9 inch rear ends

Fostang · 02-16-2001, 07:20 PM

Whats so good about 9 ich rear ends in older cars?? I put one on didn't like it seems to take off faster with the 8 inch? why all the hassle about having a 9 inch? They were the same gear ratio's. What type of rear end do you like your classic stang?

Gearhead999 · 02-16-2001, 09:07 PM

9 inch was always the stronger rears. They have their pinion down lower on the ring that gives much more tooth contact. They also have the small support bearing on the nose of the pinion.

Also, you can pop the pumpkin out to change ratio's easily.

Be it a 8 inch or a 9 inch. They should both take off the same with the same gear ratio and tire size. 9 inch is heavier too.

69fastback · 02-16-2001, 11:11 PM

A ford 9" is the best rear money can buy. U really can't break one. Most gm cars that race have ford 9" rears. Also most people don't know this but every car in NASCAR has a ford 9" including the chevys and pontiacs.

------------------
69 428 cobra jet: tons of mods.
97 f-150 5.4 xlt mark III
BUCKLE UP. SUCK IT IN.
Objects in the mirror are about to disappear...
QUICKLY!!!!!!

shovelnose · 02-17-2001, 10:36 AM

I agree with the answers here.

1: Strength(3 pinion support bearings)
2: Ease of gear changes.(Can be done in 1/2hr) with the right tools.
3: No need for C-clip eliminators.(axles don't fly out)
4: The 8" was the same design but brings the weight down, also not as strong.

Dana 44(I think is the #), I have heard this is even stronger than a 9".

------------------
82 Mercury Capri 302.
Comp. Cams
Tremec 3550
3.73's
12.8@106 N/AKevin's Capri

Bob · 02-17-2001, 01:20 PM

The dana 44 is a lot smaller than a 9" and is internal carrier type, like the 7.5 and 8.8's. They were used alot in 4wd applications as front units in F-150's and full size Bronco's. The Dana 60 is a beefier than a 9", but not nearly as easy to work on.

Fostang · 02-18-2001, 12:03 AM

Since I put my 8" back in I am much happier. I had gone through a numerous number of gear swaps with the 9" and never had been able to get the performance I was able to obtain with this rearend. In fact I was so amazed with the difference it made. I laid a nice long thick thread about half a block. With the 9"er it was never able to do this. Maybe if I really got on it but would have to hold the break. Now I'm just seeing what this car was capable of. It seems to have lost the meaning of traction. Dont want to over do it though. Just seemed right to do it prob wont be doing that for a while. Gotta protect the investment.

COBRA66 · 02-18-2001, 05:13 AM

Not to sound like a complete ****** here, but fostang do you have any idea what you are talking about. Performance has nothing to do with your rear end housing. The way your car takes off or rides or whatever will not change with an 8" or a 9". The gear ratio in the housing will make the differance though. The only reason people speak so highly of having a 9" is that like everyone else here said, they are vertually indestructable. Hope i didn't sound like a complete a$$ but the truth had to be said.
Justin

Fostang · 02-18-2001, 12:54 PM

Oh I know what you mean and I aknowlege that completely. It's just that after so many gear swaps I hadn't had that much take off. With the same ratio in both. Or even when I put a higher one in the 9"er it never took off as good. Yes, I know they are stronger thats why I put one on. But now that I have the 8"er I'm not going back ever. If I blow it out I'll just exchange it.

thunderbolt · 02-18-2001, 02:23 PM

Rumor mill has it that the 9in sucks up more power than the 8in. If you are not running real serious ponies then the 8 should work fine. 1 more advantage to 9in. Tons of aftermarket parts available.

Rev · 02-18-2001, 05:10 PM

Thunder, unsprung weight does make a difference in handling. And yes, you're right about sucking up extra power. Fostang is correct about the 8" being more suitable for early Stangs. 300 HP and 3000 lb Stangs, especially, street driven, do well with 8" axles, especially in bumpy twisties. Also do well in drag strip runs.

