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jpd37 05-04-2009 11:19 AM

Rear end swap for a GM 10 bolt
I'm in the middle of rebuilding my 37 Plymouth P-4 Sedan street rod. I am installing a rebuilt 1988 350 sbc bored .060 over w/ stock cam and flat tappet hydrailic lifters bolted to a 700r4 trans w/ stock torque converter. This package is replacing a 307 sbc w/ TH350 trans. Currently I have a GM 10 bolt reae end w/ 2.73 gears. I've been advised to change the gear to at least a 3.23 or a 3.42 to avoid premature overdrive downshift at moderate to highway speeds. I've learned my 8.2" rear end will not accept the larger gears, so I have to replace the whole assembly. I need a 60"-60 1/2" hub to hub axel to fit the body and I'm using 2 1/2" leaf springs. I have researched the Knowledge Base and found some data, but I'm just not comfortable yet with what I know.
Question: Is the advice I've received correct thus far?
Question: What make, model and year rear end do you recommend I should be buying?

Thanks for your advice.

cobalt327 05-04-2009 11:59 AM

To get you started, there are some rear end widths listed HERE.

alittle1 05-04-2009 01:35 PM

I would have said to go with a 68 or 69 Camaro, but they're pretty scarce right now. I would find a nice 10 bolt Corporate rear end w/ posi out of a 80 to 85 Camaro or Firebird.

I went with a 360, 727 tranny and 8 3/4 posi all Chryco and a Mustang ll front end on my '37 Plymouth to keep the wheel pattern all the same, but each to his own.

fast68 05-04-2009 02:24 PM

just for clarification purposes: the F body were totally redesigned in 82 and changed to coil rear suspension and 7.5"
or 9 bolt borg warner rears

jpd37 05-05-2009 10:49 AM

Hey, Alittle1, I have a bunch of questions for you. If you can reply with some specifics, I would really be grateful.

What make and model rear end did you use?
Did you have to modify the axle width or did you go with a stock dimension?
Does it have disk or drum brakes?
Is it set up for 2.50" leaf springs or did you reuse the original 1.75" leaf springs and spring perches?
Did you tub the body or are you using typical street tires inside the original fender wells?
Are you using a rear sway bar?
How much clearance do you have between the top of the axle tube and the frame?
Are you using axle bumpers between the frame and the axle?
If you were to build another 37 Plymouth, what would you do differently on the rear axle setup?

strokey 05-07-2009 08:27 AM

JPD- If you want to keep your rear you are currently using and install 3.23 and up gear purchase a ring gear spacer. There fairly cheap and this could probably save you some coin/headaches.


hotrod389 05-07-2009 09:14 AM

the tall geard 10 bolts are a pita when it comes to gear selection, espically the earlt 8.2 ring gear rears.

ive seen this spacer used a few times to install a shorter gear, one of them wasnt pretty. sheered the pinion in 2. but he was also running a 455 infront of it.

if this were my car, id run a 9". get the rearend length close and if its not perfect, make it so with rim spacing.

any rearend, regaurdless of suspension type will work, if the length is in the ball park.

spring perches cost about 20 bucks a set. cut off old brackets, and weld the new perches on. pay attention to the pinion angle!

to change gears in your 8.2 youll need that spacer, bearings and gears, thats over 275 dollars. if this is the route you choose, forget the spacer and install a spool. it will be a few dollars more, but both tires will be locked(remember this while driving in the rain)

a new rearend is your cheapest bet.

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