how to determine proper rear end angle

corpse

corpse

Founding Member
Jan 23, 2001
2,562
0
0
chicago area
#1
After a long hiatus of not working on the stang, I'm finally back at it again (for a short while at least)..

My gas tank has been notched and now my quick change rearend can clear the tank.. Now that THAT is done, I can get the angle of the rearend setup. My leaf spring perches/rear end mounting things came from a 3" floater racing rearend, so I need to set the pinion? angle on the rearend and weld it in place... Once that is done, I can take the tubes to get powder coated, check diff, and permanently put the rear end in the car :)

From prior reading, a long time ago, that I'm supposed to match the angle to the trans yoke angle - I guess this is called phasing? This way, the center lines of the yoke/pinion are parallel. But then I'm told some racers will adjust this by 1 or 2 degrees (positive/negative) depending on whatever..
 

  • Sponsors (?)


#4
Dude, who are you? LOL!!! Long time no see.

2-3 degrees downward on the pinion?!? from 0?!? I think I would phase the tranny yoke and pinion yoke and then make sure my wasn't more than 3 degrees off of the phased pieces. You could put steel shims in if need be later I'd think.

I can see making the pinion yoke down a bit in a drag application, but I would think in a road race app, you'd want them phased as you're in and out of the throttle all the time.
 
#5
1320stang said:
Dude, who are you? LOL!!! Long time no see.

2-3 degrees downward on the pinion?!? from 0?!? I think I would phase the tranny yoke and pinion yoke and then make sure my wasn't more than 3 degrees off of the phased pieces. You could put steel shims in if need be later I'd think.

I can see making the pinion yoke down a bit in a drag application, but I would think in a road race app, you'd want them phased as you're in and out of the throttle all the time.
Click to expand...
Well mine was set up for "drag racing" even though it never see it, but its about 2.5* down on the rear.I need to set it again after i took everything off.
 
#6
Please feel free to beat up on me but, I was taught that optimum was for the driveshaft and the pinion to be straight as poss. under load. Since the pinion rotates up on accel. there must be neg. angle at the pinion or the u-joints will hyperextend.

For a street car -2 degrees (or downward angle)at the pinion, is pretty safe for a street car with leafsprings. Ladderbar and 4 links need alot less since the rotation of the rearend is more controlled.


If I'm wrong please let me have it.:SNSign:
 
#7
1302 - just been busy with non stang stuff.. I'm a man with too many "hobbies" <g> Between climbing, kids, a g/f, work, the cnc machine I don't have enough time to watch more than 2 hrs of a tv a week (good thing).. And lately I even started on a custom harley that I'm doing with my bro from the ground up.

Onto my rearend...

I got the AOD installed, so I don't know if that changes the trans output shaft angle, but that seems to be 2.5* down. Since the rearend floats right now, it's easy for me to turn it and take measurements.. If I match the angle of the re pinion to also ~ 2.5*, for the optimal phasing, I seem to get a problem where it runs TOO straight.

I need to get a better angle measuring tool, but I have something that should be accurate to at least 1*..

The trans output shaft is at 2.5* down, with the ujoint pivot about 11.25" off the ground..
The re pinion , when set at 2.5* up, is about 9" off the ground. That creates a driveshaft angle of about 2.6* The leaves less than 1/2" between the driveshaft and yoke/pinion.. as I understand, thats bad for u joint life, as 1/2* or more is needed to create the elliptical path for the bearings to pump the grease.

Once I borrow a better angle measuring thing, I'm going to double check my measurements and see if I can post up a pic for some input... Once the rearend is welded to the mounts, I want to keep it that way, and not install any wedges to adjust the angle.
 
#8
1320stang said:
Dude, who are you? LOL!!! Long time no see.

2-3 degrees downward on the pinion?!? from 0?!? I think I would phase the tranny yoke and pinion yoke and then make sure my wasn't more than 3 degrees off of the phased pieces. You could put steel shims in if need be later I'd think.

I can see making the pinion yoke down a bit in a drag application, but I would think in a road race app, you'd want them phased as you're in and out of the throttle all the time.
Click to expand...

We need to roast marsh mellows together as I am in this camp as mine is down 3" front and rear and no problem with the pinion angle at the track. No shims in mine.

Perhaps OpenTracker can tune it.

HistoricMustang
www.historicmustang.com
 
#9
On a side note, since everyone likes pictures in threads, here's the rearend with the gas tank FINALLY in...
 

Attachments

  • rearend_qc_notchedtank_1.JPG
    rearend_qc_notchedtank_1.JPG
    56.1 KB · Views: 177
  • rearend_qc_notchedtank_2.JPG
    rearend_qc_notchedtank_2.JPG
    50.6 KB · Views: 149
#11
2-3 degrees downward on the pinion?!? from 0?!? I think I would phase the tranny yoke and pinion yoke and then make sure my wasn't more than 3 degrees off of the phased pieces. You could put steel shims in if need be later I'd think.

I can see making the pinion yoke down a bit in a drag application, but I would think in a road race app, you'd want them phased as you're in and out of the throttle all the time.[/QUOTE]



I had to reread this statement. This is correct. A u-joint has a safe operating range of 3 deg. The angles should cancel each other out. -2 deg from the driveshaft and +2 deg from the pinion equals 0 deg.

