rear end help (car, not me)

[dmdsprite 1]

Hi,

recently got a 70 vert that's undergoing an engine swap.  Trying to figure out rear end options, and still have a little confusion.  there's a few for sale locally, but I'm not sure if they're suitable...someone's selling an 8.8 from a 94 mustang, with disc brakes.  From reading various forums, it sounds like this will be 1/4 inch longer per side than the 70?  does that matter, or will that work?  There's also a 79 f-150 9-inch...I'm just a little unclear if that can be narrowed to fit?  Thanks!

[aslanefe 333]

1 hour ago, dmdsprite said:

Hi,

recently got a 70 vert that's undergoing an engine swap.  Trying to figure out rear end options, and still have a little confusion.  there's a few for sale locally, but I'm not sure if they're suitable...someone's selling an 8.8 from a 94 mustang, with disc brakes.  From reading various forums, it sounds like this will be 1/4 inch longer per side than the 70?  does that matter, or will that work?  There's also a 79 f-150 9-inch...I'm just a little unclear if that can be narrowed to fit?  Thanks!

If it is a daily driver/cruiser with a small block which is not modified for more power, even the smaller 7.25 inch that came on 6 cylinder will work. I have been using one over 25 years on one of my cars.

[dmdsprite 1]

Yes, I'll be driving it frequently...but the engine is a stroked 351...probably between 400-450 hp/torque.  Definitely need the beefier rear end.

thanks.

[det0326 179]

Any rear end that's not out of the early Mustangs, Cougars and so on, will need modifying in some form or another. An example would be the later mustang 8.8 you speak of would need possible brackets cut off it and leaf spring perches added. The difference in width could be corrected with the proper offset wheel but if you want the depth of the  fronts to match you may have to possibly add spacers. 

 

I used an 8.8 from an explorer which gave me a 373 gear limited slip and disc brakes. I centered the pinion and bought new custom length axles. If I was going to build another rear end to handle more horsepower I would just use the correct Mustang 9 inch with traction lock. It will cost more money but well worth it in my opinion.

[dmdsprite 1]

8 minutes ago, det0326 said:

Any rear end that's not out of the early Mustangs, Cougars and so on, will need modifying in some form or another. An example would be the later mustang 8.8 you speak of would need possible brackets cut off it and leaf spring perches added. The difference in width could be corrected with the proper offset wheel but if you want the depth of the  fronts to match you may have to possibly add spacers. 

 

I used an 8.8 from an explorer which gave me a 373 gear limited slip and disc brakes. I centered the pinion and bought new custom length axles. If I was going to build another rear end to handle more horsepower I would just use the correct Mustang 9 inch with traction lock. It will cost more money but well worth it in my opinion.

Thanks, yeah, I know modifications are needed...but it sounds like some models/years, modifications can't be done...either due to tapered axles, or whatever.  For the explorers, my concern was that once you center it, isn't it too narrow for a 67-70? 

[Mach1 Driver 560]

Ford 9" rear axles are legendary and used in all manner of street rods... and fortunately for me it came stock on my Mach1. If you want a limited slip I recommend: https://www.eaton.com/us/en-us/catalog/differentials/eaton-detroit-truetrac-differential.html

[Vicfreg 771]

I used a 8.8 from a Ford Ranger with a 3.73 gearset. I had to cut all the brackets off, and then re-weld the spring perches on.  It has worked out well. One drawback is that I don't like the Ranger rear emergency brake design. It for sure is a struggle with the '68 pull handle to set the parking brake, maybe not so with the '70 foot operated one.

dmdsprite - I also have a '70 Vert with a 393 stroker, so let's share some notes on that. My car is pretty much done and waiting just for paint and body.

For my '70, I built my own 9" Ford rear.  I got the parts from Quick Performance, great outfit. They built me a big tube housing, which has the sealed bearings that are pressed on. I used 31 spline axels, a nodular center section, and 2004 Mustang Cobra rear brakes with the Mustang Steve brackets.  Bolted right in.

