ZF man. trans. - Diesel Forum

warwagon82 · 10-17-2006, 02:32 PM

I was told that the first 7.3's came with a different 5-spd than the later powerstroke tansmissions which were built heavier. Is this true? What are the different model #'s? What years did they switch? On the 5 and 6-spds is there any difference other than bell housing on the gas and diesel transmissions?

nashvillebill · 10-17-2006, 08:08 PM

I'm no expert, but I've read the 94 and 95 models had the ZF-42 which is rated at 420 ft-lbs of input torque. The later models had the ZF-47 which is rated at 470 ft-lbs of input torque. I believe the two transmissions are dimensionally the same, and either would bolt right up...but don't quote me!!

However, the 6 speed doesn't interchange at all with the 5 speed if I have interpreted other people's comments correctly. (different splines/size of input shaft?)

Again, I'm no expert, but nobody else answered your question, so I figured I'd try.

PSDfreak · 10-17-2006, 08:43 PM

[ QUOTE ]
I'm no expert, but I've read the 94 and 95 models had the ZF-42 which is rated at 420 ft-lbs of input torque. The later models had the ZF-47 which is rated at 470 ft-lbs of input torque. I believe the two transmissions are dimensionally the same, and either would bolt right up...but don't quote me!!

However, the 6 speed doesn't interchange at all with the 5 speed if I have interpreted other people's comments correctly. (different splines/size of input shaft?)

Again, I'm no expert, but nobody else answered your question, so I figured I'd try.

[/ QUOTE ]

Sounds about right to me [img]/ubbthreads/images/graemlins/wink.gif[/img]

-Casey

smokyred · 10-18-2006, 12:37 AM

The ZF6 CAN be put in our trucks, but you need to modify such things as the trans crossmember, and there is some wiring IIRC.

Dave

warwagon82 · 10-27-2006, 03:17 PM

What about the 5-spds from the late 80's? Gas and diesel trans the same or different.

72Pstroke · 10-27-2006, 05:47 PM

The gas bellhousing is a different bolt pattern than the diesel. You can use an early diesel 5 speed. It is the same as the early Powerstroke 5 speed.
Tim

warwagon82 · 10-29-2006, 06:12 PM

So, the ZF-42 was the first 5-spd. Then in about 95/96 they switched to the ZF-47. Was the switch also for gas engine trans? Are there any internal differences between the gas and diesel trans? What about the gas and diesel 6-spds? Are they the same internally add what are their model numbers?

milner351 · 10-30-2006, 07:28 AM

In general, Gas and diesel transmissions do not interchange.

The diesel and Gas engines have very different torque and rpm characteristics, usually the gear trains are very different in terms of ratio's - diesels make as much torque at idle as many gas engines do at peak tq rpm ;-) but diesels are redlined out by 3500 or so... where a gas engine will wind up to 5500-6000 depending on application.

warwagon82 · 10-31-2006, 12:04 AM

[ QUOTE ]
In general, Gas and diesel transmissions do not interchange.

The diesel and Gas engines have very different torque and rpm characteristics, usually the gear trains are very different in terms of ratio's - diesels make as much torque at idle as many gas engines do at peak tq rpm ;-) but diesels are redlined out by 3500 or so... where a gas engine will wind up to 5500-6000 depending on application. [/quote
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I know they can't be interchanged because of the bolt patterns, but does ZF actually make any differences in the internal gear ratios of their 5 and 6spds?

milner351 · 10-31-2006, 09:18 AM

the gear ratios for a diesel and gas are not the same as far as I know....

warwagon82 · 11-12-2006, 07:43 PM

So if the 5spds were the ZF-42 and ZF-47 what are the 6spd model number(s)?

klhansen · 11-13-2006, 03:55 AM

[ QUOTE ]
So if the 5spds were the ZF-42 and ZF-47 what are the 6spd model number(s)?

[/ QUOTE ]

The 6-spd used in the 99 & up trucks is a ZF S6-650 rated at 650 nm (~535 ft-lb) input torque.

The 99& up gassers still use the ZF S5-47 5-spd, which is rated at 470 nm (~385 ft-lb) input torque.

Garbage_Mechanic · 11-13-2006, 08:30 PM

There is a nice ratio chart on US Gear's site for the overdrive.....

I frankly like the ZF42 for normal driving because 1st gear is higher and actually useful to take off. But for very HD use the 47 first gear ratio is lower. I don't care because if I'm in that tight of a place I'll put the transfer case in low range to take the stress off of the clutch.

I havent heard of anyone breaking the ZF42 in a high perf truck.

shannon80 · 11-21-2006, 11:18 PM

I have a 95 with 5 spd. Can the 99 and up 6 speeds bolt right up to mine? Will this drop my rpm down at all, or just spread the shifts out a little? I want to drop 200-300 rpm on highway.

jbawilliams · 11-21-2006, 11:27 PM

The 6 sp in my 99 has nearly the same top gear ratio. 5sp in my 96 was .77:1 for OD, and 6th in 99 is .72:1. Low is also the same at 5.??:1. They are just closer together in the 6sp. I do not know about fitment. [img]/ubbthreads/images/graemlins/wink.gif[/img]