My 40 GMC truck.... I have presently a Turbo 350, but I have a 87 or so 700r4 from a Blazer..... SO Which is best....Which is trouble free reliable? Some say the T350 is super reliable..... 700 r4 has an extra gear which is nice, but it needs a TQ converter lock up and a cable adjusted right.... Is it worth it? I don't do very much freeway driving, my gears aren't steep, my truck is light....
The 700 is best. Lower first, more gears mean better gear splits, and overdrive. Reliability being a dead heat mean the 700r4 wins. No compe***ion. You have to decide if the juice is worth the squeeze as far as the installation. Setting up a TV cable isn't hard, people just find it terrifying because you can toast an O/D in about 10 minutes with it set incorrectly. I have vehicles with both, and the vehicles with the 700r4 or 4l60e are just better drivers.
If you can hook it up correctly, I'd go with the 700r4. I run a 350T in my T Bucket, but if I knew how to correctly hook up the cable, I'd have a 700r4. I have 3:73 rear gears and would love overdrive. About this time someone is going to say it's easy to hook up, blah, blah, blah. But I personally know 2 people who fried theirs by not having it hooked up correctly. And these are mechanically minded guys who do their own work. So, if you are confident in your trans knowledge or know someone who can do it for you... get the 700r4.
Well, I am mechanicaly minded, but also know when-enough to let a guy who is perhaps a ****** guy do the cable.... I am planning next winters projects for my truck, and while I have time, I would like to save and have a direction before I pull the pin.... I am pretty wrapped up as far as this years direction.... The ****** issue is like oil or carb selection, and I would like the extra gear, but don't want a headache if there is one that may come with it....
700r4 without question. Go with http://www.bowtieoverdrives.com/index.shtml and buy there set-up for the TV cable and call it done...
From what you have said about your vehicle, I see nothing to be gained by swapping out the 350 for a 700R4. You will spend time and money and see no significant payback for your investment, other than "braggin' rights'. Your time, your money, your truck, your call. Ray
http://www.transmissioncenter.net/subject.htm This pretty accurately describes the steps involved. The first couple steps basically mean that you NEED THE CORRECT BRACKETRY FOR THE CARB YOUR'E USING. Most people I've seen will try to scab something together, and don't get the geometry right.
As one who has destroyed a 700R4 by not adjusting the cable correctly, I like the simplicity of the TH350. But, the other gear is nice. Depends on your current rear gears, how you drive it, etc. Considering gas prices these days, it might still be cheaper to have a pro adjust the cable (although there are thorough explanations on the net), & use the 4 speed.
I just ran numbers on my calculator, and I am surprised at the rpm difference... running 3.08 gears and 28 inch tall tires, and 55mph.... The T350 has a 1.00 final ratio....2033 rpm's The 700r4 has a .70 final ratio.... 1423 rpm's
Here's this,Trust me when i say they guys here know their stuff http://www.jalopyjournal.com/forum/showthread.php?t=791462
Where is your engines power band? I am running a 700r4 in my bucket. The first rear end had 2.88's in it. At highway speeds when the convertor locked I was at 1000rpm. It was a pig. I swapped to 3.54 and am now much happier. As for adjusting the cable. If you have the right brackets for the carbs and a good book on how to do it, its not bad. Going from a 350 to a 700 you will need: - a new crossmember (or the relocation of the current one) - most likely a new shortened driveshaft - lock up kit for the trans I am sure I am missing something else. But overall I am very happy with my 700r4
My 2 cents- with 3:08 gears you don't need an overdrive, especially a '87 700R4. They had a lot of problems in the early years. I had an '86 and was told don't install. It's been so long ago I don't remember the specifics, but, I did have a 3:08 with TH400 & a 396 and it cruised all day long @ around 2000rpms. I think you would be disappointed in the results with your combo. Maybe that was 3 cents!
BTW, Nice truck you have there. Your profile album shows it has a 350 V8. If you changed the axle ratio to a 3.50 or numerically higher, I'd say install the 700 R4. CAUTION: It would change the character of your truck enormously and you might drive it more often.
