Pinion Angle

[Erik W. Treves]

thanks for the pics..that looks ok to me of first look.

[BB767]

yeah that looks like full droop to me as well Jeff. Although in one of the pics you can see the jack stands...

the rear shock looks like it's angled pretty good.. don't remember mine be like that.... can you take some pick of the lower control arms and mounting of the brackets... I would expect needing over 1" of tranny spacer.. for sure you need some... the few I have done, I think I am in the 3/4" range

From the top of the axle tube to the top of the 4 inch main chassis tube is exactly 4 inches.

The rear axle is supported by jack stands, the front main tubes are supported by jack stands near the tow hoops. In this configuration there should be slightly more weight on the rear axle than when on the (front) wheels. But the car is not finished so this should closely approximate the finished ride height (in theory).

[Joee]

I went out and rechecked my car as it is up on stands now. My frame is level front pulleys are off so my crank is 3 deg up my trans out put 3 deg down, my rear is 5 deg down. Net 2 deg.
My rear ride height in 4". Here is a pic of my magnetic gauge and a shot of my shock in relation to mounting bracket.

[Joee]

Attachment 78443Attachment 78444Attachment 78445

I know someone said the shock adjustments looked high but as they are, with 4 3/4 ride height, the side pipes only clear the neighborhood speed bumps by one and a half inches. Any lower and I will not be able to leave my driveway!

My pipe clearance (UTC) is about 2 3/4 - 3" there is a fine art to speed bumps. Unless yours are huge...

[BB767]

I went out and rechecked my car as it is up on stands now. My frame is level front pulleys are off so my crank is 3 deg up my trans out put 3 deg down, my rear is 5 deg down. Net 2 deg.
My rear ride height in 4". Here is a pic of my magnetic gauge and a shot of my shock in relation to mounting bracket.

EXACTLY! Everything looks and sounds very similar to mine EXCEPT the the rear! Yours is down 5 deg (I assume you are measuring front to rear) and mine is UP 1.5 degrees with no way to adjust it further!

[Joee]

How is your banana bracket attached? If aligned properyly with the sleeve turned all the way in the rear should be pointing down almost 10 deg, then by lengthening it the rear comes up.

[BB767]

How is your banana bracket attached? If aligned properyly with the sleeve turned all the way in the rear should be pointing down almost 10 deg, then by lengthening it the rear comes up.

Now you are confusing me. When you say "the rear comes up" Do you mean the pinion comes up or the rear cover plate comes up?

When I extend the upper control arm, the pinion comes up. Sorry, I have not gotten the technical terms completely straight yet, I am trying.

[Joee]

Now you are confusing me. When you say "the rear comes up" Do you mean the pinion comes up or the rear cover plate comes up?

The plate that the drive shaft bolts too goes from pointing down, toward ground, with adjuster turned all the way in and as adjuster is turned, to lengthen it, the plate starts to rise from facing down to level to facing up towards car's under carriage.

When I extend the upper control arm, the pinion comes up. Yes thats right

I am not good with tech terms either, thats why I try not to use them

[BB767]

In order to help me determine if my axle is set up correctly could someone please do the following measurement(s) for me? To be relevant it must be a Moser 8.8 with the welded brackets.

I made the axle perfectly level as measured on the back housing cover mounting surface. Then using a level I measure from the FRONT of the axle tube to the furthest rear point on the top of the banana bracket. That distance measures 10 and 7/16 inches on my axle.

I then measured the angle of the shock mounting brackets, the welded on part.

From above they have a "U" shape. When measuring the vertical angle on the tips of the "U" my phone leveling app shows between 0 and 4 degrees (tops angling towards the front of the car) depending on which of the 4 points I measure. I know this is a rather imprecise measurement but it still might help if yours come out to be something more than 5 or less than 0.

Anyway, thanks for helping me narrow down my problem.

[BB767]

I am not good with tech terms either, thats why I try not to use them

LOL, good, we are on even terms.

You have confirmed my suspicion. I have the Moser rear end which is welded. That plate on mine cannot be adjusted up (in our terms) more than (negative) -1.5 degrees! The banana bar hits the frame and the shocks hit the mounts.

