NP 200 T case.

[Fordtrucks]

Hay guys. I am new here. I am currently in the planning stages of building my mini monster truck. Its an 81 F150 pick up. I'm almost done with the 650 horse 472 I am working on. The goal is Rock-wells and 53" Michelin tires. From the little research I have done it seems that an M37s NP200 T case may be what I am looking for. From what I know it has a high and low range. It had a divorced mounting style with center front and rear output drop. I need a T case that I can drop straight down with a front and rear output in line with each other. What are these worth? I need one. Any info would be greatly appreciated.

Thanks
Fordtrucks.

 

[gimpyrobb]

I don't know how fast you plan on running, but that case is stock in the m715 trucks too. Our trucks have a habit of melting the seals out out of that case if you go over 50mph. Not all of them, but enough for me to warn you to look for an np 205 or np202.

 

[ucfjeeper]

nah, if hes doing what I think, he won't be going over 25-30 for more than a few minutes at a time. The 205 / 202 don't have the rear offset output he's looking for. The rear offset output on the 200 allows him to clock the divorced case vertically and use it as a drop box giving lower rear driveline angles for a short wheel base truck. If it's a longer wheel base truck, standard single rear output should be fine unless you want to have a doubler setup.
It's the more affordable way of dropping driveline angles vs getting a profab or scs case for $2-3K

 

[Fordtrucks]

Well you are correct about what I want it for. I do want to clock it straight down. Like I said Rock wells and 53s. What can a guy do to keep the seals in good shape? Honestly this truck will be on the street some, and roll as fast as the tires will roll smoothly. A 205 or the like will not do cause I cant clock it down and have the outputs inline with eachother.

 

[sermis]

With 52" tires it might not make that much of on issue. With my M725 I am rinning 38" tires and it will hold 55 with out geting hot if you can pay for the gas at 6.5mpg. 52's will act like an overdrive for the truck. Unless he wants to run 70+ it might not get too hot however the extra power needed might caue some heat.

 

[gimpyrobb]

Should we warn him about the "straight cut" gears too? (inside joke, don't worry)

 

[sermis]

Mine must be one of the few, not that loud.

 

[Recovry4x4]

Also consider the oiling issue created by clocking the case. All the upper gears will not get oiled as designed. Consider some Lucas additives or a light synthetic to preserve life.

 

[sermis]

He will know if he toasts a seal. With it clocked the gear oil will really run out.

 

[Elwenil]

Didn't Mikel mod a NP205 on his M715 6x6 project for dual outputs? He had a rear output on the normal (center) of the 205 but also another rear output on the downward side, opposite the front driveshaft location. I know he used some NP200 parts to get what he wanted out of the 205. I don't think it has been road tested as yet though. His build is still up on Pirate 4x4 somewhere.

 

[Barrman]

Lanty, you are correct since the offset hole is in the 205 case with a plate over it. Yep, I just walked over and looked. I have a 205 and a 200 sitting next to each other here in the class. The 205 has the same hole in the case with the same bolt pattern as the 200. Blank aluminum plate there to hold the front output shaft in place.

The heating issues in the 200 seem to be because of the bearings and the fact that they were built by the lowest bidder. Anytime you sustain drive shaft rpms of 2500 or more for 45+ minutes, they will get hot. I have had case temps of 280 or higher on mine. Synthetic fluid, 205 seals and such don't really seem to help.

Now, many people just swap in a 205. The few dedicated souls who spend the $200-$300 for a complete bearing/shim/seal/gasket set for a 200 and then rebuild them to spec report no heating issues.

Figure out your drive shaft rpm requirements and think about it some.

