Your thoughts on transmissions

[Beatcoaster]

Now that I am finally done restoring the interior of my truck it is time to work on the drivetrain, beginning with my TH350 that is leaking all over the driveway. Supposedly the previous owner had it rebuilt, and it did shift fine when driven, but I plan to put some power through this thing and question whether it will be able to handle it (350/355/383 @ 350-400hp) with it's unknown to me history and 1969 metals. Would it be wise for me to take the $300 for a performance rebuild kit/parts and time spent, and just invest it in a new summit tranny already done for $650 that can handle 400hp? Then, I question that because I know I am going to need/want an overdrive gear as this truck will be making 300mile road trips over to our property for many summers to come - which leads me to finding a 200r4. The whole TV cable worries me a bit though, as there are some horror stories on the net with people not having it adjusted correctly, and frying their new tranny....You all have any thoughts or ideas for me?

[69GMCLonghorn]

Why would you consider a 200R4 if you're putting serious power behind it? Those were meant for V-6's or underpowered V-8's.

A decently built 700R4 would be what you want to look into.

[americanmusc1e]

A fresh TH350 will take 400hp fine, but my worn out one killed a front pump and yours probably won't last long either.

I was told by a reputable local transmission guy that does performance rebuilds to "forget the 200-4R!!"

I have a 700r4 and I like it, but I wouldn't recommend using it with 3.08 or 4.11 gears. I have 3.08's and I can't really use overdrive because my rpms are too low, although you may be fine with them. the TV cable isn't bad. My local transmission guy did my rebuild, and he had me bring the truck back when I had the transmission installed so he could check the TV cable. (I have a Holley carb and I used Holley's 700r4 kickdown brackets)

another thing to consider, a 700r4 is weaker than a TH350, I put $1300 in to mine, but you could get a good 400hp capable one for about $1000


EDIT: for all you 2004R fans, a 2004R can be built to handle more HP than a 700r4 can, its just really expensive

[69GMCLonghorn]

Here's a thought: Build a reasonable motor. If you're not racing it, make it fast, but not 12,000 HP fast... I've seen a nicely built 700R4 take some punishment with a 383 stroker in front of it. Unless you NAIL it every single time you start out, you should be fine and will get at least double digit gas mileage on the highway.

[prostreetC-10]

I will be of no help here because the only speed for me is a 4 speed. M-22 to be exact!!

Taint nuthin' like rolling true dem gears on a Sat night!

[DjS71]

If I recall, the 200-4R is dimensionally the same as the TH350, so no new drive shaft required. Either the 200-4R or the 700R4 can be built to handle that kind of power, all depends on the pocketbook.

As always, I could be mistaken.

[chevy_mike]

200R4's can be built to handle in the 1000 HP range. Some of the big dogs in the Turbo Buick world run these with no problem but anything built to handle these level is $$$.

I personally like the 200R4 for a couple reasons. First, it's the same overall length as a TH350 so your driveshaft doesn't have to be shortened like a 700R4. Second and the biggest reason to me, I like the gear spacing much better. First gear on a 700R4 is 3.06 and second gear is 1.63. That's a huge drop between gears.

The 200R4 first gear is 2.74 and second is 1.57, a much smaller drop. Basically it would be almost the same as a TH350 but you would have the .67 overdrive 4th gear.

For my money, a built 200R4 is a better tranny unless you really need a stump pulling first gear. I had a 700R4 in my last '68 and first gear was useless with my stock 4.11 rear end. I would just lite the tires up at will. Fun at first but got old quick.

[3quartertime]

I think if your at all worried that the trans won't hold up under the driving conditions you plan on then spend the extra cash.

In my opinion one of the things we tend to forget with projects like these is that when the vehicle was designed it was set up by an engineering team to handle the work loads it was rated for. From engine to trans to rear end gears to tire size, etc...

If I ever get past maintaining/refreshing my DD and building a fun/performance truck that's the approach I wanna take.

[Beatcoaster]

Thanks all for the input!

