"driveline lathe":shock:, it must have been a BIG ONE! The local shop here that's shortening and balancing my driveshaft said they couldn't do it "because of the size of the center section." (from the looks of thier machine, it might do up to 8" in diameter?)

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1964 Dart GT

Its big,,,,they mostly do graders , excavators ,log trucks and yarders.

They think an 8.8 is tiny....

must confess my ignorance. why is this a desirable swap? disc brake upgrade, or some other reason?

Since I'm currently collecting information on the "how," I at least can answer the "why": It is MUCH stronger than the stock 7.25" or even 8.25" Mopar rear ends, they are dirt-cheap relative to clean Mopar units with limited slip/locker differentials, they have better 'performance' rear ratios of 3.73 or 4.10 without any additional kits involved, get disc brakes if you get the right year, replacement/upgrade parts are cheap and plentiful, and they allow you to use a modern 5-bolt wheel pattern for a much greater selection of wheels.

The only catch is that if you convert the rear to discs, you have to do the same with the front, not to mention convert to the same wheel bolt pattern, which can get pricey... but hey, still cheaper and easier to find than a decent Mopar 8.75" rear.

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1972 Plymouth Duster:
- 225ci
- Offy 4-Barrel Intake
- Weber 38/38 DGES
- Clifford headers
- Split 2.25" dual exhaust
- Pertronix digital ignition conversion
- Black-out custom digital gauges
- Front disc brake conversion
- Viper Blue

I am doing the conversion for Performance (ie: Better Brakes, Beefier Axles & Splines, a Real Parking/Emergency Brake!), other perks are parts availability, and reasonable cost.

-Good usable as is condition 1998 Ford Explorer 8.8 ($100)
-extra short side axle ($35)
-Diff. gasket, Seals, brake pads and shoes(parking),brake hoses, wheel bearings, New brake hardware ($98 )
-New Heavy Duty Spring perches ($28 )

so parts I am in alittle over $250 ( I will pay a professional to do the welding, but I will do everything else)

guess $100 for welding and another $50 for drill bits sand paper and paint.

TOTAL = $400(+-) for a Stout Rear Axle behind my Slant!

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1964 Dart GT

glad i asked. the ford 9 inch is a common swap among the v8 crowd (such as forward lookers). now i will start looking for an 8.8 for future use. didn't know i could upgrade to rear discs so easily. my rear end was recently serviced, but still clunks when i put it in reverse, so it won't be around for ever.

even though i am trying to get rid of various junk, it's not a bad idea to look now because the race car boys have snapped up all the ford driveshafts. they like to use them for straight pipes. meanwhile, the ford 300 six fans have snapped up all the chevy rockers for a cheap "cam upgrade." funny how lovers of one make can cause a run on the parts of another!

Ford 9's are expensive (like Mopar 8 3/4!). This is a very affordable swap in my opinion.


Sure it's your rear end? Transmission? U-Joints? Idle off?

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1964 Dart GT

Kind of along the lines of this topic, is there anybody here that had a 3.55, 3.73, or 4.10 8.8" rear put in? I keep reading and running calculators (:roll:), but having never changed the rear ratio on anything, can somebody testify to the driving "feel" and or performance gains after having done the swap from something like a 2.72 ratio 7.25" rear? How much did it liven-up your ride in terms of feel or numbers? Thanks!

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1972 Plymouth Duster:
- 225ci
- Offy 4-Barrel Intake
- Weber 38/38 DGES
- Clifford headers
- Split 2.25" dual exhaust
- Pertronix digital ignition conversion
- Black-out custom digital gauges
- Front disc brake conversion
- Viper Blue

I installed a 3.55 8.8

I have had it installed in 2 cars. The car pictured below and my 65 Valiant.

The Desoto is a 4 speed OD automatic (4L60)

The Valiant was a manual 5 speed OD.

Without OD the 3.55 would be noisy on the highway.

The size of your tires can make a big difference. On the Desoto I use 265/75/15 tires. With the 3.55 gears they give me the same effective ratio as 3.23 gears and 225/75/15 tires.

I do that so my speedo is correct and the puter thinks its in its donor car.

(I can cruise all day at 100 km/hr at 2000 rpm.....or 160km at 3000.)


On the Valiant I used 235/60/14 tires 80 mph at 2300 rpm in 5th

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Looks like my total wheel diameter will be about 27" with my 15" rims, however after researching all of the madness associated with the speedo cable and the dang gears to adjust for ratios and tire diameter, I just got a GPS speedo sender unit... getting installed at a shop as I type this. lol

Doing the math, my 3.73 rear will put me at about 1,000 RPM higher than you at 103 kmph (65 mph), and topping-out at around 6,000 RPM and 207 kmph (129 mph). I'm OK with that. I <3 engine revs... just need it to survive for a few more months until the head comes out and pistons, rods, valve train, compression, etc get upgraded. I'm OK with 'noisy'... The '94 NSX regularly gets redlined at 8,000 RPM with a custom race exhaust, and I would not have it any other way.

The real question is just how much more lively is the car getting up to those speeds? Is the acceleration substantial by your seat radar? Any modern-car comparisons anybody can make? I mean I know it was not going to be a sports car when I bought mine stock with all of 110 hp (at best), but still curious as to what changing some of those ratios really does for stuff like 0-60 and 1/4 mile times. To quote Ricky Bobby: "I wanna go fast!"... but mostly on my drive to work daily. lol

I guess in worst-case scenario I will find-out just how much of a "feel" difference it will make once the trany is rebuilt and I'm ready to pull the trigger on getting that rear end that's been sitting in my garage for 6 months into my car... maybe I can even enlist the girlfriend to assist in doing some timing for me before and after.

EDIT: I just realized the new Summit Racing speedometer I'm having put-in can track both 0-60 and 1/4 mile... I don't know how useful that will be while missing a 3rd gear currently (well, maybe just 0-60), but I should be able to test and record my times with the rebuilt transmission. I wonder what other toys I'm forgetting about laying around the house.

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1972 Plymouth Duster:
- 225ci
- Offy 4-Barrel Intake
- Weber 38/38 DGES
- Clifford headers
- Split 2.25" dual exhaust
- Pertronix digital ignition conversion
- Black-out custom digital gauges
- Front disc brake conversion
- Viper Blue

UPDATE: - Don't follow me I'm lost!

O.K., I can admit when I am wrong, and trying to press the axle tube out is wrong! Drilled out the weld/rivets all the way through the axle tube just to make sure they were gone. Made a jig to hold the axle tube and press the casing off of the tube! 20 ton press and the tube wouldn't budge!
Easy way is like Sandy mentioned! Cut the tube and weld them back together.
The FORD 8.8 rearends are all alittle different and you need to measure and re-measure everything. 2-7/8" wasn't enough. I had to cut 3" out to make the tubes even (17" from back of brake mount to casing)
This actually made things somewhat easier as I was able to cut the tube flush with the casing and still have enough to even it up before reinstalling the tube.


Further Updates to follow!

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1964 Dart GT