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Transmission swap

Victor Roberts

New Member
Joined
Mar 18, 2009
Messages
7
Loc.
San Diego
I have a 70 Bronco and want to put in a 4 spd transmission as 1st gear is just too high in the stock three speeds(2.99) and an overdrive would be great in this concrete jungle. . The easy bolt on ford 4 spd toploaders actually have a higher 1st than the 3 spd so they do not solve the problem, the other 5 spd's available like the 3550 and 4550 or t-18 t-19 do not help as 1st is a granny (which i dont want) and second is 3.0 same as the 3spd, besides that they are tough to shift. Anyway the trans I like is the SMOD or 170 F which came in 71 to 84 ford light trucks and Vans which offers a 3.29 1st gear and an overdrive for the freeway. My question is do I have to get a SMOD out of a 4wd or can I replace the output to fit the dana 20 transfer box, has anyone done this swap? None of the bronco websites talk about the SMOD as an option.

Thanks!
 

73stallion

Bronco Guru
Joined
Mar 5, 2004
Messages
16,786
Loc.
Eugene, OR
not sure what the SMOD trans is, but duff does offer a 4 speed adapter kit to put a 2wd trans in;
http://www.jamesduff.com/eb/shifters.html

the NV3550 doesn't really have a granny, it's a 4.01 first gear which isn't bad. i can hit about 15 mph in mine pretty easily with my NV3550. IMO it's geared pretty perfectly.
 

Wyldebill

Full Member
Joined
Feb 8, 2008
Messages
292
Loc.
Berthoud, Colorado
I think that you are refering to the M5OD that is used in the late 80's and 90's in the F150's and Full size Bronco's. It is a Mazda, 5 speed, Over Drive, or M5OD. It is very comparable to the NV3550 in ratios and I think it might be rated a little stronger.
 

fordtrucks4ever

Bronco Guru
Joined
Oct 8, 2006
Messages
1,280
Loc.
DFW
The SMOD is a side mounted(shift linkage) overdrive 4 speed toploader style. A better choice is the RTS 4 speed(T170FT) or TOD. Very concrete jungle friendly. Both basically the same except has a top shifting tower with internal setup. Used in 85-89 F 150/250 and Broncos. Advance Adapter has the correct mainshaft for either conversion.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
I don't think the NV3550 4:1 first gear is a granny. It's the same as many 5-speeds these days. 5:1 is a wussy granny, 6:1 is a granny, 7:1 is a great granny. The T19 with a close ratio is about 4:1 and drives great on the street other then it drives like a big truck transmission.

Go to a used car lot and find a jeep with a 5-speed and take it for a drive. Then see if you would like that in the Bronco. I bet you will like it (transmission, not the Jeep)
 
OP
OP
V

Victor Roberts

New Member
Joined
Mar 18, 2009
Messages
7
Loc.
San Diego
I learn somthing new everyday! Is the T-170 FT an aluminum Case and is it still the "RUG" coded transmission? Or is the code "TOD" coded?
 
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OP
V

Victor Roberts

New Member
Joined
Mar 18, 2009
Messages
7
Loc.
San Diego
I stand corrected! when looked at the ratios I thought the NV3500 and NV4500 were the same ratios, 4:1 is good! I am expecting around 350 hp out of my rebuild with twisted wedge heads. I was worried as alot of people say the 3500 is not a really a strong tranny and rated at only 3,300 lb GVW.
 
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Victor Roberts

New Member
Joined
Mar 18, 2009
Messages
7
Loc.
San Diego
Nv3550

Sorry, I meant 300lbs of torque, but after doing more checking it looks like the 3550 is a pretty good trans, there are lots of wrecked jeeps as they seem to end up on thier tops with the way californians drive on the freeway. What years did they come in on the jeeps?
 

b4opec

Jr. Member
Joined
Jun 28, 2005
Messages
71
Loc.
Sausalito, CA Marin
You said in your initial post you were looking for the 4speed OD with the 3.29 1st...I'm not positive on this but I have the TC OD 4sp (shift rails on the side) and I'm pretty sure it is a 3.29 first. I've complained on this board that the ratio is too wide on this tranny, but from the standpoint you're looking for a lower 1st, it's fine. that and 4.10's (or 4.56's!) and the overdrive, you're looking good around town for sure, and purring on the freeway

this guy used to have the ratios for the OD tc, I don't see them but you could ask:
http://4speedtoploaders.com/
 
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