Pinion angle question (sorry)

[exukpaul]

Sorry because I know this has been gone over many a time but I just got engine and transmission in. So, I've got a 351w mated to a tko500 with a ford 9" rear end. So I measured angle at the crank pulley and it was on 0 degrees. The rear end is also at 0 degrees. The thing is the transmission yoke is about 4 and a half inches higher than the rear end yoke. Is this too much ? Thanks

[dbo_texas]

Sorry because I know this has been gone over many a time but I just got engine and transmission in. So, I've got a 351w mated to a tko500 with a ford 9" rear end. So I measured angle at the crank pulley and it was on 0 degrees. The rear end is also at 0 degrees. The thing is the transmission yoke is about 4 and a half inches higher than the rear end yoke. Is this too much ? Thanks

You are likely going to get a lot of opinions on this based on other threads. Some will say don't worry about it move on....and maybe they are right. Others will say there are general guidelines you should try to achieve to minimize vibration and wear and tear on the yokes. Some will say it depends on the type of driving you intend to do. There are some pretty good threads about the guidelines so I won't repeat them, but here are some good threads below to reference. The 3 basic guidelines are:
- angles on each end of the driveshaft should be equal to or within 1 degree of each other
- maximum operating angle at either end is 3 degrees
- at least 1/2 of a degree continuous operating angle (this is to prevent flat-spotting the u-joint needle bearings)

Good reference threads:
https://thefactoryfiveforum.com/showthread.php?22594-Driveline-Setup-(aka-Pinion-Angle)
https://thefactoryfiveforum.com/showthread.php?35320-Pinion-Angle-Yes-again

[exukpaul]

Thanks for the quick reply. I had a quick flick through of those links but still a little confused. Is the operating angle the pitch of the driveshaft ? Thanks

[BornWestUSA]

OPERATING ANGLE
For example, the output shaft to the driveshaft, or the driveshaft to the pinion shaft. Most driveline companies recommend operating angles of 3° or less for maximum u-joint life. There should be a minimum of ½° to allow the needles to rotate.

That said most Cobra's are not driven enough to ever wear out the U-Joints, even if you are at 7 degrees.

This is with the diff on jack stands supporting the cars weight?

Are the side pipes level to the 4" frame tubes? many need to shim up the TKO at the rear mount 3/4"

[exukpaul]

Well, to level engine and trans I've got almost a 2" shim under trans mount. Haven't got as far as the sidepipes yet.

[rich grsc]

Lower the transmission, raise the front of the differential. The output shaft of the transmission and the pinion shaft of the differential should be parallel within 2*

[exukpaul]

Lower the transmission, raise the front of the differential. The output shaft of the transmission and the pinion shaft of the differential should be parallel within 2*
Well, I can lower the trans easy enough by taking shims out but not sure how to raise rear end. There is upper and lower control arms but doesn't look likevyou can adjust them. Soory, first time into all this stuff !

[dbo_texas]

Thanks for the quick reply. I had a quick flick through of those links but still a little confused. Is the operating angle the pitch of the driveshaft ? Thanks

Here's a quick diagram showing the operating angles on each end of the driveshaft. This is my diagram and also my first time building so take it with a grain of salt - I'm pretty sure I got the angle labeling correct but if anyone disagrees I'm sure they will chime in. I have IRS so the differential angle is set - I can only modify the transmission angle using spacers (or removing them).

https://thefactoryfiveforum.com/attachment.php?attachmentid=195927&d=1708648937

[exukpaul]

Thanks for those pics. Mine is very similar to your diagram but both are at 0 degrees. Its just the 4 and a half inch difference in height that I'm worried about

[rich grsc]

Sorry, I see you have a 9" differential. Is it a 4 link, or a 3 link?

[exukpaul]

Its a 4 link

[exukpaul]

Here it is

[BornWestUSA]

Its a 4 link

You should be able to get adjustable lower control arms if you need to adjust the diff. https://www.amazon.com/Lower-control-arms-chrome-moly-offset/dp/B09RTHRN9F

Put your angle guage on the engine crank pulley, zero it. Put it on the diff flange, that reading is the angle you want within 2 degrees.

The frame is only a reference for the side pipes. The trans or diff doesn't care where the frame is, just the relationship between the two.

[exukpaul]

Thanks. So my question is....what would you say is the maximum height difference you can work with between the trans yoke and the rear end yoke. Being that its such a short driveshaft ?