[GoDadGo]

BB767,

Just sent you a private message.

Steve

[NAZ]

Might be interesting to look at your axle position relative to a chassis datum and compare to others'. So a measurement from the front side of the axle tube to some point on the chassis for a sanity check. If your axle is further to the rear than other builds that may shed some light on the banana bracket interference issue. And in the meantime it wouldn't hurt to make sure your axle is square in the chassis as if it is skewed that may also cause an interference issue.

[BB767]

Might be interesting to look at your axle position relative to a chassis datum and compare to others'. So a measurement from the front side of the axle tube to some point on the chassis for a sanity check. If your axle is further to the rear than other builds that may shed some light on the banana bracket interference issue. And in the meantime it wouldn't hurt to make sure your axle is square in the chassis as if it is skewed that may also cause an interference issue.

NAZ - Right side is 8 and 9/16, left side is 8 and 11/16. Measurements are from the REAR of the axle tube to the end of the 4 inch tube. (Easier to get an accurate measurement from the back of the axle.)

[NAZ]

Small error but nothing that would cause an interference issue. Now let's see if someone with a car like yours can provide a dimension from the same points.

Adjustable LCAs will allow you to adjust pinion angle without causing the banana bracket to hit but it will shorten your wheelbase a bit. Not sure if that would create another problem or not. Maybe one of the guys who has a car like yours has an opinion.

[BB767]

Small error but nothing that would cause an interference issue. Now let's see if someone with a car like yours can provide a dimension from the same points.

Adjustable LCAs will allow you to adjust pinion angle without causing the banana bracket to hit but it will shorten your wheelbase a bit. Not sure if that would create another problem or not. Maybe one of the guys who has a car like yours has an opinion.

That appears to be what this is boiling down to. Adjustable lower control arms and doing something with the shock clearance. Steve (GoDadGo) had the same problem and used shorter lowers with good results. Only question now is, am I on my own on this or will FFR and Moser help me out?

[Joee]

That appears to be what this is boiling down to. Adjustable lower control arms and doing something with the shock clearance. Steve (GoDadGo) had the same problem and used shorter lowers with good results. Only question now is, am I on my own on this or will FFR and Moser help me out?

To me you are spending too much time and re-engineering of the rear end. Are you absolutely married to your Moser? Mine is a '99 Ford 8.8 with our cars weight not a problem with your power plant you are just going to smoke tires anyway.

T.he kit is set up to use stock Mustang parts of given years. I bet your whole problem is because you aren't using the Ford pumpkin you arent using the small black square link that goes from pumpkin snout to banana bracket. My bad I am not familiar with the Moser option.

[edwardb]

Don't want to pile on, but with all the talk about pinion angle, just needs to be said that 22+ degree U-joint working angle (if it's accurate) is completely unacceptable. Spicer and others typically talk about anything beyond 3 degrees will affect bearing life and likely will be felt. Some offset is desirable, but you're way beyond that. Given the position of the diff (pointing down vs. up) and the shock interference issue, seems that something is wrong with the rear suspension. Fixing it with spacers under the transmission beyond the usual 3/4 to 1 inch maybe isn't getting to the root cause. But then an argument could be made for just the opposite too. Hang in there. This will get resolved.

One thing I have to ask though. You say you have ride height at 4-3/4 inches. Which is OK to start. But you're doing it with jack stands under the suspension and no wheels/tires. I assume you adjusted the coilovers to achieve the 4-3/4 inches. Are you sure your wheel hubs (and resulting suspension overall) are the same height they would be with the wheels/tires mounted? I don't think it would make a huge difference and won't solve anything. But it would be possible to have wrong settings on the coilovers if the relative position of the suspension isn't the same as it would be if the wheels/tires were mounted and sitting on the ground.

Since the Moser option is offered by FF (and I assume where you purchased it) I would start by calling FF. Maybe you have already.

[karlos]

I can see Steve needing to do something unique as his setup is anything but standard. But your setup is fairly common and should follow the same trends as other similar builds. I haven't yet seen that anything wrong has been identified with the rear end, other than not having enough adjustment capability to overcome an unusual situation with the engine/trans position.

