Inliners International Forums General Discussion Drive Train What's a Pumpkin?

Ok, I keep hearing the term "pumpkin rearend". What is it? Is this the rearend I'm looking at in my '50? Someone installed a later rearend. IOt has no bolts going around the housing as your looking at it from behind.

Thanks,

Butch

A pumpkin is a large round orange vegetable that is hollowed out and has a face carved in it for Halloween.

But in a car it refers to a removable center section in the rear axle. The bolts that hold it in the housing face toward the engine and after removing the axles the entire unit ( center section / gear carrier ) is removed. 55 to 57 Chevy rears and the popular 9 inch Ford rear are built this way, as are other makes.

Starting in 1965 in full sized GM cars the rear end was changed to what is commonly called a Rear Loader. These have a steel cover held onto the axle housing with 10 or 12 bolts as viewed from the rear bumper looking under the car. Gear ratio changes and clearance setting are more time consuming with a rear loader since the pinion gear remains in the housing after the ring gear carrier assembly is removed. A Ford rear loader that is getting more popular for street rod conversions is the 8.8 inch. Mopars and Dana's were rear loaders.

Mike G ( 4355 )

Interesting. So I most likely have a 55-57 rear end in this thing. What kind of a gear ratio came in the 55-57? (please don't tell me they varied). I'd just as soon keep it if it's going to work with my setup (by work I mean ok for city or highway driving)... I'm thinking a 250/th350 combo..I know I'm going to hear it from people that think I should do other combos, but this is the one that I've finally decided on.

IF the rear end is from a 55 - 57 Chevy then the axle ratios offered were 3.36, 3.55, 3.70 as shipped from the factory depending on the engine / trans combo. Dealer installed 4.11 and 4.56 ratios were also available. That exact axle with a pumpkin was used right up through 1964 but starting in 1958 Chevy used coil springs in the rear so the bracketry had to be removed and leaf spring pads welded onto the tubes to use one in an earlier leaf spring car. That's why the 55 - 57 rears are the most commonly used in the pre 55 cars. The 58 -64 axles had a variety of ratios from 3.08, 3.23, 3.36, 3.55, 3.70, and 4.11 again depending on the year and the drive train package or how the customer special ordered the car.

One thing you didn't mention was whether or not the car has a conventional open drive shaft or is still using the torque tube. The torque tube rear ends also bolted in from the front and some even had a removeable rear cover as well. The 55 - 57 axle uses an open driveshaft. Your original 50 axle was a torque tube set up.

I have no idea exactly which ratio you may have but running a TH350 with any of those gears will work ok. The 3.70 might be a little stiff for highway driving but the 3.36 and 3.55 are good all around ratios and 19 points difference in ratios amounts to about 200 rpm difference at highway speeds, hardly worth worrying about.
4.11 and 4.56 are not highway gears unless you have an overdrive trans.

Mike G ( 4355 )

Thanks. Yes, it's a open driveline. Somebody had done an update before I received the car (the later 235, powerglide and open driveline). Side Note: I just located a '79 4 door Nova complete and running with a 250 six, TH350.. all this for only $350. Perhaps the rearend in this car will work as well. Love the idea of buying the complete car and stripping it for the parts. What a savings of time and money!

A 55-57 era rear axle is the best you can get for that car. I would leave it alone.

These were used in 'muscle cars' throughout the 60s & 70s.

If it had a Powerglide It's a high ratio.

Good luck, John M...

Not meaning to be smart or find fault, just keen to set the record straight...

Chrysler rear axles, where the Dana wasn't specified as an option or even standard equipment, were what we call 'banjo' housings with what we call 'nosepieces' bolted into them... ie. 'pumpkins'.

The ones I know about are the 8 3/4" (most full size Mopar cars from 1957 on) and the 8 1/4" (pretty much all before that time). I imagine that the 9 1/4" is also a 'nosepiece' or 'pumpkin' style, it seems to live in stuff like the Imperials and big-power cars like the 426 Hemis etc of the sixties.

My main point is that there was a lot of Mopar stuff that wasn't 'rear loader' style (known better to me as a 'Salisbury').