Info/help on Axle Upgrades and brake parts

[tonydamato]

Good morning everyone, just joined this forum as I purchased a very clean low milage '91 M998 over the weekend for a great price and I am looking for some guidance from those of you with far more experience than I. I am a Machinist and instructor by trade and am no stranger to turning a wrench. Ive built several 1000+ hp race cars and I know my way around suspension and powertrain very well. What I don't know is the specifics with these HMMWV's and the changes that were made year to year. I have done a lot of reading before making this post and I just seem to be confusing myself so I am looking for some definitive answers. So if anyone is willing to help me out, I would greatly appreciate it. Also, being a dealer for many parts in the performance racing industry I understand the importance of service before and after a sale, so if any of you are dealers for the parts I need, please let me know and Id be more than happy to work with you directly.

What im noticing so far is that my brakes feel a little odd and the rear brakes seem to have more stopping power than the front, this in my opinion is completely the opposite of the way things should be. Especially my drivers side rear brake with seems to lock the wheel up with ease. So in the name of preventative maintenance I am looking to start going through the rear end of this thing and im not the kind of person to cut corners. After crawling under this turd Ive noticed that the rotors have some hot spots on them and that is likely contributing to the brake squeal as well as the lock up issue so Im assuming I should just replace the rotors and pads. While im in there though I would also like to upgrade to these 12K lbs half shafts im reading about. In my opinion there is no reason to take this thing that far apart without doing that upgrade. From what I understand it will require grinding on the caliper mounts for clearance as well as changing the pinion gear inside the hubs. No big deal.

What im looking for is a comprehensive parts list of what I need and where I can buy it as well as any tech info that may help me with this project.

I would like to replace the rotors, pads, half shafts, and re-build/seal the gear boxes as well as change out the upper and lower ball joints if possible.

So if anyone can help me out with this, I would greatly appreciate it.

 

[Sintorion]

Congrats on your purchase. Please say that you were joking with the low mileage thought.

As for swapping the shafts, what is your need for the extra beef and what do you expect to gain? It is a lot of money, time, and effort for something that unless you are planning on converting it to and expedition vehicle and adding armor, that there really isn't a lot of benefit.

Brakes on this are no different than any other vehicle. You should get about 75% stopping power to the front. Bad calipers are typically to blame for uneven braking. If you are replacing one, you should replace both, but I would probably replace all 4. You are looking at probably $750-1000 for calipers, pads, and rotors. Add in the cost of new axles and the price goes higher.

One thing to consider with the brakes is your familiarity with them. The feel and action is much different than if you have been driving a newer vehicle with ABS, traction control, etc. You may end up at the same spot with brake feel after spending $1000 because the system is working as designed. Of course you will have better peace of mind.

If you think there is value that you can gain out of the investment, by all means jump in. I probably would put my upgrade money elsewhere, but my needs are probably different.

 

[tonydamato]

Thank you for the input. My thoughts on upgrading to the beefier shafts is because I have a 12v Cummins sitting in my shop that will likely end up in this thing within the next year or so. I don't mind spending the money on the parts to do things the right way, im not the kinda guy that cuts corners to save a buck. You mention that you yourself would put upgrade money in different areas, care to elaborate on that? Do you have a good source for the brake parts? Thanks!

 

[papakb]

Front brakes calipers are from an '87 AMC Eagle and only run around $20-25 at most auto parts stores with no core charges.

 

[Dock Rocker]

These brakes are hydroboost, inboard disk, non ABS brakes. They are never going to feel like anything else you have ever driven.

I will say that before I swapped everything I would check the pads and lubricate the pins to make sure the pads are floating as they should and not slow to retract because of poor lubrication. There is a very high probability that they are just gummed up from sitting most of the trucks life.


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[86humv]

No grinding on caliper bracket needed if using 12k shafts.
12K upper hub gears can be installed .
There are two types of 12k shafts...solid and vented rotor type.
The difference is in the rotor mount end.
The vented 12k rotor type shaft will fit the stub shaft and rotor on your current 10k diff. rotor.
The solid 12k rotor shaft will need an adapter ring made to adapt to your current rotors.
There was some made by RWH on here awile back.

