Pinion angle question Mk4 Update - comments?

[Jeff_J.]

Not a complicated process but it's new to me and an important thing better to get it right..... I’ve read a lot of posts on this so I’m pretty sure I understand the goal here but here’s what I’m dealing with. (BP347 & TKX with IRS)
Engine slopes down to the tail, which was expected, IRS sloped so that the pinion is pointing downwards towards the front of the car as well at 1.05*. The goal here is to get the trans tail to within 2* (.5* if possible) of the pinion shaft angle. Based on the two angles, I’ll have to lift the tail of the trans to get parallel angles, I think the U joint angle will end up around 5* maybe worse but from what I’ve read and understand that angle is secondary.
Am I correct in my direction here?
Thanks in advance for any input...
Jeff

(should have dealt with this on engine install day!!!)

[rich grsc]

You have IRS, the center section doesn't move, so it's not that important.

[michael everson]

I usually end up spacing the trans up 3/4 of an inch. I put an angle finder on the lower pulley and then on the pinion flange and try to get them close to zero.
Mike

[Jeff_J.]

Hi Rich and Mike, Yes I knew the IRS was fixed which is why I mentioned the angle. I used a digital angle finder on the harmoniser to get the slope of the trans and put a straight edge on the pinion face as well (not the easiest place to measure).
I'm thinking it will be more than 3/4" of spacers to get the tail shaft at 1.05* which made me wonder where the Drive shaft angle will end up.. I guess we'll see. The important part for me here was to confirm my understanding and method was right.
Thanks for the comments guys - stay tuned for where this ends up....
J.

[Jeff_J.]

So I have increased the height of the trans to be .55* up slope to compare to the Pinion angle of 1.05*, difference being .50*
The DS angle however took a beating and is 16.5*. picture is like a thousand words.
195363

I could add another shim to be less than .50 difference to parallel but that would further increase the 16.5* DS angle. should I be concerned here???
Thanks for your help.
J.

[F500guy]

Jeff,
I had similar situation, I ended up with 1.5 inch shim and still was not ideal but and I think the angle was still about 1 deg opposing angles and not parallel plane of the diff and transmission. but I figured it was a fine compromise with such a short drive shaft and still workable. I tested over 1.75 shim and the transmission was stuffed so far up and the drive line was like 12 deg so I backed down to 1.5. This is a Dart block 427 with TKX. Have not yet driven it, but not to concerned with those angles, especially street with occasional track use.

Lance

[cc2Arider]

It seems the comments can be partitioned into "why are you bothering?" to "make it match -- equal and opposite"...

One thing that I don't hear about often is that the u-joints actually need a touch of "dither" to maintain long life. Not too much and definitely not zero.

Jeff_J, your pictures do say a lot. I am in the process of mocking up my drivetrain installation and appreciate your observations. It seems the outcome will be good and I agree with Lance that it will be a compromise...as all of these problems end up being :)

Craig C

[Jeff_J.]

Thanks for your comment, Lance & Craig. When I was reading posts on this it was clear to have output and input as close to parallel as possible. The video explained the problem of not being parallel so that’s how I proceeded. I was just under there again, to get to the measurements listed above I have 2” of spacers from the top of the tranny support bracket (“A” bracket) to the bottom of the tranny mount. It’s a lot. I can live with it if the DS angle at 16.5* isn’t going to be an issue for me. Kinda hopeful one of the senior builders can chime in on this just so I know there isn’t an option I’ve missed..
** with the change rotation of the engine I found I also have to lengthen my PS braided line to the hydroboost and the braided fuel line from the regulator to the sniper.. Again – would have saved time and grief if I did this on engine install day…

[Jeff_J.]

I'll have to get longer bolts for the tranny mount but I'm going to stop here for now and see if there are any further comments on that DS angle.
J.

[ggunter]

I ran your measurements through my Eaton Road Ranger Driveline analyzer and they come up in the Red and the thing that makes the measurements red is drive shaft rpm and angle. At 2000 they are in the green but at 5000 this is what you have.195377 Most of that is drive shaft angle. when I lessoned it to 10 it got much better. I assume your rear angle is point upward not down, correct? If it's down it will change this for the worse. And 5000 in high gear is probably not where you will go very often if ever. You need to lesson the drive shaft angle if you are going to run any high rpm in top gear.

[ggunter]

By the way those red numbers only change to green when they are under300 rads/sec2

[Jeff_J.]

If you notice on the picture I attached a few posts above - to get the Pinion and Trans output shaft close to parallel the transmission is pointed up at .55* as it points to the back of the car - the pinion is pointed down as it points to the front of the car. It's IRS so the down angle right from installation was 1.05*. the DS has an upward angle of 16.5* as best I can check with a digital angle finder. Not sure how I should proceed based on these numbers.

