Jeff Balazs Posted February 21, 2012 Report Share Posted February 21, 2012 Hi Guy's; I was looking through the parts book to find a good exploded view (21-8) of the transmission in my Pilothouse and noticed a reference to an overdrive gear. It looks as if the overdrive gear #21-54-29 (from the 5 speed list) can be used in place of standard top gear # 21-10-43. Does any one out there know if this is true? I have not found any other reference to this.....but??? Jeff Quote Link to comment Share on other sites More sharing options...
HanksB3B Posted February 21, 2012 Report Share Posted February 21, 2012 http://laraandsonsdifferentials.auto.officelive.com/default.aspx It's in East LA man, so either ask Vin to Diesel to ride shotgun or do what I did, got my wife to drive me in her truck! Hank Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted February 21, 2012 Author Report Share Posted February 21, 2012 Hank; I don't need no stinking escort to East LA man........I am a native. The first house I lived in as a child was in Pico Rivera. And my High School was about 50% low riders.........can you say "thats a charp chort man" ? It is probably a good idea for you furiners though ................. but not Vin...they would just laugh at him......and then mess you up. Will give them a call as the idea of having overdrive gearing without a lot of fuss or fabrication........ sounds muy bueno. Surely someone here must have looked into this ................ I can't be the only person to have noticed this. Jefe (El Guapo) Quote Link to comment Share on other sites More sharing options...
mechresto Posted February 21, 2012 Report Share Posted February 21, 2012 (edited) Hi Guy's;I was looking through the parts book to find a good exploded view (21-8) of the transmission in my Pilothouse and noticed a reference to an overdrive gear. It looks as if the overdrive gear #21-54-29 (from the 5 speed list) can be used in place of standard top gear # 21-10-43. Does any one out there know if this is true? I have not found any other reference to this.....but??? Jeff as the 4th gear in a standard 4spd unit is direct, meaning the mainshaft turns 1 to 1 in fourth, the fourth gear simply locks the mainshaft to the input shaft. the five speed (overdrive model) runs the fifth or OD gear off of the countershaft to provide a less than 1 to 1 ratio. just changing the one gear will do nothing, you have to provide an extra gear on the countershaft as well. Bryan Edited February 21, 2012 by mechresto Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted February 23, 2012 Author Report Share Posted February 23, 2012 Bryan; I've spent a bit of time studying the exploded views (plates 21-6 & 21-7) for both versions of the 4 speed transmissions and it appears that overdrive gearing is possible with either of these gearboxes. There are clear notations on both plates and these appear to show both the standard gearing and OD gearing options. Swapping more than one gear component is involved but if this is true it would be far easier than fitting a T-5 or something else. I don't know my way around the Mopar parts numbers well enough to be absolutely certain about all this. But it sure looks like they offered optional gearing for the 4 speeds. Can anyone shed some light on this? I don't know if there is some sort of master parts list with detailed descriptions of the parts for Mopar. In the case of some other manufacturers these master list's exist and are quite useful. Thanks, Jeff Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted February 23, 2012 Report Share Posted February 23, 2012 No OD gears were ever available for the 1948-53 NP 4 speeds. 5 speeds yes-I have one and they are very difficult to find. As mentioned earlier the cluster gear is different and there are a few extra other spacers/washers and design differences between a regular direct in 5th and the factory NP OD transmission. Bob Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted February 23, 2012 Author Report Share Posted February 23, 2012 Bob; You are probably right.....but these drawings have me intrigued. They clearly reference the standard 4 speed parts and alternative parts from what seems to be the 5 speed you refer to. With notations regarding OD. Really makes me wonder. I spent too many years maintaining drawing files in engineering companies to dismiss this as a mistake. Is it something that was developed but never sold ? I don't know......but the fact is these notes are present on the drawings of both versions of the 4 speed. I wonder if this "option" is physically possible even if no other documentation about it exists? I am not sure at all how one would go about following up on this. Or how to even start to collect more info on this. The parts lists that I have waded through so far offer little or no descriptive information about the individual parts. Maybe it is a pipe dream......or perhaps there is another clue waiting to be found. To me these kinds of mysteries make working on older machinery really interesting. A form of archaeology if you will. For what it's worth I have found a few puzzles like this before that turned out to be true. Jeff Quote Link to comment Share on other sites More sharing options...
HanksB3B Posted February 23, 2012 Report Share Posted February 23, 2012 Hank Quote Link to comment Share on other sites More sharing options...
