Technical 8.8 Ford rear end in a 1940 Ford coupe

I have a 1940 ford coupe with an 8" rear end w/ 3:25 gear (non-posi) I would like to upgrade to an 8.8" with disc and Posi trac around a 3.7 rear ratio. What year/vehicle should I be looking for with leaf spring pads? I do not have the car in my garage right now to measure the width of the 8" (I believe its out of a Granada) but if someone has done this swap I would appreciate a reply. The car currently has a CE dual spring set up with tube shocks, and sway bar(CE)
Thanks
Geoford41

 

I'd look at one from a Ranger. IIRC the earlier ones had a WMS measurement of 56.5" while later ones were 58". Some earlier Rangers had 56.5" ones that were 7.5's but the 8.8's are out there if you need 56.5 WMS to WMS. If the 8" you have is from a Grenada it is probably wider than 56.5" Ranger 3.73 Posi rear ends out of 4x4's are pretty easy to find but they are 5 on 4.5 not 5 on 5.5 Spring pads are on top of the rear end but the width will be wrong so you'll have to relocate them anyway.

 

Yup. All that.

I have a Ranger 8.8 in my Falcon.

 

I have been scrap booking info & this is an excerpt on the 8.8 axles.
"If you went with a '96 or newer Explorer axle they will have disc brakes. The 1990-1994 Explorer 8.8-inch axle came with 10-inch drum brakes. 1995 and newer Explorers have disc brakes. People have reported that they have swapped in a newer disc brake 8.8-inch axle in place of their original drum brake axle without having to switch to a disc brake master cylinder. Most ’91–’01 Explorers have 8.8s and 31-spline axles." The axle code for the limited slip 3.73 is L73. There are lots of articles on how to shorten the 8.8 rear end.
https://www.retreadtrails.com/blog/f88

 

8.8 rear ends in 1995 and up Explorers come with disc brakes, and have a 59.5" WMS to WMS. The pinion offset on both rears are 2 inches to the right. Rangers with 4.0 engines have 8.8s. The axle tubes are welded in on the Rangers, pressed in with a dimple on the Explorers.

 

I’d just pull the center out of the 8”, change the gear and add the posi unit, a lot easier than changing the whole rear. If you really want rear disc, the Explorer/Crown Vic are supposed to be a bolt on setup.


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Have a 8.8" 3.73 in my '39 Chev coupe, and it's the 5th 8.8" I've used in various builds. I love them, and beyond being super strong, they're the best bang for the buck of any decent posi axle. The late model Explorer axles are the easiest to find as a posi, and others are a lot tougher to find in a posi axle.
For a '40 Ford it wont really matter where the spring perches are, or if they even have a spring perch because they wont match your needs, nor will they be for the same width spring. So you'll need to weld new perches on, and set the pinion angle to fit your vehicle.

 

What 31apickup said.

 

My OT DD 97 Explorer has disc brakes, trak-lok with 3.73:1 and 31 spline axles. It's approx. 59.5" wide. If need be, shorten one axle tube (Driver's side) and use another short axle

OEM track, wheel mounting to wheel mounting surface width: 59.5"
Drivers side axle shaft length: 30.688"
Passenger side axle shaft length: 27.813"
Axle shaft length difference: 2.875"

This means cutting 2.875" out of the driver's/long side axle tube, resulting in an overall axle width of about 56.5". Conventional pinion flanges and other ratios are readily available. I can't recall the pinion offset, 2.5" or close to it.
Plenty of information out there,

• http://www.therangerstation.com/tech_library/Ford-8_8-axle.shtml
• https://www.therangerstation.com/tech/ford-8-8-inch-rear-axle-history-and-specs/

 

If the Ranger axle fits the bill, and you really must have disc brakes, Mustang discs can be fitted with minor mods.

I have Mustang Cobra discs on mine.

 

8.8 going under my 39 Chevy too! Axle tubes are 3 1/4" dia. so grab the u bolts from the exploder while you're at it and the driveshaft too so it matches your pinion. Make your life easier

 

I used a 2001 explorer, posi, . 3.73, 31 spline. Cut perches off and reset them to spring width and pinion angle. There are better charts out there but this is a summary

 

Well I have decided that the 8.8" is not going to work unless I cut it down to a 56" face to Face dimension, As) 31Apickup posted I really was looking for a Posi and a little better gear ratio (3:55) so even though the 8" Trac Loc rear end assembly is a little costly in the long run all i have to do is pull the axles and throw in the center section (I have a lift so its a little easier even for a 73 year old!)
Thanks for all the input.

