silicone brake fluid and unit markings question pics added..

[lowell]

there are lots of m35s around with silicone brake fluid but what about m211s? when did the military switch over to silicone? My truck was surplused in the late 70's. Ive been working on it a bit lately and havent decided which fluid to go with. also my truck has the following markings on it G1 SCOM 198 S HQ97 can any one make any thing out of this? Im guessing a National Guard unit but not sure. Id like to know were the truck came from. Lowell

 

[maddawg308]

RE: silicone brake fluid and unit markings question

I don't think the M135/M211 series used silicone. By the time they were surplused out, silicone was only starting to be used in the M880s and the newer M35s. They can use it, but your have to make sure the brake system is COMPLETELY flushed of the old fluid before you add the new DOT 5.

 

[clinto]

RE: silicone brake fluid and unit markings question

Wow, that's a really original looking truck.


Now let's see some more pics of it and the one behind it!

 

[DMgunn]

RE: silicone brake fluid and unit markings question

My truck is a '53, and it specifies "silicone fluid only", or something to that effect, in stencil on the floor hump.

 

[acetomatoco]

RE: silicone brake fluid and unit markings question

Yes, but your truck was rebuilt in the 80's, I bet... It probably has seatbelts and directional signals and west coast mirrors which were not on in when it was made by IHC, or Diamond T or Mack....At that rebuild all of the modern stuff was added to bring it up to "code".... or if it was in service in a NG or AR outfit, they had directives to change all trucks to silicone...and there was quite a procedure including running alcohol and compressed air thru all the system to flush out all the Dot 3.

 

[acetomatoco]

RE: silicone brake fluid and unit markings question

Regarding the M211... If it has dot 3 in it, I would stick with it.. the chances of one of the 12 wheel cylinders leaking with silicone changeover is high. Those systems are fussy for leakage and you do not want to do anything to disturb the peace.. so to speak....you can bleed some old fluid off thru the extremities and top off with Dot 3 if you want to extend its life.. Don't forget the OHT in the booster.

 

[butch atkins]

silicone brake fluid

so if iam doing a complete brake job ,as in new wheel cyls,master cyl,hydrovac,and replacing ALL of the rubber lines on my m211 would you switch to dot 5 or go back with dot 3,btw the hydrovac that i bought doesnt look exactly like the one that is on the truck,should i have to flush the lines ,or since they will all be disconected ,will just blowing air through them be good enough to purge system of dot 3,or should i just play it safe and go back with dot 3,,iam doing brake job now and this would be the time to change to dot5 ,is there any real advantage to dot 5,i know this is a lot of questions,but has anyone had a bad experience changing over to dot 5,want to do this right this time around,so i dont have to do it over,thanks in advance

 

[acetomatoco]

RE: silicone brake fluid

I don't believe there was an upgraded AirPak for the M135/M211 trucks..(I could be wrong, what say you GMC guys/) The ones for the M35 and M54 series will not work... be sure you have the right one...be careful.. the choice of fluid is up to you....each has advantages...I still think I would rather have moisture in suspension rather than pooling in small puddles, but that is me...good stopping to you!!

 

[Recovry4x4]

RE: silicone brake fluid

According to TB 43-0002-87 you just need to do a very thorough flush with the fluid of choice. That TB is available in the TM section.

 

[DDoyle]

Re: RE: silicone brake fluid

According to TB 43-0002-87 you just need to do a very thorough flush with the fluid of choice. That TB is available in the TM section.

The reason for the very thorough flush, per the army test reports, is that any DOT3 left in the system negates the "benefits" of DOT5.

The military changed over to silicone in about 1981-82, IIRC.

DD

 

[Recovry4x4]

RE: Re: RE: silicone brake fluid

David, when they switched over, did they do everything in inventory or just certain classes of vehicles?

 

[nattieleather]

RE: Re: RE: silicone brake fluid

IMHO If you are doing a break job now unless you have to have silicone I would just stick with the DOT3. Your not going to be doing deep water fording and you may do some puddles at that's about it. The cost for the DOT 5 will not out way the DOT3.

The air pack is different from the M211/135s and the M35s. You need one that looks like the one you have. I've heard that you can make a M35 air pack work, but I could never figure out how and ended up putting a rebuilt M211 pack on my truck many years ago.

As for the markings....Here is the best I can make out.
G1 SCOM 198 S HQ97 G1, Administration or Adjutant for a command (General command). SCOM...Signial Command. 198 S, 198th Signial (Brigade, Group, Division not sure), HQ97 Headquarters vehicle #97.

 

[lowell]

pics

Clinto, here are the pics of both trucks. Thats my Dad in the non winch truck the day he bought it. The last time he sat in a 211 was in Korea during 1953. Both of our trucks had been sitting sense the 80's.... Lowell

 

[nattieleather]

RE: pics

Not bad looking trucks. Looks like you got a good deal there.