[BornWestUSA]

first. Is the car at "ride height" as in are all 4 wheels on wheel stands? like: https://www.youtube.com/watch?app=desktop&v=0R2W3CocHhU

Or is the rear diff on jack stands and the frame in front of the engine on jack stands? either way will work. but the diff needs to be supporting weight first.

The picture you posted won't work.

Then start with about 3/4" of shims MAX between the trans mount and the trans and do your angle measurements as I describe above.

Let the class know what you get. post a diagram.

[exukpaul]

Ha. No, all 4 wheels are on the ground. That was just an old pic of the underside. I'm going to go buy an angle meter tomorrow as I've been using iphone. I'll post back findings tomorrow. Thanks

[exukpaul]

Ok guys. Here is what i have. Measured angle on crank and transmission is pointing down by 0.6 degrees. I have an 1.25" shim under trans mount. Sorry BornWestUSA, i know you said 3/4" but i will need to cut a bit of trans crossmember mount off to get it lower as it is just touching part of the trans now.
So the rear end Measured 0.6 degrees but facing up slightly. I also measured the difference in height between the transmission yoke and the rear end yoke and center to center the trans yoke is two and a half inches higher.
Is this all doable now do you think ?
Thanks

[rich grsc]

You're just fine

[exukpaul]

You're just fine

Really ! Thats made my day. I've been fretting over this all week ��

[CraigS]

Have you set your front and rear ride height? What is you rear height? With the cars wheels on the ground, bottom of 4 inch tube at it's end to the floor. A common height is 4.0 to 4.5 inches. If your car is too high you will have that big difference trans to diff. Give us ride heights and also a side view pic of the trans mount so we can see the mount and where it is contacting the trans. I can't keep all the possible trans fitting things in mind but there have been some mods done to some trans cases to get clearance. BTW, depending on details I have no problem w/ cutting the trans mount. There was a thread in the last 6-8 months where someone did exactly that. Also in your description you say "transmission is pointing down by 0.6 degrees". Pointing down at the rear or the front? Also "So the rear end Measured 0.6 degrees but facing up slightly." Up at the front I guess? I 'think' you have the eng/trans parallel to the diff right? But the trans is too high. A little backround re; angles. On a solid axle, due to the diff pinion wanting to rise under max acceleration, it is often recommended that the diff points down at the front 2 deg relative to the trans. This is because all the control arm bushings flex a little so, if the diff starts pointed down at the front, it will come up to close to parallel under max accel. Think of the trans and diff angles looking like a very flat letter 'V', a 2 deg 'V'.

[exukpaul]

Have you set your front and rear ride height? What is you rear height? With the cars wheels on the ground, bottom of 4 inch tube at it's end to the floor. A common height is 4.0 to 4.5 inches. If your car is too high you will have that big difference trans to diff. Give us ride heights and also a side view pic of the trans mount so we can see the mount and where it is contacting the trans. I can't keep all the possible trans fitting things in mind but there have been some mods done to some trans cases to get clearance. BTW, depending on details I have no problem w/ cutting the trans mount. There was a thread in the last 6-8 months where someone did exactly that. Also in your description you say "transmission is pointing down by 0.6 degrees". Pointing down at the rear or the front? Also "So the rear end Measured 0.6 degrees but facing up slightly." Up at the front I guess? I 'think' you have the eng/trans parallel to the diff right? But the trans is too high. A little backround re; angles. On a solid axle, due to the diff pinion wanting to rise under max acceleration, it is often recommended that the diff points down at the front 2 deg relative to the trans. This is because all the control arm bushings flex a little so, if the diff starts pointed down at the front, it will come up to close to parallel under max accel. Think of the trans and diff angles looking like a very flat letter 'V', a 2 deg 'V'.

Thanks a lot for that. So I just measured bottom of frame to the floor and its about 5 and half inches. So the end of the trans where the yoke is is sloping downwards by 0.6 degrees and the front of the diff with the yoke is sloping upwards by about 0.6. Heres a pic of side of trans mount.

[GoDadGo]

I wish Factory-5 would move the engine forward to give these cars a little more engine bay room while improving the driveshaft angles.

Naked Roadster Video Includes Driveshaft & Other Stuff:
https://youtu.be/_wnHDNgnNqs

Pinion Angle Phasing Video:
https://youtu.be/Idk3BVDVHq4

Three Year Update:
https://youtu.be/iwslgKJUaKc

Moving the engine forward really improves all sorts of things while making maintenance a lot easier but what do I know?

Good Luck, Happy Wrenching & Keep Up The Great Work!

[BornWestUSA]

When you put the angle gauge on the crank pulley you "zero" it. "level" or the relationship to the ground or frame does not matter.

