7.5 or 8.8" Rear End In My Car?

CyberPrey · October 26th, 2006, 07:35 PM

I have a 1997 3.8 Auto Mustang. It definitly has a regular differential in it, as the right wheel spins like mad while the left just kinda does nothing.

I am wanting to improve the rear end with gears and a traction lock, but am not sure if I have a 7.5 or 8.8 rear end.

Is there a way to identify which one I have on my car?

The reason I ask is that I am the 3rd owner. It looks like the car has had a couple things done to it before I got it, so am not sure if the rear end was part of this...

thanks

itschristorres8 · October 26th, 2006, 07:55 PM

if your car is stock you have a 7.5...

mdvaldosta · October 26th, 2006, 07:57 PM

Yes, you have a 7.5" rear end. They make trac-lok / posi differentials for your 7.5, or you could swap in an 8.8 from a GT if you wanted.

CyberPrey · October 26th, 2006, 08:04 PM

Thanks!!

I was thinking it would be the 7.5", but wasn't sure. While I don't THINK that I would blow up a nice built 7.5, I think I will visit the local salvage yard and see if I can grab an 8.8 to set up.

Would I be able to take the rear from ANY v8, or would it need to be a GT?

itschristorres8 · October 26th, 2006, 08:10 PM

blow up an axle? more like bend or crack

find a v8 of your year

mdvaldosta · October 26th, 2006, 08:13 PM

You can break an axle also Chris, though it's not likely to happen with a V6. Will some hard launches on slicks at the track to damage an axle (usually).

CyberPrey you'll need to find a rear end from a Mustang GT of the same bodystyle as yours. If you get one from another bodystyle you'll have backspacing problems with your wheels.

itschristorres8 · October 26th, 2006, 08:20 PM

Originally Posted by mdvaldosta

You can break an axle also Chris, though it's not likely to happen with a V6. Will some hard launches on slicks at the track to damage an axle (usually).

CyberPrey you'll need to find a rear end from a Mustang GT of the same bodystyle as yours. If you get one from another bodystyle you'll have backspacing problems with your wheels.

crack break... same lines..i ment basically the axle wont blow up as an engine were too

CyberPrey · October 26th, 2006, 08:22 PM

Thanks Everyone

Onemanzu · October 26th, 2006, 08:51 PM

... if your really serious about getting a 8.8" ... you could look at online salvage places.... that is if you can't find a local place... im waiting for a response from an online place on prices if your interested at all

CyberPrey · October 26th, 2006, 10:11 PM

I found a local place that has a couple 96's and 97 GT's in their yard... He told me between $300-$400 for one, depending on if I just wanted the basic rear end, or with the complete brake system and the driveshaft....

I have one more question.. and this might be kind of stupid...

my 'stang is a 97, v6, auto, Ac, pw, 4whl disk brake....

Is there more than 1 factory gear ratio in these??

I was told by a guy who thinks he is a ford guru that ALL V6 auto's came with a 3.27:1 gearing.......

Anyway, I run 2000rpm at 70... If I go with a 3.73, that would put my RPM at 2281, or if a 4.10 it would put it at 2500, IF... IF... I have a 3.27... or are my calculations way off????

This site said the '97 came with a 2.73 in the base model (http://www.mustangforums.com/timelin...-ford-mustang/) which would (again, according to my possibly messy calculations??) put me at 2732RPM on a 3.73 and 3000 on a 4.10??

AtlanticBlue99 · October 26th, 2006, 10:59 PM

Originally Posted by CyberPrey

I found a local place that has a couple 96's and 97 GT's in their yard... He told me between $300-$400 for one, depending on if I just wanted the basic rear end, or with the complete brake system and the driveshaft....

I have one more question.. and this might be kind of stupid...

my 'stang is a 97, v6, auto, Ac, pw, 4whl disk brake....

Is there more than 1 factory gear ratio in these??

I was told by a guy who thinks he is a ford guru that ALL V6 auto's came with a 3.27:1 gearing.......

Anyway, I run 2000rpm at 70... If I go with a 3.73, that would put my RPM at 2281, or if a 4.10 it would put it at 2500, IF... IF... I have a 3.27... or are my calculations way off????

