3.61 to 3.94 FDR swap info
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blindmandesigns
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3.61 to 3.94 FDR swap info
Well after a few days with some interuptions I finally got the 3.94 tranny from a quad Z26 in my 91 GTZ and let me tell you if you are ever considering doing this swap save up a few extra bucks and make it your next project. You will not only have a much better gear ratio and impressive reductions in 1/4 time (around 1/2 second in some cases) and increases in your trap speed. but your gas mileage will go up (maybe not with the W41 trans because of the close gearing in 5th also vs the ecconomy 5th gear) but it takes much less effort driving around daily. 65mph in 5th on the highway is at 2400RPM's with the ecconomy 5th gear.
First step is to gather parts. Here is what was needed.
1. clutch pedal assembly from a 92+quad 4 powered vehicle. And from what I heard from Dennis ramairGTZ he got his from a 96 2.4 GA Make sure if you are getting this from a 92 that it is an internal slave style transmission seeing as some were internal slave (rubber gromet on hydraulic line/bleeder valve at the transmission) and some, very few but still are some, were external slave (look at your transmission to see what this looks like if you don't know, you should see a black cylinder with a line line running to it.)
2. Plastic hydraulic line connecting the master cylinder to the slave cylinder(quick connect fitting on slave cylinder line not needed if getting a new one)
3. Master cylinder. Doing a swap you SHOULD want to use all new parts but when you find out you will pay roughly 130 to 150 for a master cylinder try to get one from a junkyard. Worst case is that it doesn't work and you will need to get a new one. (no big deal would take 5 minutes to change) If you get one from a yard, attach the hydraulic fluid resovior and the plastic hydraulic line to the master cylinder (should be connected if you got it from a yard) and start pumping clean DOT 3 brake fluid through it to flush out any possibility of dirt/old fluid out.
4. Internal slave cylinder for the year of the tranny you are swapping in. I strongly recommend spending the cash to get one from GM seeing as if you get a used one (which would be a PITA to get at a yard) and it goes out on you soon after the swap You have to take the whole transmission out to get it.
5. Two new bolts for rear transmission mount. These are the two bolts that are on top of your tranny that have bigger holes. Simply undo a bellhousing bolt and a mount bolt and go to an autoparts store and tell them you need a bolt that is as wide and has the same threading as your bellhousing bolt BUT it needs to be as long as your tranny mount bolt. You will only need 2 They should be 1/2 inch wide threading and I think 1 1/4th inches long. Measure the length to make sure. I got my at advance auto for a few bucks.
6. New axle seals for the year of the tranny you are installing... I dont know if it was just mine but these are a royal pain getting them in even with a seal installer (NEEDED). I could only get them in removing the metal sheild. Best of luck to you with them you will need it unless you get them from GM (they might fit better than generic ones.)
7. 1/2 inch wide drill bit to enlarge the holes on the rear tranny mount (only top holes not the hole where the bolt connects on the side of it. Simply just drill them out.
I beleive that is all the extra parts I used.
Now for what you need to use from your tranny you are ripping out.
1. Shift linkage components from your old transmission. shift lever(up and down motion for your gear shifter in your car) and shift selector (side to side motion with your gear shifter)
The reason for doing this is that even though everything is in the same exact place, the 3.94 trannys shift lever could be bent slightly (like mine was)possibly from removal from the yard I bought it from. The selector assembly IS different on the 3.94 tranny. The cable connects either 1 inch closer or 1 inch farther away I do not remember which direction but when you compare where the cable connects on the selector its not the same and would be a problem.
Use all the old sensors from your tranny if you know they work. (speed sensor and reverse sensor)
With all of that taken care of there shouldn't be any differences/ in swapping it directly in as if it was your old tranny.
When you put in a new flywheel or have your old one resurfaced be sure to clean your flywheel and clutch pressure plate (NOT THE CLUTCH ITSELF) with brake cleaner to remove any oil residue that might have gotten on it from your hands...
I am using the spec stage 3 clutch with the lightened pressure plate and a Fidanza flywheel. I was scared when I pressed the clutch pedal down for the first time and felt how light it felt... when the time came to take it for a drive that light feeling whats quite misleading! That Spec clutch seriously does feel like there isn't anything there but is great... Very good clutch with not as much chatter as I was expecting (comparing to a stage 3 clutch from some other brand in a friends car) Once you have it broken in which is VERY important, it is VERY snappy and engages perfectly and really takes off once it engages. Chirping 3rd gear is very fun btw
This tranny makes daily driving so much easier too from what I have felt... 3rd and 4th are much closer than the 3.61FDR. For example. I was getting onto a highway taking it easy with the new clutch and was on one of those 270 degree clover onramps... once it straightened out I reached to shift from 3rd to 4th when I was already in 4th! 4th really does feel closer to the old 3rd gear. 5th gear is awesome too for just cruising on the highway... If you get a W41 tranny 5th gear will also be close which is great if you want to do some other racing other than 1/4 mile where you are up at speeds above 100.
