8 inch rear end advice

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jtgb428
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8 inch rear end advice

Post by jtgb428 »

Hey guys, I'm in need of some schooling...roughly 15 years ago I had a 1,500 dollar pickup truck a friend wanted real bad...he gave me a grand and a bunch of parts for my 1965 Caliente... My friend is a Ford fanatic and has had some very nice muscle cars..one of the items he have me as a 8 inch posi center section that he said was stuffed with the best of parts and was worth roughly 800 bucks alone..he mentioned that it had 389 gears in it..I have a 8 inch rear in my comet and would like to install this unit in there..is there anyway of telling what size gears are in this unit without taking it apart? My friend has passed away so getting more details isn't going to happen..I would like to make sure it is what he described before having it installed...thanks, Jim...

popscomet
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Re: 8 inch rear end advice

Post by popscomet »

count the number of teeth on the ring gear and divide it by the number of teeth on the pinion gear,,,,,that'll get you close.......
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popscomet
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Re: 8 inch rear end advice

Post by popscomet »

another thing to always keep in mind.....the thicker the ring gear,,,,the lower ratio it will be....pop
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jtgb428
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Re: 8 inch rear end advice

Post by jtgb428 »

Hey Pops, thanks a bunch..if it pans out just mite be a nice little way to wake up my mildly built 289..thanks, Jim..

popscomet
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Re: 8 inch rear end advice

Post by popscomet »

if you have a clutch it will be great.,and don't do much free way driving.....
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jtgb428
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Re: 8 inch rear end advice

Post by jtgb428 »

Well I don't do any freeway driving just bomb around town..I don't think 389s will be to low and it's a cheap way to improve performance.. I have a tci streetfighter trans with a 2500 - 2800 stal converter but I would like a 5 speed manual conversion... I will see how it acts with the setup I have now but disc brakes at least on the front is my next move after installing the center section...Jim...

popscomet
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Location: Jacksonville, Arkansas

Re: 8 inch rear end advice

Post by popscomet »

I had added a stall verter in my post,,,but deleted that part,,,,your set up will be a lot of fun tooling around town,,it will quick on the trigger,,,,,those gears will work great with a 5spd,,,even on the freeway....best of both worlds,,,pop
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popscomet
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Re: 8 inch rear end advice

Post by popscomet »

I have a 1984 mercury 5.0 5spd CAPRI,,with a very strong built engine long tube headers and other goodies and I installed an 8.8 3.73 LS rear gear,,,it is quick on the trigger,,,,so a 3.89 will bring a smile to you fast,,,,pop
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jtgb428
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Re: 8 inch rear end advice

Post by jtgb428 »

Hey Pop, I will get a pic or 2 of my comet on here very soon..it's nothing like your car, mine is a work in progress and has been put on the back burner for 15 years..I'm still paying for kids college and weddings (4 girls) but I'm inching closer...my car is a weekend warrior, 289 edelbrock rpm dual plane, 500 cfm 4bbl, long tubes with flow masters, fuel cell, mallory unilite dizzy, aluminium radiator, no back seat that is being tinned in, stock cam but runs strong, crites hood and front bumper, no carpet, no headliner..making car as light a possible..don't want a picture perfect car, I've had a few, just like being different..going to get some slapper bars and frame connectors this week, front disc brake kit next week and a few other things and will hopefully be crusing this summer..she's got some tiger hair but the white paint hides things nicely..thanks for your info and if you don't mind I will be asking you for advice from time to time if you don't mind...your car looks great...thanks Jim Jtgb428...