This site said the '97 came with a 2.73 in the base model (http://www.mustangforums.com/timelin...-ford-mustang/) which would (again, according to my possibly messy calculations??) put me at 2732RPM on a 3.73 and 3000 on a 4.10??

those calcs are wrong. i have 4.10s and at 70 turn 3k rpms on the nose. stock you should have 2.73, but check the tag on the differential

99mustang232 · October 27th, 2006, 07:57 AM

awhile back ford had a tsb out on the 7.5 due to noise, and some of the owners had theirs upgraded to an 8.8... the easiest way it to look at the diff cover

ssajdowitz · October 27th, 2006, 08:49 AM

The 8.8 rear from a fox body 5.0 is a bolt in swap for your 97 car. You just need to switch the brakes over (4 bolts on each side). Also, the 7.5" rear axles are exactly the same as the 8.8" axles. The difference is the diameter of the ring gear.

I swapped in an 8.8 from an 89 fox body 5.0 into my 98 3.8. I re-used my original axles and rebuilt the diff in the 8.8 with 3.73 gears.

The only axle housings that will not fit are the 99+ since they are slightly wider.

CyberPrey · October 27th, 2006, 12:40 PM

Hmm, I have a noise from the rear end of my car also... It isn't the tires, the ujoints are all new, and I had the rear end fluid changed out for synthetic and the mechanic said all the bearings were good....

LOL, I wonder if ford will give me an 8.8 for my 10yr old car as I am the 3rd owner..

I have never had to deal with TSB's, does that work?

ssajdowitz · October 27th, 2006, 05:50 PM

How many miles are on your car?
Do you do a lot of peg leg burnouts?

If you do a lot of one wheel burnouts, the planetary gears in the open differential will begin to gall rather quickly. This is not able to be properly checked during a fluid change since the large pin needs to be removed in the center of the diff.

Just make sure it is not your tires. I've also had a set of u-joints go out after less than 1000 miles. If you have a lot of miles and do lots of burnouts, either the planetary gears or the ring and pinion gear might be worn. But, this is expensive, relatively speaking, to the tires and u-joints. Try not to jump right to the expensive repair unless you are sure.

mediaultra · October 27th, 2006, 06:53 PM

I'm in the exact same boat as you...

partially modded 2000 v6 auto when I got it...not sure what all was done to it....

AFTER much searching and price comparisons I have found it best to just go ahead and get the 8.8 rear end out of a GT....

Only thing I need to know from someone is what GEARS come stock in a 99-00 GT....????anyone know?..

Should I get the GT 8.8 rear and then put in 4.10's???

take care and good luck on your search...

<thinks>DAMN why didn't they just put T-Lok in 7.5's?? Who wants to spin one back tire and get all crooked off the line...?? That should be a safety issue...lol</thinks>

AtlanticBlue99 · October 27th, 2006, 11:47 PM

Originally Posted by mediaultra

I'm in the exact same boat as you...

partially modded 2000 v6 auto when I got it...not sure what all was done to it....

AFTER much searching and price comparisons I have found it best to just go ahead and get the 8.8 rear end out of a GT....

Only thing I need to know from someone is what GEARS come stock in a 99-00 GT....????anyone know?..

Should I get the GT 8.8 rear and then put in 4.10's???

take care and good luck on your search...

<thinks>DAMN why didn't they just put T-Lok in 7.5's?? Who wants to spin one back tire and get all crooked off the line...?? That should be a safety issue...lol</thinks>

the gt will usually come with 3.27 and is labeled on the diff cover tag.
yes you should put 4.10s in the 8.8
and i never got crooked off the line with an open diff, but the traction is much more evident- harder to spin both as opposed to just one.

Darrell · October 27th, 2006, 11:56 PM

You don't get crooked off the line with an open differential. That is a characteristic of a locked rear axle (traction lok) because both tires are spinning. With an open differential one tire stays planted while the other one spins which effectively holds the car from going sideways.

