overdrive opinion

[davischevy]

Originally Posted by HO455

A couple of points on the 700r4.
If your looking to maximize fuel mileage the 700r4 has an edge due to the lock up converter.
To improve the life span of the unit only shift it into overdrive on the highway above 45 mph for distances longer than a mile. When the transmission is continually shifting in and out of OD extra heat builds up to the detriment of the transmission. 700r4s are prone to hunting when driving in the 35 to 45 mph.

I have a friend that has a stock 72 C10 big block with 3.08 gears and a 700R4. His truck "hunts" the OD.

I had a 55 Chevy and a 65 Chevelle with 2.73 gears and a 700R4. Overdrive was absolutely Interstate only. I think 3.42 is minimum rear gear for an overdrive to operate properly. Especially with a small block.

[72c20customcamper]

Originally Posted by davischevy

I have a friend that has a stock 72 C10 big block with 3.08 gears and a 700R4. His truck "hunts" the OD.

I had a 55 Chevy and a 65 Chevelle with 2.73 gears and a 700R4. Overdrive was absolutely Interstate only. I think 3.42 is minimum rear gear for an overdrive to operate properly. Especially with a small block.

My 85 has factory 3.23s and OD

[davischevy]

Originally Posted by 72c20customcamper

My 85 has factory 3.23s and OD

My 55 Chevy has 3.23's with OD and it works great. Yeah, I'm a hyprocrite.

[72c20customcamper]

Originally Posted by davischevy

My 55 Chevy has 3.23's with OD and it works great. Yeah, I'm a hyprocrite.

[jocko]

If the options are 700R4 or TH350 with GV O/D, the strength benefits of the GV unit are somewhat irrelevant as the trans will be the weaker (not weak, but weaker) link compared to the GV. 700R4 about the same strength as the TH350 in stock, form. I disagree on a couple points - a 700R4 is not necessarily "simpler" - the GV unit is pretty darn simple too, and there's no TV cable setup that one can screw the pooch with in a GV setup (not that TV is hard, it's just something you have to be aware of and set up properly). A TH350 and a 700R4 can be built to be built to withstand some abuse, but it takes a little coin to make either stand up the abuse a stock TH400 or 4L80E can withstand. It really comes down to what you plan to do with the truck - if you're going to REALLY abuse it, then you'll either need to sink some money into the TH350/GV or 700R4 - so I'd recommend leapfrog to a TH400/GV (if you happen to have a TH400 lying around or can find one that's somewhat inexpensive), or just go with a 4L80E. If you're just going to drive like a normal human being that drives a truck and not a gasser wannabe, then TH350/GV or 700R4 will be more than sufficient. Personally, I like the GV unit - and my preferred approach is to not alter the original driveshaft - remove it and save it - and shorten a non-original driveshaft so that I can return to bone stock if I ever want to. If your truck isn't original, then there's no need to worry about that aspect. Again, if you're just going to drive it normal-like then EITHER approach you're considering will work. A GV unit will run you $3K unless you're shopping for a used one - and used ones are easily worth $1500-2500 because they are very durable.

[davischevy]

The reason I didn't put a GV in my Longhorn?
I didn't think of it.

[jimijam00]

The TV cable isn't that big of a deal as long as you know there is one, what it does, and that is has to be set correctly. Bowties sells an idiot proof TV setup.

[57taskforce]

Originally Posted by Accelo

Sorry, I am voting for the 4l60. Or 700r4 if you prefer.
If you add the overdrive to the 350 you still have a used transmission.
You can split shift with the GV unit but who does that except for heavy loads?
I just think it keeps it simpler.
Rick

One problem, the 700r4 isnt known for great gear ratios or to hold up to any real amount of HP without being built up, I believe the th350 is stronger simply for the fact that there’s no overdrive to hunt in and out of and generate extra heat and wear and tear. Sorry I’m likely a bit cynical as I’ve been bitten by a couple of 700R’s and I have nothing good to say about them. I get what your saying, but I really think in the long run the gear vendors is a better path.

[Sheepdip]

Originally Posted by '68OrangeSunshine

Would a Gear Vendors OD work in a '67 K/10 Suburban w/ TH350/NP205? Or are you only considering 2WD here?

To answer your question, the GV Unit is a lets say generic unit and you buy the proper adapter (if they make it) for whatever tranny you are running. They do make them for various 4WD Xfer case applications but they can only be used in 2WD Xfer case gear selection.

[lil hoodlum]

Thanks..

You guys really are having me wanting a Gear Vendors OD in my set up. 1968 C10, 327, 3 speed manual, 3:73 rear end....

[SCOTI]

Originally Posted by Accelo

GM didn't do it but I did. Never had an issue. Big changes on two fronts. Fuel mileage went from 10 to 13 on the highway a 30% improvement. The noise in the cab dropped significantly. I was amazed at how much noise came from the motor.
Rick

In this original post (https://67-72chevytrucks.com/vboard/...6&postcount=22) it appears to be a quoted statement w/my name attached to it but I did not make that statement.

