New M998 Fuel Tank Install

[bcheval]

I certainly could use some advice.

I couldn't get my old tank to stop leaking so I bought a brand new one off of Ebay. First the tank is differently shaped from the old tank and I purchased the additional guard that is required for the new tank. As I try to slip it in it just wont fit. My M998 is the old style with the e-break on the axle not on the pumpkin like the new type and I am running a NP-218 transfer case and there is a plate guard at the rear yoke . Does anyone have any advise or did I just waist money.
Thanks
Ed Ft Worth

 

[Wire Fox]

Upgrade to the rear caliper parking brakes or sell the tank and buy the correct part. Pretty sure there's no way to install a non-center brake tank on a center-brake HMMWV. We've all made a mistake like this, so take it as a learning experience to always double check your part numbers, as there's a lot of revisions through the years.

I'm not sure how hard it is to find that old tank, though...

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[bcheval]

Good advice. I am really not sure what it would take to convert the e-brake so I'm going to start looking for a new fuel tank to replace the old.
TY
E

 

[Wire Fox]

I attached the MWO that gives a basic overview on the process. Effectively, you're disconnecting and removing the existing parking brake, replacing both rear brake calipers, and installing a new parking brake cable assembly to both new calipers.

Reading through this MWO myself, I don't think any part of it says that the original parking brake rotors itself is removed, plus every HMMWV in service was supposed to have this done by the end of 1995. Why don't you check and see if MWO 9-2320-280-35-1 has been applied to your HMMWV? You'd be looking for both a lack of parking brake cable going to your center propeller shaft brake and parking brake actuators going to both rear calipers (and an MWO tag on the B pillar is a good confirmation). If this has been done, then you can just replace the propeller shaft and call it a day, then be able to install the new tank you already have.

I know the replacement propeller shaft will be remarkably cheap because the market is flooded with the ones needed for the TH400-NP218 combo. Brake calipers are much more expensive for the rear (fronts are dirt cheap), and the associated small parts will add up quick. Some people sell the whole MWO kit, but they want exorbitant amounts of money.

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PDF wouldn't attach...here's a link http://imfmotorpool.com/049068.PDF

 

[Retiredwarhorses]

You not going to find the original tank NOS, I personally haven’t seen one in 25yrs.
for safety sake, get rid of the old ebrake system. I have thrown away numerous old style fuel tanks.
I still have several I’ve kept for some odd reason, many folks pulling them out due to upgrade to 4L80e.

 

[Retiredwarhorses]

I attached the MWO that gives a basic overview on the process. Effectively, you're disconnecting and removing the existing parking brake, replacing both rear brake calipers, and installing a new parking brake cable assembly to both new calipers.

Reading through this MWO myself, I don't think any part of it says that the original parking brake rotors itself is removed, plus every HMMWV in service was supposed to have this done by the end of 1995. Why don't you check and see if MWO 9-2320-280-35-1 has been applied to your HMMWV? You'd be looking for both a lack of parking brake cable going to your center propeller shaft brake and parking brake actuators going to both rear calipers (and an MWO tag on the B pillar is a good confirmation). If this has been done, then you can just replace the propeller shaft and call it a day, then be able to install the new tank you already have.

I know the replacement propeller shaft will be remarkably cheap because the market is flooded with the ones needed for the TH400-NP218 combo. Brake calipers are much more expensive for the rear (fronts are dirt cheap), and the associated small parts will add up quick. Some people sell the whole MWO kit, but they want exorbitant amounts of money.

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PDF wouldn't attach...here's a link http://imfmotorpool.com/049068.PDF

Many many truck had the brake disk left on the drive shaft and didn’t have a new rear drive shaft and yoke
installed. I personally used to plasma cut the old disk and use it as the proper spacer for the old style shaft.
was a quick and easy....

 

[bcheval]

This is exactly the information I am looking for. This is what I have. Yes it looks like my M998 had been updated for MWO 9-2320-280-35-1. No tag but all parts are in place. My yoke does have the disk in place so I am thinking it still has the old yoke and prop shaft. The fuel tank I am trying to install is PN #12460105 NSN #2910-01-447-3911 does anyone have the PN's or NSN for the new parts I have to buy? Prop and rear yoke? Will I need to replace the yoke at the rear of the NP-218 transfer case? Thanks to everyone on this post. Ed

 

[Retiredwarhorses]

Simple, remove the disk from yoke, look at the outline of the old yoke on the disk, now turn that old disk into a shim spacer by cutting and grinding from the foot print from the outline.
Once done bolt it back up and install your new A2 fuel tank.
That or replace the rear yoke and DS to newer style, but that’s not necessary if you do the mod I’m referring too.

 

[bcheval]

Thank you for the help. The tank went right in. All I have left is to modify the shim and stab the prop shaft.

One last question, is their any good way to set the 1/2" distance on the strap and still pull torque? I just snubbed the nut up to the bolt shoulder and set torque. Is this right, wrong or doesn't matter?
TY
Ed

 

[DREDnot]

View attachment 765974

I am gathering parts to replace my tank with an A2 tank and add a skid plate. It looks like the skid doesn't fit to the tanks contour in the strap area?

I'm curious to see a pic of the tank/skid assembly installed.

 

[Retiredwarhorses]

Thank you for the help. The tank went right in. All I have left is to modify the shim and stab the prop shaft.

One last question, is their any good way to set the 1/2" distance on the strap and still pull torque? I just snubbed the nut up to the bolt shoulder and set torque. Is this right, wrong or doesn't matter?
TY
Ed
View attachment 765974

View attachment 765975

View attachment 765976

The tank is shimmed from above to line up the valley for the driveshaft, you can use strips of rubber, like an old mud flap.
the old tank should have had rubber isolators with taped too the tank or the 2 cross beams above.
The skid plate just goes under the front and rear straps...it’s not a perfect fit.

 

[bcheval]

The skid plate you see is the military HMMWV Under-Body Protection Kit as recieved from a DOD contractor. Its not much to look at. It might stop a puncture from a tree limb or a hard hit from a rock. Side note: It does cover the yoke of the prop shaft at the diff. P/N #6005553
Hope that helps
E