Still think the fact that you're 1.5 degrees tailshaft down with a nearly 2" thick spacer is an indication of some as-yet unidentified problem up front. Very much out of family with respect to what others have reported. Even if you can make everything come in by moving the rear, it seems to me that it's ultimately a band-aid for something else going on up front.

Not trying to be critical. Hope it doesn't sound that way. Just not sure all the issues contributing to this problem have been identified.

[GoDadGo]

That appears to be what this is boiling down to. Adjustable lower control arms and doing something with the shock clearance. Steve (GoDadGo) had the same problem and used shorter lowers with good results. Only question now is, am I on my own on this or will FFR and Moser help me out?

I purchased my Rear End directly from Moser & we all know that my set up is far from typical.
In your case, I'd contact Factory Five since you purchased the unit through them.
For the record, I think they welded the brackets a few degrees off.

[BB767]

Edward - The ride height and measurement were originally set weeks ago with the car on the ground, measurement from the frame to the ground on a level surface.

I spent all afternoon fabricating and installing permanent shims. The final tail shaft (and crank pulley) angle is 2.4 degrees with shims equaling just over 1 inch.

I was able to tweak the rear end slightly and get it to near 0 degrees (plus or minus .5 due to difficulty getting an accurate reading). That leaves the drive line at 10 degrees. Again, all of these measurements are relative to the ground so we are just looking at relative positions. New Angles 123117.png

[karlos]

Guys...

Let's assume the brackets on the rear end are incorrectly located. And that after you get a replacement with the brackets in the correct position you are able to then set the differential with the pinion flange pointed up at at 3.5 degrees. Note that 3.5 degrees is required to get the pinion angle to be 1 degree with the transmission pointed down at 4.5 degrees. The operating angles in this scenario are 7.5 (front) and 6.5 (rear)*. Not even remotely acceptable. And as the pinion climbs under power the rear angle gets even worse (8.5).

One way or the other I believe the situation with the trans angle needs to be addressed.


* Assumes a 3 degree driveshaft angle. May be worse than that as connecting a 4.5 degree low tailshaft with a 3.5 degree high pinion will require a pretty steep angle. If worse than 3 degrees (likely, I think) the operating angles also become worse.

[BB767]

I can see Steve needing to do something unique as his setup is anything but standard. But your setup is fairly common and should follow the same trends as other similar builds. I haven't yet seen that anything wrong has been identified with the rear end, other than not having enough adjustment capability to overcome an unusual situation with the engine/trans position.

Still think the fact that you're 1.5 degrees tailshaft down with a nearly 2" thick spacer is an indication of some as-yet unidentified problem up front. Very much out of family with respect to what others have reported. Even if you can make everything come in by moving the rear, it seems to me that it's ultimately a band-aid for something else going on up front.

Not trying to be critical. Hope it doesn't sound that way. Just not sure all the issues contributing to this problem have been identified.

karlos - What do you propose? Not trying to be smart, I really hope you can find a problem, but.......

The block is what it is, nothing to change.

The motor mounts are what they are. I have shaved them enough so the engine sits right in them like they were made for it. I put them on while the engine was hanging on the hoist, I could view theme easily 360 degrees, the fit was sweet! Bolts went in by finger until they needed the torque wrench.

The mounts sit on the frame very nicely as well. When the engine was initially set on the mounts, the pins did not go into the holes, I know what you are talking about when you ask about them. A small push with a pry bar and they fell right in snugly. They are sitting in there tight. Absolutely nothing to change unless they need to be modified from stock.

That's it for the front of the engine! What could I change?

The rear is now permanently jacked up as most of you suggested with a final angle of 2.4 degrees. From what some have said here I think that is now within the "normal" range. Although I feel I have constructed some pretty substantial shims, I would not raise it any higher. Also, I do not remember being asked what the current angle of the frame is, but I just checked that as well. It is down 1.4 degrees so the angle of the engine/transmission relative to the frame is only 1 degree down, which is even better!

But none of this completely fixes the problem, so, what to do now?

[BB767]

Guys...