CyberPrey · October 29th, 2006, 11:55 AM

The car itself has about 97,000 on it. The tires it came with were goodyear eagle gt+4's on the factory wheels. I replaced them with 16x8 wheels (cobra knock-offs from americanmuscle.com) and 'Fierce' brand 225/55R16's. As I don't like buying tires, I try to not spin the wheel (as in one... heh heh) very often.

It "sounds" like the noise is coming from the drivers side of the car, I was thinking of the outer bearing on the rear end, but I went ahead and replaced that and I still have the whine...

October 26th, 2006, 07:35 PM	#1
CyberPrey Regular Join Date: Oct 2006 Posts: 333	7.5 or 8.8" Rear End In My Car? I have a 1997 3.8 Auto Mustang. It definitly has a regular differential in it, as the right wheel spins like mad while the left just kinda does nothing. I am wanting to improve the rear end with gears and a traction lock, but am not sure if I have a 7.5 or 8.8 rear end. Is there a way to identify which one I have on my car? The reason I ask is that I am the 3rd owner. It looks like the car has had a couple things done to it before I got it, so am not sure if the rear end was part of this... thanks

October 26th, 2006, 07:55 PM	#2
itschristorres8 I Post Entirely Way Too Much 2000 Mustang V6 unknown @390 Join Date: Aug 2006 Location: south florida Posts: 14,171	if your car is stock you have a 7.5... __________________ When the Turbo spins The bullshit ends

October 26th, 2006, 08:10 PM	#5
itschristorres8 I Post Entirely Way Too Much 2000 Mustang V6 unknown @390 Join Date: Aug 2006 Location: south florida Posts: 14,171	blow up an axle? more like bend or crack find a v8 of your year __________________ When the Turbo spins The bullshit ends

October 27th, 2006, 07:57 AM	#12
99mustang232 MM Fanatic 1999 Ford Mustang V6 Join Date: Sep 2005 Location: newport news, va Posts: 3,719	awhile back ford had a tsb out on the 7.5 due to noise, and some of the owners had theirs upgraded to an 8.8... the easiest way it to look at the diff cover __________________ ...even fire and single cammin

October 27th, 2006, 06:53 PM	#16
mediaultra Regular Join Date: Sep 2006 Location: Lexington, SC Posts: 155	I'm in the exact same boat as you... partially modded 2000 v6 auto when I got it...not sure what all was done to it.... AFTER much searching and price comparisons I have found it best to just go ahead and get the 8.8 rear end out of a GT.... Only thing I need to know from someone is what GEARS come stock in a 99-00 GT....????anyone know?.. Should I get the GT 8.8 rear and then put in 4.10's??? take care and good luck on your search... <thinks>DAMN why didn't they just put T-Lok in 7.5's?? Who wants to spin one back tire and get all crooked off the line...?? That should be a safety issue...lol</thinks> __________________

October 26th, 2006, 07:57 PM	#3
mdvaldosta Maintenance Man 2002 Mustang GT 11.47@120.58 Join Date: Aug 2005 Location: Valdosta, GA Posts: 3,945	Yes, you have a 7.5" rear end. They make trac-lok / posi differentials for your 7.5, or you could swap in an 8.8 from a GT if you wanted.

October 26th, 2006, 08:04 PM	#4
CyberPrey Regular Join Date: Oct 2006 Posts: 333	Thanks!! I was thinking it would be the 7.5", but wasn't sure. While I don't THINK that I would blow up a nice built 7.5, I think I will visit the local salvage yard and see if I can grab an 8.8 to set up. Would I be able to take the rear from ANY v8, or would it need to be a GT?

October 26th, 2006, 08:13 PM	#6
mdvaldosta Maintenance Man 2002 Mustang GT 11.47@120.58 Join Date: Aug 2005 Location: Valdosta, GA Posts: 3,945	You can break an axle also Chris, though it's not likely to happen with a V6. Will some hard launches on slicks at the track to damage an axle (usually). CyberPrey you'll need to find a rear end from a Mustang GT of the same bodystyle as yours. If you get one from another bodystyle you'll have backspacing problems with your wheels.