Joe Travers
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Location: Louisiana

Re: 8 inch rear end advice

Post by Joe Travers »

jtgb428 wrote:
Wed Feb 10, 2021 10:46 pm
Well I don't do any freeway driving just bomb around town..I don't think 389s will be to low and it's a cheap way to improve performance..
The guy sold me my car said 3.55+ ratio, based off his calculations but he didn't count driveshaft revolutions. I'm pretty sure I'm running the same gear you have, or very close. It's a street stomper, for sure. Can't drive it on the freeway without winding it out a good bit but like you, I romp around on the street and old 2 lane highways. You'll have happy face, for sure. :D

JT
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fryedaddy
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Re: 8 inch rear end advice

Post by fryedaddy »

i have put a 3.25,3.50,3.89 and 4.11 gears in my comet over the years.it has a 4.11 in it now but when it goes im looking for another 3.89.it was my favorite gear for the street.it will take off well and its not so low you cant drive it.great all around gear!
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popscomet
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Re: 8 inch rear end advice

Post by popscomet »

right now outside there is a solid sheet of ice,,,,so when it thaws and walking is safe,,,I'll go out to shop and get the cam number of the cam shaft I have in my comet,,and my factory five cobra 289 and my 5.0 capri....that is how much I like that camshaft....it works great with either 1 4bbl or with 2 4bbl....I also like a gear drive,,have a pete jackson on the comet and a edelbrock acu-drive on the cobra......thank you for the kind words,,,POP don't get on here and tell many people what to do ,,I am from the old school ,if I ain't had my hands on it... keep it to my self,,,there is lots of go to guys on here then there is a few libary mechanics....but over all this is the place to be for help and or advice,,have a great day,,,,wife just told me we in for some snow in a day or so,,,ground is so cold it'll stick for sure,,,,pop,is staying inside and warm and dry,,,if at all possible..............
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lavron
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Re: 8 inch rear end advice

Post by lavron »

popscomet wrote:
Thu Feb 11, 2021 3:57 pm
wife just told me we in for some snow in a day or so,,,ground is so cold it'll stick for sure,,,,pop,is staying inside and warm and dry,,,if at all possible..............
Sounds like Pop gets his weather forecasts the same way I do, from the wife :P It just keeps snowing here, the wife said 2"4" on top of what we already have out there, mostly ice, we already canceled church on Sunday with the weather, and the preacher has been sick :roll:

Of course, by the doctor's orders, I have been staying inside, the only thing I am good at right now is sleeping a lot :lol: I guess my body is trying to heal this infection. I have stuffed a cart full of rubber seals on the Steele Rubber website but haven't pressed the money button yet, I wish the vent windows did not need to be rebuilt, that is expensive when you also have to replace every other seal on the car, but once that is done it will be tighter than it ever has been since I have owned it and I will probably never have to do it again, I thought about trying to find a different set of wing windows but I figured any I could buy would need the seals replaced as well, so I may as well rebuild mine, I will try to document the process when I do it so anyone who is attempting to do the same thing in the future will be able to see how I did it, and learn from any mistakes I might make.

I need to get some welting or whatever it is called and my headliner, I think for some reason I want a black headliner so that is probably what I will get, anyone have prefered vendor for those kinds of things?

See Ya,
Mike
64 Comet 202 Sedan, My first car, I have owned it since 1979!
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Performance rebuild on a BUDGET - Installed; 250-6, T-5, 8.8 LSD, MII, Air Ride - Boxes are too restrictive I would much rather think outside of them :wink:

Joe Travers
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Re: 8 inch rear end advice

Post by Joe Travers »

lavron wrote:
Fri Feb 12, 2021 8:36 am
I thought about trying to find a different set of wing windows but I figured any I could buy would need the seals replaced as well, so I may as well rebuild mine, I will try to document the process when I do it so anyone who is attempting to do the same thing in the future will be able to see how I did it, and learn from any mistakes I might make.
Please do, Mike. The latch handle is missing on my driver's side vent window. I need to hustle up another and replace it. Looks like it's all one piece and can't be disassembled? I have a pretty good idea how to replace the whole thing. I'm going to do the window felts at the same time while the panel is off and the glass is pulled. My upper seals are like new.

Thanks

JT
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fryedaddy
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Re: 8 inch rear end advice

Post by fryedaddy »

you can check a rear end ratio with the rear end gear already installed in the car.jack up the back half of the car,put in neutral.and spin the drive wheel,turn the tire-wheel two turns,count how many times the yolk turns to get the ratio.three and a half turns of the yolk is 3.50,the 3.89 should turn a little over three and three quarter turns of the yolk.just thought i would throw that in here,everyone probably already knew this.
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