Rev

------------------
'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

Jaydee · 02-19-2001, 08:23 AM

Still seems strange that an 8" with (pick a ratio) would feel substantually different than a 9" with the same ratio, in the same car. Almost seems that there is some other problem going on here.

------------------
1965 K code coupe - numbers matching - restoration ongoing. 1987 LX notch, stock heads and intake, 3.55's and typical bolt on's 13.89@100.25

Fostang · 02-19-2001, 03:54 PM

Thats what I thought jaydee. But I went through 4 different gear ratios in the 9". Still not good enough. Now with the 8" all you need to do is get in shut up and hold on.

02-19-2001, 07:23 PM

That is kind of weird how it would make that much of a difference in performance, but cars are weird like that sometimes.

I am planning on swapping my 8" rear out for a 9" with posi (Any posi unit advisable? I know the Detroit Locker is the best but it is expensive.) and 3.89s. With the power I'm making, should I go to the 9" or would the 8" be strong enough to handle the torque and power of my engine for quite awhile? I plan on getting the Performer RPM heads sooner or later too so keep that in mind. Thanks.

------------------
'69 Coupe with 351W
=========================
Edelbrock Performer-RPM intake manifold, Edelbrock Performer-RPM cam, Edelbrock lifters, Edelbrock 750 cfm carb, Accel coil, Moroso Blue-Max spark plug wires, Hedman headers, 2 1/2" pipe, glasspacks, Edelbrock double roller timing chain, Edelbrock valve springs, Flex fan, C4, Lakewood traction bars, 3:1 open rear-9" 3.89:1 posi coming this summer
=========================

02-16-2001, 07:20 PM	#1
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	9 inch rear ends Whats so good about 9 ich rear ends in older cars?? I put one on didn't like it seems to take off faster with the 8 inch? why all the hassle about having a 9 inch? They were the same gear ratio's. What type of rear end do you like your classic stang?

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02-16-2001, 09:07 PM	#2
Gearhead999 Registered Member Join Date: Sep 1998 Location: Oviedo, FL Posts: 992	9 inch was always the stronger rears. They have their pinion down lower on the ring that gives much more tooth contact. They also have the small support bearing on the nose of the pinion. Also, you can pop the pumpkin out to change ratio's easily. Be it a 8 inch or a 9 inch. They should both take off the same with the same gear ratio and tire size. 9 inch is heavier too.

02-16-2001, 11:11 PM	#3
69fastback IRAQ VET Join Date: Feb 2000 Location: high desert California Posts: 1,480	A ford 9" is the best rear money can buy. U really can't break one. Most gm cars that race have ford 9" rears. Also most people don't know this but every car in NASCAR has a ford 9" including the chevys and pontiacs. ------------------ 69 428 cobra jet: tons of mods. 97 f-150 5.4 xlt mark III BUCKLE UP. SUCK IT IN. Objects in the mirror are about to disappear... QUICKLY!!!!!!

02-17-2001, 10:36 AM	#4
shovelnose Registered Member Join Date: Oct 2000 Location: Ontario, Canada Posts: 234	I agree with the answers here. 1: Strength(3 pinion support bearings) 2: Ease of gear changes.(Can be done in 1/2hr) with the right tools. 3: No need for C-clip eliminators.(axles don't fly out) 4: The 8" was the same design but brings the weight down, also not as strong. Dana 44(I think is the #), I have heard this is even stronger than a 9". ------------------ 82 Mercury Capri 302. Comp. Cams Tremec 3550 3.73's 12.8@106 N/AKevin's Capri

02-17-2001, 01:20 PM	#5
Bob "Old School Gearhead" Join Date: Oct 1998 Location: Peru, Illinois Posts: 617	The dana 44 is a lot smaller than a 9" and is internal carrier type, like the 7.5 and 8.8's. They were used alot in 4wd applications as front units in F-150's and full size Bronco's. The Dana 60 is a beefier than a 9", but not nearly as easy to work on.