[cc2Arider]

GGunter,

That is a cool GUI tool. Is it on the "inter-webs"? Can you share the link?

Thanks,
Craig C

[ggunter]

I work at a Mack Truck Dealership, and we use that tool all the time for vibrations and wheelbase changes, and yes, it is a great tool. It was given to me by our Eaton rep years ago and I have tried to copy it but when I do it will not open. This is what it would look like with a lot less driveshaft angle and rpm's around 85 mph in high gear.195410

[ggunter]

If anyone wants me to check their numbers and angles I can easily do it. Only takes a minute. In a happy world all the angles should be as close to one degree of each other as possible. This program also has a corrective mode which tells you which item to change and which way to move it.

[CraigS]

A few thoughts.
- Since it is reasonably easy to change the trans shim later I think I'd reduce it some. Just reading this forum it is very common to use 3/4" to 1" trans shim. Reduce the drive shaft angle and accept (until driving the car) some extra angle diff between trans and diff. On solid axle cars they usually run the diff down 2* in relation to the trans. They do that so, w/ hard accel, as everything flexes some, they expect the diff to climb 2*. So the whole setup is expected to go through 2* of motion every time you nail the gas.
- Also, in back of your mind, think if different engine mounts could lower the engine which would have the same effect as raising the trans. I sure don't remember any details but have seen discussions of different engine mounts when dealing w/ an air cleaner hitting under the hood or an oil pan sticking below the frame rails.
- Another thought just in case. Be super careful when doing your angle measurements. It is very easy, since engine and trans are usually 0 to 2 deg, that you get mixed up and interpret a -.5* as a +.5*. I know the first time I ran through this I didn't have the easiest to use angle measurer and was getting frustrated. Frustrated enough that I dropped the front wheels back onto the floor and jacked the rears as high as I could get. Things are a lot easier when your engine and trans angles are in a range of 4 to 8deg and no + or - to deal with.
- Decades ago I was a service manager at a BMW dealer. Had a customer come in for a vibration in the 20-30mph range at > about 2/3 throttle. Turned out the body shop hadn't gotten the frame quite right. You could look at the front door to fender gap and see it was wider at the bottom than top. Frame machine fixed it. I mention this to point out that a pretty major driveline out of alignment caused a symptom that was reasonably minor.

[Jeff_J.]

This is a really good tool. If the graphic is intended to show then number input to the program then the pinion angle and trans angle is opposite to how mine is pointing currently. My pinion points down 1.05 degrees towards the front of the car, my transmission is pointing up as it proceeds to the back of the car .55 degrees. I raised the trans to get the trans and pinion angle to parallel, by doing that I created a large drive shaft angle in this direction " \ " this is exaggerated of course. I think I'm going to return everything to where I started - if I supply you my starting numbers can you put them into the program so I can make the adjustments that make the best sense?
Thx
J.

[ggunter]

Just remember, starting at the engine, any angle pointing down towards the rear is a + positive angle. The rear looking up towards the trans is also a positive angle. Reverse the two for negative angles. Measure your frame angle to see how far off of level you are and add or subtract that off of 90 degrees to get true angle relationship to the engine and rear.

[sdeal0527]

I found this quick tool out on the web. https://spicerparts.com/calculators/driveline-operating-angle-calculator

[ggunter]

That one works too

[Jeff_J.]

I was using the spicer calc tool as well just now - I think I have this figured out.
transmission measures down slope at 1.35 deg
driveshaft measures down slope at .92 deg
pinion IRS fixed at up slope at 1.05 deg (from what I read - normally the pinion would be down slope as well but mine is counter to that the face of the pinion looks downward slightly as it looks to the front of the car, pretty sure this means "UP" on the calculator.

using the spicer calc tool and these numbers
Operating angle 1 is .43
Operating angle 2 is 1.97

If I raise the transmission to say 1.39 the Op angle 1 gets worse to .63 but OP angle 2 gets better at 1.81 - I guess this is the trade off.
Does this work in your Eaton calc the same way?
Jeff

[ggunter]

If these are your numbers, then life is good. 195433

[ggunter]

How did you get from 16.5 degrees driveshaft angle to .92? Where you measuring wrong?

[ggunter]

Even if your pinion angle is on the minus or down angle the numbers still work. 195434

[Jeff_J.]

It was obvious from the start it wasn't right. I measured wrong. I stepped away and thought about it a little then it made sense, now I look back and realise how crazy I was on this... Oh well I won't tell this story!
Thanks for confirming the numbers gives me peace of mind...
Jeff

[ggunter]

Glad it worked out:cool: