Rear End Help

[N/ACrazy]

F/22/fl
I've made a thread previously but can't seem to navigate correctly on the site to find it or the responses. I'm fairly new to the drag racing. So here's my issue. I need a rear end that has the highest gear ratio for the highway. Was it the automatic of the
93 n/a's that has it? It would make sense. I have a built 2.3l half esslinger motor that was in my stock car years
Back. Now its in a gutted notchback. Motor and trannie have been moved back 2.4 inches for weight transfer.
it has the new aluminum head that's as beefed as it'll get. All forged internals. Bored 30 over. 150 shot. Drag lights. Mickys slicks. 80 lbs lead weight in the back right.(4.5 inches to the right from center to help even tire
Lift). 2480lbs with me in it and only getting lighter. Also I need the lightest rear end with the smallest rear gear to
Swap for race day. Figure you guys would have some tricks of the trade for me you wouldn't mind giving
up.

 

[Shawneebear93]

The autos have 3.73s, manuals have 3.45s.

 

[N/ACrazy]

Thanks. Any. Ford rear end that was in the 200's region or is that silly?

 

[N/ACrazy]

Thanks. Any. Ford rear end that was in the 200's region or is that silly?

 

[Shawneebear93]

I think the manual Fox Body 5.0's have 2.73's.

 

[tca7291]

If you are planning to pull it from a car, check the ID sticker inside the drivers door jam. It will have a little box labeled "AX" and a single digit code under it. 8 is an open 2.73, M is a trac-loc 2.73, Y is open 3.08, Z is loc 3.08, F is open 3.45, R is loc 3.45, 5 is open 3.27, E is loc 3.27, 6 is open 3.73, W is loc 3.73, 2 is open 3.55, and K is loc 3.55. This is all for a 1991 Mustang, but I believe the codes are the same for at least the majority of foxes. Hope this helps!

 

[tca7291]

Oh yeah, my buddies 1990 5.0 automatic has an M code (8.8 trac-loc 2.73), and my 1991 manual 2.3 has the 2 code (7.5 open 3.55), but has had an aftermarket 3.73 set put in. All 2.3 have a 7.5 rear, and 5.0 have the 8.8 rear, but they swap straight out except for the break line. But you can take the brake line off the 7.5 rear and it will fit right on the 8.8 rear.

 

[N/ACrazy]

Nice! Thanks! Gonna hit craigslist or the junk yard ASAP. I knew i could count on the boys to help a girl out.ha with the car being just under 2500lbs and having more power then a stock 5.0 a 273 should be no problem for it to pull on the highway. I'll let hall know the mpg. Thanks again.

 

[rd]

I have Fox rears from 2.47 to 4.56. You can find most ratios in both 7.5 or 8.8.

If you do some internet searching you can find lists of door sticker codes as noted. Explorers are a good source of 8.8 31 spline posi units. Rangers are good for 7.5 stuff.

 

[tca7291]

N/ACrazy- please let me know how it turns out because I've been debating on doing a 5.0 swap, or building my 2.3 up. I use the car as a daily driver and planning on keeping it that way. Don't really want to do the turbo swap, mostly because if I do any swap it will be to a 5.0, but really want to know how your built 2.3 handles on a regular driving basis. Keep us informed!

 

[Shawneebear93]

All 2.3 have a 7.5 rear, and 5.0 have the 8.8 rear, but they swap straight out except for the break line. But you can take the brake line off the 7.5 rear and it will fit right on the 8.8 rear.

So it is a straight swap or not? You said the brake line doesn't swap straight out but then said it will fit right on?

 

[tca7291]

Yes, it is a straight swap. The brakes are the same, but the line from the body to the flex hose on the 7.5 is on the passenger side, and it is on the driver's side on the 8.8s. If you take the line off of the 7.5 rear that runs along the axle and use that to replace said line on the 8.8 rear it will fit right in. The only other difference is the mounts for the dual shock setup on the 8.8 (the shocks that sit horizontally), which can be omitted.

 

[N/ACrazy]

I daily drive it now on the highway and around town. Idle is high for this HUGE cam.ha i keep mobile 1 oil in it for 9k miles and change the filter every 3k and just ad a quart. 93 oct only and 110 oct when i spray it. Been doing this for 30k miles now and that was after 65 laps screaming on the track when i retired it 5 years ago. My brother does the boosted 5.0 stuff. In my eyes to much work for tuneing and money. Without a good tune 10lbs of boost won't do anything for you. Only sprayed a 150 on it twice. Probably won't handle to many more. On 110 Oct its dynoed at 255hp and 223lbs.

 

[N/ACrazy]

O ya and thanks for the help guys. Didn't think these "mustang" forums were this helpful. I'll take vids and pics soon...of my car.LOL

 

[N/ACrazy]

Went to the junk yard and found a 2.47 in an 83 f150. Gonna change the fluid hopefully it wasn't sittn to long for moisture to build up. O well then ill change seals. Thanks guys.

 

[tca7291]

Are you just goin for the gears, or tryin to swap the whole axle assembly? I believe the truck axles are a whole different tube legnth/axle legnth, as well as control arm mounts.

 

[rd]

Any Fox housing will bolt in. The brake lines can be swapped whatever way you need. I have had both 7.5 and 8.8 housings in my 82. My 79 Capri came with a 2.47. Fairmonts and Thunderbirds are bolt ins, but Tbird axle shafts are longer. The truck housings are different, but the gears will interchange. Note that an F150 will have an 8.8 gear set and a 31 spline diff, not a 7.5. Most Rangers, B2's and Aerostars had the 7.5. IIrc you did not say which axle you have or want to use.

 

[N/ACrazy]

It was a lot for me to swallow so I gave in and had my brother tacial it. Got the 2.47 gear and put it in the 8.8 for me. 36 mpg on the highway with a high performance nitrous breathing 2.3l mustang! Ha

 

[Sharad]

It was a lot for me to swallow so I gave in and had my brother tacial it. Got the 2.47 gear and put it in the 8.8 for me. 36 mpg on the highway with a high performance nitrous breathing 2.3l mustang! Ha

Being light will help ease the load a little, but honestly if you're making decent power and launching hard on slicks, you really need to consider upgrading the axles and diff. Suspension upgrades are critical as well, but I'm sure you've already thought of that.