Over the summer I changed all my suspension and lowered the car. After struggling with the pinion I finally found the information I needed to set it right. I was driving the car though while it was out of spec but only city driving.

Now that everything is set, the rear is starting to make noise. I am hearing a whinning noise when I accelerate from the rear and there is a knocking sound whenever I let off the gas and accelerate again going over 60km/hMy car is a 07 PP V6.
So I think it's time to replace the rear axel, which is something I've been wanting to do for a while now.What I would like to do is change it with a rear axel from a 2010+ GT 8.8 with 3.55 or 3.73(?) gears and I know I need the M-4851-b pinion flang (for axel).Is there anything else that I need? Or need to know?
My other question is, what is the worst thing that can happen if I continue to drive the car in this way? Any help or advice would be appreciated.

 

So no one knows or no one cares to help me out?

 

Well, now, I care to help you out, certainly. But I can't, as I personally don't know the answers you seek. That's why I didn't post. Past that, hopefully these bumps will produce the result(s) you need, but as far as the worst that can happen... you blow out the axle in some way and wind up putting another one in. Pretty much it, when you get down to it. The axle housing is quite stout, and unless something causes the axle tubes to explody out (my dad's Falcon had that happen for some reason!) then the absolute worse thing is parts get scattered inside and possibly exit the rear seal cover. The pinion probably () won't exit forwards and cause a driveshaft issue... Well, that and/or the rear joint of the driveshaft gets angry due to the vibrations or such so that might mean a driveshaft... but then they do that anyway sometimes.

But yessir, past that generality, I ain't got a clue. Sorry. But I still hope that helps!

 

What did you do involving the pinion? Do you ever do one wheel burnouts?
What is about a 2010+ GT 8.8 that you hope to benefit from? What rear is in the car now?
Worse that can happen depends on failure and situation (including trtaffic, speed, weather, your skill, etc) at time of failure. I saw the results of one rear lock up both rear tires at 70+ on a straight road, car spun around facing backwards and went off the highway backwards into a patch of woods. I destryed a 12 bolt rear in a 65 GTO going to third, coasted into a parking lot and borrowed a phone to call a wrecker.

 

Well since I lowered the car the pinion angle was out of spec. No I didn't do any burnouts.
Right now I have the 7.5 axle and I know the 8.8 are stronger.

 

How do you know the lowering upsert the pinion angle? I understand 8.8 vs 7.5, but I don't see going to 8.8 is gonna correct any issue with pinion angle. How much lowering did you do? Have you measured pinion angle versus drive shaft angle. It could be just a coincidence that low lube ... or just a failed bearing is at play. Yeah, 8.8 is stronger, but a 7.5 is plenty strong, our '85 5.0 T-bird had a 7.5, we had it from 1985 until 2009, and 147,xxx miles. I think I changed lube it it once.

 

If I can also remind myself of something, go 'oh yeah...' and then interject it here...

Also, you'll have to swap out the driveshaft, and it may or may not be a custom one that has to be done. IDK. See my first post about 'helpin', but one thing's for sure: Plenty of people have tried to do things to their V6s and their driveshafts said 'nope'.

'course, they were also doin' the whole 'I know my car, ain't needin' no more speed limiter here!'. Yes. Yes they do.

Then there's bracketry and all that mess that might need swappin'... It just becomes a money/time/materials pit. And for... what? At the end of it, truly, what's the point? Mileage? No, because you want better gears. More oomph at launch, more speed, sounds like it. More stress. And if you're doin' that, sure, the GT axle might be a thing.

Still... things being equalish... overall, the easier thing is this: The V6 axle is plenty stout for what you need on an otherwise stock V6 application. I'd be looking into maybe swapping gears in a 'new to you' housing and swapping it out. You'll have an easier time of it, and you'll get what you want: Better leave at the lights. Then sell the old one for parts/core and recoup a little money. Even better if you can do most of the work yourself.

Just a thought process I'm havin'. I'm sure I'm wrong. You do you, and that'll do!

 

Houtex why would I need to replace the driveshaft? It's a one piece and all I would need is the cobra pinion flange to bolt up the 8.8 to the car.
Can I put a 3.73 or a 3.55 gear set in a 7.5? I don't think so. I haven't found any info that I can.

 

Hey buddy. How's Canadian life going? Been a bit.

On your axle. You should have used the axle upper pinion adjustable mount. That is really an easy way of doing it.

I bought a 8.8 out of an 2012 GT with 273's. I installed 373 Ford racing gears, and it still sits on my deck. It's been 3 years and I've been lazy.

You do not need to buy the Cobra flange as all S197's with 8.8 seems to have it. At least every one I've run across. You won't need another driveshaft.