Let's assume the brackets on the rear end are incorrectly located. And that after you get a replacement with the brackets in the correct position you are able to then set the differential with the pinion flange pointed up at at 3.5 degrees. Note that 3.5 degrees is required to get the pinion angle to be 1 degree with the transmission pointed down at 4.5 degrees. The operating angles in this scenario are 7.5 (front) and 6.5 (rear)*. Not even remotely acceptable. And as the pinion climbs under power the rear angle gets even worse (8.5).

One way or the other I believe the situation with the trans angle needs to be addressed.


* Assumes a 3 degree driveshaft angle. May be worse than that as connecting a 4.5 degree low tailshaft with a 3.5 degree high pinion will require a pretty steep angle. If worse than 3 degrees (likely, I think) the operating angles also become worse.

Using the calculator you originally posted 4.5, 3, 3.5 equals a perfect setup. Working angles of 1.5 and .5.
Even if the drive shaft raised a degree due to resetting the rear it still would have worked, 4.5, 2, 3.5 = 2.5 and 1.5.

Now, using 1.4, I cannot make it work. I think I should have left it alone and fixed the rear end.

[NAZ]

This thread is so long I sometimes loose my place of where you are right now. But it seems you still need to rotate the pinion angle up a bit. You're too close to give up on rotating the pinion angle now. Remember, with a short driveshaft the angle changes significantly as you change elevation of the front or rear u-joint. Rotating the axle up to change the pinion angle will also elevate the rear u-joint and change the operating angle. You may get this closer than at first it appears possible.

[karlos]

Difference in the numbers is due to the assumed slope of the driveshaft. I assumed upward; you selected downward. Based on your photos it appears your pinion flange sits (a lot) lower than the trans output shaft. Is that typical for a solid axle car? On my IRS car the pinion sits above the trans, which explains why I selected upward.

Very frustrating, I'm sure, and I sympathize. Trying to help but we're all hamstrung by only being able to work off of what we can see in the photos. I appreciate that you've looked for and not found any obvious issues with the motor mounts. Something is in fact different, however, as a 3/4" shim in my car (same chassis, same engine, same trans) has the output shaft angle above zero (above level).

Is there anybody local with knowledge of these cars that can come take a look?

[karlos]

Searched the forum to try to find photos of a typical installation. Came across this one from Paul's 7750 build. Can you confirm you're seeing something similar (pronounced downward slope on the driveshaft)? I believe Paul's photo shows the situation with the rear suspension unloaded (looks like the car is on a lift). But if I understand correctly, you're seeing a similar driveshaft angle with the suspension loaded, right?

If so, I now understand why you initially had so little shim under the transmission. Gotta get the tailshaft down to more closely match the height of the pinion flange and therefore reduce the severity of the driveshaft angle.

So if I'm understanding correctly, not sure I'm seeing a fix. If you lower the transmission you improve the driveshaft angle but make the pinion angle worse. If you raise the transmission you improve the pinion angle but make the driveshaft angle more severe. Same thing happens as you raise and lower the pinion flange (improve one to the detriment of the other).

All seems to be driven by the fact that the pinion flange is very low as compared to the output shaft. Is that unique to the Moser? How did you other guys running a Moser get it to work?

[NAZ]

Here's some food for thought. I ran the trig calculations for the longer driveshaft and for every inch of height change between the u-joints you will see ~5-deg change in angle. Of course the shorter one will be even more. So again, I'd suggest you rotate that rear end and move the pinion angle up to achieve Jeff's 2-degree offset and then measure the operating angle again. I think you're close enough that a nudge here and a nudge there and you will find the sweet spot.

From my experience building off-road vehicles with extreme operating angles; the u-joint angles are much more important than the driveshaft operating angle. Think about that 5-deg change per inch and consider how much angle change you get in these cars with the operating range of the rear end suspension travel.

[GoDadGo]

This Thread Is Now Bugging The C--p Out Of Me So Sorry Gang But This Chevy Guy Has The Solution!

17" Lower Arms will do the trick as long as you move the Upper Shock Mounts back a bit.

Look at this video (39-51 seconds in) to see how I, Your Humble Chevy Guy From The Swampy South, corrected the problem.

https://youtu.be/PCngiKoopkA

Good Luck, God's Speed & May God Bless You All For Putting Up With Me!

