4T80E 3.11 to 3.71 swap

[MisterBlue]

Originally Posted by Maxb49

Is there a significant improvement in acceleration?

Yes, on the order of .3 to .5 tenths of a second in the 0-60 time. Passing times (50-70) wouldn't be as significantly affected, though.

[AJxtcman]

I did a 3.11 to 3.71 gear swap today in less than 1 hr.
Custom cradle hepls

Now it is even faster

[BlackCaddy87]

What was the total cost of this swap?

[AJxtcman]

Originally Posted by BlackCaddy87

What was the total cost of this swap?

$0.00

It was in my very own little turd.

I am well aware that the 99 and prior needs the correct trans calibration to shift correctly. The 00+ is much easiers to swap that part of the program so now I have to work that out of my 99 program. It bounces of the revlimiter about 10 times before it will shift

[BlackCaddy87]

What all is needed to do this swap and how much money would it take?

[AJxtcman]

Originally Posted by 94greencaddysls

Could this swap be done with from 3.11 to 3.71 without a computer modification? I have a 94 so I OBDI, I'm just thinking an inline resistor of some sort could modulate the signal to the computer and fool it, though I really dont know how the signal works. I have my trans apart and the differential at hand, I'm just not sure how I could get the computer to co-op with me. Any ideas? or electronics wizards?

From what I have experienced you will need to change the PCM program on 93 to 99 cars. the 00 to 03 may not require it. I am not sure.

Originally Posted by BlackCaddy87

What all is needed to do this swap and how much money would it take?

You need 3 parts + fluid
Carrier #24205233 List $659.60 Trademotion.com $379.73
Sun gear #08678825 List $144.56 Trademotion.com $83.22
The Extension Case to Case Seal $??
Fluid about 6 quarts
96 to 99 PCM tune for this $200
$700 or so. New

[AJxtcman]

[dalamak]

I was thinkgin about this swap myself, did you ever do it?

[Highline Cady]

Yep, been running around with the gears for well over a year now, threw in a stall while we were doing it. Love it!!! Should have been the first thing I did was get rid of those 3.11's. I personally think the 3.71's work real nice with the "base" cams. Why they didn't come from the factory that way, I'll never understand, they do stick the higher gear with the base N* finally but only in Pontiacs, go figure. God the Corsa's cackle on the highway from the extra rpms, I love that too!

[dalamak]

So it requires you to drop the Transmisson to do it?

[dalamak]

I Gonna be doing this swap, to wake up my SLS, MY question are the indicated tools Necessary, I don't see them refered to in the Procedure?

Also I have a 2001 STS Computer, since this swap is being done with a 2001 SLS, Is it better to swap the computers to have the Shift points match up but throw the fuel/timing tabels off or is it better to leave the SLS PCM and have the shift points off?

Originally Posted by AJxtcman

2000 to 2005 Devilles and Sevilles.
Case Extension Replacement
Tools Required
• J 8001 Dial Indicator Set

• J 25025-7A Dial Indicator Mounting Post

• J 28585 Snap Ring Remover

Removal Procedure

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
2. Support the vehicle with safety stands.
3. Remove the right drive axle. Refer to Wheel Drive Shaft Replacement .
4. Remove the wiring harness.
5. Remove the vehicle speed sensor. Refer to Vehicle Speed Sensor Replacement .
6. Remove the right transmission to engine brace. Refer to Transaxle Brace Replacement .
7. Remove the ground wire from the case.
8. 
   
   FIG #1
9. Remove the following parts from the case extension:
10. • Five 13 mm bolts (128, 129)
    
11. • One 15 mm stud (127)
    
12. Remove the case extension (134) and the seal (126).
13. Remove the roller thrust bearing (132) and the selective washer (133).
14. 
    FIG #2
    
15. Remove the 8 mm scavenge tube bolt.
16. Remove the scavenge tube by prying on the differential.
17. Remove the scavenge tube seal.

.
.
Final Drive Assembly Replacement
Removal Procedure

1. Remove the case extension. Refer to Case Extension Replacement .
2. 
   
   FIG #3
3. Rotate the manual shaft (16) counterclockwise in order to place the transaxle in Park (P) and prevent the differential from rotating.
4. 
   FIG #4
   
5. Remove the 4 bolts (119) from the differential housing to transaxle case.
6. Remove the differential carrier.
7. 
   FIG #5
   
8. Push on the output shaft in order to expose the left side differential gear snap ring. Remove the left side differential gear to output shaft snap ring (56).
9. Remove the differential side gear (118) and thrust washer (117).
10. 
    FIG #6
    
11. Remove the final drive carrier (100) and the thrust bearing.
12. Remove the final drive sun gear (121).

Installation Procedure

FIG #7

1. Install the sun gear (121) with the bushing and the seal side facing differential.
2. Install the final drive carrier (100). Turn the unit until it meshes with the sun gear and the internal gear teeth.
3. 
   FIG #8
   
4. Install the left thrush washer (117).
5. Install the left differential side gear (118).
6. Install the snap ring (56).
7. 
   FIG #9
   
8. Use the manual shaft to place the transaxle in park.
9. This will lock up the final drive unit. The actuator rod will move up.
   
10. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
    
11. Install the differential housing and the four bolts (119). Hand tighten, using a star pattern.
12. Tighten
13. Tighten the bolts to 76 N·m (56 lb ft).
    
14. Install the case extension. Refer to Case Extension Replacement .

[K STS]

Highline and AJ,

I was thinking about doing a swap from the base 2.73 gears in my 1SE V8 STS to the 1SG 3.42 gears. Do you think either of you would have any information this install, IE whats required, etc?

[K STS]

bump...

[submariner409]

The title of this thread is "4T80E 3.11 to 3.71 swap".

You are fooling with an entirely different critter. Based on your Profile post count you can PM either member and/or maybe start a new thread here or up in RWD STS.

[K STS]

I tried to start a new thread, it got moved to the 05-2010 STS section?