmission mounts. Without the transmission mount you really can't mount the engine and everything is guesswork.

I looked at your site... interesting concept. Keep us posted on how it goes. I hope you are a good welder, if you aren't you will by the time the project is complete! Sorry about the transmission deal.

The main reason for the angle is parts longevity. I don't like to rebuild or replace stuff unnecessarily. Replacing a custom driveshaft is foolish, expensive and dangerous (because it came apart at speed) simply from having incorrect angles. I know 2 guys in separate incidents who lost a u-joint that took out the tail shaft of their transmission and nearly lost the car in the process - extreme case, but it happens.

Pop N Wood

iTrader: (1)

The link below will tell you everything you need to know about trans-rear alignment. You need the two shafts to be parrallel, preferrably when under some load. Having the engine higher/lower than the trans or even offset side to side is OK as long as the total U joint angle is within some range.

http://www.4crawler.com/4x4/CheapTri...line-101.shtml

Simply tilting your engine 1 to 5 degrees is not going to do it. It has to match the diff. In theory if you use the laser pointer idea in the link above you might be able to align the motor and diff without the trans, but you will have to redo it anyway once you get the trans so you might as well wait until then.

As for the engine itself, I had the same worry when I did my swap. I rotated the diff to where it is almost level. That allowed me to get the hood clearance I needed without the tail of the trans dragging on the ground. That in turn means my engine sits almost level. I wondered about oil drainage and what not. Then I decided that the small amount of tilt was nothing compared to going down a hill (or accelerating at max G's) and just didn't worry about it.

spartanv8

iTrader: (4)

I was thinking the same thing.. It's not mentioned in that link, but is there a MINIMUM angle? I recall looking under various cars and noticing that the diff center section was not centered on the axle, rather it was slightly to the drivers or passengers side. At the time, it was explained to me that this ensured that even if the pinion and trans were perfectly aligned (as viewed from the side), the u-joints would still be exercised (since things are not aligned from the top view)...

spartanv8

iTrader: (4)

Hoping to find a decent T56 rather soon.. then will get it modeled in SolidWorks, mate it to the engine, and see how the output shaft lines up with the pinion.. well, virtually anyway Looking into rebuilding a core vs buying a good used 6 speed.. we'll see

Steve VanS

iTrader: (1)

As a machine designer, we set ujoints at 3degs. This allows for a little rolling of the needles, and keeps re-greasing the needles. Less of an angle causes the grease to just squeeze out, leading to brinnelling of the races. More of an angle (more than 5-6 degs) causes big forces on the ujoints as the middle member of the driveshaft speeds up and slows down twice per rev. Check online with Dana or Zurn, they have precise info. Whatever you do, get the diff pinion at the same angle as the engine crank so that the speed-up/down of the middle member does not also apply the the diff.

Whenever I see a really lifted truck, I think to self: That guy is good at changing ujoints.......

spartanv8

iTrader: (4)

Thank you, thats what I meant, but much better said!

My driveline is at zero degrees, as is my differential. I know the approximate distance between them, but still don't know the exact location of the trans output shaft..

I hope it ends up pretty close to 3 deg once I get the t56 modeled, or I'm not sure how I'll get it right.. The differential must be at zero deg, as the suspension mounts to it, and the engine/trans is designed in at zero.. so really it just comes down to the distance between them and their difference in height..

gofastwclass

iTrader: (2)

Hahaha! Glad to know I'm not the only one thinking that!

spartanv8

iTrader: (4)

Anyone else with a good argument as to why I shouldn't install the motor/trans level?