 

[rizzo]

Re: RE: NP 200 T case.

nah, if hes doing what I think, he won't be going over 25-30 for more than a few minutes at a time. The 205 / 202 don't have the rear offset output he's looking for. The rear offset output on the 200 allows him to clock the divorced case vertically and use it as a drop box giving lower rear driveline angles for a short wheel base truck. If it's a longer wheel base truck, standard single rear output should be fine unless you want to have a doubler setup.
It's the more affordable way of dropping driveline angles vs getting a profab or scs case for $2-3K

x2

the 200 is what you want

 

[ucfjeeper]

RE: Re: RE: NP 200 T case.

yes you can make a 205 dual offset output but I believe that you need to have 2 cases to do it, and I believe one of them needs to be a divorced case. (that is if you are going to run a mated case clocked, otherwise, if you wanted a floater case, you'd need 2 divorced cases.) I'm not sure how it's done, but as stated above since the 205 has helical cut gears, it might be worth it. The 200's straight cut gears running at high speeds will be a little noisy and have a tendency to get hotter than the 205 with the helical cut gears.

Yes, the 205 and 200 are basically the same case with few differences, obviously like stated, how the gears are cut, and if it's a ford side drop vs a chevy side drop.

I have a slew of new shift rail seals and a complete gasket kit for a 200 but am now looking for input/output seals. Will the 205 seals work on the 200 since a majority seems the same?

 

[Barrman]

RE: Re: RE: NP 200 T case.

Yes, the 205 seals work in a 200. But, the military 200's had a seal with an extra dust cover on the outside. This made the seal itself taller than the normal 205 seal. You will see if you get one. For the 200 seals, try AB Linn.

 

[ucfjeeper]

Re: RE: Re: RE: NP 200 T case.

try AB Linn.

Thats where I got my shift rail seals and gasket kit. He didn't have any input/output shaft seals at the time.

 

[Fordtrucks]

RE: Re: RE: Re: RE: NP 200 T case.

Thanks for the replies guys. I realize the straight cut gears are going to be noisy. That's fins cause I really dought I will hear them over the headers. The street time is limited. Its a 700 horse truck and is only a toy. As for the over heating and under lubricating of the gears I thought I would tap an outlet in the bottom of the case the remove the oil via an electric pump, push it through a cooler and return it on top of the case near the planetary to lubricate the upper gears. Is this a cast iron case or aluminum? I will guess cast. Also I will assume these 200s are a divorced set up. What size U joints are the input/outputs? I would like to buy the 3 yolks and a GOOD T case from someone if there was one for sale here. It sounds like this is the case I need. I am wondering how well it will hold up to the power. The 2.5 ton rock wells have a low gear ratio of 6.72-1 so there shouldn't be to much stress on the T case really. If its similar in build to a 205 then I think it will be fine.

Got one to sell?

Laterz
Will.

 

[ucfjeeper]

RE: Re: RE: Re: RE: NP 200 T case.

The case is cast iron and remember, it's only a 3/4 ton case. When in it's donor vehicle, it makes an extremely stout driveline. Even though the gear ratio in 2.5 ton's is 6.72:1, the np200 is still the weak point of the driveline. I've seen cases split as well as input and output shafts shear. In a mud truck, you won't notice the noise, especially if your only running headers. I would say that if you truely are running 700 horse, the 200 probably won't last long. A lubrication system would be neat/interesting, but I've seen trucks run them a long time without anything.
Yes, the 200's are divorced cases. I believe the u-joint on a powerwagon NP200 is a 1310 where as the input/output on a military M715/M37 NP200 is a square 4 bolt flat flange that a yoke flange bolts to. There is no difference in the case though, still the same 10 spline shafts.

 

[Fordtrucks]

RE: Re: RE: Re: RE: NP 200 T case.

Hmm, A 1310 U joint is pretty small. Thats the sise of the joints in a D44 front steer axle. I would preferre a bigger joint. Are you sure there not a 1410? This is more common in 3/4 ton trucks in my experence... Thanks for the info. I would like to try one since this seems to be my only routs besides spending 2-3K on a better one.

 

[oilcan]

RE: Re: RE: Re: RE: NP 200 T case.

1310 is correct, but the M715 uses the same yokes as above. Not a flat flange. And yes, they are pretty small. 700hp might hurt 'em!

 

[ucfjeeper]

RE: Re: RE: Re: RE: NP 200 T case.

I figure, I'd rather a ujoint break than an axle.