Fox T-Bird/Cougar Forums

Technical => Drivetrain Tech => Topic started by: booksix on December 31, 2007, 12:53:02 PM

Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on December 31, 2007, 12:53:02 PM
Yeah, so I had a pretty rough day last week...

Someone tried to steal my Cobra R's the other day (the first time I left the car outside in a long time) and they got stuck at the locking lug nuts.  So, needless to say, I didn't last very long at 75 in the San Diego AM traffic.  My left rear broke off and I was left with about 30% brakes riding on a rotor to get across 4 lanes of traffic to "safety."

When the rollback got my car back home, we put my full size spare on (the other 4 lugs on the axel were intact and we borrowed a couple lug nuts from other wheels that were so kindly retightened to hand tight).  For some reason, the identically sized spare is a little wider than my Nitto drags but none-the-less my rear-end now seems quite crooked!  The pics don't tell the same story as being in person, but what do you all think?

edit:  Also, this is the stock rear-end and control arms with Mark VII axels and brakes
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: Kitz Kat on December 31, 2007, 01:07:58 PM
Might of bent a control arm some?Lets see some side pics.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on December 31, 2007, 01:09:37 PM
Yeah, I was thinking that too but it's so hard to tell just visually. 

What kind of side pics?  Straight on looking at the wheel?
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: Kitz Kat on December 31, 2007, 01:14:07 PM
You need a tape messure,Something moved!
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on December 31, 2007, 01:20:37 PM
I was going to do that first, but where do I measure that will be easy and accurate?
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: bhazard on December 31, 2007, 01:24:33 PM
You didnt notice the wheel was loose just driving around? :P
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on December 31, 2007, 01:27:58 PM
I would have, but I wasn't just driving around.  I immediately get on the highway to go to work the next day.  I got about three miles and all of a sudden a deep, rumbling vibration started and before I could even think what it was and react (probably about 2-3 seconds or less) the wheel was gone...  I've actually known a couple people this happened to that made it even further with no signs of a problem before they lost a wheel.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: blu84302 on December 31, 2007, 01:58:12 PM
I'm pretty sure all of my birds were like that.  The rear did seem a little off to the driver side.  But then again, I've lost a wheel too and maybe I bent something.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on December 31, 2007, 03:12:27 PM
Hahahaa, now that's funny.

But anyway, I also noticed this a bit before this whole wheel thing happened.  But now I'm looking much closer (perhaps worrying about little things more than ever) and I have to have an insurance guy come out to look at it before I can decide if I want to file a claim.  I just want to know whats all there before hand. Can anyone else chime in on whether or not this in normal?  Seems strange to me.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: 347Thunder on December 31, 2007, 07:57:57 PM
dont feel bad mine looks the same the car has never been in a wreck and has all new control arms I just kind of deal with mine lol
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on December 31, 2007, 10:02:00 PM
So this is a fox thing?  I can't imagine why...  This will now drive me nuts for the rest of my life!
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: 347Thunder on December 31, 2007, 10:36:30 PM
I will take pics of mine so we can be sad together lol
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on December 31, 2007, 10:59:50 PM
LOL, ok...  sounds like a plan.  And since it's New Years Eve we can drink our rear-end woes away and just appear to be celebrating!  :banana:
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: slowfoxbird on January 01, 2008, 01:26:08 PM
Did you know you were missing lug nuts before you drove the car??
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: SLEEPER T-BIRD 87 on January 01, 2008, 01:30:51 PM
All RWD cars have the rear installed offset it helps with the driveshaft phasing/aligment and plays a small role in the cars tracking.

try shoving some 28-10.5W's under one.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: JeremyB on January 01, 2008, 02:37:08 PM
Quote from: SLEEPER T-BIRD 87;195321
All RWD cars have the rear installed offset it helps with the car tracking itself.

Why is that?
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on January 01, 2008, 03:40:06 PM
hahaha, well...  if I knew there were lug nuts missing I would have NEVER driven the car!!

As far as the offset/tracking deal... it kinda makes sense.  I mean, I don't quite understand how having the rear centered would make the tracking worse but whatever... 

I was also looking around on stangnet and found various guys talking about this.  Some with classics and a few foxes, with differenent degrees of offset - from none and all the way up to 3/4" off on one side (which is what I appear to be close to).  Weird part was some had the offset to the right and some to the left.  There was also a discussion about large tolerancances in manufacturing causing the differences and that a frame straightening machine could correct the problem somewhat by bring the frame even closer to 'spec' than the factory did....?

Either way, it drives me NUTS!  I think it looks absoutely horrible...
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: SLEEPER T-BIRD 87 on January 01, 2008, 04:21:01 PM
Quote from: JeremyB;195331
Why is that?


guess i used the wrong words lets see if this explains what i was getting at a hair better.


