Author Topic: Drive line angle  (Read 6318 times)

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Bolted to Floor

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Drive line angle
« on: September 08, 2018, 07:07:49 PM »
I need to check the drive line angle and don't want to spend the time to learn how to interpret the angles. Can someone tell me how good or bad am I looking??
The tail shaft is 5 degrees down
The pinion is 1 degree down.

Any help is greatly appreciated. This thing is going back together tonight.
John D -- 67 Mustang 390 5 speed

jayb

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Re: Drive line angle
« Reply #1 on: September 08, 2018, 07:26:54 PM »
Usually you'd like the pinion to be 2-3 degrees down from the transmission output shaft.  If I understand you correctly, a line coming directly out of the back of the transmission towards the rear of the car  is 5 degrees from level and would eventually hit the ground, and a line coming directly out of the pinion towards the front of the car is 1 degree from level and would also eventually hit the ground.  So, right now based on that you're angle between the two is six degrees.  So, if you were to rotate the pinion so that it was pointing up at 2-3 degrees, you would have the idea angle.  However, as it is you're not too bad, and what you could do at some point is buy some of those pie shaped wedges that go between the leaf springs and the axle housing, to raise that pinion angle so that it was pointing 2-3 degrees up.

In any case though, the way it is now won't cause any short term problems. 
Jay Brown
- 1969 Mach 1, Drag Week 2005 Winner NA/BB, 511" FE (10.60s @ 129); Drag Week 2007 Runner-Up PA/BB, 490" Supercharged FE (9.35 @ 151)
- 1964 Ford Galaxie, Drag Week 2009 Winner Modified NA (9.50s @ 143), 585" SOHC
- 1969 Shelby Clone, Drag Week 2015 Winner Modified NA (Average 8.98 @ 149), 585" SOHC

   

Bolted to Floor

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Re: Drive line angle
« Reply #2 on: September 08, 2018, 07:55:34 PM »
You accurately comprehended my jibberish!!

Thanks Jay

Edit for spelling
« Last Edit: September 09, 2018, 12:46:19 AM by Bolted to Floor »
John D -- 67 Mustang 390 5 speed

Stangman

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Re: Drive line angle
« Reply #3 on: September 08, 2018, 08:47:37 PM »
Ya know on a stock vehicle meaning not a tube chassis car why would the angles be off. The tranny
sits on the tranny crossmember and mount of course and the rear gets lined up by the holes in the perches. How could it be off enough for there to be a problem. I’m curious

cammerfe

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Re: Drive line angle
« Reply #4 on: September 08, 2018, 10:28:56 PM »
A problem with any of the mount points can cause difficulties. Did you ever see a leaf-spring car 'dog-track'?

KS

Bolted to Floor

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Re: Drive line angle
« Reply #5 on: September 09, 2018, 12:58:26 AM »
Ya know on a stock vehicle meaning not a tube chassis car why would the angles be off. The tranny
sits on the tranny crossmember and mount of course and the rear gets lined up by the holes in the perches. How could it be off enough for there to be a problem. I’m curious

Hi Curious, I'm Exhausted... ;)...couldn't help it, just my poor since of humor. But I am really tired after today.

For my car, my TKO kit came either a cross member that lets the rear of the transmission point down more than it should. For the rear end, I added the extra leaf that was in the pack when I bought the car years ago to get a little more lift at the tires. I guess it could have caused a slight role of the pinion.

John D -- 67 Mustang 390 5 speed

Heo

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Re: Drive line angle
« Reply #6 on: September 09, 2018, 02:11:01 AM »
My opinion on this! in a perfeckt world, when the carb is horisontal
the trans is 4 deg down and the pinion....well on rigid chassie with
say a fourlink the pinion should be 4 deg up teoretical. But under
load the pinion tend to climb, more so on leafsprings or a coil suspesion
with soft rubber rubberbushings. What you get if the angles is to much
off is vibrations in the driveshaft. If you have vibrations do like Jay says
and try to wedge up the pinion.



The defenition of a Gentleman, is a man that can play the accordion.But dont do it

My427stang

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Re: Drive line angle
« Reply #7 on: September 09, 2018, 08:28:54 AM »
I like to see three numbers.

1 - Output shaft angle
2 - Driveshaft angle (installed, weight on wheels)
3 - Pinion angle

Under hard acceleration output and pinion angle should be within 1 degree, but it's often difficult to determine that, so some fudge is added based on what you think you have for pinion movement. The trade off for u-joint plane misalignment is vibration


Additionally, the driveshaft angle, when compared to the other angles, determines u-joint operating angle, and Spicer recommends max 3 degrees as a conservative number for any speed a car may likely go, there but never under .5 to ensure the u-joint rollers keep moving.  Sometimes that is not achievable, so you need to look at expected driveshaft speed.  The trade off for more operating angle is shorter u-joint life and vibration

With 5th gear and a decent gear ratio, your engine speed may be well under control, but the driveshaft speed will be higher, so the more care you put into this, the better.  An example of a 3.70 geared car with 26 inch tire, is a driveshaft speed of 4783 at 100 mph. (shorter tires and more rear gears will be worse)

Just because I have some Spicer tables that address this, I'll use Spicer again, they recommend a max u-joint operating angle of 3.7 degrees for a 4500 rpm driveshaft speed and 3.2 degrees for 5000 rpm..  So there is some fudge factor from the original 3 degree recommendation, but remember, that RPM ignores the 5 speed, and those of us with overdrive can easily hit that driveshaft speed. (4780 * .82) = 3919 engine RPM with a .82 OD, and 3059 engine RPM with a TKO-600 with a .64.  Even if you aren't driving around your local area at 100 mph, keep in mind, engine RPM in 4th as you enter the traps = driveshaft speed, so 4700 is realistic

So without knowing your driveshaft angle, we don't have all the pieces.  However, I can say, compared to the body, the stock output shaft angle on a Mustang is 3 degrees, and if you have a TKO crossmember that didn't require trimming of the floor, your numbers make sense.  I chose not to run it that way and added .750 (I think, it's been 12 years) under the transmission mount to get there.