Steve

NOTE: I've got the Moser TSD-500 rear with welded banana bracket and I'm 99% sure that my brackets were not placed in the proper location.

[Jeff Kleiner]

I just went to the garage, pulled back the cover and shoved the camera under mine (please forgive the grime; the poor old car hasn't gotten much love the last couple of years). This is typical of a 3 link driveline regardless of transmission---remember, the engine sits in the same place in the chassis and the crankshaft & trans output are in line therefore the trans output centerline winds up in the same location whether T5, TKO or whatever. They all make the same straight line front to back.



A few years ago we had a builder who encountered issues with the rear axle location when he put the body on. Pinion angle was brought up early on and the builder assured us that it was measured and set properly. His presented some of the same areas of concern as yours; interference at the panhard brace to banana bracket as well as with the coilovers to axle brackets. It just so happened that he had a Moser rear and there were questions about the possibility of the mounts having been improperly located. Lots of pictures, conversations, suggestions and measurements later it was finally determined that he had not correctly measured and set the pinion angle after all and this was the cause of all of his problems.

http://www.ffcars.com/forums/17-fact...-tire-rub.html

No offense or disrespect intended but with all you have going on I just can't help wondering if what we're dealing with isn't a hardware problem but rather an error in either your method of measurement or interperatation of the data.

I'll keep following along and good luck.

Jeff


driveshaft.JPG

[BB767]

Thanks again all. Lots to think about. Now that I have a pretty good idea of what my options are I am going to hold up here a while until I hear back from FFR.

I am kind of pissed off at myself, I think I cross threaded one of the transmission mount bolts when I reinstalled it. By any chance do any of you have one you are not using? (A new transmission mount I mean.)

[GoDadGo]

I'll dig through my "Didn't Use Box" to see what stuff I have that fits the standard Ford set up; however, I may have discarded the driveline mounts.
I don't know if I have them, but if I do I'll be happy send the trans mount to you.

[BB767]

I'll dig through my "Didn't Use Box" to see what stuff I have that fits the standard Ford set up; however, I may have discarded the driveline mounts.
I don't know if I have them, but if I do I'll be happy send the trans mount to you.

Thanks Steve, if you do, let me know shipping and what they are worth to you and I'll send it along.

[karlos]

FWIW, I am also reluctant to attribute what’s going on to a hardware problem. I say that because there are a number of measurements that are far outside the realm of what’s typical for similar builds.

- 2” thick shim needed to get to some semblance of normal engine/trans angle
- with trans and differential as close to level as you can get them, driveshaft is at almost a 30 degree angle

Since you’ve checked your installation and not found anything unusual, that might point to the measurements or the interpretation of the measurements as the actual problem.

Again, not trying to be critical. Sincerely hoping you get it straightened out.

- Karl

[BB767]

FWIW, I am also reluctant to attribute what’s going on to a hardware problem. I say that because there are a number of measurements that are far outside the realm of what’s typical for similar builds.

- 2” thick shim needed to get to some semblance of normal engine/trans angle
- with trans and differential as close to level as you can get them, driveshaft is at almost a 30 degree angle

Since you’ve checked your installation and not found anything unusual, that might point to the measurements or the interpretation of the measurements as the actual problem.

Again, not trying to be critical. Sincerely hoping you get it straightened out.

- Karl

karlos - I hesitate to answer due to the risk of offending someone, ALL input I am receiving here is appreciated whether I agree with it or not.

Having given the disclaimer, I do not understand why some of you just cannot believe that there is a problem with the rear axle and the it MUST be with my measurements!