Then you put that freshly zeroed angle guage on the pinion flange and read what "relative" angle you have. If it is + or - less than 2 degrees it will work.

You are only concerned about the angle of the two items to each other, they need the centerlines to be near parallel to each other, or within 2 degrees MAX.

Less than 1 degree is better. 1/2 of one degree is perfect.

Now you can visualize what needs to be moved up or down to get the relative angle within 2 degrees.

Next you can look at "working angles" of the U-joints, 3 degrees or less is good, more will just wear the U-joints faster.

[exukpaul]

Ok. Just had a look at the gauge as i didn't know about the zero thing but just sussed it out. I'll check the reading like you say in the morning. Thanks

[exukpaul]

When you put the angle gauge on the crank pulley you "zero" it. "level" or the relationship to the ground or frame does not matter.

Then you put that freshly zeroed angle guage on the pinion flange and read what "relative" angle you have. If it is + or - less than 2 degrees it will work.

You are only concerned about the angle of the two items to each other, they need the centerlines to be near parallel to each other, or within 2 degrees MAX.

Less than 1 degree is better. 1/2 of one degree is perfect.

Now you can visualize what needs to be moved up or down to get the relative angle within 2 degrees.

Next you can look at "working angles" of the U-joints, 3 degrees or less is good, more will just wear the U-joints faster.

Ok, so i put gauge on crank this morning and set it to zero. I then went to the rear end and it read 0.3 degrees. Are we good with that then ?

[BornWestUSA]

Ok, so i put gauge on crank this morning and set it to zero. I then went to the rear end and it read 0.3 degrees. Are we good with that then ?

Yep. Send it!

[exukpaul]

Yep. Send it!

What about the angle of the driveshaft ? I don't have the driveshaft made as yet but like i said, there is about a 2 and a half inch difference in height. Better than the 4 and a half I started with lol

[CraigS]

Your car is about an inch higher than it needs to be at the rear. Typical heights are more like 4" front and 4 to 4.5 rear. If you drop the rear so the frame tube to floor is about 4.5" the trans will drop maybe 3/4" and diff will remain the same so your driveshaft angle will be much less. Your trans mount to trans clearance problem is the same as the other poster had. I will try to find that thread. Edit; I can't find it. As I remember it he cut off about 1/2" from the front of the frame piece the mount bolts to. But try lowering the car and see what that does for your driveshaft angle. One other thought. Let's say your rear axle has a possible total up down movement of 5 inches. AT normal ride height it would be nice for the driveshaft to be close to level. This way if you go over a large bump and the car gets close to being airborne, the axle hangs down and your driveshaft has to hang about 2.5" below level. At the other extreme, you have a full tank, and a passenger and you hit an undulation where the rear of the car really squats down. Now it would be nice if the axle moves up so it is 2.5" above the trans. In other words your driveshaft normally sits in the middle of it's possible swing.

[exukpaul]

Ok. Thanks CraigS. I'll get on that in the morning and see what we get. So basically I just let suspension hang and tighten the adjusting ring on top of koni's right ?

[CraigS]

I went back to your old pic and see that you have the Konis mounted body down So to lower the car you want to turn the adjuster collar so it moves down the body. Also while you are there count the number of threads visible below the collar and make sure that number is the same on left and right shocks.

[exukpaul]

Ok, so do i tighten them or loosen ?

[rich grsc]

Loosen, you want to take compression off the spring to lower the car.

[exukpaul]

Thanks. Ok. I've done the rears. Spring was very loose in there till i lowered it back down but I've now got 4 and a half inch ride height on the back. Need to look at some pics of factory fives as the tire to fender arch has changed dramatically.
So, onto the fronts !

[exukpaul]

Ok. So, the fronts. The collar was very close to the end of its adjustment but I've took it all the way down to the end. I now have 4 3/4" ride height at front. Considerably more of a gap between tire and fender than the back.

[CraigS]

Yes your front is way high. I 'think' your only option is shorter springs but maybe a pic showing the top coilover mount would be good to be sure. If you need to go shorter you have a 2.5" ID spring. Now you need to know length and rate. Jack up the car and let the wheel hang and measure overall length of the spring. Order one 1-2" shorter. If yours has the spring rate labelled on it, match it, or go somewhere in the 450-550# range which were stock #s from FFR over the years. Summit has lots of springs.

[exukpaul]

Ok, thanks CraigS 👍

[exukpaul]

Ok. Just measured. Springs are 10". So you reckon get an 8" ?

