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Hey everybody, I'm fairly new on here.. Actually I think I'm slightly addicted to this forum. I've received great advice, and information reading and posting on here. Figured I'd post my dilema on here, and see if anyone can help point me in the right direction. Before you read further I wanted to explain what I'm looking for, as far as driveability. I am not looking to take this to the track, but I'm not putting a 350ci in just for Sunday driving either.:baby: I guess if there was middle ground to have fun, and enjoy a long cruise would be what I'm looking for. Of course reliability playing a big role in any decision.

I own a 78 GMC Caballero, of which I've pulled the stock 231V6 and have a 350ci, waiting to put a tranny on it and put back in the car. The original transmission was a 200 Metric, which from what I've read will not work with a 350ci. The rear end is a 10 bolt 2.73. I believe it is a 7.5 10 bolt, as it fits the descriptions I've read. Which doesn't sound like the best of options for rear ends. Here's a picture


I had a TH350 that I was just going to put in the car, which ended up being bad. So now I'm at square one with choosing a transmission. The first thing I did was try and ID my rear end, as that is the final part of the equation(besides tire diameter). Knowing what rear end I have; I started doing the math on transmission gear ratios, summed up with rear end gear ratios. I found this pretty sweet tool that calculates mph from gear ratios. Here's the link if anyone's interested..:snipersmilie:MPH CALCULATOR

So using that calculator, if I have a TH350 with a 2.73 rear end and 26" tire diameter. At my final drive 1:1 @ 2500 rpm's I'd be doing about 70mph. Actually not that bad of an equation for what I'm looking for at least for the final drive. I'm not sure how 1st and 2nd would fair with a 2.73 and a TH350. My worry is this 7.5 rear end will eventually not hold up.:bomb: I mean I do plan on putting the pedal to the floor from time to time, I'm worried that the rear end will go at some point. At that point I'll be looking for a new rear end either a 12 bolt, or a 10 bolt 8.5. I don't know much about rear ends, besides how their gear ratios effect mph at different rpm's.

This all boils down to a transmission choice. The final gear ratio of the transmission along with the rear end ratio is going to dictate how she drives. I like the idea of a OD transmission like a 200R4, and a rear end with a little higher gear ratio/lower gear(3.73). The TH350 will work for what I'm looking for, just have to have a rear end ratio of 2.73 to make it work for what I want. I'd like to get a transmission ordered here soon, but now I'm sort of lost in gear ratio land. Anyone have some advice as to the best transmission, future rear end combination that I should be looking for? Thanks in advance for reading and any help!
 

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Not sure about the tranny gear ratios, but I recently had an old powerglide replaced with a TH350, 2200 stall converter and a shift kit.

My rear axle is 2.73 with open diff, but I gotta say, it runs super with this set up. Connected to a GMPP350/290hp crate motor and spins pretty good on the highway too.

My q-jet just got replaced with a Holley, so my gas mileage is about to drop some, but the response is phenominal.
 

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I have a 2004r(shift kit) with 3.23 gears(posi) in the rear end. My tires are 25.85 inches in diameter. I have a stock 1800 stall. I run 2000 rpm's at 55 and 2500 rpm's at 70. I will say, from what I see from other people's post, my rpm's are a little higher than most. Not sure why, maybe it's because I am still running stock 14in tires and everyone else has upgraded to at least 15's or even 16's.
 

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I wouldnt worry so much about your 10 bolt. As long as you're not running drag radials or slicks it should be fine. Radial tires will just spin and as long as the tires are spinning there is little load on the ring and pinion. Now, if you're beating on it and doing hole shots, yeah it's probably not gonna last forever.

I think your best choice for a tranny would be a TH350 for several reasons. They're easy to find, priced reasonably, parts are easy to find and they're a strong transmission.
 

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Neller,
You said it well yourself. You can run a 2.73 rear with a TH350 and turn 2500 rpm on the highway, or you can run a 3.73 rear with a 200-4R and turn approx. 2500 on the highway. Meanwhile, you have another gear in between there, which means far quicker acceleration.
TH350--
2.73 rear end x 1.0 final drive = 2.73
200-4R--
3.73 rear end x .67 final drive = 2.49
Very similar highway speeds.

1st gear acceleration comes out to 33% quicker, according to the gear ratios (2.73 x 2.52 vs 3.73 x 2.74).
 

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I'm running a 2.73 with a 2004-R and at 70 turn 1750 . Great fuel mileage and all around cruising . I drive my 86 everyday so I needed to keep the gas mileage up there. The engine is a 96 305 tk block,94 Vortec heads w/quadrajet carb ,vac.dist.. . The 2004-R is a good tranny but I would steer as far as possible from a Transgo shift kit,unless you want a neck snapping shift.
 

