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rear end swap

 
patrick77
I love my Chevy Chevette!
Posts: 2
Joined: 11/12
Posted: 11/22/12 03:50 PM

I have a stock 1985 monte carlo ss 305 g code motor and 2004r stock trans  just put in a limited slip from an 84 elcamino not sure what gears it has but now my speedo reads only half the speed i am really going  does any body know what gears would do this or is it an easy fix ?  

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chevelle83
I mow my lawn and find Chevys
Posts: 2280
Joined: 11/09
Posted: 11/22/12 09:38 PM

first you need to figure out which gear you have, pull the cover and check the gears or jack the car up and rotate both rear tires and count the revolutions of the drive shaft.

then you can call these folks and buy the correct speedo gear.

http://www.cpttransmission.com/

if you have to change both gears that would require opening up the trans and pulling the tail shaft out.  
which is a whole different deal.  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 11/23/12 01:00 AM

With a (G) code engine.  Engine in the Monte Carlo SS produced 180 HO Earlier 305 L-69. From 84-88 a Piggins Designed L-69 had a Camaro L-81 Camshaft should have been produced with a 3:73:1 Rear Gear Ratio. Which made them a neck snapper. The Later Monte Carls SS had 3:42:1 Rear Gears. Grin  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 11/23/12 02:51 AM

Patrick77
To correct your speedometer.
For a 3:42 Rear Gear you need. GM Drive Gear P/N 8639906 Color Green 10 Teeth
                              GM Driven Gear P/n 403999 Color Green 29 Teeth

For a 3:73 Rear Gear you need. GM Drive Gear P/N 8639906 Color Green 10 Teeth
                              GM Driven Gear P/N 410731 Color Black 27 Teeth

This is for the TH200-R4 Transmission to correct speedometer. Grin  Cool

Bob  

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patrick77
I love my Chevy Chevette!
Posts: 2
Joined: 11/12
Posted: 11/23/12 06:23 AM

I forgot to say that the rearend I removed was a 3.73 non limited slip  

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76Skylark
Big Block power for the win
Posts: 868
Joined: 12/11
Posted: 11/23/12 01:59 PM

If some how the 84 had a 350 trans and a 2.7's-3.08 rear gear?  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 11/23/12 03:03 PM

Patrick77 and 76Skylark:

In 1983 GM installed a 350-C transmission. That year the Monte Carlo SS was the slowest. It only had 165 Horse Power. As I said earlier the 1984-1988 The Cam was redisinged by Piggins. Then the SS wore the L-69 name plate. The Horse Power went to 180. They also had a 695CFM Quadra Jet Carb. The heads,Corvette L-81 camshaft .
 The SS also had a quicker steering box with a ratio of 16/12:7:1 variable ratio recirculating ball. GM also installed the F-41 Sport Susupension, from the Camaro. The early SS' had 3:42:1 rear gears with an open rear.An Eaton positraction was available. Grin  Cool  
  In 1985 GM installed 15" Aluminum Wheels. The TH200R4 (4) speed automatic was installed. In 1986 GM designed the Aero Coupe. It was so NASCAR could qualify it for the circut.
  Mostly built in Arlington Texas, From 83-88. POntiac Mi. Built them 87-88. Canada's SS's were built in Oshawa Ont. from 85-87.

In 1985 Car and Driver did a test. All stock!
0-100 25.6 Secs.
0-60 7.8 Secs
1/4 Mile 15.9 @86 MPH
0.80 G.Lateral Acceleration.
The 1983 was the slowest.
87-88 were the quickest.

  In 1986 the Aero Coupe was produced. 200 Aero Coupes Built in 1986.
A total of 6052 were produced. The lack of public interest was the down-fall.

The Crank was Cast Steel
Connecting Rods 1037-1038 Cast Steel
Cam .404/.450
Duration .202/.206 @ .050
Adv. Dur. .320/.320
Lobe Sep. 115 Degree.
Valve size 1.84/1.5
L-69 85-88 180 Horse Power @ 4,800 RPM
Maximum RPM 5,500 RPM
(G) Code Hi Output 305
  I purchased the 1986 Monte for my wife as a Christmas present. We took pocession of it 12-24-85. I put a Shift kit, and a set of 1.6 Roller Rocker Arms in my 1986 Monte Carlo SS. The 1.6 roller rockers really woke it up...It still pulls at 5800rpm. Grin  Cool
  I am the original owner. It has 55,000 miles never smoked in. It and never seen snow. The trans shift kit was something I came up with in the summer of 1986.
  That also has 3:73 Posi Rear Gears. It will snap your neck. It will also melt the tires if I wanted it too. It shifts hard enough it will Chirp 3rd gear.

Bob  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 11/23/12 09:51 PM

Patrick77
  Why don't you remove the 3:73 gear from your old rear. Then you won't have to purchase a set of gears or a posi unit...

Bob  

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