JBNeal Posted February 23, 2012 Report Share Posted February 23, 2012 the parts manual drawings are a guide for sales and not necessarily factory build prints. For example, looking at the steering column drawing in the parts manual, it shows the B-1 gearbox, when two are listed in the parts list, and there are significant differences between the two castings that they are not directly interchangeable. The same drawing is in the shop manual for the B-3, which is inaccurate for repairs. Variations on engines and transmissions can be simplified by showing the first configuration, and a later configuration can be noted in the parts list. Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted February 23, 2012 Author Report Share Posted February 23, 2012 49D; Yes I know exactly what you are talking about. Have run into this many times over the years. And it wasn't just Dodge that used this practice. Maybe it is just wishful thinking on my part.......but I think there is more to this example. And wouldn't it be great for some of us 4 speed owners if it were possible? I know I would like my truck to be as useful as possible and still remain close to stock. I know less about Mopar than practically anybody on this site. One thing I am really curious about is the parts lists.......The ones I have seen so far don't contain much in the way of parts descriptions. For example it might give a number and call something a "gear" but I have not seen anything that tells me what size shaft it fits on or how many teeth it has, etc... I guess what I am asking is is there another type of parts book or master list out there that goes to this level? I have a hard time thinking that this type of info does not exist. If it does then it should go a long way in answering this sort of question. Jeff Quote Link to comment Share on other sites More sharing options...
mechresto Posted February 26, 2012 Report Share Posted February 26, 2012 Jeff Spent about 5 hours going thru my interchange manuals tonight. New Process 4sp models have absolutely no interchangeable parts with the 5sp versions. Dodge used 5 versions of the NP 4sp from 1932 thru 1955. The Clark transmissions 200v,205v etc were used in dodge trucks as 5speed units, both as 5th direct and 5th OD. the Clark family shares damn near all of the parts from the 4sp, 5sp, 5sp w/OD. So if your book shows parts being interchanged from 4speed to 5speed OD transmissions, and as Clark was the only manufacturer that did that regularly, I'm guessing that you are looking at a clark 4 spd picture. There were no clark 4spd units used in any dodge truck from 1932 thru 1955. (thats the newest I go in the interchanges, after all, no one made a decent vehicle after 1955, right!) As an adendum- there was 1 orphan NP trans used by Dodge trucks- a 4 speed underdrive trans, which shared most of the parts with the 4 speed Bryan Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted February 26, 2012 Author Report Share Posted February 26, 2012 Hi Bryan; The drawing I have been looking at is out of the 48-53 B series parts manual which is in the Pilothouse Knowledge section. It is in the transmission chapter and plate 21-8 shows the transmission that I have in my truck. I have tried to figure out how to show it here but can't seem to get it to work. If you look at this plate you will see the notations regarding OD. The plate for the earlier 4 speed has them as well. I suppose it is some sort of error...but why if there was nothing to it? Jeff Quote Link to comment Share on other sites More sharing options...
HanksB3B Posted February 26, 2012 Report Share Posted February 26, 2012 (edited) Jeff, I removed Plate 21-8 (which I suppose was supposed to be Plate 21-3) Either you are looking too hard at mortise & tenon joints (or smoking one). I've also linked Plate 21-4 as I don't know which 4-Speed you have. For images larger than our P15-D24 host allows (wonder how many terrabytes facebook has) you need to have some sort of "cloud" host. Probably like most of us (Reg taught me) I use PhotoBucket. I scanned your page, opened in in PhotoShop to crop and rotate it a little, saved it then opened it in Acrobat Pro Extended which allows me to convert it to a jpg which produces a smaller file format. (why the more premier program Photoshop won't do that, I don't understand but probably is a marketing thing). In our forum, you then use the little yellow icon that looks like a stamped envelope with a mountain drawn on it to "link" the image (hosted by PhotoBucket) to our P15-D24 site. I need more Coffee, Hank Edited February 26, 2012 by HanksB3B Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted February 26, 2012 Author Report Share Posted February 26, 2012 Hank; This is not the image I was referring to. This is a 5 speed.....you have to look at the 4 speed to see what I am talking about. I have to go into work today.....but when I have time I will try what you suggest. Jeff Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted February 26, 2012 Report Share Posted February 26, 2012 Jeff Spent about 5 hours going thru my interchange