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Author
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Topic: rear end gear sizes?
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trashline
Gearhead Posts: 1217
From: Levittown, Pa
Registered: Dec 2003
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posted 02-11-2004 06:55 PM
   
im guessing the higher the number thats the number of times the ring gear spins with one revolution of the pinion? so what would be a good rear gear size. i was told the stock 6 cyl is 2.70 and someone said that 3.50 would be better. obviously but can i find a new rear end or can i just put new gears in the rear?------------------
1966 mustang coupe
200ci 3 speed tranny
msd 6a ignition, blaster 2 coil, 2 inch exhaust to a glass pac, stock rear, single out header, cold air intake (homemade).
white w/ black interior
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SteveLaRiviere
Administrator Posts: 42139
From: Saco, Maine
Registered: May 99
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posted 02-11-2004 07:02 PM
If you still have the door tag you can read the code and find out what you have, and there's also a tag on one of the rear end cover bolts that will give you that info.Get the codes off either and we'll tell you what you have. ------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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trashline
Gearhead Posts: 1217
From: Levittown, Pa
Registered: Dec 2003
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posted 02-11-2004 07:17 PM
ok here are the tag numbers the door numbers are 65c2c810l2326 there was a space where the axle number was so it must not be the original tag. the diff tag from what i could read was wyce up top and then 320 6 902 the 6 didnt look like the rest of the numbers but it was on there so thanks in advance------------------
1966 mustang coupe
200ci 3 speed tranny
msd 6a ignition, blaster 2 coil, 2 inch exhaust to a glass pac, stock rear, single out header, cold air intake (homemade).
white w/ black interior
IP: Logged |
SteveLaRiviere
Administrator Posts: 42139
From: Saco, Maine
Registered: May 99
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posted 02-11-2004 07:33 PM
quote:
Originally posted by trashline:
ok here are the tag numbers the door numbers are 65c2c810l2326 there was a space where the axle number was so it must not be the original tag. the diff tag from what i could read was wyce up top and then 320 6 902 the 6 didnt look like the rest of the numbers but it was on there so thanks in advance
You have a 3.20 rear. I wouldn't change it. ------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
IP: Logged |
SteveLaRiviere
Administrator Posts: 42139
From: Saco, Maine
Registered: May 99
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posted 02-11-2004 07:48 PM
Either your door or your axle have been changed, because your door tag decodes as:65C Hardtop with standard trim and bench seat
2 {must be a Z?} Sauturne Gold
C8 Parchment vinyl and parchment vinyl rosette with ivy gold, bench seat
10L December 10, 1965
23 {must be 28?} Louisville
2 2.83 axle {?}
6 C4 automatic {?} My guess is this was a replacement door. Check the VIN on the door tag, it probably doesn't match your dash VIN. ------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip [This message has been edited by SteveLaRiviere (edited 02-11-2004).]
IP: Logged |
johnmustang
Gearhead Posts: 5701
From: British Columbia , Canada
Registered: Nov 2001
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posted 02-11-2004 08:32 PM
quote:
Originally posted by SteveLaRiviere:
My guess is this was a replacement door. Check the VIN on the door tag, it probably doesn't match your dash VIN.
Unless I am mistaken there is no VIN on the dash of the 65. Didn,t the dash VIN begin in 68?
------------------
JOHN
65 FASTBACK 2+2.....14.44 @ 107mph 1/4
87 TAURUS WAGON
03 F150 XLT SUPER CREW 4X4 SHORT BOX
Member:Vancouver Island Mustang Association
M&M #1710
65 FASTBACK
2003 F150 XLT SUPER CREW 4X4
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trashline
Gearhead Posts: 1217
From: Levittown, Pa
Registered: Dec 2003
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posted 02-11-2004 09:09 PM
i will check the vins tomorrow with the door and the engine compartment but im pretty sure they both match up. my car doesnt have a bench seat though
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trashline
Gearhead Posts: 1217
From: Levittown, Pa
Registered: Dec 2003
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posted 02-12-2004 12:18 AM
i cant remember if there is or not but i did check the numbers on the inner fender and the door and they match. it could possibly be right. but my car doesnt seem to be that great off the line. once i get to like 3000rpm in first im doing like 20mph . but i know for a fact that when im doing 80mph (according to speedometer) im really doing like 65 so somthing is different not to sure------------------
1966 mustang coupe
200ci 3 speed tranny
msd 6a ignition, blaster 2 coil, 2 inch exhaust to a glass pac, stock rear, single out header, cold air intake (homemade).
white w/ black interior
IP: Logged |
mustangboy
Gearhead Posts: 773
From: Ont, Canada
Registered: Mar 2002
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posted 02-12-2004 12:55 AM
quote:
Originally posted by trashline:
im guessing the higher the number thats the number of times the ring gear spins with one revolution of the pinion? so what would be a good rear gear size. i was told the stock 6 cyl is 2.70 and someone said that 3.50 would be better. obviously but can i find a new rear end or can i just put new gears in the rear?
Actually you've got it backwards.The ratio refers to the number of times the pinion turns to one revolution of the ring gear.Its easy to find out your ratio just jack up the car and turn the rear wheels one revolution.The number of times the driveshaft turns is your ratio.