I had to do some reading but, here is a quote from Ray Currie in a how-to from Car Craft: " The average car crafter should strive for between 1 and 3 deg. between the tailshaft of the transmission and driveshft and 1 to 3 deg. between the driveshaft and the pinion. Furthermore the two angles should be nearly equal(between 1 and 3 degrees), but always opposite."



Ok, for laymens terms since I have no clue as to include a diagram. If the driveshaft goes down toward the pinion from the trans 2deg. and the driveshaft goes up towards the trans from the pinion 2deg. this is optimal for a street car.


Remember, the more a pinion points down the more positive angle it has.
 
#13
OMFG, as I live and breath, it's CORPSE. This is so weird as I was just thinking of you today, (and no I wasn't on the crapper droping a load) :stick:. I am finally getting to the point of painting the engine bay yesterday and dropping my engine in and I had to finally dig out your machined Shelby drop template that I have had forever. Tomorrow I drill the holes!

Hope you can keep on the Stang for a while, it would be nice to see you finish it up.
 
#14
sweet - do the drop and "pay it forward" :) yes, I plan on keeping hte ride fo sure.. I've owned it over 12 years and it survived a divorce :)

Thanks for the tid bits guys.. I spent too long today reading and learning about the angles.. I hope I don't get into a problem though.. So far, based on my initial (crude?) measurements, I have almost 0* angle between the trans haft and driveshaft - definitely less than 1/2*.. I'm not sure if my measuring is off, or if it's the position of the rearend that is messing me up - as the pinion of the quick-change could be in a different position (as in, different distance from the ground). I also have 1" lowering blocks installed - I can't imagine those are changing the geometry around that much.

However, this is all on paper - I don't have a dang yoke yet for the rearend to bolt it up... Where's the jerking off icon - as I should probably put a yoke on it and attach it and take it from there <g> Tomorrow I get a yoke from the race car, and then see if I can find a u joint that will work :)
 
#15
Pakrat said:
OMFG, as I live and breath, it's CORPSE. This is so weird as I was just thinking of you today, (and no I wasn't on the crapper droping a load) :stick:. I am finally getting to the point of painting the engine bay yesterday and dropping my engine in and I had to finally dig out your machined Shelby drop template that I have had forever. Tomorrow I drill the holes!

Hope you can keep on the Stang for a while, it would be nice to see you finish it up.
Click to expand...

Hadn't seen you in a while either Pak. How's the repairs coming along.

Corpse, you got unhitched? I could see how that could slow the project down. Still working at the same place?
 
#17
1320stang said:
Corpse, you got unhitched? I could see how that could slow the project down. Still working at the same place?
Click to expand...

I've been unhitched for about 8 years now :) But better yet, I'm pseudo-hitched for the past year and a half.. Too bad she don't dig the muscle (cars), but thats ok, at least no pressure of buying her one as a present <g> Still doing much of the same work, working out of home most the time. My slowness of working on the car is mostly because of other interests.. When spring and summer are here, I spend as much time climbing as I can - last summer I had taken 5 weeks of work off for climbing outta state. This summer will have much less time out of state, which means more time on the car - hopefully I'll be driving it this summer...

Once the rearend is IN, I gotta get the brakes setup - need to machine the master cylinder to accommodate 4 wheel disc, check the new brake lines and hope I flared em right <g> (ran lines to the shifter for a prop valve and rear brake pressure guage), so I have lots of room for error :)
 
#19
tylerrocks said:
Wait, im confused. What is that splined shaft and why is it sticking out the back??
Click to expand...

Actually there are 2 spline shafts out the rear. What you don't see is the front of the tranny where the driveshaft attaches.

This is a quick change rearend which allows for quick gear changes without removing the center section. Swap 2 little gears and you have a different ratio.

Ultra cool, if you ask me.
 
#20
tylerrocks said:
Wait, im confused. What is that splined shaft and why is it sticking out the back??
Click to expand...

This is a quick change rearend.. the spline shaft let me put straight cut gears onto them with a cover on it.. This way I can unscrew some bolts with a 7/16 wrench, take the cover off and pull off the gears, and plop some new gears in.. I can change the ratio to anything I want.. So I can run a 3.23 on the way to the race track, and then run a 373 if I want when I get there, and it only takes about 10 minutes to change it. I also have more ratios to pick from, most rearends ppl have to pick things like 373, 393, 411 - see this chart for all my choices http://shed51.com/gear_chart.htm

Theres many other reasons for a QC, like weight, brake setup, floating hubs, very easy serviceability. More places to leak, so hopefully I'll have it sealed up well :)
 
You must log in or register to reply here.

Similar threads

M
Rear end sounds like marbles in a tin can.
Replies
2
Views
873
SN95 4.6L Mustang Tech
TIGGER
TIGGER
OffspringChaos
My 93 4v Fox
Replies
19
Views
2K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
mattcrp1
M
2000xp8
Time for a new clutch
Replies
110
Views
9K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
2000xp8
2000xp8
AvalancheSVT
For Sale 97 Cobra with built 99 cobra drivetrain
Replies
3
Views
2K
SN95 Mustangs For Sale (1994-04)
AvalancheSVT
AvalancheSVT
E
For Sale 1989 LX Notch 410ci 85mm turbo 8 pt cage 9" rear end
Replies
1
Views
3K
Fox Body Mustangs For Sale (1979-93)
Freakinstang
F
Top Bottom
Back
New
Hot
Menu