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TrannyMike
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try this calculater http://www.gtsparkplugs.com/GearCalc.html
you can put other trans gear ratios in..

a 700 od and a 3.73 seems just about perfect for a street car to me..:texas:
That's not a bad combo, but the 2004R is a little better. The 1-2 gear ratios are better and overdrive is is a lower ratio for even better mileage. 3:73 gears with either overdrive trans is in my opinion the perfect balance between performance and fuel economy. :beer:
 

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Also, the 200-4r uses the same driveshaft as the TH350. Makes for a slightly easier install.
 

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Discussion Starter #10
I hear
say to stay away from the 200R4, and go with the 700R4. I guess hearing the words "Problem Child" sent me reconsidering. However you hear about GN's running them without problems. :dontknow: I have two drive shafts, one is for the 200 Metric/V6 setup, and the other is a TH-350/V8 setup. Guess I'm sold on an OD tranny at this point, and a 3.73 rear end. There are pros and cons to both transmissions, ease of install, cost, reliability are my biggest concerns.. Anyone suggestions on what, who, how? I have read some of the posts on 200R4 vs 700R4, but I wanted to get your opinions based on my vehicle. Thanks again guys!! I appreciate your information.. Hope everybody had a great weekend!!
 

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Discussion Starter #11
shoot wasn't trying to embed that video, just link to it.. oops..
 

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The 700r4 is heavier, and has gear ratios that are not as friendly as the 200-4r's. Stock 200-4r's can handle 250-300 hp. Built ones can handle north of 600+.

I studied them for a long time before I made my decision. lot of folks kept recommending the 700, but only because it was "Beefier". I finally decided on the 200r4 based on the GN's using them.
 

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You cant go wrong with a Th350. I run one with 200 stall and mild shift kit, 2.73 gears. she runs real nice. get up to 19mpg on freeway and 12-14 around town. does about 2200rpm at 65mph. but im also running 18's on 275/40. out the hole car is gone. 3.44 is biggest gear you can cram into a 7.5 rear. that 10 bolt will easily hold 400hp if you dont beat on it. mines 33 years old and never touched(other then oil change) car lives in the high 13's. 700's and 200's have issues. they are not reliable with out a lot of work. get the wrong 700r4 and you are on the side of the road.(one is electronic shift other is vaccum) you can get a built TH350 for around $700. I swear you can throw sand in a TH350 and it will still give you years of trouble free operation. Just remember to tune your engine to your gear ratios and your car will haul butt and cruize nicely. I drive mine daily on this setup.

"More horespower and bigger gears doesn't mean you will go faster."
 

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I guess I must have missed something,but is this trans for drag racing,running hard from light to light,or getting decent fuel mileage and normal driving ? I had a 35o I used for normal driving and enjoyed it very much,BUT, the fuel mileage wasn't as good as a OD tranny could give us,so I switched and am very happy with the mileage and performance. I have to watch my fuel costs as I drive mine everyday ,so the 2004-R is a great tranny,to me. I have been told by many builders that the 2004-R is a tough tranny ,and I believe it.
 

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Neller,
Early 200-4Rs may have been problem children (1981-1984), but later cases tell a different story. The 200-4R is evenly geared, has the same cooling line setup as your TH350, and is slimmer--easier to work on and doesn't cause any clearance issues with your transmission hump. Yes, rebuilt ones can handle above-stock power, most rebuilders will offer Levels 1, 2, and 3 depending on your pocketbook. Like the others say, if you are shy of 300 horsepower, a 1986-newer transmission will work great!
 

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I hear some people say to stay away from the 200R4, and go with the 700R4. I guess hearing the words "Problem Child" sent me reconsidering. However you hear about GN's running them without problems. :dontknow: I have two drive shafts, one is for the 200 Metric/V6 setup, and the other is a TH-350/V8 setup. Guess I'm sold on an OD tranny at this point, and a 3.73 rear end. There are pros and cons to both transmissions, ease of install, cost, reliability are my biggest concerns.. Anyone suggestions on what, who, how? I have read some of the posts on 200R4 vs 700R4, but I wanted to get your opinions based on my vehicle. Thanks again guys!! I appreciate your information.. Hope everybody had a great weekend!!
That is a big misconception right there. The 200r4 is better with the gear ratio. Both the 700r4 and the 200r4 have to both be built correctly in order to handle power. They both are good trannies, but if you want my option get a 200r4. There are guys running Grand Nationals and other high performance cars with a 200r4. It all comes down to what parts are inside and how well the shop built it.