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1968 mustang j-code sprint.13.69@101 306cu.in, stock ported heads,weiand exellerator,650 holley DP,hedman hedders,comp 292 Magnum cam,4-speed,8 inch 4.11 detroit locker http://mustangsandmore.50megs.com/MembersPics/mustangboy.html
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SteveLaRiviere
Administrator Posts: 42139
From: Saco, Maine
Registered: May 99
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posted 02-12-2004 07:46 AM
quote:
Originally posted by johnmustang:
Unless I am mistaken there is no VIN on the dash of the 65. Didn,t the dash VIN begin in 68?
I'm sure you're right, I keep forgetting the older Mustang details. ------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
IP: Logged |
indyphil
Gearhead Posts: 2255
From: Senoia, G.A. USA
Registered: Jul 2002
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posted 02-12-2004 10:01 AM
I John is right, my 68 has an engine bay VIN, but some had dash vins.Sounds like Trashline has a 3.2 axle in a 2.8 car. if this is true then at 70mph his speedo will read 80mph. which is close to what he said. Someone swapped the rear end but didnt swap the speedo gear.
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'68 coupe 289 C code
66 heads, edel 600cfm carb, performer intake, dual exhaust http://www.geocities.com/ottouk_77/68mustang.htm
IP: Logged |
trashline
Gearhead Posts: 1217
From: Levittown, Pa
Registered: Dec 2003
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posted 02-12-2004 10:27 AM
so everyone thinks i should keep it like that? now heres another question if indypil is write then what speedo gear should i have? so let me ask another question. why would they do it like that it almost sounds stupid id think to get more out of the rear you go to a lower gear bc if its take 3.2 times of spin on the motor to spin the tires one revolution i think id mush rather be with the 2.8 . hmm tryin gto think so i dont look as stupid (too late). and i can understand what your al saying bc the pinion is smaller then the ring. i mean it feels like my car is going to blow up when i haul ass in second and shift around 3300 rpm. so i thought ok maybe higher gear maybe id be able to go quicker and use my second gear longer but i guess i was wrong. thanks for the info all------------------
1966 mustang coupe
200ci 3 speed tranny
msd 6a ignition, blaster 2 coil, 2 inch exhaust to a glass pac, stock rear, single out header, cold air intake (homemade).
white w/ black interior
IP: Logged |
adragon8u
Gearhead Posts: 4768
From: Oceano, Ca. member# 2895
Registered: Mar 2003
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posted 02-12-2004 10:49 AM
Trashline: I know just where you're coming from. My 66 had a 6 cyl. and someone before me dropped in a 289. My speedo is also off by about 10 mph. But I don't believe the rpm to speed ratio is linear. at what should be 40mph, it turns 2 grand, but at what should be 70 (as I found out the other day) it turns 3 grand. I still think a taller rearend would be nice though.------------------
http://webpages.charter.net/adragon8u/mystang
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trashline
Gearhead Posts: 1217
From: Levittown, Pa
Registered: Dec 2003
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posted 02-12-2004 12:09 PM
ok so then in third gear if im doing 3000rpm im doing 70mph? or thats what it should be doing bc if im driving at 3000rpm my speedo says 85 huh is there a way to find out what speedo gear i need? obviously pull it out but what if is like a 19 tooth or somthing do i go to a16 or like a 23 i dont know------------------
1966 mustang coupe
200ci 3 speed tranny
msd 6a ignition, blaster 2 coil, 2 inch exhaust to a glass pac, stock rear, single out header, cold air intake (homemade).
white w/ black interior
IP: Logged |
indyphil
Gearhead Posts: 2255
From: Senoia, G.A. USA
Registered: Jul 2002
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posted 02-12-2004 12:40 PM
The ratio change in the axle will dictate the speedo gear change in the tranny. And that part IS linear.The larger number rear end is like being held in a lower gear. this improves acceleration but makes the engine rev faster. in extreme cases you will see a loss in top speed (because the engine cant rev any faster). But this is of course well above most posted limits. If you are unhappy with the acceleration of your car the last thing you want to do is go back to a 2.8 ratio rear end. But If you dont like the way the engine revs too fast when you are driving along then maybe you should change back. adragon8u
You are right, you may turn 2000RPM at 40mph and only 3000RPM at 70mph. thats the torque converter at work. That doesnt happen in stick shift cars as long as the clutch is working. Modern automatic equipped cars also have a "lockup" torque converter which acts more like a direct drive while cruising and under light loads. ------------------
'68 coupe 289 C code
66 heads, edel 600cfm carb, performer intake, dual exhaust http://www.geocities.com/ottouk_77/68mustang.htm
IP: Logged |
68 S-code GT
Gearhead Posts: 2194
From: Sayreville, NJ, US
Registered: Mar 2000
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posted 02-13-2004 11:56 AM
The first year for the dash mounted VIN tag was 68 but it was mounted on the passenger side and not the driver side. I?ve noticed that the aluminum rivets that hold them down corrode very easily and if the windshield leaks the rivets get eaten up and the tag comes loose.
IP: Logged |
trashline
Gearhead Posts: 1217
From: Levittown, Pa
Registered: Dec 2003
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posted 02-13-2004 12:47 PM
is there an easy way to figure out what size speedo gear i need? i read steves thing in the tech section but i dont know what gear size my car had in it before and theres nothing on the door plate?------------------
1966 mustang coupe
200ci 3 speed tranny
msd 6a ignition, blaster 2 coil, 2 inch exhaust to a glass pac, stock rear, single out header, cold air intake (homemade).
white w/ black interior
IP: Logged |
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