I truly wish the th350 had an overdrive cause that's all I really want or need from it. The 200r was listed cause of it's overdrive gear, dimensions, lack of needing a new driveline, crossmember, etc. I agree that the 200r would really rack up the pocket book if I wanted to build it up based on the fact there are few parts out there for it(unlike the 350,400,700r). I debated on the 700r also, but I don't like the gearing, it seems very oddly spaced and probably not the best for my application, plus I see it running $1300 w/o a stall converter, new driveline,crossmember, etc...I will eventually be towing some dirt bikes over the cascade mountains to our cabin a lot during the summer months, and just driving it around town for the rest of the time. It may see a drag strip once or twice for bragging rights(or not!! hehe) but I mainly want the engine/tranny built for cruising/passing as there is 3 hours worth of two lane road and 1 hour of interstate on our way to the property.

It really all comes down to $$$(and gas mileage $$$) and with that said, perhaps a fresh th350 with a 2000-2300ish stall converter might be the best bet for me now...of course I still need to figure out what gears I have in the rear end as that may be another determining factor...

Hmmm...

[packers05]

I have owned two buick grandnationals with 200r4s I rebuilt one with upgraded cluctches and stall, both kicked ass one ran low 12,s at 120mph so it can handle whatever your talkin, just get a used one out of a montess so it will have good valvebody and gov.

[cparman]

Completely agree with Chevy Mike and Packer 05. Had to Grand Nationals and was not very nice to either one. The last one was a 11.5 sec car. We are currently having one built to go into an83 Chevy wagon??? The guy loves the car. It will be a bolt hole for bolt hole swap. I have a 700 in my 72 Blazer, but wish it was a 200 for the more even gear ratio changes as mentioned above. currently 30,000 feet up and running 500 mph ( plane ride home )

[Beatcoaster]

Guys, I just spent the past 30 mins looking for stamp numbers under 40 years of dirt and grime on the rear end and found the HB code and it has 3.07 gears...Anyone know what the typical rpms at 65mph are with a 1:1 3rd gear th350 and 3.07 gears? Is the overdrive of the 200r/700r going to drop my rpms too much?!

[mikajo39]

Originally Posted by Beatcoaster

Guys, I just spent the past 30 mins looking for stamp numbers under 40 years of dirt and grime on the rear end and found the HB code and it has 3.07 gears...Anyone know what the typical rpms at 65mph are with a 1:1 3rd gear th350 and 3.07 gears? Is the overdrive of the 200r/700r going to drop my rpms too much?!

should be around 2800-2900rpm in the 65-70 mph area if i'm right with 1:1 3rd and 3.07s same combo as mine

[85gmc2tone]

art carr 200r4 will be your best bet unless you just got a whole lot to spend on a gear vendors gear splitter so you get 1/ 1od 2/ 2od 3/ 3od

[85gmc2tone]

here is a 200r4 built to hold 450hp 1500 $
https://www.artcarr.com/merchandise/details/14/32.acpp

[cparman]

depending on tire size, I would xpect you to have a 700-900 rpm drop. So if you are running a 235/70r15 tire with a 3.07 gear, you should be around 2500 rpm now, and expect some where between 1600-1800. which will be fine if you do a alot of highway driving. If you are running around town it might be a bit low.

[Beatcoaster]

Thanks guys, I found a tire size calculator online (http://www.miata.net/garage/tirecalc.html) and it looks like I should be able to go with a built 400hp+ TH350 since my rear end is geared so low. The truck will eventually be rolling on 275/45/20"(8.5" rim) on the front and 305/40/20"(10" rim) on the rear, so that gets me a tire diameter of about 29.5". With that thrown into a rpm calculator(http://www.csgnetwork.com/multirpmcalc.html) it appears a 1:1 final drive with the 3.07 rear end will net me 2273rpm at 65mph, which seems just about right to me. If I need to pass at 60mph, it will downshift into 2nd (1.52:1) and be at 3189 rpm and should be well into the powerband of the engine at that point for passing or pulling a load up a hill/mountain pass...the final overdrive ratio of the 200r/700r put me down around 1600rpm at 65mph, which to me, seems a little low....Thoughts?

[chevy_mike]

3.07 is a little low for an overdrive tranny of any type. It will put you way down in the power band and you can actually get worse mileage because you are lugging the engine at lower speeds. My '98 truck as this gearing and around town I put it in 3rd and only use OD on the freeway.

Ideally 3.42 is a good ratio for pulling 1st gear and a useable OD. 3.73 or 4.11 work well with a 200R4 but I find 4.11 to be too high for the 1st gear on a 700R4.

My .02 worth.

[Beatcoaster]

Thanks Chevy_Mike, that was my take on it after hours of research last night also, beefed up th350 it is!