Now some shops are better at building a 200r4 then others. Still that is the way I tell everyone to go with. It is much better then a 700r4 in my option. Also to me a 700r4 seems more like a truck overdrive type tranny.
https://www.youtube.com/watch?v=exp3gWby_tE
https://www.youtube.com/watch?v=-M754r2Y0jQ
Also read this if you get time.
http://www.drwtransmission.com/thm_200-4r.htm
 

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Discussion Starter #17
I am thinking of the drivability, ability to upgrade, reliability, and ease of installation.

Upgrading: I am leaning towards the 200R4, and having the ability to upgrade to a 10bolt(8.5), or 12 bolt rear end with lower gears at some point. Seems 1st through 3rd will be fun/quick with a higher rear end ratio, and OD will be there when I need it.

If I stick with a TH-350 I'm pretty sure 2.73 would be as high of a gear ratio for what I'm looking for in driveability.

I'm not up on rear end's and ratios, but are there 12 or 10 bolt(8.5) with 2.73 ratios?:dontknow: Anyone have an idea what vehicles I should search for that had either rear ends that are a bolt up to a 78 GBody?

Reliability: Well the TH350 probably wins this battle in my mind, as the parts are more plentiful and has the reputation that it does. However the 200R4 with all the fixes, and some upgrades is pretty bulletproof as well now. Of course you pay more for those fixes, to get a good 200R4..

I know the Summit and Jegs route to finding remans., but is there any other companies you guys suggest?

Ease of Installation:
I am a little confused on this one, the crossmember and frame mount holes I have were designed for a TH200(metric). I know either transmission will bolt up to the sbc, that I'm installing, but I'm completely confused on the crossmember mounts for either transmission.

The TH350 seems to have the same crossmember mount location, as the TH200, and the 200R4 seems to have a 5+ inch difference than both the 350, and 200. This is my biggest concern/question on using the 200R4?

I have a drive shaft for a long tail shaft(9") TH350, and a drive shaft for a TH200 which also seems to fit both the short shaft TH350, and the 200R4. I guess I'm ok with driveshafts with either equation, as both came from 78 GBodies. Correct me if I'm wrong.:dontknow:

Driveability: Well this is an argument that you almost need to drive both to have a good answer to. I think aeilenstein you said it best it's apples to apples if you change the rear end ratios around to fit your transmission..
I guess I want the transmission to dictate what rear end, and not the rear end to dictate what transmission. I do believe the 7.5 will probably take what this engine/trans throws at it. Knowing if larger 10/12 bolt rear ends like I talked about support the 2.73 ratio will also add to this decision.

I know this is a tired subject, as there are soooo many bits of conflicting opinions out there, and I bet you guys have been here before. I'm still researching, and trying to make a decision this week. Again I thank all of you for your input and time!:beer:
 

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Yes you can find 12 bolts with 2.73 or similar gears, normally the 8.5 rears are out of GN's or 442's and have 3.42 or 3.73 gears.. Honestly if all your running is a little mild 350 with an auto transmission the 7.5 10 bolt will last a long time..... I would run a TH350 with the 2.73 gears you have, it's the way it would have come stock with the 350 and the gearing isnt terrible. If swapping to an OD transmission then a swap to 3:23-3:42-3:73 gears is a must because you won't actually get into the RPM range your looking for on the highway and will in actuallity be "lugging" on the highway and have worse mileage
 

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Discussion Starter #19
Yeah I agree with the fact that the .67 final drive is too high of a gear for a 2.73 rear end. Unless I want to cruise at 105mph at 2500 rpm's. I'd be way out of the powerband rpm's of the sbc. 2000 is around where I'd like to cruise which would be almost 85mph. Of course I wouldn't put the transmission into OD until I got a higher rear end ratio. Which follows the upgradeability idea.

The TH350 really is the best transmission to put in the way the car sits now. It seems the crossmembers are compatible, where I'm not sure on the TH200R4. Plus it's bulletproof, especially because I'd be buying a rebuilt/upgraded one. Was the tailshaft a 6" or 9" back then? Seems I have driveshafts for either. :nanawrench:
 

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Neller,
If you have the long shaft TH350, then your overall trans length is 3" longer than your 200-4R you're considering. You'll need a 3" longer driveshaft with the same transmission yoke.

Your crossmember should work just fine, but yes, you'll need to move it way back. I forget the exact dimension---close to 6". That doesn't mean the transmission is 6" longer, just the mount.

I recommend Art Carr's California Performance Transmissions, Bowtie Overdrives, at least for more information.

Here we go--the mount is 6 1/2" further back.
 
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