manuals tonight. New Process 4sp models have absolutely no interchangeable parts with the 5sp versions. Dodge used 5 versions of the NP 4sp from 1932 thru 1955. The Clark transmissions 200v,205v etc were used in dodge trucks as 5speed units, both as 5th direct and 5th OD. the Clark family shares damn near all of the parts from the 4sp, 5sp, 5sp w/OD. So if your book shows parts being interchanged from 4speed to 5speed OD transmissions, and as Clark was the only manufacturer that did that regularly, I'm guessing that you are looking at a clark 4 spd picture. There were no clark 4spd units used in any dodge truck from 1932 thru 1955. (thats the newest I go in the interchanges, after all, no one made a decent vehicle after 1955, right!) As an adendum- there was 1 orphan NP trans used by Dodge trucks- a 4 speed underdrive trans, which shared most of the parts with the 4 speed Bryan A quick note here on the H-Duty Clark 290-V2 and 290-VO 5 speeds used on the B-series heavy duty Dodge trucks, this 290 clark 5 speed was used only on the Dodge 4 ton (Y series) trucks 1950-1953. New Process 4 and 5 speeds were installed in all other Dodge truck models 1/2 ton to 3-1/2 ton- NP 5 speeds were standard on all J and up models. The NP overdrive 5 speeds were stamped "O" next to the drain plug at rear of case. Bob Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted February 26, 2012 Author Report Share Posted February 26, 2012 Ok let's see if this works. This is the plate I was referring to. Jeff Quote Link to comment Share on other sites More sharing options...
Dave72dt Posted February 26, 2012 Report Share Posted February 26, 2012 The parts in the plate are in 5 speed trnasmissions. The numbers on the bottom of the page are complete transmissions and found only in 1 1/2 tons and up, Quote Link to comment Share on other sites More sharing options...
HanksB3B Posted February 26, 2012 Report Share Posted February 26, 2012 Dave, So hopefully Jeff's transmission is the 4 Speed Helical cut in Plate 21-4? In the Spur Type is it necessary to double clutch in every gear? Hank Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted February 26, 2012 Author Report Share Posted February 26, 2012 Dave; The transmission that is in my truck is the same case as what is shown in this plate. I think it is just a 4 speed sychro transmission. Jeff Quote Link to comment Share on other sites More sharing options...
HanksB3B Posted February 27, 2012 Report Share Posted February 27, 2012 Hopefully you are right. If I were at the ground up stage I'd definately look into the T-5 option. I hope to do this someday. Hank Quote Link to comment Share on other sites More sharing options...
Dave72dt Posted February 27, 2012 Report Share Posted February 27, 2012 Dave;The transmission that is in my truck is the same case as what is shown in this plate. I think it is just a 4 speed sychro transmission. Jeff two things come to mind here The word "typical" and the fact that the case numbers are not the same so something is different. Whether on not you could physically put 5 speed OD parts into a 4 speed box would be interesting to say the least. Quote Link to comment Share on other sites More sharing options...
Dave72dt Posted February 27, 2012 Report Share Posted February 27, 2012 Dave,So hopefully Jeff's transmission is the 4 Speed Helical cut in Plate 21-4? In the Spur Type is it necessary to double clutch in every gear? Hank Not so much on the way up but back down, yes. No such thing as speed shifting. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted February 27, 2012 Report Share Posted February 27, 2012 (edited) Ok let's see if this works.This is the plate I was referring to. Jeff This (Plate) picture is of the lighter duty Syncro 5 speed NP transmission. 1-1/2 ton on up to 2-1/2 ton models. Your truck has to have a 4 speed trans as 5 speed NP transmissions did not have a long input shaft for your fluid drive coupling. Bob Edited February 27, 2012 by Dodgeb4ya Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted February 27, 2012 Author Report Share Posted February 27, 2012 Hi Guy's; Well I am going to have to take a closer look. I know that the shifter mechanism on the transmission I have matches the one in this plate exactly. I am pretty certain the rest of the case looks similar.....but I have not done a direct comparison. Did they use this same top case for both the 4 speeds and the 5 speeds? It has a large raised H towards the rear area....directly over the rails. Jeff Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted February 27, 2012 Report Share Posted February 27, 2012 Well I went out to the shop and took some pics of the 5 speed trans you think might be in your fluid drive truck. This 5 speed top cover is 15" long-4 bolt holes down each side. This trans was a syncro 5 speed overdrive unit. Its big and heavy unlike the NP 420 syncro 4 speed. The 3 and 4 speeds have 3 bolts down each side of the shifter top cover. Bob Quote Link to comment Share on other sites More sharing options...
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