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One trait about an automatic transmission is that one could tailor it's shifting time, feel, and/or make effective service repairs, modifications on the car providing the knowledge, expertise and tools are available. For the 4T60-E there is an easy way to have a more aggressive FDR (Final Drive Ratio). That ratio is a rather notable 3.73:1 FDR. This FDR will raise the operation speeds of the engine of them being the RPM at which the engine cruises but, it all still remains quiet. Also fuel economy is not changed greatly if at all, and cruising speeds put the engine in a better place for passing. Also there is more initial response.
To obtain the parts needed to have a 3.73:1 FDR You will need to have access to a 4T60-E from the following cars:
'91-'96 GM W-cars ('93-'96 3.1-3100, possibly later 3100 Luminas up to '02, '91-'97 3.4 TDC), '94-'96 GM N body cars will actually do as well. You should note the tone wheel on the end of the FDR, for a W car it will note and will have 30 teeth, for an N car it will note and have 29 teeth. The N car FDR will be good for cars with small wheels and/or tires (aspect ratio and or diameter). It will make the speedometer more accurate. Now if you have a 3.4 TDC with an Automatic, then you have the right Drive Chain Sprocket Ratio (DCSR) and all you'll need is the FDR Gear set. If you have a 440-T4 (4T60), 4T60-E mated to a 2.8, 3.1, 3100 then you have the right FDR and all you need is the DCSR.
3.4X TDC Code CWW- This is the easiest procedure to locate parts and replace the FDR. Locate a ‘93 3.1 with a 4T60E CODE-CMW, or a 3100 W-car is preferred. If in the car pop out the axle and remove Engine/Trans support brace. Unplug the VSS (vehicle speed sensor), remove the 4 bolts that hold the FDR extension housing, remove the extension housing, Torrington Bearing (flat washer bearing), and if it isn’t stuck to the FDR, the thrust washer, -and set all the parts aside. At this time you should be viewing the differential/FDR. Looking at the four spider gears (the straight cut beveled gears), the gear inner most towards the Transaxle case there will be the stub end of a shaft through the center. On the end of that shaft there will be a C-Clip. With a suitable tool (pliers are acceptable), position it on the ends of the C-Clip. With a hammer pound the tool and the clip should disengage the shaft and fly off. Save the C-Clip as a spare. Now carefully without disturbing the center shaft if possible, remove the FDR. Behind the FDR there will be the Output Sun, remove that as well. In most cases it will all come out together. With a new FDR and sun gear obtained from a 3.1 or a 3100(W or N car) mated 4T60-E transaxle, install. Procedures are reverse.
2.8W-3.1T/3100M,J CWM Code- This procedure is reserved for the experienced Mechanic that understands the automatic transmission. This procedure can be adapted to scavenging a DSCR from a CWW trans as well. DCSR from a CWW 3.4 TDC transmission will need to be obtained. Also you will need a Side cover gasket set (depending on year), and a valve body/channel plate gasket service kit. At this time you may also want to replace solenoids and DCSR thrust washers and replaced the drive chain as well. Drop the trans pan, drain fluid, replace the filter, and reinstall the pan. As per GM service manual, obtain access to the side cover and remove it. As per GM service manual remove everything needed to remove the channel plate. The DCSR and chain should now be completely visible. Now to be quite frank... you can actually start to pull the innards out and overhaul the transaxle thoroughly. But to focus back on the DCSR, remove the 4th clutch plates and the 4th clutch hub (just pull repeatedly on it if it does not want to pull out all the way). Remove the plastic DCSR thrust washers. Being careful not to remove the Driven Sprocket support, start pulling both chain sprockets and chain, making sure the driven sprocket is biased towards being removed first. Make sure you pull the drive Sprocket only as far as it’s willing to go possibly about a ½ an inch. The DCSR will come off the driven side 1st. Replace parts as necessary; replacement is reverse as per Technical Manual. Makes sure that if the chain has a blue link, keep it faced the same said it was installed, either facing the pump or facing the Torque converter. Note if the Drive Chain is replaced with either a new chain or a chain that wasn’t in service with the sprockets then you may hear a slight whine under power in lower speeds. This whine is actually very appealing, very classic sounding. DON’T FORGET TO FILL YOUR TRANSMISSION UP TO THE CORRECT FLUID LEVEL!!! USE DEXRON3/MERCON FLUID ONLY.
