Another NP200 heat thread!

[brute4c]

Been there...done that...stinky!

[randyscycle]

Been there...done that...stinky!

And leaky.....

[vacca rabite]

Another thing to consider re: 90wt oil vs 50wt oil is the oil now is not the same as oil used to be.

A lot of the chemicals that used to go into oil (like high zinc content) have been removed from the recipe due to federal mandate (clean air act, etc.) New types of low zinc oils work great in things that were designed for them, but kill machines that were designed for the older formulations. The oil simply does not lubricate as well. There are a few types of higher zinc formulations out there (I like Brad Penn - its the old Kendall formula, but there are others as well).

Personally, I am going to use my NP200. Cleaning off all the crud (about 1/2 inch of old oil sludge is on the outside, who knows whats on the inside), a rebuild, 4.56 axle gears and 38 inch tires (bought and sitting in my garage) should keep the stock unit nice and cool once my truck is ready to go for a drive. Of course, at my current rate of work, that might be 2010.... maybe 2110... *sigh*

Zach

[TxRider]

Until the 50's I believe many used "Lead soap" as the base in the gear oil.

Been reading up a bit on this and learning a bit..

As well we're talking about hypoid gear oil, designed for hypoid gears like a rear end gear that has to deal with gears sliding on on another. Which is why it uses high pressure additives like the old lead soap and zinc. Those same additives also cause drag and friction of their own.

The t-case gears are helical not hypoid, which is I guess why a lot of modern t-cases and manual transmissions use motor oil or even some that use ATF fluid.

Wikipedia says API viscosity standards state 75-90 hypoid gear oil is the same viscosity as a 10w40 motor oil. I've also seen references that say 90wt hypoid gear oil is equal viscosity to 50wt motor oil. The real difference being gear oil having high pressure additives specifically for hypoid spiral bevel gears(differential gears), and motor oil having different additives.

GL rating is actually the amount of high pressure additive in the oil, GL1 being basically motor oil, GL5 being the highest amount of additives.

API service specs says about gear oils and their use/rating..

GL1 (plain motor oil)...

The designation API GL-1 denotes lubricants intended for
manual transmissions operating under such mild conditions
that straight petroleum or refined petroleum oil may be used
satisfactorily. Oxidation and rust inhibitors, defoamers, and
pour depressants may be added to improve the characteristics
of these lubricants. Friction modifiers and extreme pressure
additives shall not be used.

and about GL4 hypoid gear oil... Most gear oils I see are GL5

The designation API GL-4 denotes lubricants intended for
axles with spiral bevel gears operating under moderate to severe
conditions of speed and load or axles with hypoid (see
note)gears operating under moderate speeds and loads.
These oils may be used in selected manual transmission and
transaxle applications where MT-1 lubricants are unsuitable.
The manufacturerÕs specific lubricant quality recommendations
should be followed.

GL5 oil..

The designation API GL-5 denotes lubricants intended for
gears, particularly hypoid (see note) gears, in axles operating under various combinations of high-speed/shock load and
low-speed/high-torque conditions. Lubricants qualified under
U.S. Military Specification MIL-L-2105D (formerly
MIL-L-2105C) satisfy the requirements of the API GL-5 service
designation, although the API designation does not require
military approval. Performance test details are in
ASTM Publication STP-512A.

And about MT-1 oil..

The designation API MT-1 denotes lubricants intended for
nonsynchronized manual transmissions used in buses and
heavy-duty trucks. Lubricants meeting the requirements of
API MT-1 service provide protection against the combination
of thermal degradation, component wear, and oil-seal
deterioration, which is not provided by lubricants in current
use meeting only the requirements of API GL-1, 4, or 5.

http://www.upmpg.com/pdf/gear_lube_designations.pdf

I wonder if the difference in the properties of the additives will make that big of a difference?

[HAWKEYE]

About 2 months ago I took my 715 on a 500 mile trip. Did notice t-case got warm but still seemed to do just fine at 55mph. This 715 HAD the 230 tornado and I just put new 90wt gear oil in t-case took it to the high desert and back. Granted that it was in November and not 110 degrees. Maybe I got lucky or just got a truck with the actual mileage (14,000) i do not know but loved every mile. Now I want more power off road than on road. With new motor almost installed i totally forgot about the T-case. Trying to decide if I should go with bigger tires or change ring and pinion, so i can keep np200. (Because 205s are just a dime a dozen out there and everybody can afford an atlas)

[randall555]

this is my ideal . what if you drilled holes in the tcase and put in a 12v or 24 v pump and run steel lines to a intercooler with a electric fan to cool the tranfer case oil . place the lines and cooler under the truck so it would be out of the way to be damaged . this would be like a transmission cooler or engine oil cooler

[brute4c]

Been proposed many times...problems are:

Cost of a pump hardy enough to pump thick fluid, like gear oil, for years and years
Cost of all the hoses, connectors, cooler, fan, etc.

These costs are likely to be well over, like 2-3 times, the cost of buying an NP205 for $100-$150 and fabbing some mounts off the stock mounts and running it.

If one does all this to the NP200, it sure wont be stock and will be very complicated compared to stock...an NP205 would look more like stock than such a modified NP200...

[black rock trucks]

Hey guys IM a new member and have been reading a lot on the np200. I am not a m715 or m37 owner (wish I was) but I am planning on using a np200 in my truck. IM running 2 1/2 ton Rockwellswith a 6.72 ratio and an .7od 700r4 tranny with 41" tall tires at 2500RPM I should be able to go 64MPH (fast enough for me). I know you guys don't run these 90degress upward, but if you did and could added more fluid with some type of pumping system what do you guys think will it work? i know there has been lots of talk about a pump but has anyone ever done it? thanks Kyle

[randyscycle]

I don't think anyone has done a pump for the reasons mentioned above.

Good gear oil pumps are very expensive and if it gets below freezing, pumping gear oil would be a challenge.

All the excess lines, cooler, pump and associated stuff would be a hindrance in any off-road situation. Keeping it tucked enough away to prevent damage would be tricky. Pluse the location of the cooler would have to be in the airstream all the way up front. A lot of line length.

I thought of a lot of things until I finally decided that when my 200 dies, I'll replace it with a 205 and be done. Easier and much more reliable.

[black rock trucks]

For me its cheaper to run the np200 and buy the pump, and cooler with a fan built this way ill just stick it in my bed. If I run a np205 the rear driveshaft is going to cost me $800 alone, thats not including the 4 yokes I have to buy for it.

But, on topic of the fluid being cold it shouldn't matter if you hook the sensor up so that it only comes on when the fluid is it 150 degrees ext. Cause it will not be so thick. IM going to do the pump and I will post pics of my build up.

IM in need of a good rebuild kit though, the roller pins are in bad shape does anyone know if the np205 roller pins are the same for the np200?

ALso, i just took apart my np200 today and the center gear cluster where the pin goes threw with the two bearings on the outside had no shims inbetween? i never seen that before is that a common thing? thanks Kyle