3 speed th350 to a 4 speed th2004r in a 78-80?

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anthonychacon80

Master Mechanic
May 4, 2010
303
18
I have a 1980 Cutlass. It has a th350. Want to convert to overdrive tranmission. But not sure I can tackle EVERYTHING in one weekend. So I want to do it in stages.


So I have determined that I will need the following...

1. Used transmission
2. transmission jack (buy or rent?) hmmm
3. t/v cable with the Qjet accelerator/kickdown mounting bracket
4. tube/dipstick/fluids
5. Right speedo gear for my tire/rear gear combo
6. New upper steering column from junkyard so that I can select PR(D)D21 as my current one is PRNDSL, plus Paint to match it to my interior and while I am at it install a antitheft column shield.
7. aftermarket lockout switch solenoid doohickythingababobber? Suggestions on a brand?
8. Torque converter
9. Misc nuts and bolts
10. New Iceman crossmember with extension because the 1980 Cutlass has no provisions for the TH400
11. Do I need a new flywheel?

Can anyone think of anything else? Suggestions on getting the current trans out and new one in without a car lift? I have a floor jack, some stantions, a 2 ton cherry picker and can get a transmission jack at Harbor Freight for $80.

Can I easily put a 4 speed in and run it as a 4 speed without changing the steering column? This would mean no 1st gear selection correct? Are the spaces between shift points the same on the 3speed and 4speed upper steering columns? If so I think I can get the car road ready in a weekend and then another time this summer worry about getting a new column, take my time getting it prepped, change out the internals to convert the wand from the Wiper/Cruise Control combo to the Cruise only wand, and the turn signal switch harness to the 78-80 switch and paint her up nice.

OR should I just poke a hole in my floor and install an aftermarket floor shifter ? Keep in mind I have a bench seat and no inner studs for putting in my bucket seats that have been sitting in my basement 8 years. Is there even room for a floor shifter on a bench seat pulled all the way up? (I am SHORT...5'5...kinda have to worry about that!) Im assuming that I would still have the same issue though with no 1st gear since the steering column is still attached in some way to the transmission?
 

Wildmani

Master Mechanic
Sep 17, 2010
294
28
Brantford, Ontario, Canada
Somebody can correct me if I'm wrong on this, but I'm pretty sure you don't need to swap columns. The gear selector indicator on the dash would need to be switched to one that came from a car with a 4 speed, but that's easy (if you wanted a true indication of gear selection that is). The wire that hangs from the needle on the indicator just clips to the steering column cover and as you move through the gears it moves accordingly.
 

Evan11

Royal Smart Person
Apr 17, 2009
1,259
38
Southern Indiana
Wildmani said:
Somebody can correct me if I'm wrong on this, but I'm pretty sure you don't need to swap columns. The gear selector indicator on the dash would need to be switched to one that came from a car with a 4 speed, but that's easy (if you wanted a true indication of gear selection that is). The wire that hangs from the needle on the indicator just clips to the steering column cover and as you move through the gears it moves accordingly.[/quote. X2 u do not need a steering column!! U simply need the gear indinicator from a cutlass that had the 4 speed, don't waste your money on un-needed parts.
 

anthonychacon80

Master Mechanic
Thread starter
May 4, 2010
303
18
huh. So the one I have will move the extra gear down? Finding a new PRN(D)D21 is easy!
 

axisg

Comic Book Super Hero
Jul 17, 2007
2,681
113
YYZ
anthonychacon80 said:
huh. So the one I have will move the extra gear down? Finding a new PRN(D)D21 is easy!

Yes, the linkage from the column to the shifter is the same. The only difference is the plate over the gear indicator on your dash. IF you had a console shifter then they are different.

You dont really need a trans jack. I have swapped transmission(s) in the laneway behind the house by putting the front of the car on ramps and jacking the body as high as it can go on the side to pull the trans out of. Remove the saddle on your floor jack and mount an 18" x18" sheet of plywood with some ratchet straps to hold the trans to the wood until it's unbolted then slide it on/off the plywood onto the ground so you can drag it out.

Otherwise you need everything you mentioned above ( TV cable, TV Cable clip on your carb same as the kickdown IIRC, crossmember will need to be modified or aftermarket ). Driveshaft is the same, flywheel is the same, all the bolts from the old trans are re-used, the steering column won't need to be touched, although you may need to adjust your PN switch to get the reverse lights lined up.

7. aftermarket lockout switch solenoid doohickythingababobber? Suggestions on a brand?
I assume you mean a lockup switch, I run a toggle on my car but you can buy one of the many aftermarket ones if you like.


My question to you is this .... are you going to do all this work and install a used trans ??? The 200r4 was pretty weak when left stock. I know I like do do things right the first time ( when I can ) so you should likely look into a rebuilt trans and a new TC while you have it all apart. It's not a very difficult job, just about everything will bolt right up as the General Intended.
 

anthonychacon80

Master Mechanic
Thread starter
May 4, 2010
303
18
Oh! yes. I have some ramps too i forgot about!

axisg said:
My question to you is this .... are you going to do all this work and install a used trans ??? The 200r4 was pretty weak when left stock. I know I like do do things right the first time ( when I can ) so you should likely look into a rebuilt trans and a new TC while you have it all apart. It's not a very difficult job, just about everything will bolt right up as the General Intended.

Well I am looking for a later model one with the "better" components. I think after 86? The closer to 1990 the better right? I have never rebuilt a trans and have found some great looking how-tos with pics, but I do not have a place to do that. Looks like I need a nice basement with a drain to catch all the fluids that will be all over the place AND I am in Chicago which means any place I bring a used transmission is going to overcharge by %50 what it should cost to rebuild a trans. Plus i am keeping my recent rebuilt TH350 as a spare.
 

axisg

Comic Book Super Hero
Jul 17, 2007
2,681
113
YYZ
The year of the trans has no effect on the 200r4 ( it was the 700r4 which got better internal parts in the later years ). What I would recommend if rebuilding yourself or having a local shop do it for you is to grab a core from a GN, MCSS or 442. They got the better valvebody and the GN and MCSS they have a higher shift point than the 442 did. Of course this can all be adjusted in with another 200r4 core but it takes time ,skill, and parts to get it right.

Myself I went through 3 months of having my trans re-built, installed, yanked, re-installed until we were happy with the valvebody, linepressure and shift points. I have somewhere around $1500.00 in parts+labour in my trans alone not including my time spent. Had I known then what I know now I would have paid for one from Bowtie, CK, ArtCarr or one of the other shops transmissions as they seem to have a great rep. I might have the skill now to tear one down but I would still bring it to the pros for the final setup.

This is one of the many threads on the subject of rebuilting a 200r4
http://www.montecarloss.com/community/u ... 035&page=1
 
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