Figured id post up a thread on this with some information that ive gathered and also some pics of the swap, hopefully this can help some people on the topic I know this is a popular question item around the boards......ill be updating this tomorrow and until the car is going down the road again

First off ill post up some info I gathered prior to the swap....

Few important things to note when doing the swap:
1. If you run a 9" tail shaft and output shaft on the TH350 you are swapping to it will allow you to run the same driveshaft you used for the 4L60, the length works out to be the same
2. The transmission mount works out to be .75" forward in the car from where the 4L60E mount is

here's a pic of the layout on the different transmissions




For mine I grabbed an old short tailshaft th350 I had sitting in my shed for about 25 years, turns out it came out of my dads old impala back in the day....we tore it down and rebuilt it with all coan internals including a transbrake and their "clean neutral" valvebody and drums...I picked up a 9" tailhousing on ebay for $40 and a GM OEM 18" output shaft for $55 so I could swap the 6" tail for the 9" so I could retain my existing driveshaft....
heres the trans all done up


next I ripped out my center console and all the brackets on the floor took out some weight so im no longer racing a battle tank.....I got 5 yards of black ozite carpet again off fleabay for like $110 and used 3M super 77 and laid it in the car, came out better than I expected....topped it off with a PPP Kwik Shift I shifter and the interior was done.....




for controlling the transbrake I used my FAST XFI I got the firmware update for it from FAST to update it to the 2.0 platform, they were great on this charged me only $50 for the upgrade, it downloads right from your laptop to the pcm no need to send it to them........I used the transbrake control section of the XFI to control it....I picked up one of the FAST solid state relays to control the TB also so I can pulse width modulate the brake on release fast and properly....it was easy wiring the TB button on the shifter gets wired through ground to pin A20 "Clutch Input" of the XFI, this signals the XFI to engage the brake....Pin A18 is the sinking ground output to the solid state relay to control it the other side of the relay "coil" is wired to ign 12V.......for the load side of the relay a 25A fuse to battery power and the other side to the TB solenoid......quite easy wiring I got PPP's shifter mounted coil button to control it...



I ordered an ATI treemaster MRT converter for the car also taking recommendations from a lot of guys on here and also locally to go to ATI for the converter....when I got it I realized its QUITE lighter than the 9.5" vigilante that came out of the 4l60



next up I realized the tabs on the side of the th350 needed to be chopped off to fit in the car let alone put the trans shield on it......(ill get a pic of this tonight)

also if you are reusing a CSR Super shield the 4l60 one DOES NOT FIT, the 4l60 has little divits where the bolts go through the bellhousing, the th350 does not....this causes fitment issues and requires a dedicated th350 shield....ill also post up pic of this tonight when the new shield shows up...

as for trans lines I just swapped out the stock th350 pieces in the trans for RUSSELL -6an adapters made to thread right into the trans they fit great, look great, and are ALOT easier to thread a fitting onto rather than the stock stuff.....plus you can run a braided flex line vs a steel hard line which makes it wayyyy easier to tie in when its in the car

im gonna pop in the trans tonight ill take pics and document any issues I ran into.....updates coming tomorrow.......also ill show how I modified my bmr 4l60 crossmember to fit the th350 rather than blowing $275 on a new one

 

Very nice write up, lots of great info here, kind of curious as to the reason on the th350....instead of th400. Everybody seems to have there own reason as to why they use either tranny.. Love the shifter and the new carpet very clean .......Very nice job on the pics, again thanks for the write up.

 

th400 is too heavy and takes too much to spin.......no need for it here with 650-700hp on tap a well built th350 is plenty to hold it in a heads up na car

 

Thank you very much for the answer .....makes complete sense, U said you had this tranny sitting around...... If you dont mind me asking how much did you have in the rebuild, transbrake, and the mount.

 

the mount I modified here.......the trans was a quite expensive build being a clean neutral setup, if I did a normal build with a TB it prob would've been in the 1500 area on parts plus labor

 

Just to get this straight...you've been running a 60e this WHOLE time?

 

yup had a 4l60e with a 4800 stall vigilante 9.5" lockup converter....pretty much a street setup....

 

Thats amazing dude, you should def see some pickup with just the rotating mass reduction. I just assumed you had a TH400/350 or PG this whole time. The car is even more impressive now...ha. I had a manual valve body TH350 in the black car in my avatar, blast to drive on the street and never had any issues with it.

 

You are gonna love the new set up. You will never go back and launching off the brake always puts a smile on my face. Hold on and keep it straight! Nice job on the shifter and carpet. Looks great.

 

What happened to my cup holder!

 

Excuse the uneducated question but wtf is a clean neutral setup and how is it better than a normally built TH350?

 

Nice write up Mike, can't wait to see new times with your new trans/stall combo. I'm still running the 4L60E as well and I will probably do the same swap when my car can run as fast as yours.. wishful thinking.

 

Clean neutral valve bodies allow you to put the transmission in neutral at the end of a run without the risk of the entire transmission turning into a handgrenade from over spinning the internals.

 

Thats useful there. Could I get a link to a parts list for something like that?

 

^^ what would be the advantage of that, besides accidentally putting into neutral?

 

Do a weight comparison of both trannies with the converters attached. I'd bet you'll shed 50-60lbs.

 

advantage is I don't have to spin the motor down from a 7800-8000rpm trap every pass, I can come through and neutral the car and just slow it down....also it cant accidentally go in after I shift to 3rd I pull the handle and push forward and it will neutral

with the aluminum parts and new converter it shed a bit over that joel

 

sooooo....some updates...........heres how tonight went....found some issues easily solvable


here's where I cut the ears off the side of the trans so the super shield will fit........just lopped em off ground em down and repainted the spot...did the same thing on both sides


after that the shield fit right on easily.........


after shoe horning the thing in once I realized that I had to take a weeee bit out of the brace to make it clear the body so I could the the trans in the car so I hit it with the grinder a bit on the left bolt one up that holds the trans in...




after that it went right in with no issues.......but I will say the bolts on the top left side were a PAIN IN THE A$$!!!!!!!!!!!! none the less about an hour later I had it bolted in solidly....as you can see below the bolts are burried quite well



I test fitted the driveshaft and it fits perfectly!!! just as planned


the only issue I found was the math on the mount position from the chart above was wrong....the mount needs to be moved 2" not .75"...no big deal ill post up the mod ill make to the cross-member tomorrow....


other than that it all fits very well more to come tomorrow

 

I vote for a sticky on this one

 

Looks good Mike. Wow, those headers come down pretty low. Any ground clearance issue?