 

I'm upgrading the rear end of my '54 Ranch Wagon that's going to have a 302/AOD combo. I considered having a 58" WMS 8" Ranger rear end narrowed to accept the 2 shorter axles to give me the 56" or so overall width I wanted (my initial search didn't turn up a 56.5" 8" Ranger unit). By the time I figured in the cost of narrowing the rear end, re setting up the gears with new bearings etc., and sourcing the shorter axle it wasn't in the budget. What I did end up doing was sourcing an 8" Maverick rear end that is 56.5" WMS and having 3.55's installed in the third member. The overall cost was probably about the same looking back but it is what it is. The one thing the guy who set up the third member told me is that the Maverick third member I had was a later unit that is stronger than the earlier 8" units. So if you're worried about an 8" being strong enough maybe a later pumpkin would be a thought. And if disc brakes are important they can be added.

 

Out of curiosity; what do you think the weight difference is between the Rotating Mass 8" vs 8.8 ? Noticable performance differences?

 

One of the main differences is the pinion location on the 8" is near the lower section of the ring gear same as a 9". This location gives superior gear engagement that leads to the strength issue versus a Salisbury type rear end like the 8.8 that the pinion engagement with the ring gear is more centrally located on the ring gear. The 8.8 rear makes up for that pinion angle with the ring gear size making them slightly superior to the 8". With that being said it does take more power to rotate the gears in an 8 or 9" than in a typical Salisbury rear with the same or larger ring gears.

 

Is 1/2" extra width, as in 1/4" per side, going to break the deal?

 

Cutting down an 8.8" is not a tough task, or expensive if you can't do it yourself. My local junkyard charges $20 for the short side axle, so that's all that's needed to purchase and narrow the wider 59.5" down to 56.5" width. And shops around me charge $50-$75 to narrow the tube to accept the shorter axle, so paying someone isn't expensive.
Can't imagine the slightly wider 59.5" vs. 59" would create a problem?

 

He's looking for 56".

A Ranger 8.8, circa 1990, is 56-1/2.

 

Does the shop doing the narrowing use a jig and does the quoted price include reinstalling the gears? If so that's a really good deal IMO, I was quoted $250.00 by a reputable shop just to do the narrowing using a jig. Maybe they saw me coming but from everything I found out about the shop they were top notch and their prices were in line with other area shops.

 

My clearance using TTD 15 X 6 with 3.66" offset leaves me about 3/8 between fender lip and tire wall. The coupe is just a 300 HP SBC 350/350 so its not a race car. The effort to switch out to the 8.8 is a lot of work and if I just look at going to a TRA LOC the cost of the 3:55 gear change is doable easily done in a few hours. I have seen a few U-Tube videos that make the shortening not that complicated BUT I am staying with the 8" Graada rear with the new posi center.

 

You can see how I narrowed mine here.

https://www.jalopyjournal.com/forum/threads/the-mild-custom-transformation-mamas-55.1119265/page-5

 

Just to add to the info here, a narrowed explorer rear that is 2 and 7/8's as stated correctly with 3 5/8's backspace wheels will be less than 48" between the tires. Measuring the distance on the wheel tubs will answer this question on many cars. Also, an 8.8 is 10% more efficient as per Ford's testing.

 

I charge $350 to narrow a housing, with a jig.

Overhead is higher here.

 

I have been running an 8 inch with a Yukon limited slip kit behind a 435 lb torque engine for several years now. I have not been gentle with it as I like to get up to the speed limit quickly. It's holding up fine. I think you will be satisfied with your choice. Nothing wrong with the 8.8 choice though. You have received a lot good advice here. It always amazes me how a simple question by one guy can lead to helpful and useful information that can used by many of us on our projects.

 

I think it comes down to what you can find (width, lug pattern) what it comes with (brakes, gears, limited-slip), and how much you want to put into it.

I work a lot more with 8.8s than anything these days, and the reason is real estate values. Yeah, I know that sounds weird, so let me explain.

Where I live, real estate is extremely expensive. The few remaining yards need to churn late-model stuff as quickly as possible. Nothing gets left to sit. Once the return from a vehicle has plateaued, it gets crushed and scrapped. Often that is not more than a month.

There is nothing old here to get, unless you go WAY inland, or buy from a private seller (who went way inland).

I have a jig, and can make the long-side of an Explorer housing into a short side, in about two hours, dead straight.

 

Yes, but he also said he wanted posi and disc brakes. So the 1990 Ranger isn't disc brakes.

 

True, so narrowing one is the ticket. Good ratio choices, and a high prevalence of limited slip differentials make them a win!

 

The 8.8" in my car does not have axle tubes...... It's got half shafts.....

 

Street rod?