I can see why people have gotten up to a half a 2nd off of the 1/4 with this tranny it hits the sweet spots each shift
First step is to gather parts. Here is what was needed.
1. clutch pedal assembly from a 92+quad 4 powered vehicle. And from what I heard from Dennis ramairGTZ he got his from a 96 2.4 GA Make sure if you are getting this from a 92 that it is an internal slave style transmission seeing as some were internal slave (rubber gromet on hydraulic line/bleeder valve at the transmission) and some, very few but still are some, were external slave (look at your transmission to see what this looks like if you don't know, you should see a black cylinder with a line line running to it.)
2. Plastic hydraulic line connecting the master cylinder to the slave cylinder(quick connect fitting on slave cylinder line not needed if getting a new one)
3. Master cylinder. Doing a swap you SHOULD want to use all new parts but when you find out you will pay roughly 130 to 150 for a master cylinder try to get one from a junkyard. Worst case is that it doesn't work and you will need to get a new one. (no big deal would take 5 minutes to change) If you get one from a yard, attach the hydraulic fluid resovior and the plastic hydraulic line to the master cylinder (should be connected if you got it from a yard) and start pumping clean DOT 3 brake fluid through it to flush out any possibility of dirt/old fluid out.
4. Internal slave cylinder for the year of the tranny you are swapping in. I strongly recommend spending the cash to get one from GM seeing as if you get a used one (which would be a PITA to get at a yard) and it goes out on you soon after the swap You have to take the whole transmission out to get it.
5. Two new bolts for rear transmission mount. These are the two bolts that are on top of your tranny that have bigger holes. Simply undo a bellhousing bolt and a mount bolt and go to an autoparts store and tell them you need a bolt that is as wide and has the same threading as your bellhousing bolt BUT it needs to be as long as your tranny mount bolt. You will only need 2 They should be 1/2 inch wide threading and I think 1 1/4th inches long. Measure the length to make sure. I got my at advance auto for a few bucks.
6. New axle seals for the year of the tranny you are installing... I dont know if it was just mine but these are a royal pain getting them in even with a seal installer (NEEDED). I could only get them in removing the metal sheild. Best of luck to you with them you will need it unless you get them from GM (they might fit better than generic ones.)
7. 1/2 inch wide drill bit to enlarge the holes on the rear tranny mount (only top holes not the hole where the bolt connects on the side of it. Simply just drill them out.
I beleive that is all the extra parts I used.
Now for what you need to use from your tranny you are ripping out.
1. Shift linkage components from your old transmission. shift lever(up and down motion for your gear shifter in your car) and shift selector (side to side motion with your gear shifter)
The reason for doing this is that even though everything is in the same exact place, the 3.94 trannys shift lever could be bent slightly (like mine was)possibly from removal from the yard I bought it from. The selector assembly IS different on the 3.94 tranny. The cable connects either 1 inch closer or 1 inch farther away I do not remember which direction but when you compare where the cable connects on the selector its not the same and would be a problem.
Use all the old sensors from your tranny if you know they work. (speed sensor and reverse sensor)
With all of that taken care of there shouldn't be any differences/ in swapping it directly in as if it was your old tranny.
When you put in a new flywheel or have your old one resurfaced be sure to clean your flywheel and clutch pressure plate (NOT THE CLUTCH ITSELF) with brake cleaner to remove any oil residue that might have gotten on it from your hands...
I am using the spec stage 3 clutch with the lightened pressure plate and a Fidanza flywheel. I was scared when I pressed the clutch pedal down for the first time and felt how light it felt... when the time came to take it for a drive that light feeling whats quite misleading! That Spec clutch seriously does feel like there isn't anything there but is great... Very good clutch with not as much chatter as I was expecting (comparing to a stage 3 clutch from some other brand in a friends car) Once you have it broken in which is VERY important, it is VERY snappy and engages perfectly and really takes off once it engages. Chirping 3rd gear is very fun btw
This tranny makes daily driving so much easier too from what I have felt... 3rd and 4th are much closer than the 3.61FDR. For example. I was getting onto a highway taking it easy with the new clutch and was on one of those 270 degree clover onramps... once it straightened out I reached to shift from 3rd to 4th when I was already in 4th! 4th really does feel closer to the old 3rd gear. 5th gear is awesome too for just cruising on the highway... If you get a W41 tranny 5th gear will also be close which is great if you want to do some other racing other than 1/4 mile where you are up at speeds above 100.
I can see why people have gotten up to a half a 2nd off of the 1/4 with this tranny it hits the sweet spots each shift