Rear Axle: 65/66 Mustang REAR END, Silver Hawk swap!!

[Treblig]

Does anyone know the leaf spring perch width (center to center) on a '59 Silver hawk rear end?/ I'm replacing mine with a Ford 8 inch rear end and want to install (weld) the perches before removing the old differential.

PS - Please don't ask why I'm doing this!!!

treblig

[dynolou2]

What vehicle did the ford 8 inch come from? there are different widths. Lou Cote

[Alan]

You had better crawl under there and measure it. But most I have run across are between 41" and 41 1/2" inches.

[karterfred88]

Should be 40" if I remember right, 3/4" out on each side vs. explorer or ranger rear 8.8 at 38 1/2". Easy to measure, drop a plumb bob from center of each spring at center bolt and mark floor, measure between marks. Be sure to set nose angle correct or be ready to install tapered spacers to get it right later. Best to cut off the pads, slide axle in with new pads loose on axle, u-bolts through hangers (different diameter than Stude-need to slot holes), line up everything mark it or quick spot weld the perches, slide it out and get it welded right.

[Treblig]

What vehicle did the ford 8 inch come from? there are different widths. Lou Cote

It's a '66 Ford Mustang rear end but with the '69 heavy duty chunk. It's almost exactly the same width (within 1/8") from mounting surface to mounting surface. Will post pics later. The '69 Mustang rear end is wider, I also have one of those. The '69 would also work but I'd have to get different off set wheels.

Treblig

[Treblig]

Should be 40" if I remember right, 3/4" out on each side vs. explorer or ranger rear 8.8 at 38 1/2". Easy to measure, drop a plumb bob from center of each spring at center bolt and mark floor, measure between marks. Be sure to set nose angle correct or be ready to install tapered spacers to get it right later. Best to cut off the pads, slide axle in with new pads loose on axle, u-bolts through hangers (different diameter than Stude-need to slot holes), line up everything mark it or quick spot weld the perches, slide it out and get it welded right.

Your explanation on how to install is spot on. I've done this before so I appreciate what you're saying. Marking the floor using a plumb bob is a great idea. I already have the Ford rear end so it's easy to measure but it's a real pain to jack the car up, remove the wheels and get a good measurement. I was hoping someone would know so I could see if the Mustang perches were (by chance) close enough to use as is.
I do need to order new axle pads, I guess Mustang pads should work as well (the springs are the same width).

treblig

[Treblig]

Mustang rear end

Should be 40" if I remember right, 3/4" out on each side vs. explorer or ranger rear 8.8 at 38 1/2". Easy to measure, drop a plumb bob from center of each spring at center bolt and mark floor, measure between marks. Be sure to set nose angle correct or be ready to install tapered spacers to get it right later. Best to cut off the pads, slide axle in with new pads loose on axle, u-bolts through hangers (different diameter than Stude-need to slot holes), line up everything mark it or quick spot weld the perches, slide it out and get it welded right.

Well if it's forty inches on my Silver Hawk I'll have to move the perches. Looks like the Mustang (65 thru 69) has a 43 spring perch width. Mounting surface to mounting surface is 58 inches which is very close to the Silver Hawk. The '69 Mustang rear end is longer, I'll have pics later but the perches stayed in the same place. The '69 also comes with the heavy duty pumpkin which I'll also show later.

Treblig

[Alan]

Well, I went out and measured 4 cars. 2, 53K's. 1, 62 GT Hawk and a 63 Avanti. They all measured between 40 3/4" and 41 1/4". Treb, you can pull the springs out sideways a little and that rear should drop right on. Might cause a little bind in the bushings, but will work.

[Treblig]

Well, I went out and measured 4 cars. 2, 53K's. 1, 62 GT Hawk and a 63 Avanti. They all measured between 40 3/4" and 41 1/4". Treb, you can pull the springs out sideways a little and that rear should drop right on. Might cause a little bind in the bushings, but will work.

That's some great info!! I wonder if anyone here knows if any of those rear ends you measured (perch width) are the same as the '59 Silver Hawk?? I really need to get under my car and check it (tomorrow). It's probably 40-42 inches or so?? It's no big deal to remove the Mustang perch and install a new one in the correct spot. If the pinion angle is off by a degree or two I can easily correct it with some angle shims.

Treblig

[Treblig]

As promised here are the pics of the '69 Mustang rear end. As you can see, when compared to the 65/66 the '69 rear end has many more strengthening ribs on the pumpkin. The pumpkins are interchangeable so it's just a matter of pulling the axles and swapping the pumpkins. Axles are interchangeable (28 spline) but the '69 axles are longer. Around 59 1/2" - 59 3/4" mounting surface to mounting surface. My Silver Hawk Mounting to Mounting is around 58 3/8" like the '66 Mustang.

Treblig

[jpepper]

- - - Updated - - -- - - Updated - - -

If you need any other dimensions let me know.

[jpepper]

One other thing you should know. Ford added strengthening ribs on later housings but it was only marginally successful. The weak link was the bearing caps. They tended to break through the clip bolt hole. From 57 through about 70 or 71 the housings were standard cast gray iron. Only HD and severe duty housings were cast from nodular iron. (both 9" and 8"). Starting in about 72 all pumpkin/housings were cast from nodular iron and the added ribs from a few years prior were removed. The 72 and later pumpkins may look weaker but are stronger. The cap breakage problem went away with the material change on street vehicles. 9"s built for severe duty drag racing usually use billet steel caps. Just thought you should know this.

[Treblig]

- - - Updated - - -- - - Updated - - -

If you need any other dimensions let me know.

WOW jpepper!! That's some great info. This morning I jacked up the car and pretty much verified what you posted, the perches are 41" apart (center to center) as close as I could measure. But I'll have to disagree about the width on the 65/66 Mustang rear end. The one I have is 58" wide (see previously posted pics) and if I remember correctly the Silver Hawk is 58 3/8", that's only 3/16" per side which shouldn't make any difference at all.

However....the angle on the pad relative to the pinion is truly GREAT info and I appreciate it a lot. Now I can put the pads in the correct location AND also get the correctly pinion angle saving me lots of time laying on my back under the car getting welding splatter in my ears!!.

Now I'll have to go out and check the Mustang rear end to see if the pinion is off set to either side!! For anyone else thinking about this swap, here are some pics that show how much and where the pads will need to be moved (relocated). The chalk marks indicate (basically) where the center of the new pads will have to be located.

Thanks, GREAT INFO!!

Treblig

[5brown1]

How about changing the title of your thread so others will be able to find it in a search. Include the words axle, Mustang, 8" or something similar.

[Treblig]

Mustang Rear End Swap Silver Hawk

How about changing the title of your thread so others will be able to find it in a search. Include the words axle, Mustang, 8" or something similar.

I realized that after I saw the direction this thread was going but couldn't figure out how to change (edit) the title!!

Treblig