Moparchat - Home of MOPAR enthusiasts worldwide!



Go Back   Moparchat - Home of MOPAR enthusiasts worldwide! > Technical Forums > Performance Talk

Click here to search for Mopar cars and parts for sale.


Reply
 
Thread Tools Display Modes
  #1  
Old 02-23-2009, 12:16 AM
1978cordoba 1978cordoba is offline
Inactive User
 
Join Date: Nov 2008
Location: bethlehem, pa
Posts: 18
Default school me on gears

ok so i was talking to some on about gears and they told me that if i put like 4.10 gears in my car it will have better acceleration. i have a 1978 cordoba with a 8.25 rearend.
my question is basically can anyone tell me about re gearing and will it make my car faster and what the #s mean and what ones would best suit me, and basically just tall me all about gears. sorry for such a noob/general question

thanks a lot
mike
Reply With Quote
  #2  
Old 02-23-2009, 11:13 AM
peg leg peg leg is offline
Inactive User
 
Join Date: Jan 2005
Location: Star, Idaho
Age: 88
Posts: 2,669
Default Questions

Are how we all learn. Don't apologize for trying to get info!
Yes, 4.10 gears will accelerate your car faster. They will also reduce your fuel mileage by raising the engine RPM's at all speeds. That's why they cause faster acceleration. The engine is turning higher RPM's, and is developing more power at low speed. At 65 MPH, you would be turning about 3200 RPM!

I would not change any gearing until I knew what I have in the first place. See if there is a steel tag on the differential housing with the ratio stamped on it. If not, have someone who knows axles turn the drive shaft with the wheels off the ground, and count the number of turns the drive shaft makes for one turn of the wheel. That will get you in the ballpark, close to the actual ratio. Example: 3.2 driveshaft turns makes one tire rotation. That's a 3.23:1 ratio.
What engine is in the car? What mods have you made?
Reply With Quote
  #3  
Old 02-23-2009, 12:24 PM
passing you passing you is offline
Banned
 
Join Date: Dec 2008
Location: ca
Posts: 731
Default

gears multiply the torque your engine makes.
Add gear [numerically higher] and you will increase the cruise rpm at any given speed.
Reply With Quote
  #4  
Old 02-23-2009, 06:11 PM
rumblefish360's Avatar
rumblefish360 rumblefish360 is offline
Moparchat Bronze member
 
Join Date: May 2000
Location: C
Age: 57
Posts: 11,120
Default

Quote:
The engine is turning higher RPM's, and is developing more power at low speed. At 65 MPH, you would be turning about 3200 RPM!
SOrry, it may be splitting hairs, but not devceloping more power but releaseing the power in it's gear multiplied state. The engine never made more power. But I get what your saying.
(He has a 78 Cordoba. )
Reply With Quote
  #5  
Old 02-23-2009, 06:21 PM
rumblefish360's Avatar
rumblefish360 rumblefish360 is offline
Moparchat Bronze member
 
Join Date: May 2000
Location: C
Age: 57
Posts: 11,120
Default

1978, peg leg is right. He's on the side of caution as well. Lets not jump yet.

Your car has the 8-1/4. You can get a large verity of gears for that rear. The higher the gear ratio, the more RPM's you'll turn on the Hwy. Also, you'll need more RPM's for the same speed. There are calulators on line for this. I think you can get a basic one at Keisler since there selling OD trannys, they have a calc to play with. It helps them sell the tranny conversion.

Also, is your rear a suregrip equiped rear? (AKA - Posi)
If not you may really like to get a new suregrip unit before you do gears.

If your looking to hot rod the car a bit and still cruise the street and some Hwy travel, look to a set of 3.55's max.

If your looking to create a street light terror, start @ 4.10 to 4.56's. But these gears limit Hwy. driving to the right lane @ 50 - 55 mph MAX!
Reply With Quote
  #6  
Old 02-24-2009, 05:18 PM
4eyes 4eyes is offline
Inactive User
 
Join Date: Feb 2009
Location: indiana
Posts: 45
Default

if your gears are 3.25 that means that your drive shaft is turning 3 and a quarter turns to 1 turn of the rear wheels if your gears are 4.10 then your drive shaft is turning 4 and 1/10 of a turn to 1 wheel rotation thats what the ratios mean. passing you said it best. it is mutiplying horse power into torq. the bigger the ratio and more torq the more torq is what gets us moving not horse power also the higher rpm might mean slower top speed for your car if your asking witch makes your car faster thats one thing but if your asking for quicker thats another. bigger ratios are mostly for quicker
Reply With Quote
  #7  
Old 02-26-2009, 05:17 PM
1978cordoba 1978cordoba is offline
Inactive User
 
Join Date: Nov 2008
Location: bethlehem, pa
Posts: 18
Default

thanks a lot everyone for the replays i just looked at the tag on my axle and it said that i have 2.45 so im thinking that i want to get a different ratio and i know that some cherokees and dakotas and such also have 8.25 in the rear i was wondering if i would be able to use the ring and pinion out of one of those rears the swap into mine

thanks
mike
Reply With Quote
  #8  
Old 02-26-2009, 05:41 PM
rumblefish360's Avatar
rumblefish360 rumblefish360 is offline
Moparchat Bronze member
 
Join Date: May 2000
Location: C
Age: 57
Posts: 11,120
Default

Yes you can, but know this, they have a slightly different ring gear that holds the key to anti lock brakes. It'll work, but it'll look a little different.
Reply With Quote
  #9  
Old 02-26-2009, 09:42 PM
fox fox is offline
Inactive User
 
Join Date: Apr 2000
Location: Chatham, Il. usa
Age: 71
Posts: 834
Default

I'd suggest looking at a ratio of about 3.23 or 3.55.
your motor may run out of air/power sooner too. But it will be faster getting up to speed.
If you do jack it up to count the drive shaft turns, lift only one side and turn it TWO revolutions while counting the drive shaft turns.
If it has a suregrip axle you won't be able to turn one wheel, so jack both up and count the drive shaft with one one revolution of the wheels.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Old School Shatto Off-Topic Forum 6 10-24-2010 01:24 PM
Old school to New school pulley swap 74sunburst Dodge Viper Chat... 0 11-22-2009 12:18 PM
School's out! Dodgital Dakota Truck Forum 0 05-14-2003 10:16 PM
old school dodgeboy93 Dakota Truck Forum 5 12-22-2002 12:32 AM
WTB Complete Dana 70 rear 3.08 gears, or just the gears Thierry Trucks - Parts Wanted 0 08-31-2001 01:50 AM




All times are GMT -4. The time now is 04:06 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
. . . . .