I included pics of the axles with the lengths on them

 

[Vicfreg 771]

Correction from my last post, on my '68 coupe I used the 8.8.  On my '70 I used the 9"

[dmdsprite 1]

14 hours ago, Vicfreg said:

I used a 8.8 from a Ford Ranger with a 3.73 gearset. I had to cut all the brackets off, and then re-weld the spring perches on.  It has worked out well. One drawback is that I don't like the Ranger rear emergency brake design. It for sure is a struggle with the '68 pull handle to set the parking brake, maybe not so with the '70 foot operated one.

dmdsprite - I also have a '70 Vert with a 393 stroker, so let's share some notes on that. My car is pretty much done and waiting just for paint and body.

For my '70, I built my own 9" Ford rear.  I got the parts from Quick Performance, great outfit. They built me a big tube housing, which has the sealed bearings that are pressed on. I used 31 spline axels, a nodular center section, and 2004 Mustang Cobra rear brakes with the Mustang Steve brackets.  Bolted right in.

I included pics of the axles with the lengths on them

Thanks for all the great info and photos.  I'd love to go with a new 9", but this project is spinning out of control, and I'm trying to save money somewhere.  Is the 94 mustang 8.8 rear just too long/wide? Can a truck 9" be cut down, and just get new axles (I think the 28 spline can't be cut)?  Once you cut the explorer 8.8 to center it, is it not too narrow?  sorry, just a lot of info to sort out.  

[det0326 179]

 For the explorers, my concern was that once you center it, isn't it too narrow for a 67-70? 

If u cut the normal 3 inches off the long side and use a short side axle on the shortened side then yes it will be around 56 inches and pinion out of center 1 inch the other way. I did it a little different than most I cut 2 inches off long side and added the 2 inch piece  to short side making the pinion in the center. Down side I had to get 2 custom made axles that cost me around $300 for the pair. 

Yes the 94 mustang rear end housing can be used. As I said u may have to use an offset wheel to prevent tire rub on the outside lip of the quarter/wheel house. Yes the truck rear end can be used too. It would have to be cut and new ends welded back on. Any rear end housing can be cut and welded back but it is not an easy task. The reason some axles can't be cut is the spline dia.  tapers off smaller and it is not large enough to cut new splines. Keep in mind too that u may have to cut drive shaft or possibly have a new one made depending on which rear end u use or the length of the yoke.

[dmdsprite 1]

1 hour ago, det0326 said:

 For the explorers, my concern was that once you center it, isn't it too narrow for a 67-70? 

If u cut the normal 3 inches off the long side and use a short side axle on the shortened side then yes it will be around 56 inches and pinion out of center 1 inch the other way. I did it a little different than most I cut 2 inches off long side and added the 2 inch piece  to short side making the pinion in the center. Down side I had to get 2 custom made axles that cost me around $300 for the pair. 

Yes the 94 mustang rear end housing can be used. As I said u may have to use an offset wheel to prevent tire rub on the outside lip of the quarter/wheel house. Yes the truck rear end can be used too. It would have to be cut and new ends welded back on. Any rear end housing can be cut and welded back but it is not an easy task. The reason some axles can't be cut is the spline dia.  tapers off smaller and it is not large enough to cut new splines. Keep in mind too that u may have to cut drive shaft or possibly have a new one made depending on which rear end u use or the length of the yoke.

Gotcha, that makes sense what you did with the 8.8.  will this work:

https://www.speedwaymotors.com/Speedway-9-Inch-Ford-Cut-to-Fit-Axles-w-Bearings-Big-Ford-Pair,447298.html

...oops, just realized those are for the 9 inch...

[dmdsprite 1]

how's highway driving with the 3.73?  Seems like to get the limited slip, it has to be the 3.73...I'd rather have a lower gear, for better highway driving and better mpg...I figure with a 393, it's going to be plenty quick even with a 3.27...but it seems like the 3.27 and 3.55 don't have lsd.

[skidmarky 50]

39 minutes ago, dmdsprite said:

how's highway driving with the 3.73?  Seems like to get the limited slip, it has to be the 3.73...I'd rather have a lower gear, for better highway driving and better mpg...I figure with a 393, it's going to be plenty quick even with a 3.27...but it seems like the 3.27 and 3.55 don't have lsd.

What transmission are you going with?

[det0326 179]

3 hours ago, dmdsprite said:

how's highway driving with the 3.73?  Seems like to get the limited slip, it has to be the 3.73...I'd rather have a lower gear, for better highway driving and better mpg...I figure with a 393, it's going to be plenty quick even with a 3.27...but it seems like the 3.27 and 3.55 don't have lsd.

