Im doing another swap unfortunately the steering rack is in the way of oil pan. It hits before i can drop it all the way(the front part of an fbody pan)

I would like to aim for less than 4* driveshaft angle for the diff/IRS and transmission only way i can do this (without redesigning the whole steering component) would be to bolt the engine as is and drop the transmission down a bit.

BUT how much is acceptable? i figured cars go up and down hills all the time so some angle is ok but how much is too much for it to sit at on the daily basis?


the way im measuring is putting the car on a flat surface and putting a digital level on the valley cover to see the angle.


it might look a bit funky with the front of the engine a bit higher but i figured its better than having too much DS angle.

I think i may have to angle roungly 5-8*

 

Depending on this driveshaft length, 5-6* is within normal range.

 

The engine and trans operability is not the limiting factor in the maximum engine/trans inclination angle a specific vehicle can tolerate; achieving desirable U-joint working angles and staying below the maximum designed U-joint working angle tolerance is. 3 degrees of working angle is the maximum a U-joint will tolerate safely by design , but that specification is RPM dependent...the higher the RPM they are subjected to, the less tolerant U-joints are of angularity before failure. There is also the effect on performance to consider as minimized U-joint working angles are able to more efficiently transfer power than those having to overcome greater degrees of angularity. Although a discrete engine inclination angle by itself will not tell you what your U-joint working angles are, you usually cannot achieve optimized U-joint working angles with an engine inclination angle of more than 3.5" unless you're working on a pick-up truck.

 

i have 7-8* engine tip back in my Jeep TJ swap. helps out with the stupid drive line angles jeeps have to run.

 

Yes, Jeeps are like trucks and need to run a steeper engine inclination angle to acheive optimized U-joint angles. That is due to their much lower pinion height compared to typical passenger cars.

 

why does the ds length matter? i thought it was just the angle of DS with the engine and differential being parallel?

the issue that im having is the front of the engine sits way to high, the rear differential i can "shim" to raise the front to face it up and if i angle down the engine on the back so the transmission is facing the differential i think i can make those two parallel and keep the angle of the driveshaft low.(i thought it was 4* max but ill aim for 3* max) 0 if possible of course.

just wasnt sure if an engine could be angled to make sure the u joints are happy and if it ok how far can i angle the engine?

 

Even if you possibly can, don't set them at 0 degrees.You want to have at least a half a degree of operating angle to allow the needle bearings in the caps to rotate and perform their function (they won't rotate at 0 degrees and will brinnell the U-joint trunnions).

 

Your looking at the angle of the engine/trans in isolation, when you need to address the whole driveline as a system. What will happen if you angle the engine/trans at 7 degrees (presumable in reference to gravity) is that most likely your driveshaft will make a shallow V relative to the engine/transmission. This is an undesirable configuration as you will not be able to set the angle of the pinion in such a way as to have small enough (less than 3 degrees) in the front and rear operating angles. You'll be able to set the pinion so the front and rear operating angles match, but the angles will be too great for smooth highway operating.

On a Jeep, a steep engine/trans angle (relative to the frame) is more tolerable, because the rear end is hanging low compared to the frame.

Andrew

 

oh ok good to know

thanks

I see what you mean. hmm ill have to remeasure again. perhaps im doing this wrong.

Should should I be referencing gravity instead of body so that its consistent? as long as the diff and engine are in parallel?

 

You need to know the engine inclination angle, the installed driveshaft angle and the pinion angle to determine your U-joint working angles. If any of those three angles are unknown you can only guess what your U-joint angles are. You can make your engine and pinion angles perfectly parallel and still have excessive U-joint operating angles, depending on the height disparity between the transmission output shaft and the pinion.

 

^^^^This...

Andrew

 

I understand that let me clarify. Its a swap meaning the only thing mounted is the differential even that i can shim the front so i can sort of raise it acouple of degree.

the only thing i know now is length of DS +- .5 inch

I do understand that i can still have excessive angle even if parallel thats why i said goal of 4* (until someone said 3* is max) but the article i read said two different angle is a no no. so I figure set them parallel first then drop or raise the engine.

the engine and trans are NOT mounted so i can still move it around.

my question was can the engine me tillted so that i can match the drive line
within 3* diff flange and trans yoke with both diff and engine parrallel.

 

Keep in mind that you are making static adjustments to arrive at suitable dynamic U-joint operating angles. This means that the type of year suspension you are using will determine the static setting required to account for deflection of all the suspension components during acceleration. If you have a quality 4-link with spherical link ends for example, you will more than likely be able to set the static angles of your engine and pinion to match and be done with it. If you have a leaf spring set-up, or a stock-style 4-link with rubber or poly bushings, don't be surprised to end up with a degree or two of down-tipped pinion angle to account for axle wrap. Set them up to match, confirm that your U-joint angles are less than 3 degrees once your driveshaft is installed and go flog the car to check for vibration.

 

If you don't have a driveshaft, you can run a string from the output shaft to the pinion and get a good approximation of the driveshaft angle.

Andrew

 

I mounted mine in my fairmont at 3 degrees. Measured off the tail shaft of trans and the valley cover.

 

the engine or DS angle?

its an IRS so should stay the same as my static measurement?

yea i did that and im having the driveshaft made already. I have a basic idea but i wanted the driveshaft so the angle is forsure when i make the motor/trans mount

 

Yes, absolutely match the engine inclination and pinion angles if you have an IRS.

 

You could use a constant-velocity joint to compensate for weird driveline changes but that is normally a Band-Aid for engineering restrictions of angles. Quite a few offroad vehicles use CV setups to help their driveline angle changes.

 

I use a CV driveshaft in my GTO, and it isn't a crutch, but an alternate solution. My Cougar has a dual CV shaft (front and rear) and it is as smooth as glass. The CVs used in my driveshaft are not the old double cardan style CVs, but modern Rzeppa style CVs...think Porsche drive axle CVs.

Andrew

 

Andrew Who made the driveshaft for you?