What I have been doing since the Mustang install is start with a measurement from the center of the output shaft to the floor before I pull the old factory tranny.  Then I match it, and even with some slight differences in length depending on spacers, bellhousings etc, I am usually very close and usually exact where I want to be.


« Last Edit: September 09, 2018, 08:36:13 AM by My427stang »
---------------------------------
Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

wowens

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Re: Drive line angle
« Reply #8 on: September 09, 2018, 09:25:31 AM »
1 agree with Jay, you should be good to go. However, if you shim make sure you don't go up too far with pinion, it should not be angled above drive shaft. If you change, I would rather see trans go down a little.
Woody

Phil Brown

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Re: Drive line angle
« Reply #9 on: September 09, 2018, 11:57:36 AM »
https://youtu.be/gmV4qwLfOMY
Interesting video about drive shafts and what happens with angles

66FAIRLANE

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Re: Drive line angle
« Reply #10 on: September 09, 2018, 06:12:52 PM »
I did a lot of research on this when I fitted my GV unit. Heres what I determined, lifted from my old post.

"After much research on driveline angles (and there is plenty of misinformation and lack of understanding out there) these are the rules I am playing by, There are only 2:

1) The output shaft of trans and input shaft of diff (yoke) should be parallel to within 1 to 1/2 a degree with the diff pinion being down that 1/2 to 1. Diff pinion angle is all a compromise. With a leaf sprung car the more hp and the more strip time it sees the more angle down on the diff pinion. As this is a street car I will shoot for the 1/2 to 1 degree down. This keeps the operating angles of front and rear unis very close to equal.

2) These shafts should be brought to within that tolerance in such a way as to try and ensure that the operating angle of the unis does not exceed 3 degrees. This is for a hottie. Standard passanger cars & 4wd's etc can tolerate angles up to 7, but angles within 1/2 to 3 degress are more desirable. Operating angles of 0 degrees are a no no.

End of story and no debate will be entered into. There is enough debate out there on other forums and beleive me I think I have read it all!"

My427stang

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Re: Drive line angle
« Reply #11 on: September 09, 2018, 06:32:46 PM »
I did a lot of research on this when I fitted my GV unit. Heres what I determined, lifted from my old post.

"After much research on driveline angles (and there is plenty of misinformation and lack of understanding out there) these are the rules I am playing by, There are only 2:

1) The output shaft of trans and input shaft of diff (yoke) should be parallel to within 1 to 1/2 a degree with the diff pinion being down that 1/2 to 1. Diff pinion angle is all a compromise. With a leaf sprung car the more hp and the more strip time it sees the more angle down on the diff pinion. As this is a street car I will shoot for the 1/2 to 1 degree down. This keeps the operating angles of front and rear unis very close to equal.

2) These shafts should be brought to within that tolerance in such a way as to try and ensure that the operating angle of the unis does not exceed 3 degrees. This is for a hottie. Standard passanger cars & 4wd's etc can tolerate angles up to 7, but angles within 1/2 to 3 degress are more desirable. Operating angles of 0 degrees are a no no.

End of story and no debate will be entered into. There is enough debate out there on other forums and beleive me I think I have read it all!"

No debate here, well said!
---------------------------------
Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

Bolted to Floor

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Re: Drive line angle
« Reply #12 on: September 10, 2018, 09:47:35 AM »
Thanks for all the responses.

Too be fair to you guys, I had one of those moments where I can't comprehend the numbers I'm looking at on the protractor. I didn't realize it till I took the reading off the drive shaft and saw which side of the 0 the needle was on, then went back to the pinion out of curiosity. And it was on the same side as the driveshaft, so, I screwed that up!!  :-[

The car is back down off of jack stands and I drove it to work this morning. I will be taking another look at the drive line angle this afternoon when I get home and report back with findings and pictures.
John D -- 67 Mustang 390 5 speed

BattlestarGalactic

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Re: Drive line angle
« Reply #13 on: September 10, 2018, 10:25:35 AM »
I know my wagon is all kinds of odd when it comes to angles.  The motor/trans points down in the back horrible.  I've never been able to raise it up to make the numbers more "correct".  In 23 yrs of racing, I can't even recall what the numbers are.   As long as it doesn't vibrate OR throw the driveshaft out of the car....it must be good enough.

When I put the third transmission in the Mack, I did work to make sure the angles cancelled themselves out.  Same kinda deal.  Motor/trans points down, so I had to tip the third transmission up in nose/down in back to even out the angles on the front u joints, then the rear was whatever it was.  I think it worked out okay.  Again, it doesn't vibrate and hasn't thrown the shaft out.
Larry

Chrisss31

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Re: Drive line angle
« Reply #14 on: September 10, 2018, 11:28:51 AM »

"After much research on driveline angles (and there is plenty of misinformation and lack of understanding out there) these are the rules I am playing by, There are only 2:


I couldn't agree more, there is a lot of really bad info to sort through on this topic.  If you have a smart phone.....Tremec makes a pretty good app that takes the trans, driveshaft and pinio angles into account and gives a go/no go evaluation.