If you're going to quote someone/something, make sure you tag the correct person.

['68OrangeSunshine]

Originally Posted by davischevy

Yes.

Good to know.

['68OrangeSunshine]

Originally Posted by Sheepdip

To answer your question, the GV Unit is a lets say generic unit and you buy the proper adapter (if they make it) for whatever tranny you are running. They do make them for various 4WD Xfer case applications but they can only be used in 2WD Xfer case gear selection.

So I couldn't split gears in 4WD? Of course I already have 4 HI and 4 LO in the transfer case.

[ChevyRacefan]

The G/v is tested to handle 2000hp and hard drag strip launches.
The 7004r is never going to be this strong and last . No matter who the builder is.
The 7004r requires the tv cable adjustment to be on the money or kiss your transmission bye bye. The 4l60e (computer controlled 7004r) requires a controller. and not much stronger. If I was the o/p and did not want to go with the G/V I would bypass the thought of a 7004r/4l60e and go straight to a 4l80e. In basic terms it is a th400 with o/d.
Build a 7004r if you want. but plan on rebuilding it a few times if you don't get everything correct, The tv cable, the cooler, the lock up clutch. It can be done. but many don't and burn them up in short order.

[gmc684x4]

https://sites.google.com/site/sloppy...ans-controller

[Sheepdip]

Originally Posted by '68OrangeSunshine

So I couldn't split gears in 4WD? Of course I already have 4 HI and 4 LO in the transfer case.

The GV unit needs a driveline/speedo speed of approximately 40mph to engage, the GV unit only mates/transitions to the rear driveline not the front, it works in 2WD high only.

In a 4x4 you can't have front and rear driveshafts rotating at different RPM's.

GV would be able to answer all of your questions better than I, They are very knowledgeable about their product.

[72c20customcamper]

Another advantage to GV is if you sell the truck you cant take out the unit and put it in the next one

[MikeB]

Originally Posted by HO455

When the transmission is continually shifting in and out of OD extra heat builds up to the detriment of the transmission. 700r4s are prone to hunting when driving in the 35 to 45 mph.

That's definitely a benefit of having a switch to engage/disengage lockup. That 37 Chevy I mentioned above uses a 4th gear pressure switch in series with the manual lock-up switch, so lock-up works only in 4th gear.

As for SCOTI's comments about the car's "tall" gearing, he's right on the money. A 3.73 axle would make a lot more sense. BTW, I was mistaken about tire height. It's actually around 27.5", but still, that 3.36 axle is too tall.

[SCOTI]

Originally Posted by MikeB

That's definitely a benefit of having a switch to engage/disengage lockup. That 37 Chevy I mentioned above uses a 4th gear pressure switch in series with the manual lock-up switch, so lock-up works only in 4th gear.

As for SCOTI's comments about the car's "tall" gearing, he's right on the money. A 3.73 axle would make a lot more sense. BTW, I was mistaken about tire height. It's actually around 27.5", but still, that 3.36 axle is too tall.

3.36/27.5"/700r4's .70 4th = ~2300rpm @ 80mph & ~1850rpm 'in town' @ 45mph in 3rd gear.

Both would work fine w/a mild motor. I'm doing 3.42's/26.5"/.67 4th/3300lb G-body combo (1950rpm @ 45mph in 3rd/local; ~2300 @ 80mph).

['68OrangeSunshine]

Originally Posted by Sheepdip

The GV unit needs a driveline/speedo speed of approximately 40mph to engage, the GV unit only mates/transitions to the rear driveline not the front, it works in 2WD high only.

In a 4x4 you can't have front and rear driveshafts rotating at different RPM's.

GV would be able to answer all of your questions better than I, They are very knowledgeable about their product.

Well, thanks for your time and expertise.

[HO455]

Originally Posted by '68OrangeSunshine

So I couldn't split gears in 4WD? Of course I already have 4 HI and 4 LO in the transfer case.

I was unable to find the pictures of an automatic transmission with the GV between it and the divorced transfer case i have.

Here is a thread with some other 4x4 OD options.


http://67-72chevytrucks.com/vboard/s...d.php?t=729273

[jimijam00]

Who drives around town with their 700R4 in OD and complains it hunts for gears? OD is for the highway.

[SCOTI]

Originally Posted by jimijam00

Who drives around town with their 700R4 in OD and complains it hunts for gears? OD is for the highway.

People who just put it in 'drive' & go.

[weq92f]

.

https://easttexas.craigslist.org/pts...280555316.html

-klb

[jimijam00]

Originally Posted by SCOTI

People who just put it in 'drive' & go.

You mean "overdrive" and go? Having four gears, the fourth is overdrive, not drive.