Well pinion shaft is offset to the ring gear, and the pinion is aligned with the driveshaft(phasing). To have the same length axle shafts (saves money to have one part) requires that the housing be offset by a small amount (Think pinion offset). This means your housing is offset to the chassis.Most won't notice it till you fill the wheelwell with tires.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: cougardoc on January 01, 2008, 05:25:15 PM
I have a Mark vii also a fox body and noticed the same problem toward the drivers side after I got hit in the pass. rear quarter panel.
I am still driving the car with no ill effects, not sure if it was like this before the hit or not, never noticed.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on January 01, 2008, 05:30:34 PM
I get it.  So, technically, the ring gear is what is offset...?  And, because both axels are the same length, the offset is handed off until it reaches the wheels/tires?
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: SLEEPER T-BIRD 87 on January 01, 2008, 05:32:01 PM
Quote from: booksix;195351
I get it.  So, technically, the ring gear is what is offset...?  And, because both axels are the same length, the offset is handed off until it reaches the wheels/tires?

basicly
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: CougarSE on January 01, 2008, 08:47:35 PM
General Motors had the tailshaft of the transmission higher than the pinion.  Chrysler typically offsets the entire engine and transmission.  Ford either makes an unequal axle or shifts it.  If this was not the case the needle bearings would not move in the u joints and wear out prematurely.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on January 01, 2008, 08:49:41 PM
But the offset in the rear-end should have nothing to do with the needle bearings because we already have few degree pinion angle for that purpose (right?).
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: CougarSE on January 01, 2008, 08:54:23 PM
Its been a while since I've been under a Fox so I'm not sure.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: Beau on January 02, 2008, 12:07:40 AM
It's a Ford, so fvck-all is gonna be offset, misaligned, bent, whatever. LOL.

Seriously...I wouldn't worry about it...nearly every rear drive vehicle has to allow for this in some way.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on January 10, 2008, 10:38:18 PM
Ok, I'm not so sure anymore.  Anyone else following this thread:

http://www.foxtbirdcougarforums.com/showthread.php?t=15098&page=7

Thundr306 has some pics of his 10.5's (also pics of drivers side on page 12) and the centering looks pretty dead on...  anyone have any explaination for this?
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: JeremyB on January 10, 2008, 10:43:10 PM
Mine are centered.

I was a dumbass a while back and didn't tighten down the lugs on my rear wheels all the way. I got on the interstate and about 5 miles down the road I noticed the car felt "funny". I took the next exit and stopped at a gas station. The passenger side wheel was ready to come off. Ho-boy!

[edit]
Actually, the last time I worked on the car was several weekends before that incident. I had driven hundreds of miles before it got loose. WTF!
I still used my ninja-like skills to ascertain the rear wheel was wobbly. I'M AWESOME!
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: daboss351 on January 10, 2008, 10:45:22 PM
get under the car. find a center point. measure from the mounts and see if there is a difference.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on January 10, 2008, 11:59:36 PM
Hahaha, classic!  To bad I'm not a ninja, maybe my wheel wouldn't be lost in a revine somewhere or on it's way to the swap meet in Mexico!

Anyway, I'm gonna get the rear up tomorrow.  My rotor is pretty chewed up, but now that the car's weight is back on a wheel/tire my brakes are good and the car actually drives fine (got up to 55-60 and heard nothing abnormal - above the volume of the exhaust anyway).  Gonna try to not replace the rotor just yet; I may be switching to 94-98 rear setup instead of the Mark VII. I figure, now that I'm in the process of buying a new wheel and all the new tires I needed anyway, I may go wider out back...  we'll see.  Anyway, as I was trying to say, I'm gonna measure tomorrow... Thanks everyone.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on January 11, 2008, 03:16:27 PM
Ok, I need help guys.  Does anyone know a good way to measure this?  I tried using the holes on either side of the subframe (just in front of the gas tank).  They measured 33" apart.  I then measured 16.5" in from these holes each side and marked that on the rear-end cover; this gave me the vehicle center.  Then, I measured in from each axle  to the mark on the rearend to see if there was an offset, but I'm only getting about an 1/8", when according to my tires and the wheel lips it's about 1/2".  Does anyone have a more accurate way of measuring?

PS:  Could having a weak spring have anything to do with the offset?  I have the same ride height on each side if the car but I know for a fact that one spring is weak because my ride height adjusters are about 3-4" higher on one side (I know, they need to be replaced anyway, just haven't gotten there - and don't know what springs to use)...
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on January 14, 2008, 03:27:13 PM
anyone??  Could the weak spring pictured above be the culprit??  And if not, is there a better way to measure??
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: 347Thunder on January 16, 2008, 08:54:34 AM
finally got some pics
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: 347Thunder on January 16, 2008, 08:56:53 AM
it does not look that bad in the pictures but it is really noticeable
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on January 16, 2008, 02:09:01 PM
what size tires/wheels are those, just out of curiousity..
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: 347Thunder on January 16, 2008, 04:21:05 PM
275/50/15
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: EricCoolCats on January 16, 2008, 04:31:05 PM
Honestly--and I should have jumped in here sooner, forgive me--I don't think Fox platforms were manufactured to have everything perfectly aligned. For example, the steering column is off-center in relation to how you face the front of the car. The column leans toward the driver's door...that's why the ol' Fox twisted seat problem exists. I recall reading somewhere (perhaps the Mustang 5.0 bible?) that the dimensions of the frame in the rear end area isn't symmetrical. And laying under these cars for as long as I have, I tend to agree with that. There is a slight bias toward the driver's side. I would say that, unless you have a bent control arm, then it's probably just a normal Fox chassis off-centered thing.
Title: Shouldn't my rear-end be centered, before OR after a wheel brakes off?
Post by: booksix on January 16, 2008, 06:10:31 PM
Thanks Eric, that's interesting...  and not surprising.  Mine, however, is more offset than others that I've talked to.  I guess I'll have to wait until I get some MM lower arms and new springs to know for sure.  Wondering if I need to go for new upper arms right away as well.  I wouldn't think these would bend as easy as the lowers may, but idk...