02-18-2001, 12:03 AM	#6
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	Since I put my 8" back in I am much happier. I had gone through a numerous number of gear swaps with the 9" and never had been able to get the performance I was able to obtain with this rearend. In fact I was so amazed with the difference it made. I laid a nice long thick thread about half a block. With the 9"er it was never able to do this. Maybe if I really got on it but would have to hold the break. Now I'm just seeing what this car was capable of. It seems to have lost the meaning of traction. Dont want to over do it though. Just seemed right to do it prob wont be doing that for a while. Gotta protect the investment.

02-18-2001, 05:13 AM	#7
COBRA66 Registered Member Join Date: Feb 1999 Location: Central Valley, Ca Posts: 58	Not to sound like a complete ****** here, but fostang do you have any idea what you are talking about. Performance has nothing to do with your rear end housing. The way your car takes off or rides or whatever will not change with an 8" or a 9". The gear ratio in the housing will make the differance though. The only reason people speak so highly of having a 9" is that like everyone else here said, they are vertually indestructable. Hope i didn't sound like a complete a$$ but the truth had to be said. Justin

02-18-2001, 12:54 PM	#8
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	Oh I know what you mean and I aknowlege that completely. It's just that after so many gear swaps I hadn't had that much take off. With the same ratio in both. Or even when I put a higher one in the 9"er it never took off as good. Yes, I know they are stronger thats why I put one on. But now that I have the 8"er I'm not going back ever. If I blow it out I'll just exchange it.

02-18-2001, 02:23 PM	#9
thunderbolt Registered Member Join Date: Oct 1998 Location: Houston, TX, USA Posts: 380	Rumor mill has it that the 9in sucks up more power than the 8in. If you are not running real serious ponies then the 8 should work fine. 1 more advantage to 9in. Tons of aftermarket parts available.

02-18-2001, 05:10 PM	#10
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	Thunder, unsprung weight does make a difference in handling. And yes, you're right about sucking up extra power. Fostang is correct about the 8" being more suitable for early Stangs. 300 HP and 3000 lb Stangs, especially, street driven, do well with 8" axles, especially in bumpy twisties. Also do well in drag strip runs. Rev ------------------ '66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph 1/4 mi.

02-19-2001, 08:23 AM	#11
Jaydee Registered Member Join Date: Sep 2000 Location: Conn. Posts: 220	Still seems strange that an 8" with (pick a ratio) would feel substantually different than a 9" with the same ratio, in the same car. Almost seems that there is some other problem going on here. ------------------ 1965 K code coupe - numbers matching - restoration ongoing. 1987 LX notch, stock heads and intake, 3.55's and typical bolt on's 13.89@100.25

02-19-2001, 03:54 PM	#12
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	Thats what I thought jaydee. But I went through 4 different gear ratios in the 9". Still not good enough. Now with the 8" all you need to do is get in shut up and hold on.

02-19-2001, 07:23 PM	#13
BennyBoy Guest Posts: n/a	That is kind of weird how it would make that much of a difference in performance, but cars are weird like that sometimes. I am planning on swapping my 8" rear out for a 9" with posi (Any posi unit advisable? I know the Detroit Locker is the best but it is expensive.) and 3.89s. With the power I'm making, should I go to the 9" or would the 8" be strong enough to handle the torque and power of my engine for quite awhile? I plan on getting the Performer RPM heads sooner or later too so keep that in mind. Thanks. ------------------ '69 Coupe with 351W ========================= Edelbrock Performer-RPM intake manifold, Edelbrock Performer-RPM cam, Edelbrock lifters, Edelbrock 750 cfm carb, Accel coil, Moroso Blue-Max spark plug wires, Hedman headers, 2 1/2" pipe, glasspacks, Edelbrock double roller timing chain, Edelbrock valve springs, Flex fan, C4, Lakewood traction bars, 3:1 open rear-9" 3.89:1 posi coming this summer =========================