OK guys, need a tranny expert here...........Exactly what is the difference between the SD42 and SD47 transmissions.............I guess one was made for early on and one for 95 and later..........but what was the differences in them..............

 

The SD47 will take more torque than the SD42. I was told by a tranny guy that the SD42 was built for gas engines and then used on some diesels with low torque.

 

<HR align=left width=600> <TABLE cellSpacing=1 cellPadding=5 width=600 border=0><TBODY><TR><TD vAlign=top width=100> </TD><TD vAlign=top width=135>S5-42, ZF


</TD><TD vAlign=top>ZF S5-42 – 5 speed manual transmission has an aluminum alloy main gear case and tail housing with the bell housing integral to the case.

The ZF S5-42 is built in both a 2 wheel drive and 4 wheel drive version with gas and diesel designs

ZF first introduced the S5-42 in 1987 and was used in the Ford F250, F350, F450 and Super Duty trucks until 1994.

All gears on the S5-42 are fully synchronized with an input torque rating of 420 ft-lb

Standard gear ratios on the ZF S5-42:
<TABLE cellPadding=0><TBODY><TR><TD><TABLE cellPadding=0 width=166><TBODY><TR><TH scope=col colSpan=2>Close Ratio </TH></TR><TR><TH scope=row width=85></TH><TD width=73>4.14 </TD></TR><TR><TH scope=row></TH><TD width=73>2.37 </TD></TR><TR><TH scope=row></TH><TD width=73>1.42 </TD></TR><TR><TH scope=row></TH><TD width=73>1.00 </TD></TR><TR><TH scope=row></TH><TD width=73>0.77 </TD></TR><TR><TH scope=row></TH><TD width=73>3.79 </TD></TR></TBODY></TABLE></TD><TD><TABLE cellPadding=0 width=166><TBODY><TR><TH scope=col colSpan=2>Wide Ratio</TH></TR><TR><TH scope=row width=85></TH><TD width=73>5.72 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>2.94 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>1.61 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>1.00 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>0.76 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>5.24 </TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>The ZF S5-42 main case cast number is “1307”
</TD></TR><TR><TD vAlign=top width=100> </TD><TD vAlign=top width=135> </TD><TD class=style11 vAlign=top><HR></TD></TR><TR><TD vAlign=top width=100> </TD><TD vAlign=top width=135>S5-42 4x4, ZF


</TD><TD vAlign=top>ZF S5-42 – 5 speed manual transmission has an aluminum alloy main gear case and tail housing with the bell housing integral to the case.

The ZF S5-42 is built in both a 2 wheel drive and 4 wheel drive version with gas and diesel designs

ZF first introduced the S5-42 in 1987 and was used in the Ford F250, F350, F450 and Super Duty trucks until 1994.

All gears on the S5-42 are fully synchronized with an input torque rating of 420 ft-lb

Standard gear ratios on the ZF S5-42:
<TABLE cellPadding=0><TBODY><TR><TD><TABLE cellPadding=0 width=166><TBODY><TR><TH scope=col colSpan=2>Close Ratio </TH></TR><TR><TH scope=row width=85></TH><TD width=73>4.14 </TD></TR><TR><TH scope=row></TH><TD width=73>2.37 </TD></TR><TR><TH scope=row></TH><TD width=73>1.42 </TD></TR><TR><TH scope=row></TH><TD width=73>1.00 </TD></TR><TR><TH scope=row></TH><TD width=73>0.77 </TD></TR><TR><TH scope=row></TH><TD width=73>3.79 </TD></TR></TBODY></TABLE></TD><TD><TABLE cellPadding=0 width=166><TBODY><TR><TH scope=col colSpan=2>Wide Ratio</TH></TR><TR><TH scope=row width=85></TH><TD width=73>5.72 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>2.94 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>1.61 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>1.00 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>0.76 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>5.24 </TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>The ZF S5-42 main case cast number is “1307”
</TD></TR><TR><TD vAlign=top width=100> </TD><TD vAlign=top width=135> </TD><TD class=style11 vAlign=top><HR></TD></TR><TR><TD vAlign=top width=100> </TD><TD vAlign=top width=135>S5-47 4x4, ZF


</TD><TD vAlign=top>ZF S5-47 – 5 speed manual transmission has an aluminum alloy main gear case and tail housing with the bell housing integral to the case.

The ZF S5-47 is built in both a 2 wheel drive and 4 wheel drive version with gas and diesel designs

ZF introduced the S5-47 in 1995 and was used in the Ford F250, F350, F450 and Super Duty trucks.

All gears on the S5-47 are fully synchronized with an input torque rating of 470 ft-lb

Standard gear ratios on the ZF S5-47:
<TABLE cellPadding=0><TBODY><TR><TD><TABLE cellPadding=0 width=166><TBODY><TR><TH scope=col colSpan=2>Close Ratio - 7.3L Diesel </TH></TR><TR><TH scope=row width=85></TH><TD width=73>5.08 </TD></TR><TR><TH scope=row></TH><TD>2.60 </TD></TR><TR><TH scope=row></TH><TD>1.53 </TD></TR><TR><TH scope=row></TH><TD>1.00 </TD></TR><TR><TH scope=row></TH><TD>0.77 </TD></TR><TR><TH scope=row></TH><TD>4.66 </TD></TR></TBODY></TABLE></TD><TD><TABLE cellPadding=0 width=166><TBODY><TR><TH scope=col colSpan=2>Wide Ratio</TH></TR><TR><TH scope=row width=85></TH><TD width=73>5.72 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>2.94 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>1.61 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>1.00 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>0.76 </TD></TR><TR><TH scope=row width=85></TH><TD width=73>5.24 </TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>The ZF S5-47 main case cast number is “1317”
</TD></TR></TBODY></TABLE>

 

I appreciate all the quick info........so it appears all that is different is the input torque and the the "close ratio"............just what is the "close ratio"

and what is the wide ratio?

 

Close ratio has the gears spaced further apart (numerically, not physically)than the wide ratio. In other words the change in ratio is more pronounced in the wide ratio transmission.
Wide ration transmissions are usually used behind engines with a narrower rpm band, like diesels.

 

Well I guess what I am getting at is: if I have a pto unit off a 460 CI 42 tranny......will it work on my 7.3 47 tranny?

 

Diesel_Dirk, I think it is the other way around. Close ratio has the ratios closer together so the change in RPM is less at each shift. Wide ratio has the ratios further apart so you drop more RPM on each shift.

 

You're right...was thinking one thing and typed another.

 

Figured that was what happened.

 

i have a 1990 7.3 IDI...do yall reckon its the close or wide gearing?

 

It's about your intended use. Winding it out, not under much of a load, wide ratio. The engine does not have to start over at a lower RPM. More of a gasser thing, as they make torque at a higher RPMs. The close ratio is for the big load rigs, where the drop in RPM may cause you to lose wheel speed. Wreckers would normally have a close ration, they'll pull loads that are heavier than they are. You can listen the 18 wheelers gearing up under load. The RPM bearly drops as they shift-shift-shift to get the 80,000 lbs a movin'

 

I heard that the input shafts are different between the two. Also heard that the bellhousings are a different bolt pattern. Can a 47 take the place of a 42 without any modifications?

 

The 42 and 47 are interchangable without modification.

The gas version has a different bolt patter than a diesel version so they will not interchange.

 

x2 I just had this conversation with my tranny guy. He said that the cases are absolutely interchangeable from bellhousing to tailhousing as long as they are from concurrent motor types and drive types.

 

in a 9 speed the RPM drop is about 700 RPM's atleast the way I drove the truck that was about the average drop was 700 to 1000.