On the 373 for a 7.5. I have a set of Ranger 373's with carrier for the 7.5 in mine now. Works great. I just want to go to the 8.8. Sway bars still work the same, so it's just a beefier set up. No real apparent value to out 4.0's, so that is why I haven't swapped it out yet. The 373's 7.5 is plenty strong enough to hold up to our horsepower.

 

V6 driveshafts have failed because of such shenanigans such as what you're contemplatin': Goin' outside the design envelopes in some way. Plenty of videos/posts/articles out there about it. Just something to consider is all, hence the suggestion. Perhaps you won't have the problem, but still... you'll find out eventually I'm sure. Either it lasts a lifetime, or it blows up in some way and then you'll know for sure.

Far as the gear, know that I do not know everything. And if it's gears you're lookin' for, sure, you'll have to do swaps... and that causes extra stresses somewhere else... so the driveshaft suggestion.

However, it sounds like you got this on lockdown, so go forth and experiment away, sir. I trust you'll be as safe as possible for both you and your car.

Again, everyone, y'all do y'all, and that'll daw. Do. Eh. Stupid rhyme doesn't work with multi-people adjectivity...

 

Houtex you crack me up on every post

As for the gears,as mentioned,you can get about any ratio for the 7 1/2.I've even seen 4,56 and I think even more extreme than that advertised for the 7 1/2

 

Thanks everyone for the suggestions. Guess I have some rethining to do. But what about wheel hop or the 1 wheel burn out (not that I do them). 7.5 are really known for that, yes?
I just want to make the car stronger and have better take off and I know the 8.8 are much stronger.

Also really good to hear from you akdoggie. Its been ages since I have last heard from you!
Email/PM me sometime we should catch up.
Also "You should have used the axle upper pinion adjustable mount." Do you mean the rear upper control mount?

 

Yes. That is it. I have a BMR unit for the 8.8 but again, it's just sitting on my deck.

Using the Ranger 7.5 locker makes all the difference in the world with our take off. Especially in the snow. I don't really use Sonya in the winter, but I like it for my Fairbanks runs. If you remember, I stuck all the springs, shocks, struts and sway bars from that wrecked 08 Bullitt. It only had 4k miles on it when he totalled it. I have a lot of fun running the mountain roads 6 or 7 times a year. I just miss the softer ride of the oem v6 suspension, but love the sportiness of the v8.

Next spring I'm swapping my blue accent stripes for purple. I'm going to change the blue calipers to purple also. Time for a change. LOL Here is Sonya this summer with the 18's. So much softer ride than the 19's she usually has on her.

 

Regarding wheel hop, they're the same overall suspension. Wheel hop can still happen. Which is usually the bushings in the control arms and/or the control arms themselves flexing about causing instability of the axle as it tries to rip itself out of the chassis.

You get the stronger lower control arms, perhaps the upper while you're at it, with the poly bushings and it pretty much goes away. Might look into bigger diameter wheels with shorter sidewalls, but there's an argument to be made regarding smaller wheels and taller sidewalls, depending on what you wanna do...

I mean, even the bestests of drag cars can't completely control wheel hop, you see them break them tires loose and MAN do they just shake the car like a mad... um... thing. I'll stop there. :unsurre:

The one wheel peel thing is the non-posi axle. You'd just need to swap out for a posi like AK says up there.

 

Houtex what is posi? So it sounds like you are against upgrading the axel to the 8.8?
I do want to upgrade or add to the engine down the line at some point.

Akdoggie let me tell the whole story.
I bought new suspension parts over during the spring. This includeed, shocks l, struts, lowering springs, adjustable panhard bar, adjustable rear upper control arm, rear lower control arms and sway bar brace. I already had new control sway bar and links installed from last year.
So I did all the work myself. Front and back.
As you know lowering the car off puts the pinion angle. I couldn't find the proper info on the subject. So I got an alignment and my bother (he's a mechanic) tried to set the proper pinion angle. I forgot to measure what it was before changing all my suspension and after to see the difference.
So he set it pinion angle and I test it out. I find out that going over 140km/h makes this awful noise in the rear that was never there before.
So he ties again and sets it to 0°. But that didn't help at all. So I've been driving it while it was like this. Then post about my issue on a fb group and I was told I need relocation brackets for the lower control arms. So I buy that and install them.
Then I was able to find out the pinion angle information from a YT video. It said to make it 2 deg left of 0 from whatever the deg is on the transmission. So my trans is at 4°, so he set it 2° left of 0. Then I went out to test it. The noise in the back is still there going over 140km/h and now it has a whinning noise. Then I noticed that the whining noise it there no matter how fast or slow I go. Also there is a clucking noise that happens in the rear whenever I let go of the gas and push it again going over 60km/h. Doesn't happen all the time but often enough. So I ask online and was told my gears are shot. Hence the reason why I want to upgrade the axel to the 8.8 and go with 3.73 gears. I was going to go with 3.55 but read its no good.
I also want to add some kind of upgrades to the engine down the line. So I'll need a beefier axel yes? The driveshaft should be okay because it's a one piece.
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'Against': Nosir, I'm just doin' what I can to maybe informing you as to what you got for options so as to minimize strife and strain on your end. Sometimes the best of intentions lead one down a weird, twisting, dark, ominous... and costly in time and effort and money, the true devil of the matter... road. Informed, considered decisions tend to lead to better executions, dontcha know. That's all. Newer/bigger is not always better, just makin' sure to poke my head in and kibitz. I'm all for it, get that Dremel, Hammer, and welder out and do what you want, it's your project!