October 26th, 2006, 08:22 PM	#8
CyberPrey Regular Join Date: Oct 2006 Posts: 333	Thanks Everyone

October 26th, 2006, 10:11 PM	#10
CyberPrey Regular Join Date: Oct 2006 Posts: 333	I found a local place that has a couple 96's and 97 GT's in their yard... He told me between $300-$400 for one, depending on if I just wanted the basic rear end, or with the complete brake system and the driveshaft.... I have one more question.. and this might be kind of stupid... my 'stang is a 97, v6, auto, Ac, pw, 4whl disk brake.... Is there more than 1 factory gear ratio in these?? I was told by a guy who thinks he is a ford guru that ALL V6 auto's came with a 3.27:1 gearing....... Anyway, I run 2000rpm at 70... If I go with a 3.73, that would put my RPM at 2281, or if a 4.10 it would put it at 2500, IF... IF... I have a 3.27... or are my calculations way off???? This site said the '97 came with a 2.73 in the base model (http://www.mustangforums.com/timelin...-ford-mustang/) which would (again, according to my possibly messy calculations??) put me at 2732RPM on a 3.73 and 3000 on a 4.10??

October 27th, 2006, 08:49 AM	#13
ssajdowitz Regular Join Date: Sep 2006 Location: West Bend, Wisconsin Posts: 141	The 8.8 rear from a fox body 5.0 is a bolt in swap for your 97 car. You just need to switch the brakes over (4 bolts on each side). Also, the 7.5" rear axles are exactly the same as the 8.8" axles. The difference is the diameter of the ring gear. I swapped in an 8.8 from an 89 fox body 5.0 into my 98 3.8. I re-used my original axles and rebuilt the diff in the 8.8 with 3.73 gears. The only axle housings that will not fit are the 99+ since they are slightly wider.

October 27th, 2006, 12:40 PM	#14
CyberPrey Regular Join Date: Oct 2006 Posts: 333	Hmm, I have a noise from the rear end of my car also... It isn't the tires, the ujoints are all new, and I had the rear end fluid changed out for synthetic and the mechanic said all the bearings were good.... LOL, I wonder if ford will give me an 8.8 for my 10yr old car as I am the 3rd owner.. I have never had to deal with TSB's, does that work?

October 27th, 2006, 05:50 PM	#15
ssajdowitz Regular Join Date: Sep 2006 Location: West Bend, Wisconsin Posts: 141	How many miles are on your car? Do you do a lot of peg leg burnouts? If you do a lot of one wheel burnouts, the planetary gears in the open differential will begin to gall rather quickly. This is not able to be properly checked during a fluid change since the large pin needs to be removed in the center of the diff. Just make sure it is not your tires. I've also had a set of u-joints go out after less than 1000 miles. If you have a lot of miles and do lots of burnouts, either the planetary gears or the ring and pinion gear might be worn. But, this is expensive, relatively speaking, to the tires and u-joints. Try not to jump right to the expensive repair unless you are sure.

October 27th, 2006, 11:56 PM	#18
Darrell MM Ninjas! 1990 Mustang LX 9.36@143 mph Join Date: Jan 2006 Location: Fond du Lac, Wisconsin Posts: 7,015	You don't get crooked off the line with an open differential. That is a characteristic of a locked rear axle (traction lok) because both tires are spinning. With an open differential one tire stays planted while the other one spins which effectively holds the car from going sideways. __________________ Racing in memory of Dave Bandt 11/19/69 - 3/23/08 "he's traded his wheels for wings" Professor of Natural Aspiration Thanks to: Artie at Trick Flow, Dave at Team Z Motorsports, Brian at Total Engine Airflow and Harold at Furo Racecraft

October 29th, 2006, 11:55 AM	#19
CyberPrey Regular Join Date: Oct 2006 Posts: 333	The car itself has about 97,000 on it. The tires it came with were goodyear eagle gt+4's on the factory wheels. I replaced them with 16x8 wheels (cobra knock-offs from americanmuscle.com) and 'Fierce' brand 225/55R16's. As I don't like buying tires, I try to not spin the wheel (as in one... heh heh) very often. It "sounds" like the noise is coming from the drivers side of the car, I was thinking of the outer bearing on the rear end, but I went ahead and replaced that and I still have the whine...

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