The 3.73 FDR is one of the many ways to refit the 440-T4/ 4T60-E. This ratio will help your application step off the line a lot better and make cruising a snap. Proper understanding of the transmissions is mandated before making any attempt on refit.
To obtain the parts needed to have a 3.73:1 FDR You will need to have access to a 4T60-E from the following cars:
'91-'96 GM W-cars ('93-'96 3.1-3100, possibly later 3100 Luminas up to '02, '91-'97 3.4 TDC), '94-'96 GM N body cars will actually do as well. You should note the tone wheel on the end of the FDR, for a W car it will note and will have 30 teeth, for an N car it will note and have 29 teeth. The N car FDR will be good for cars with small wheels and/or tires (aspect ratio and or diameter). It will make the speedometer more accurate. Now if you have a 3.4 TDC with an Automatic, then you have the right Drive Chain Sprocket Ratio (DCSR) and all you'll need is the FDR Gear set. If you have a 440-T4 (4T60), 4T60-E mated to a 2.8, 3.1, 3100 then you have the right FDR and all you need is the DCSR.
3.4X TDC Code CWW- This is the easiest procedure to locate parts and replace the FDR. Locate a ‘93 3.1 with a 4T60E CODE-CMW, or a 3100 W-car is preferred. If in the car pop out the axle and remove Engine/Trans support brace. Unplug the VSS (vehicle speed sensor), remove the 4 bolts that hold the FDR extension housing, remove the extension housing, Torrington Bearing (flat washer bearing), and if it isn’t stuck to the FDR, the thrust washer, -and set all the parts aside. At this time you should be viewing the differential/FDR. Looking at the four spider gears (the straight cut beveled gears), the gear inner most towards the Transaxle case there will be the stub end of a shaft through the center. On the end of that shaft there will be a C-Clip. With a suitable tool (pliers are acceptable), position it on the ends of the C-Clip. With a hammer pound the tool and the clip should disengage the shaft and fly off. Save the C-Clip as a spare. Now carefully without disturbing the center shaft if possible, remove the FDR. Behind the FDR there will be the Output Sun, remove that as well. In most cases it will all come out together. With a new FDR and sun gear obtained from a 3.1 or a 3100(W or N car) mated 4T60-E transaxle, install. Procedures are reverse.
2.8W-3.1T/3100M,J CWM Code- This procedure is reserved for the experienced Mechanic that understands the automatic transmission. This procedure can be adapted to scavenging a DSCR from a CWW trans as well. DCSR from a CWW 3.4 TDC transmission will need to be obtained. Also you will need a Side cover gasket set (depending on year), and a valve body/channel plate gasket service kit. At this time you may also want to replace solenoids and DCSR thrust washers and replaced the drive chain as well. Drop the trans pan, drain fluid, replace the filter, and reinstall the pan. As per GM service manual, obtain access to the side cover and remove it. As per GM service manual remove everything needed to remove the channel plate. The DCSR and chain should now be completely visible. Now to be quite frank... you can actually start to pull the innards out and overhaul the transaxle thoroughly. But to focus back on the DCSR, remove the 4th clutch plates and the 4th clutch hub (just pull repeatedly on it if it does not want to pull out all the way). Remove the plastic DCSR thrust washers. Being careful not to remove the Driven Sprocket support, start pulling both chain sprockets and chain, making sure the driven sprocket is biased towards being removed first. Make sure you pull the drive Sprocket only as far as it’s willing to go possibly about a ½ an inch. The DCSR will come off the driven side 1st. Replace parts as necessary; replacement is reverse as per Technical Manual. Makes sure that if the chain has a blue link, keep it faced the same said it was installed, either facing the pump or facing the Torque converter. Note if the Drive Chain is replaced with either a new chain or a chain that wasn’t in service with the sprockets then you may hear a slight whine under power in lower speeds. This whine is actually very appealing, very classic sounding. DON’T FORGET TO FILL YOUR TRANSMISSION UP TO THE CORRECT FLUID LEVEL!!! USE DEXRON3/MERCON FLUID ONLY.
The 3.73 FDR is one of the many ways to refit the 440-T4/ 4T60-E. This ratio will help your application step off the line a lot better and make cruising a snap. Proper understanding of the transmissions is mandated before making any attempt on refit.