I am telling you, this does not pass the common sense eyeball test! When I look at the angles I do not have to measure them with anything to tell you there is a zig zag in the drive line! It is also plainly obvious just looking at it without any math that the angle from the output shaft is not that bad, it doesn't matter if the transmission angle is 4.5, 10 20, or upside down, the angle relative to the drive line is excellent! (4.5 to 3.5 originally) So, looking at the angle between the pinion gear shaft and the drive shaft, again it is obviously apparent that this angle is the problem, it needs to be straighter! It is also obvious that tilting the rear axle higher in the front by only 3 or 4 degrees will make that angle almost parallel WITHOUT making the other angle worse, in fact it would be improved to less than one degree. This observation is confirmed using the calculator you posted above. No amount of measuring, correct or incorrect, will change the fact that this angle is messed up! Yes, I am stuck on my preconceived notion. I asked for advice here HOPING that you would find an error that I had made. So far I have checked and tried every thing you have suggested. Since none of that has worked I have no choice but to conclude that my initial observations were correct. I guess what annoys me is not the fact that you persistently question my measurements, it's the fact that unless you come to the same conclusion I have, I still could be wrong! So, now that I have vented, please keep the suggestions coming if you have any new ones. in the mean time I expect a call from FFR sometime today to get their take on the issue. Thanks again for you input everyone.

[Joee]

Steve

NOTE: I've got the Moser TSD-500 rear with welded banana bracket and I'm 99% sure that my brackets were not placed in the proper location.

This prob bugs me too. If this is the case then I guess you do need to reconfigure hardware.

[jwebb]

Confused??
From manual:
"To set the pinion angle, make sure that your ride height is where you want it, and then adjust the upper arm until the desired angle is reached. We usually run about 2° up on the rear axle, but you can adjust this to fit your particular set-up."

Everything above is saying 2 degrees DOWN not UP??

[BB767]

Confused??
From manual:
"To set the pinion angle, make sure that your ride height is where you want it, and then adjust the upper arm until the desired angle is reached. We usually run about 2° up on the rear axle, but you can adjust this to fit your particular set-up."

Everything above is saying 2 degrees DOWN not UP??

Yea, I can never keep straight what each post is trying to say. From what I understand the correct way to state the pinion angle is looking towards the rear of the car, in this case, I need about 2 to 3 degrees DOWN. I tend to simply say that the pinion shaft itself, which comes out of the front of the pumpkin, needs to go up. I think that is what the manual is saying, but again, not positive. Regardless, it is clear mine needs to go up (in the front) to be within 1 degree of the input shaft and within 3 degrees working angle. Any change in the other angles (transmission or drive shaft) just makes the numbers worse and impossible to reconcile.

[Joee]

Confused??
From manual:
"To set the pinion angle, make sure that your ride height is where you want it, and then adjust the upper arm until the desired angle is reached. We usually run about 2° up on the rear axle, but you can adjust this to fit your particular set-up."

Everything above is saying 2 degrees DOWN not UP??

This graphic, thanks Jeff, explains it all visually. The idea is that when the car is under hard acceleration the rear will twist so it lifts about a degree or so and then parallel with the trans out put shaft. ** Also the manuals are a guide which is fine tuned by builders like Jeff **

[Big Blocker]

QUOTE: We usually run about 2° up on the rear axle, but you can adjust this to fit your particular set-up."

Everything above is saying 2 degrees DOWN not UP??

What needs to happen here is an unsolicited user pole about the picture Jeff submitted . . . How many think the pinion is "down" in his picture and how many think it's "UP"??

Once you all agree on which is which, this issue will be resolved for good (I hope).

I'l post my answer after some responses by the reading, and arguing population.

Doc

[BB767]

http://spicerparts.com/videos/measur...erating-angles

This video from Spicer answers the question. I admit I have been stating the rear end angle incorrectly most of the time but have tried to be clear about what I was referring to. Unfortunately it in no way changes my predicament, the angles are STILL wrong. From now on I will use the correct terminology. Amazing what you learn here!

Currently setting at 2 degrees DOWN, 4.5 degrees DOWN and 2 degrees UP.

http://spicerparts.com/calculators/d...gle-calculator

Using this calculator, if I change the rear end angle to 1.5 degrees DOWN, I would have a decent set up. This is assuming that the driveshaft rises .5 degrees to 4 down (due to raising the end near the pinion). So I would end up with 2 down, 4 down, and 1.5 down leaving working angles of 2 on the front and 2.5 on the rear, which would decrease to 2 down under acceleration. All within the 1 degree parallel limit and 3 degree working angle limits!