Trans Options...

[SRD art]

The TH200 behind the 307 Olds in Grandpa started slipping and not shifting correctly yesterday. Fluid is full. If I powerbrake it while stopped it will take a couple seconds to build enough pressure (?) to go solidly into gear but clunks and grinds a little when it does. Normal taking off it's like it has very low fluid and slips real bad. Once it gets going it seems to drive ok, until you stop and go to take off again. I'm assuming it's toast, even though it only has 75,000 miles on it. 🙁

My other future project 86 Bonneville has a high mileage 305 SBC/200R4 in it, The engine is hosed and smokes like Willie Nelson but it still drives/shifts fine. It's in storage so I can't go check on it today, but I'm wondering what are the chances it might have a dual bolt pattern bell housing?

Anybody else do the Th200 to 200R4 swap? What all will I need? I'm assuming I'll need the cross member and driveshaft from the Bonneville. Will the 200R4 torque converter from the SBC bolt right up to the 307 Olds' flexplate?

Thanks for any insight.

 

[SRD art]

Also wondering if the 3 speed Th200 column will shift the 200R4 ok?

 

[fauxfour2]

I put a 200-4r into my 84 olds that had a th200 in it. I will let someone with more technical knowledge give you the breakdown but i do know the 3 speed column shift will work. I know this cause it works on mine. I went with a new crossmember and a tci lockup controller (because i removed CCC and computer). Driveshaft was a direct fit.

Had i kept the CCC and installed the 86 computer into my 84 i was told that i could have used the factor lock up connection. But when it comes to that i would say be skeptical and verify lol. Good luck with the switch.

 

[fauxfour2]

Just saw the 200-4r you have is attached to a sbc. In my case it was a direct sbo to sbo so i cant speak to the particulars with your exact swap.

 

[SRD art]

Thanks for the input! So do the TH200 and 200R4 both have a lock up converter connection that swaps right over?

 

[pagrunt]

Somewhere there's 5 speed gear box waiting for a grandpa car to be it's new home

 

[SRD art]

Lol, that depends on how deep your wallet is and how deep is your love and gift giving for your fellow man? My shipping address is... 😉

I have an NV3500 I bought for an S10 project that I may use in my Bonneville instead but I think for easy driveability this one will stay an automatic.

 

[olds307 and 403]

Thanks for the input! So do the TH200 and 200R4 both have a lock up converter connection that swaps right over?

It should be, the TH250/350C uses the same connector as the 2004R. It has been a long time since I swapped out a TH200C. With the 2004R crossmember it will be a direct swap. The case will be a dual bolt pattern and the converter will bolt right up, they are all lug style and the drive shaft is the same.

 

[SRD art]

Update on the trans situation- I got up to speed on research and learned the TH250C replaced the TH200 in the G-bodies and the 250C is what I have. Since it was only a $10 gamble I added some Lucas stop slip stuff to it. It maybe made a slight difference in how much it slips taking off from a stop in D but the problem is still there. Playing around I found something a little weird, if I put it in low and take off from a stop there's no slippage at all, and it shifts great if I change gears manually. I wonder if there's some sort of bad seal or passage blocked or something with the gear selector piston/shaft in the Drive position that's causing a low pressure situation, but when the piston/shaft moves into the first gear position it opens that pressure back up? Still swapping to the 2004R but sure am curious about what's wrong. 🤔

 

[fleming442]

TV cable too tight?