Hello all,

Im interested in finding out from a few of you what your opinions are regarding these transmissions-which do you believe is better and why?

I'm not going to pretend to be completely ignorant of the specs regarding both these transmissions, and in fact I am going to give my opinion on them now.

About a month ago I found myself test driving a new Chevy Silverado-this was an odd ball which had a manual transmission .. and I walked away very impressed. It was a 6.0L and gave me the impression of having lots of power.

It seems to me that alot of talk takes place comparing engines between the different manufacturers, and no doubt engine performance is a very important consideration when making comparisions about towing, durability, daily driving, etc,etc, - without a doubt it's the most important consideration.

But you also need good gearing to get the most from any engine to serve a particular use. Take the PSD for example, lets imagine for a moment that Ford utilised a very close ratio 5 speed manual behind it, one with adequete input splines and parts heavy enough to handle all the torque but with a first gear ratio of only 3.42 and that this tranny was mated to a rear differential with a 2.73 gear. I don't see a rig like this being able to pull a whole lot regardless of all the torque produced by the engine-it'd be one fast truck though at 325 HP!

It may seem like I'm getting off topic, but all I'm trying to do is emphasize the importance of good gearing.

Anyway after that test drive I went online to look up a few specs on the truck to see if I could find out what tranny it utilised and found out it was called NV4500.

After gathering as much info as I could on this tranny, I have to say that it seems to me that this is the transmission Ford should be using in their gas powered SD line of trucks.

I've looked at the specs for the ZF S6-650 as well, and while it is rated for heavier use than the NV4500, it seems to me that it relys alot on unconventional technology-unconventional at least as far as manual transmissions go.

A few spec comparisions;

NV4500 ZFS6-650

Dry weight 195lbs 220lbs
Case Material Cast Iron Cast Aluminum
Gearing type Helical Helical
Lubrication Castrol Syntec 90wt ATF
Type 5 spd w creeper 6spd w creeper
Trans cooling No Yes
Max Torque 450 FTLB 520 FTLB
GCWR 19500Lbs 26000lbs

Looking at the spec's it would appear that the ZF would win the comparision hands down, it uses cast aluminum which dissipates heat faster, uses ATF which is supposed to hold up better to heat than ordinary gear oil(it would seem the reverse to me) and it has a built in cooling system like automatic transmissions do.

On the flip side(there always is one) cast iron is stronger, the ZF relies on transmission cooling to achieve its superior ratings, which also takes away one of the most outstanding benefits of owning a manual-simplicity, and if a coolant line is punctured for what ever reason you will end up spewing ATF all over the trail and could quite possibly end up warping your gears before you even realise theres a problem.
Someone also mentioned to me in another thread that a transmission with gear oil runs quieter, and indeed that was another observation I made during that test drive- it was quieter as well as being smoother, but with just as much low end gearing as the ZF's I've test driven.

Then there is the fact that I am comparing a 5 speed with a 6 speed. Many have made the point that the 6 speed offers the advantage of closer ratios so as to keep the engine running more closely to it's optimum operating speed for towing.

I can't say I agree with this wholeheartedly. While I can definately see the advantage of having an additional gear in diesel applications, it seems a waste in gasoline applications.

We all know that gasoline powerplants operate peak performance at higher RPMs anyway, and to me the wider ratio's of a 5 speed more closely optimizes this type of powerband, while the 6 speed seems to have an additional unnessary gear for this application.

With a 450LBFT torque input rating the NV4500 is more than capable of handling any gasoline motor applications-esp since most of the power is made higher up.

The thing that probably surprised me most about the NV4500 was how closely it resembles the old NP435 4 speed granny gear box of yester year.

It's obvious from looking at cross sections of this transmission that this is basically an old 4 speed gear box with a syncronized 1st gear, and the fact that the OD gear is set in the countershaft
shows it is more of an add on to an existing basic design, rather than a design originally intended to have an overdrive gear.

From what I remember the old four speeds were pretty indestructible transmissions, and the NV4500 utilises many of the same features as these transmissions.

For the diesel application, the choice is clear; the ZF 6 speed offers an extra gear which is desirable in diesel applications, and it also offers the neccessary torque ratings to handle the diesel motors, but in gasoline engines for the reasons stated above I would much rather have the NV4500.

This subject especially interests me and so do all of your opinions ands experiences regardless of what they are, my thanks in advance for all the replies.

I am a stick shifter and would never consider an automatic tranny-it's just not the same for me-I like having as much control over my trucks as possible, plus we all know that even modern auto trannies could never hang with HD manual trannys without the auxillary fluid coolers and lockup torque converters.
Besides there is already an abundance of opinions and information to be found in many threads regarding all the automatic transmission offerings from the different manufacturers.

Thanks again, and please try to keep the responses as unbiased as possible(even if you think the Chev is total garbage-and the Ford as the truck of trucks-just try to keep to comparing the trans themselves rather than the trucks they come in...thx)

Chances are this is not going to be a very popular subject-probably as popular as manual transmissions are today..lol, but I'll take my chances....thx guys.

 

I have a 04' F-350, 4x4, V-10 with the 6-speed, 4:30 LS, Dana 80 DRW, while I agree with you about having the manual over the automatic, I also like the control better. I cant say I have driven the Chevy standard, never even wanted too, because of the IFS front end !

I have a 9' Fisher MM plow, and I have seen the chevy's with them on (might or might not be the 9' plow) and they are doing one serious nose dive, while my truck hardly shows the weight.

With the ZF-6, you hardly need low gear, but I have used it, for instance plowing along a curb, finding the edge, it works great.

I also like the manual transfer case, and manual hubs, shifting the transfer case to low range while hubs are unlocked works excellent for backing a loaded trailer uphill or into a tighter space with no front end binding on dry surfaces. you cant do that with shift-on-the-fly, or full-time, 4x4 systems !

Have a nice day. later,,,,,,,,,,Mark

 

The ZF6, across the board, is a better transmission. It has 6 forward speeds vs 5, has the oil cooler (internal by the way) and lower gears with, I think, a taller overdrive.

Also, cast aluminum is every bit as strong as cast iron in THIS application. You need to look under a truck with the ZF6...that thing is massive. It makes that Mazda 5 spd look like a Tinker Toy.

 

6 speed is better because the OD gear will be taller and give you better mileage. You wanna know how those F-bodies from GM can get 30 MPG on the highway with a high output V-8? The engine barely spins with the incredibly tall 6th speed on their Tremec T56.

 

1800 RPM at 80 miles an hour. I miss my Trans Am.