View Full Version : Th200r4 Vs. Th350
07-16-2002, 07:58 AM
What are the advatages/disadvatages of replacing the Th200 with the Th200r4 versus replacing the Th200 with the Th350? Are there any special mods that need to be made to go from a non OD tranny to an OD tranny? I know if I go with the OD tranny I could put 3.73 or 4.11 gears in the rear (would 4.11 be alright for a street car), but is that the only advantage?
Here's the thing, I found a guy who would rebuild a Th350 with the parts I want for total of $600 which is around the amount I had budgeted for my tranny. Yesterday I found several Th200r4 that a guy had and would sell me one for $150. I know I would have to have it rebuilt, but I was wondering how much should a rebuild of this type of tranny cost? I don't plan on doing any racing so I don't need the tranny bullet proof. My car is a daily driver. My engine specs. is estimated to make around 300 hp and 320 to 350 pounds of torque.
Any advice would be appreciated.
07-16-2002, 05:18 PM
A th350 is a drop-in for the 200c...
The 200-4R requires a different crossmember...
The 200-4R not only has the OD but it has a steeper 1st gear ratio...
Rebuilding the 200-4R should be a little more expensive but not TOO much...
I replaced the th-350 somebody replaced the 200c with with a 200-4R...
Christopher In Tampa
07-16-2002, 05:53 PM
Yeah he' right the 200-R4 has a better first gear and all the other gears set eachother up better then the TH350. With the TH350 you need a larger engine too handle the internal friction and to better handle the large leeps in ratios from gear to gear. The 200-R4 has better gear to gear ratios, has less internal friction and a overdrive lockup converter but the 200-R4 wont last as long under race conditions unless you put some $$$ into it but for day to day street use I would stay away from the old fashion 70s style TH350 and use the more modern designed GM foot stool the 200-R4
07-16-2002, 06:34 PM
I don't know if I would say the TH200-4R sets the gears up better than the TH350 as it has a larger gap from 1st to 2nd than the TH350 does. Compare the gear ratios:
So it would appear that the TH350 is a closer ratio tranny than the TH200-4R. I agree with everything else that was stated, though.
One thing to keep in mind with the TH200-4R is the lower first gear. A TH200-4R pushing a 3.42 rear gear will give the same overall gear reduction as a TH350 and a 3.73 rear gear.
Christopher In Tampa
07-17-2002, 04:59 AM
Good point. Second gear on the 200-r4 is still lower but not much
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07-17-2002, 07:13 AM
So if I'm not going to race my car the Th200-4R would be alright in stock form? If I put a B&M Transpack in it will that strengthen it up a little bit?
Christopher In Tampa
07-17-2002, 07:34 AM
Well the shift kit will only help it live longer due to the fact that it will lessin slipage and lower the tranny temp a tad bit but the real problem with the 200-4R is the splines inside the tranns wear out and sometimes break under high horse power engines with repeated full throttle runs. But this only happins (at least to what I have experianced) when using a very firm shift kit because the fast firm jolt of a strong shift is more terror to the trannies solid stress parts than the smooth power output of even some of the strongest engines. The GN guys really know how to make an 200-R4 last and perform great! I once killed one and when it would shift under a load the tranny would make a grind sound like a old worn out zipper during the shift. If I was you I would use the 200-R4, put a mild shift kit just enough to get positive shifts but no neck breaker, put a 2400 stall converter for better hole shots and USE USE USE a trannie cooler to protect your investment. You can see 75.000 miles of perfect behavier (keeping fresh fluid and filter in there) and 25 more of still good but about time to replace behavier out of the 200-R4 but I usaly dont trust them after 100.000. Trust me the TH350 is a boring 3 speed strong but boring and old fashined
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07-17-2002, 09:19 AM
Yupper use a tranny cooler it's really a no brainer not to have one.Auto Zone $40-$50 saves you alot of $$$ down the road. I have one on both my cars.Later
07-17-2002, 09:21 AM
Where is a good place to mount a tranny cooler on a G-Body? Also, is there a specific type of cooler to buy?
07-17-2002, 12:04 PM
I actually replaced the Th200C tranny with the Th200-R4 tranny. 1st 2nd and 3rd are exactly the same gear ratios. the only difference is the final drive is a .67:1 which is great for interstate speeds and more streetable w/ a 3.73:1 gear ratio. The reason why i went with this tranny instead of a Th350 is not only for the 4th gear, but also the gears are spaced out a little better than the 350 was.
Some of the things I did when i rebuilt mine was a 10 vein pump, B&M stage 2 shift kit, and upgraded everything else a little, along w/ a 2200 stall lock up converter. (brand new) I got the whole thing rebuilt for $350 and installation for $150.
Only thing you really have to change is the cross member and change out the speed-o gear in the tranny depending on the rear end u use and the tires u have on the car. I am running a set of 235/60/r14s on my car w/ the Stock 307, hedders true dual exhaust, electric fan, re-did the hood for cold air induction and some other stuff, but I am able to chirp them into second and *sometimes* 3rd
w/ a 3.73 rear end and the Th200-r4 tranny w/ the tires on there right now (235/60/R14) w/ shifting @ 4200rpm respectivly..
4th 120+ mph
Crusin around @ 75mph is approx. 2200rpm
Th200C w/ the stock 2.41 rear end same tires
Crusin around 75mph is approx. 2500rpm
Good luck w/ the decision! hope that helps out a little!
Christopher In Tampa
07-17-2002, 12:11 PM
yeah chirping 3rd is the tough one did you know that you can use a GN sevro and get a stronger 3rd and second.
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07-17-2002, 01:40 PM
Thanks to all who have responded. I think I'm going to go with the TH2004r. This is a great site!
07-17-2002, 01:42 PM
No problem! good luck w/ everything! be sure to let me know how it turns out!
Also check out my website there is some tech stuff on there to..
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