I used the AOD that was heavily modified, which I would not do again, which made the 373 gear tolerable. If I was not going with overdrive transmission of some sort I believe  I would stay around  320s or 330s lot of people use 350 on street without overdrive and it works but is a little much for interstate driving.

[Vicfreg 771]

You don't have to cut any axles or the rear.  I directly installed a Ford Ranger 3.73 posi into my 1968 Mustang coupe. The center section is slightly offset, but that did not interfere with anything.   The width was perfect.

My '68 coupe with the 3.73 has a Ford Motorsport "T-5Z" 5 speed transmission in it.  It works very well.  Super quick, but good highway cruiser.

My '70 Vert with the 9" rear has a 3.25 posi.  I picked this because I am using a vintage C-6 with a 1:1 3rd gear.  I also wanted to avoid the stall region of my torque converter at highway speeds

 

Here are some 8.8 rear end widths:

• 1990-1992 Ford Ranger 8.8-Inch Axle – 56.50 inches
• 1993-2009 Ford Ranger 8.8-inch Axle – 58.50 inches
• 2010-2011 Ford Ranger 8.8-Inch Axle – 58.50 inches *
• 1991-2003 Ford Explorer 8.8-Inch Axle – 59.625 inches
• 1989-1997 Ford Aerostar 8.8-Inch Axle – 62.50 inches
• 1983-1996 Ford Bronco 8.8-Inch Axle – 65.125 inches
• 1986-1993 Ford Mustang 8.8-Inch Axle – 59.25 inches
• 1994-2004 Ford Mustang 8.8-Inch Axle – 61.25 inches
• 1989-1999 Ford Crown Victoria 8.8-Inch Axle – 62.50 inches

Here is a great site with all the pertinent info

Ford 8.8-Inch Rear Axle History & Specs - The Ranger Station

[Vicfreg 771]

Here are some pics of the 8.8 that went into my '68..

 

[dmdsprite 1]

More great info.  Thanks.  I had read that if you don't do something about the offset, you "may" have issues if passengers are in the back seat, or if you have things in the trunk, with bumping / rubbing of the rear end into the floor pans (I think...I've read so many threads on this that things are getting jumbled together at this point).  Vicfreg, just noticed you're in Charlotte...bought my car from a guy in Haw River, not too too far from you.  He's currently doing the work on it (hopefully).  I'm in Raleigh.

 

[Vicfreg 771]

I had no problem with the offset, and my '68 is lowered 1"+ from stock height.   You will need to modify the driveshaft and in particular, the rear u-joint, but lots of shops that can do that for you.  

Cool that you are in Raleigh.  I am working out of the country a bit, but will be more available after mid-year.   Would love to stop by and check out the car.  Vic

[dmdsprite 1]

19 hours ago, Vicfreg said:

I had no problem with the offset, and my '68 is lowered 1"+ from stock height.   You will need to modify the driveshaft and in particular, the rear u-joint, but lots of shops that can do that for you.  

Cool that you are in Raleigh.  I am working out of the country a bit, but will be more available after mid-year.   Would love to stop by and check out the car.  Vic

sounds great.  I just found a guy selling a 69 fairlane 9 inch...says it needs to be "cleaned up", but I think I'm going with that, if he doesn't sell it before I can pick it up.  Just need to figure out how to "clean" it up.  Maybe pressure washer, wire brush, and paint?

[Vicfreg 771]

Too wide I think a couple inches wider than a Mustang. But, not 100% sure, perhaps others can comment.

 

[dmdsprite 1]

Pretty sure the 69 fairlane is same as 67 to 70 mustang, and the later fairlane is same as 71 to 73 mustang. 

Anyone do the mustang steve or similar rear disc adapters? Lets you use 94 mustang cobra discs on the rear.  I'm thinking that rather than spending money getting the rear drums working, might make more sense to just put discs on it.

[Vicfreg 771]

I have the Mustang Steve brackets on the rear end with 94 cobra brakes.  it is in my pictures above.  When I get back to my shop, I will take another picture, I had to rotate the calipers to the front side of the car to avoid interference with my rear sway bar hardware.

I used stock 1994 Mustang emergency brake cables, works great.  I have pics/details on that I can share.

Vic

 

[jmlay 80]

https://m.roadkillcustoms.com/ford-9-inch-rear-end-widths-and-potential-donor-cars/