transmission swap

C

Crazyc

Not-quite-so-new-guy
Aug 19, 2019
19
3
Long story short. 84 GP. Original v6 car. Trans blew, put in a BOP 2004r. Pulled out motor and trans and threw motor in garbage for engine swap (hence why I got the BOP because I was plannng the engine swap anyways). Currently have a 350 olds rocket installed that came with a t350 and I’m running the original (2.56?) v6 rear end. I’m changing out the rear end with a Richmond 4.10. Problem is with the t350 I won’t be able to freeway drive anymore due to the high gear ratio and no overdrive or forth gear. So.... I’m thinking of putting the 2004r back in (possibly getting it rebuilt ) when I do the rear end swap. (Driveshaft fits both transmissions) so two questions. First. What do you guys think of the idea ? And secondly, I remember having to change the trans mount when I did the motor swap. What will I need to do as far as the cross member and trans mount for switching the trans back if anything ?
 
olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
4,935
113
Melville,Saskatchewan
Why so steep on the gearing? Even 3.42 gears make a big difference. I swapped between a 2004R and a TH350. Being a 84, should be minimal. Plug the modulator line, move the crossmember to the rear position and they use the same driveshaft. I would install a lock up kit like the TCI kit. How much power is the Olds 350 putting out? Some upgrades like the stator shaft and a hardened sun shell with bigger boost valves, a servo, quality clutches and maybe a deep pan and bottom feed filter. Depends on the torque output. I ran 14's with a mild cam 9.6 to 1 Olds 350 in my heavy 88 Cutlass with a 2300 stall 2004R and 3.42 gears. If your motor even just has a cam, get a 2000+ stall lock up converter.
 
Longroof79

Longroof79

Rocket Powered Basset Hound
Oct 14, 2008
10,139
113
Gainesville, Fl
I would keep the 200-4R and have it built for longevity as suggested. . I also agree that 4.10 gears are not recommended for any kind of hgwy driving. Even with a 200-4R, I would stick with a 3,42 or 3.73 gear tops.
 
H

hoffa65

Greasemonkey
Mar 11, 2019
232
43
Atlanta GA
2004r for sure get it rebuilt with good quality hard parts, performance pump and keep the lockup feature.
4:10's at 70 with a 26 inch tire will spin close to 2500 w/OD and 3700 with the TH350
3:73's will spin at 2250 w/OD and 3375 with the TH350

your 84 frame should have the extended frame on the left side for the 2004r cross member, if not G-force offers a dual cross with a frame extension
 
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64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
928
93
Upstate NY
We spin faster than that at 75 with 3.73's and a 26" tire.

You better build that 200 for 400+ HP. We run a 200 and make over 700whp, but it's built too say the least.
 
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C

Crazyc

Not-quite-so-new-guy
Aug 19, 2019
19
3
2004r for sure get it rebuilt with good quality hard parts, performance pump and keep the lockup feature.
4:10's at 70 with a 26 inch tire will spin close to 2500 w/OD and 3700 with the TH350
3:73's will spin at 2250 w/OD and 3375 with the TH350

your 84 frame should have the extended frame on the left side for the 2004r cross member, if not G-force offers a dual cross with a frame extension
So yah I was going for the 2200-2500 rpm range with OD running a 275/60/15 (27”)

I believe your correct on the frame extension but just Incase, Do you have link for the GeForce frame extension ? When you say “keep the lockup feature” are you referring to the torque converter, because I have no idea what one it has. I think it’s just a plain Jane factory 2004r. I included picture of torque label
 

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C

Crazyc

Not-quite-so-new-guy
Aug 19, 2019
19
3
I would keep the 200-4R and have it built for longevity as suggested. . I also agree that 4.10 gears are not recommended for any kind of hgwy driving. Even with a 200-4R, I would stick with a 3,42 or 3.73 gear tops.
I kind of got this rear end for a steal. ($150) and I don’t daily drive it, just if I wanted to go to a car show a hour or two away, I’d like to freeway it. And a t350 won’t cut it with this ratio.
 
C

Crazyc

Not-quite-so-new-guy
Aug 19, 2019
19
3
2004r for sure get it rebuilt with good quality hard parts, performance pump and keep the lockup feature.
4:10's at 70 with a 26 inch tire will spin close to 2500 w/OD and 3700 with the TH350
3:73's will spin at 2250 w/OD and 3375 with the TH350

your 84 frame should have the extended frame on the left side for the 2004r cross member, if not G-force offers a dual cross with a frame extension
So yah I was going for the 2500 rpm range with OD running a 255/60/15
Why so steep on the gearing? Even 3.42 gears make a big difference. I swapped between a 2004R and a TH350. Being a 84, should be minimal. Plug the modulator line, move the crossmember to the rear position and they use the same driveshaft. I would install a lock up kit like the TCI kit. How much power is the Olds 350 putting out? Some upgrades like the stator shaft and a hardened sun shell with bigger boost valves, a servo, quality clutches and maybe a deep pan and bottom feed filter. Depends on the torque output. I ran 14's with a mild cam 9.6 to 1 Olds 350 in my heavy 88 Cutlass with a 2300 stall 2004R and 3.42 gears. If your motor even just has a cam, get a 2000+ stall lock up converter.
What is the TCI kit ? Trans internals I’m guessing ? Which kit ? Also what’s the modulator valve ? Sorry I’m trans illiterate !
(That’s why I’m coming here for advice)
I do know about the upgraded cluthes (redlines) the servo and pressure boost valves as I had those all upgraded to “corvette” ones on my trans am.
The motor has a mild can and bored +.10? Over nice carb on it, but I think it’s running too rich. When I swapped the motors over I think I messed with something on carb cause it’s not running as aggressive as before and seems to not like starting and running well on it’s own but that’s for another section in the forums. I would have rather had a 3.73 but this one came across my lap and had a really nice brand new Richmond Posi so I couldn’t say no.
 
Ribbedroof

Ribbedroof

Comic Book Super Hero
Supporting Member
Jan 4, 2009
2,900
113
Wellston, OK
Ahhhh, kids today.

We used to drive 4.11 geared stuff everywhere with no overdrive...just takes a little longer if you don't want to rev the daylights out of it. I did draw the line at driving the 4.56 geared 69 Chevelle SS on long distance trips, though.

TCI kit will allow convertor to lock up to reduce RPM a little at cruise. I believe it's generally around 200 RPM. Side benefit is a little less heat in the trans as well. I don't know why people hate so hard on lockup transmissions in street cars.
 

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