I'm putting the 700 behind a cad 390 on my 34 pu. I plan to pay my ****** man to make sure I don't screw it up. I've got bad ****** mojo.
My friend has a 200R in his 32 3W coupe behind a 350SBC. We've been very happy with performance and mileage on the road.
I thought is was pretty easy to adjust. I have done it with no problems. I found this on the net. Instructions 1 Locate the slider on the end of the TV cable that goes to the engine. Refer to the service manual for a diagram if you are unsure of its location. 2 Press the adjustment tab on the slider and hold it while pushing the cable into the slider as far as it will go. Release the tab. 3 Get in the vehicle and press the accelerator as far as it will go. The TV cable will self-adjust as you do this. 4 Drive the vehicle and check that it shifts from first to second gear at 15 to 20 mph, from second to third at 25 to 30 mph and from third to fourth at 40 to 45 mph.
3.08 rear gears are NOT compatible with the OD for normal driving. If you are willing to re-engineer your whole drivetrain you can get a suitable combination. But, again, where is the payback on the investment for a mostly town driven car? Currently you will be in third gear ( 1 to 1 ratio) at about anything over 25 or 30 MPH. With an OD trans, you will be in it's third gear, also 1 to 1, at the same speeds. You'll have to reach about 40 or better to get the OD engaged HOWEVER....that ain't gonna happen with the 3.08 and OD. As already pointed out in a post above, your engine torque curve very likely won't handle the 3.08 very well when in OD. Your trucks driveability will be worse. If you correct for that, perhaps a 3.50 to 3.70 rear gear that the OD can handle, you'll actually be at a higher rpm in town driving than you are now. So, unless you get to the highway more often, the benefits are not to be found. edit:While the rpm would be higher in town, it may produce the same or very slightly better fuel economy because you wouldn't need quite as much throttle opening to maintain speed. Stated another way, you would probably have a slightly higher manifold vacuum and that usually translates into using less fuel. But overall, I stand by my comments. Personally, I LIKE the OD automatics, have a few on hand with places to put them. But, I intend to put them in vehicles that will be highway driven often enough to justify including them in the build. Ray
To me, the great thing about od's is that I have have my cake (4.10-4.88 rear gear) and eat it too (reasonable 2100-2300 cruise rpm, instead of 3500-3800 rpm). The HAMB obsession with driving down the freeway at 1500 rpm escapes me completely, I just dont get it at all.
Yeah, the main reason that works with the cars that the transmissions originally came in is that they were set up to make their best power at an extremely low rpm.
I've had a couple 700R4 overheat and throw fluid all over the place.. one catching stuff on fire underneath car.. I'm sticking with TH350's.. if I want lower rpms I'll take care of it in the rear of the car.. not the ******.
While I'm NOT a fan of the 700, what are you doing with the truck (has anyone asked this simple question ?) ? Is it for around town, short hops on the freeway, show queen ? Unless you are on the freeway moving at 60+ MPH more thAn once or twice a year, go with the T-350. If you are always traveling some real distance at real freeway speeds, then yea, the 700 might be worth looking into. MIke
The 700R4 is the better choice *if* the rest of the combination is set up to take advantage of it. Your 3.08 gears are a bit tall, but your combo may work if rear tire size and engine torque characteristics work out. You have light weight, which helps, but not exactly the most aerodynamic vehicle, so wind resistance is up there to cause more load against the engine. If your highway driving is not so much, then just tolerate the higher rpms and less gas mileage for the small amount of time. The 350 SBC will live fine. A 700R4 is bigger than the T350, so you may run into other mods required to make it fit. That is another consideration.
I am kinda leaning at this point , Just keep my Turbo 350 in my truck, and My dream is to either own a shoebox, or a 50 merc.... The 700 will be better suited toward a heavier car. What ever I do, I will go through the ******, and I always have a bigger pump and large capacity pan on it as well. Not to mention a cooler... Heat kills any ******....
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