As to 'posi' that means Positraction, the GM term for what you're looking for: Two wheel peels. When talking about the equivalentish Ford Trac-Lok, it's also manytimes called 'Ford Posi', and then just a 'Posi' rear end, which I why I used the term:
https://www.google.com/search?q=ford+pos

So there ya go.

 

I still run the stock upper control arm, stock LCA's, stock sway bars and stock driveshaft with Eibach pro springs, Koni yellow adjustable struts/shocks, BMR adjustable panhard bar and GT500 strut mounts.
With the front suspension lowered approx 1.3" and rear suspension lowered approx 1.5" I haven't noticed any negative issues affecting the alignment of the pinion angle, nor has anyone recommended installing a bump steer kit or upgrading to an adjustable upper control arm in order to readjust the pinion angle. From my understanding, unless the suspension has been lowered by 2 inches and beyond? the alignment of the pinion angle doesn't require a readjustment. Perhaps the reason your pinion angle was out of spec/alignment, is due from having your suspension lowered by 2 inches or more. Also keep in mind that once your suspension has been lowered beyond 1.5 inches, you'll also need to install control arm relocation brackets in addition to replacing the stock upper/lower control arms along with adding a bump steer kit, as just replacing the control arms themselves won't be quite enough to eliminate wheel hop.. Anyhow, just my $.02

 

Thank you Houtex. I really appreciate your help and suggestions. Because of you I am starting to look into gears for the 7.5. You may be right that putting in a 8.8 might be to much. Still exploring my options.
I'll have to look more into posi to know what it is.
If I go with upgrading my gears in my 7.5 to the 373s I still need to recalibrate the cluster yes?

M05fastbackgt you know this is what makes me so angry/annoyed. There is so much misinformation out there it's really hard to know what is the right thing to do.
​​​​​​I installed the Steeda ultra lite springs. Front dropped 1.25" and the rear 1.5"(according to the site). I kept reading on websites like steeda, watched YT videos, and have asked around and was told that I needed the items I listed which is why I bought them. I do have control arm relocation brackets as well.
So I could have gotten away with my stock upper control arm and not have to fool around with getting the correct pinion angle? Then I wouldn't be in this mess. I'm going to try putting back my stock UCA (or a non adjustable since mine is old and rusty) one day and see what happens.

 

VGM! You are exactly 100% spot on in regards to all the misinformation out there and unfortunately large aftermarket companies such as Steeda Autosports happens to be one of them and the reason is to make a profit. They pretty much also told me that even if the vehicle is lowered by just 1 inch, that it would throw off the alignment of the pinion angle and would therefore require the purchase of one of their bump steer kits and also one of their adjustable upper control arms in order to get the pinion angle back within OEM specs.

Needless to say, I contacted the manufacturer (Eibach Springs) and also JDM engineering who both debunked Steeda's marketing hype claims and confirmed that lowering a vehicle under 1.5 inches does not throw off the alignment of the pinion angle to which neither a bump steer kit nor an adjustable upper control arm is required for making any corrections or adjustments regarding the vehicle's suspension.
Therefore, neither of those items you were told were needed were not really necessary being that you lowered your suspension by under 2 inches with Steeda ultra-lite springs.

At any rate, other than what I've previously mentioned in the thread, no other suspension mods have been made to my "06" GT during the past 8 years and haven't run across any negative issues in regards to the car's suspension.

 

Yes if you want it to be accurate...and you don't go changing the size of the wheel/tire outside diameters either. Any change in output rotation like gears or tires/wheels will cause the speedo to be out of spec.

That said, I didn't when I put on the smaller diameter tires on them big GT500 wheels (the 275 all 'round spec), I just know that '70' means '65ish' and I'm good to go. Although I do have the Forscan and the cable so... Maybe I will one day fix that...