dbsupra GM transmission swap

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dbsupra90

toonar
Apr 1, 2005
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indiucky
in this thread i will post pictures, "how to", and what will and will not work. this is not the end all be all of gm trans swaps. there are different ways to go about it. this is the direction i decided to go. i thought this might be helpful since there seems to be more questions than answers regarding this swap.

first and foremost, i'd like to thank a few people that have been involved or contributed in this project:

sean t (x-man)
shawn c (besttransmission)
frank "big dawg" walker
adam walker


step 1: out with the old

stage 4 build PHP 340e. kolene steels, blue clutches, modified valvebody, kevlar bands

supra&


roadrunner 4200 stall converter

sm_4200stall.JPG
 
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dbsupra90

toonar
Apr 1, 2005
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indiucky
i wanted to go with a turbo 400. frank helped me out here, he had a built up 400 with 5 passes on it. on the 5th pass the bellhousing broke but i had a solution. buy a JW Ultrabell and bolt it on.

here is the besttrans adapter plate (413-736-9496) mated up to the ultrabell. will need to make some space for the starter for sure. the ultrabell is massive!

supra&


might run into some issues due to how much bigger the ultrabell is vs stock. check it out

housing_comparo.jpg
 
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dbsupra90

toonar
Apr 1, 2005
2,374
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indiucky
here is the 400 from frank. sean cut the bellhousing off to fit the ultrabell.

sm_th400front.JPG


sm_th400top.JPG


i will use a custom hybrid vigilante 9.5" converter from Precision (901-466-0267). Terry made a toyota front side and gm back side hybrid and we decided a 3800 stall would be ideal for my setup. converter looks well made, but i dont know what they were thinking on the color lol.

toyota side

sm_PI_toyoside.JPG


gm side

sm_PI_gmside.JPG


the great thing about using the besttrans plate and this converter is i can use the stock starter and flexplate. however, you will need to slot the holes on the flexplate.

sm_flexplate2.JPG


sm_flexplate.JPG
 
suprahero

suprahero

naughty by nature
Staff member
Aug 26, 2005
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This is going to be awesome Dave. I'm glad someone is doing this step by step with pretty purple pictures.
 
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dbsupra90

toonar
Apr 1, 2005
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indiucky
IJ- yeah i guess thats why. yep, there is our gay pride converter in that car.

problems arise.

the heater core hardline is in the way. the upper section of the ultrabell and adapter plate are for the buick/olds/pontiac applications. don't need it, so off it comes.

supra&


still not enough clearance, so sean goes after it with a cutoff wheel and grind wheel

sm_ultrabell_trim.JPG


the adapter plate is trimmed up and ready to mount. also note the small clearance made in the upper left corner of the cutout for a bolt.

sm_finished_plate.JPG
 
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dbsupra90

toonar
Apr 1, 2005
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indiucky
hardline is cleared.

supra&


you could pull everything apart and use a ss line or make a new hardline to make more clearance. or you remove the heater. def did not want to get rid of the heater, nor did i want to pull everything apart to modify for a stupid hardline. since the upper portion of the plate and bell is not needed, this seemed like the logical approach.

here is a pic of the full plate mounted. pic taken from trans tunnel. you can see the bolt the plate was clearanced for in this pic.

sm_plate_mounted.JPG


you can see how tight the clearance is. you can also see some of the hammer marks to make space for the ultrabell.

sm_plate_tunnel.JPG
 
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dbsupra90

toonar
Apr 1, 2005
2,374
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indiucky
now for bad news. despite many swings with a snap-on hammer and 4 letter words, the ultrabell just will not fit. with the motor jacked up in the front it is still atleast 1/2 hole from mounting on. did i mention the ultrabell is massive? i had high hopes of using it. it is a very nice piece, sfi rated and super strong. it just isnt going to happen. i suppose if i wanted to cut out the stock trans tunnel and make a new one it would work. don't want to do that.

plan B. i'm going to go with a stock case th350. i had considered trying to find a stock case th400, but they are getting harder to find these days. even more, space is so tight i'm not 100% convinced a stock case 400 will fit at this point. it is roughly 1" wider than the th350 bellhousing. i'm not saying it wont fit. if you want to try by all means. at this point i've decided to go with what i know will work, and can pick up all day long for cheap ($100-200 for stock th350). that way if i do manage to blow it up, i can easily and cheaply find a replacement.

only thing i will have to trade is my full manual valve body and transbrake.

sm_transbrake.JPG


a full manual valve body allows you to manually shift each gear. it is reverse pattern, meaning P R N D 1 2 3. you have to use a reverse pattern to work with a transbrake. the transbrake locks 1st and reverse together when you activate it. this will keep the car from moving and can true stall the converter. you can do a high/full boost launch without having to worry about overpowering the rear brakes and spinning.

here is the b&m quicksilver ratchet shifter i will be using. it will work on the th350 just fine. i chose this shifter because i wanted a ratchet shifter instead of a detent (like stock), i liked the way it looked, and it uses a gate reverse lockout instead of lever. the reverse lockout keeps you from accidently slamming the shifter in reverse when downshifting.

sm_qs_shifter.JPG


more to come...
 
Yblegal91t

Yblegal91t

it finally runs!
Apr 22, 2006
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IJ.;1124259 said:
Dave: Considered using a 340 bellhousing on the TH400 with an adaptor plate?
(this is how I did the Tremec TKO in my car a few years back)
Click to expand...


thats how mine came from the 400 i got from oneandgone a couple years back.
 
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dbsupra90

toonar
Apr 1, 2005
2,374
0
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indiucky
IJ.;1124259 said:
Dave: Considered using a 340 bellhousing on the TH400 with an adaptor plate?
(this is how I did the Tremec TKO in my car a few years back)
Click to expand...

i had considered this route. the reason i chose this route was i wanted to run an ultrabell and the pti converter had already been designed to work with this plate. plus i'm pretty sure i'd have to run an 8" converter with the 340 bell. obviously the ultrabell isnt going to work tho. but i could still use my existing equipment if i just swapped to a stock case.

kevin- yeah long time no see. i haven't been on the forum in several months, just got back on the past week. glad to see you are still around.
 
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dbsupra90

toonar
Apr 1, 2005
2,374
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indiucky
who knew there could be hurricanes in ky? finally got power back, but still have a 65' maple tree on my house. it smashed my porch and did some roof damage, but luckily it didnt come thru the house.

progress has been stopped, but now everything is semi back to normal i'm going to work on the shifter, gauge and cooler lines until the th350 is ready. stay tuned for pics.
 
joliroger4

joliroger4

Flying Dutchman Pilot
Apr 4, 2005
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www.geocities.com
I had it working in a ghetto fashion by installing a gm speedo end on the toyota cable just to temporarily get me by but the cable broke due to too sharp of a bend. I since don't have mine hooked up, but you need to have a custom cable made. I plan on taking care of it this winter in my downtime. You can get the abs working as well with an 8k ppm signal generator and a dakota digital sgi-5 too. Many speedo shops can do the cable for you, usually you have to supply the end coming out of your dash however(with the green plastic clip) to make one long cable that will go straight to the trans. You will have to tell them how long to make it. If your car is anything like mine, you'll need a 90 degree 1:1 gear drive adapter to 90 out of the trans so the cable will fit with no sharp bends.
 
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