[Jeff Kleiner]

Ok. Just measured. Springs are 10". So you reckon get an 8" ?

Looks like you have well over 2 inches of thread available on the adjustment collar. If that is so 8" should work.

Jeff

[exukpaul]

Just ordered. Thanks guys

[CraigS]

Yes, 8" has been the standard front spring for quite a while.

[exukpaul]

Just arrived. I'll stick 'em on tomorrow and report back 👍

[exukpaul]

Ok. New front springs are on. I've now got 4" ride height on front and 4 1/2" on rear.
So now i have angle on crank pulley is 0.4 degrees with trans sloping down towards rear and the diff is 1 degree sloping up towards front. I then zero'd angle on crank pulley and then checked the rear end and it was 0.7 degrees.
The center of trans yoke is 1 1/2" higher than center of diff yoke.
Does this look ok now ? Thanks

[Jeff Kleiner]

Ideally the nose of the pinion should point approximately 2 degrees down relative to the transmission output when static:

https://thefactoryfiveforum.com/attachment.php?attachmentid=201373&d=1514586767

Under acceleration torque will rotate the rear axle and cause the front of the pinion to raise thus it will be parallel to the trans output when under load. If the front of the pinion is pointing up (again, relative to the trans output) while static as the rear axle rotates upward when loaded the pinion will become farther from parallel which is the opposite of what we want. It sounds like this is what you have currently.

Jeff

[exukpaul]

I understand what your saying Jeff, thanks. Makes a lot of sense. Problem I have, the oil pan at the moment is about 1/2" higher than bottom of frame. Doesn't seem like i need to be dropping it much more. And its already 1 1/2" higher than diff. I could get some adjustable control arms to tilt the rear end lower but then I'm going to be more than 1 1/2" in height difference and the angles will be further out (all this coming from a complete novice). Any thoughts ? Thanks

[rich grsc]

Leave it alone

[CraigS]

I agree w/ Rich. I'd leave it as is and drive it. Decades ago at a BMW dealer we had a car come in for a slight vibration at >1/2 throttle between 20 and 30mph. Turned out it had been in a wreck and whoever fixed it did a nice job cosmetically but the frame was left bent. Once discovered, we could see the gap front edge of door to fender edge was a triangle but only by <1/8" variance top to bottom. It went on the frame machine to be pulled straight and the vibration was gone. My point here is that the vibration only occurred under specific conditions, and even then it was not that bad. Noticeable but not scary at all. By all the numbers your setup may not be perfect, but I am betting you won't feel a thing.

[exukpaul]

Ok. Sounds good. I just can't understand the problem I'm getting. I have the factory five urethane mounts, 351w with champ shallow pan, tko, nothing out of the ordinary but seem to have more obstacles than a lot of you other guys. I know you said just go with it but do you think i should get some adjustable control arms at this stage. I could definitely close the 1 1/2" height difference in pinion and output yoke but i think the angle will change on the pinion. If you think I'll be good 'as is', I value all your opinions 👍

[rich grsc]

The only problem seems you just won't move on, it's just fine. No matter where you set it, it isn't going to stay exactly there when you start driving. The axle moves up & down so everything is in constant change.

[exukpaul]

Ok Rich. I'll go with it. Its just that i feel good getting your previous post then i get a conflicting post. I'll move on 👍

[Railroad]

After 100K miles your U joints will wear out and you will know you did not do it right, LOL.

[exukpaul]

Lol ��

[Jeff Kleiner]

I understand what your saying Jeff, thanks. Makes a lot of sense. Problem I have, the oil pan at the moment is about 1/2" higher than bottom of frame. Doesn't seem like i need to be dropping it much more. And its already 1 1/2" higher than diff. I could get some adjustable control arms to tilt the rear end lower but then I'm going to be more than 1 1/2" in height difference and the angles will be further out (all this coming from a complete novice). Any thoughts ? Thanks

I told you what was ideal. Fact of life is that it sometimes isn't easily possible to get there (particularly with a non-adjustable 4 link). As Rich and Craig said run it and if you have a vibration address it.

I get in a lot of 3 link cars and probably 50% of them have the pinion angle off and pointing nose up (some so much so that the banana bracket is hitting the panhard bar brace) but the the owners aren't complaining about vibration. The giveaway that tips me off is when I see the back wheels sitting rearward in the wheelwell! After I adjust the upper link the wheels are centered, the pinion angle is correct and the bracket is no longer contacting the frame.

Jeff

[exukpaul]

Got it ! Thanks Jeff