ScottyDsntKnow
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- Joined
- Mar 22, 2008
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I just got done with this swap because I was able to get a brand new fresh rebuilt 3650 with no core charge for $1060 to my door from a transmission shop in Minnesota. I know its not a very common swap and ppl get skeered of the VSS to OSS speedometer thing but its not a big deal.
You will need:
-3650 from 2001-2004 (note ALL 02-04 3650s have a .62 overdrive vs .68 for the 01 and the T-45 if that matters to you)
-79-95 style trans mount
-Stiffler's T-45/3650 Crossmember for 96-98 Click me
-3650 shifter
-Shifter pivot ball cup if your 3650 doesn't have one (ebay)
-OSS sensor
-Reverse switch from your T-45
-Dallas (dallas not FRPP) speedcal
A new OEM/McCleod/DD TOB is always a good idea when the trans is out.
Pull the t-45 and install the 3650 on the block like normal. I had to put a block of wood under the front of my oil pan and tilt the motor as far back as it would go to get it in there because the 3650 case is a little bigger than the T-45. Then, bolt on the trans mount and install the crossmember like in the instructions but WITHOUT the spacer. NO idea why they have that spacer in there but all it does it push the trans up against the tunnel. One might be asking, why not use the stock crossmember? Well, because it wont' clear the 3650 case, even if you grind off the casting tab at the bottom of the tailshaft housing. The actual body of the case itself sits down on the crossmember and the 96-98 style mount won't fit the 3650 at all. The bottom of the mount does not clear the case either. I suppose one could use a Cobra crossmember setup and then toss a 94/95 hangar plate onto the 3650 which moves the mount itself back an inch and a half or so. That would be what I would do if I had a 96-98 Cobra and was doing this swap.
Anyway, after the crossmember shenanigans, the driveshaft is a direct bolt in, install your OSS sensor and wire in your speedcal if it isn't already. My car had it wired in by the previous owner so don't ask me about it lol. Also install your reverse light sensor (teflon or rtv on the threads) at this time. Button the exhaust back up and everythign else that you need to do, fill with 3.2 quarts of fluid through the shifter hole (3.2 NOT 3.8, 3.8 is the old fill and is too much), install the pivot ball cup onto your new shifter install the shifter into the 3650. The 3650 has internal stops so do NOT set the stops if your shifter has them, you can damage the transmission if shifter stops prevent it from engaging fully. I removed the stop bolts completely on my Tri-Ax.
Now, onto everyone's favorite part, the dreaded VSS to OSS. It is stupid easy. You multiply your current rear tire's revolutions per mile, (look it up on discount tire direct) by your rear gear ratio by 12. 12 is the number of OSS pulses for the 3650. Once you have said number, plug it in here in the "current setup VSS pulses per mile" block. The extended range speedcal number it spits out is your switch setting . 1 is up and 0 is down. All new and newer Dallas Speedcals are extended range so unless you have a really old one you will be good. I was able to get my speedometer dead on accurate the very first time and it really is that easy.
Now... break it in for 1000 miles, change the fluid out if you want to and have fun with your trans. For fluid, I use Pennzoil Syncrhomesh, its like mother's milk for the 3650.
Hope this helps anyone wondering about this swap. I sure as hell got fed a TON of bad info such as grinding off that casting tab, being able to use the stock crossmember/mount and seems everyone is scared to death of the VSS to OSS thing. Yes I understand the T-45 that is built properly with the single rail design is going to shift better. I am into this transmission fully for under $1200 shipped to my door after I just sold my shifter for $100 and I still have the t-45 core I can get a few $hundred for as well. It shifts smooth the .62 overdrive is great for 4.10s and I'm not trying to set the world on fire right now with this thing. Any other questions or if I left something out just ask. I also did use Cobrabob gaskets on the shifter and its nice and quiet.
You will need:
-3650 from 2001-2004 (note ALL 02-04 3650s have a .62 overdrive vs .68 for the 01 and the T-45 if that matters to you)
-79-95 style trans mount
-Stiffler's T-45/3650 Crossmember for 96-98 Click me
-3650 shifter
-Shifter pivot ball cup if your 3650 doesn't have one (ebay)
-OSS sensor
-Reverse switch from your T-45
-Dallas (dallas not FRPP) speedcal
A new OEM/McCleod/DD TOB is always a good idea when the trans is out.
Pull the t-45 and install the 3650 on the block like normal. I had to put a block of wood under the front of my oil pan and tilt the motor as far back as it would go to get it in there because the 3650 case is a little bigger than the T-45. Then, bolt on the trans mount and install the crossmember like in the instructions but WITHOUT the spacer. NO idea why they have that spacer in there but all it does it push the trans up against the tunnel. One might be asking, why not use the stock crossmember? Well, because it wont' clear the 3650 case, even if you grind off the casting tab at the bottom of the tailshaft housing. The actual body of the case itself sits down on the crossmember and the 96-98 style mount won't fit the 3650 at all. The bottom of the mount does not clear the case either. I suppose one could use a Cobra crossmember setup and then toss a 94/95 hangar plate onto the 3650 which moves the mount itself back an inch and a half or so. That would be what I would do if I had a 96-98 Cobra and was doing this swap.
Anyway, after the crossmember shenanigans, the driveshaft is a direct bolt in, install your OSS sensor and wire in your speedcal if it isn't already. My car had it wired in by the previous owner so don't ask me about it lol. Also install your reverse light sensor (teflon or rtv on the threads) at this time. Button the exhaust back up and everythign else that you need to do, fill with 3.2 quarts of fluid through the shifter hole (3.2 NOT 3.8, 3.8 is the old fill and is too much), install the pivot ball cup onto your new shifter install the shifter into the 3650. The 3650 has internal stops so do NOT set the stops if your shifter has them, you can damage the transmission if shifter stops prevent it from engaging fully. I removed the stop bolts completely on my Tri-Ax.
Now, onto everyone's favorite part, the dreaded VSS to OSS. It is stupid easy. You multiply your current rear tire's revolutions per mile, (look it up on discount tire direct) by your rear gear ratio by 12. 12 is the number of OSS pulses for the 3650. Once you have said number, plug it in here in the "current setup VSS pulses per mile" block. The extended range speedcal number it spits out is your switch setting . 1 is up and 0 is down. All new and newer Dallas Speedcals are extended range so unless you have a really old one you will be good. I was able to get my speedometer dead on accurate the very first time and it really is that easy.
Now... break it in for 1000 miles, change the fluid out if you want to and have fun with your trans. For fluid, I use Pennzoil Syncrhomesh, its like mother's milk for the 3650.
Hope this helps anyone wondering about this swap. I sure as hell got fed a TON of bad info such as grinding off that casting tab, being able to use the stock crossmember/mount and seems everyone is scared to death of the VSS to OSS thing. Yes I understand the T-45 that is built properly with the single rail design is going to shift better. I am into this transmission fully for under $1200 shipped to my door after I just sold my shifter for $100 and I still have the t-45 core I can get a few $hundred for as well. It shifts smooth the .62 overdrive is great for 4.10s and I'm not trying to set the world on fire right now with this thing. Any other questions or if I left something out just ask. I also did use Cobrabob gaskets on the shifter and its nice and quiet.