 

[Retiredwarhorses]

We sell 12k adapter rings to use newer, cheaper halfshafts on older, larger rotor flange.

 

[tonydamato]

Great information so far guys, thank you! Keep it coming.

 

[Sintorion]

My view on upgrades is need based and value for time and effort. I haven't seen an excessive amount axle failures that would drive me to want to spend the time and effort to upgrade them. Would they be better? Sure, but is using a larger caliber bullet better when you can accomplish the task with the caliber you have?

Not sure where Hales Corners is ,but it looks flat so I would assume rock crawling is not in your future which for me would be the motivating factor to go with beefier axles. Are you building for off road or on road? How soon are you dropping in the Cummins (btw, super jealous)? That is where I would start. Get that in along with a 4 speed tranny and see where you are. If you find that you are snapping axles, then make the swap. Totally understand and appreciate the mind set of wanting to go with the best solution now, but if you are like most of us that have to work with a budget, it may not be the best approach now. That is unless of course if you find bad parts when you get into your brakes. Then it makes perfect sense.

 

[Action]

When you put in stronger halfshafts, what is the next thing to break? Simce they will no longer be the fuseable link?

 

[ryanruck]

When you put in stronger halfshafts, what is the next thing to break? Simce they will no longer be the fuseable link?

From what I understand, it would be the diffs. Also as I understand, this is why the H1 Alphas had Dmax engines that were detuned compared to their Chevy/GMC truck counterparts. Would the latest version of the diffs for the uparmored trucks solve this? I don't know enough about the newest diffs to know if they were strengthened in addition to having cooling loops added.

After that, I'd imagine the prop shafts/driveshafts would be the next in line since those are just hollow tubes. And that would likely be an acceptable failure point.

 

[Sintorion]

When you put in stronger halfshafts, what is the next thing to break? Simce they will no longer be the fuseable link?

That is a solid point. In the world of modification the suggestion is to start at the end of the line and work your way back. That would mean tires and wheels, suspension, driveline, etc. so that you are not getting into that situation where your modification has created down stream failure points. Of course that is good in theory, but I could never stick with a plan like that. If I had a Cummins sitting in my garage right now, I would be doing everything I could to get that in.

 

[Retiredwarhorses]

The diffs on A2's are 2:73, newer trucks use 3:08 diffs, the drive shafts are larger and so are the diff yokes and u-joints.

 

[tonydamato]

Thanks for the input guys. As far as the Cummins just sitting there, its honestly not a priority. Racing season has come to an end and its time to start rebuilding for next year. The Humvee will get worked on as I have time but just like with a race car, I prefer to start at the weakest link and work backwards. Id rather eliminate all the weak links before installing the more powerful engine. All the power in the world does you no good if you cant put that power to the ground reliably. I will likely be moving forward with the 12K axle swap. Need to find more information on the 12K brake conversion as well....

 

[86humv]

You can't do 12k brakes, unless you change the 4 X members between rails, and 4 ea. U channel brackets, 4ea. diff hanger brackets, front diff's rear bracket.
12k trucks have a different hydro boost, and master cyl., and different lines to master cyl..
And there is 2 different 12k brake set ups that both use the same calipers as A1 10 k trucks.

 

[Al Capone]

is this correct ? 1987 amc eagle front calipers? if so yes they are $19.99 at my local autozone store! great info.

 

[Action]

is this correct ? 1987 amc eagle front calipers? if so yes they are $19.99 at my local autozone store! great info.

Yes same casting numbers too. I think the RF amc caliper is LF on humvee

 

[tonydamato]

I would assume that means you can use the pads for the '87 AMC eagle as well?

It appears that Autozone also carries the 10.5" rotors for the '92 H1 for $38.00 each as well, one would think those would be dimensionally the same to the OE 10.5" rotors on the Hmmwv.

 

[86humv]

I would assume that means you can use the pads for the '87 AMC eagle as well?

It appears that Autozone also carries the 10.5" rotors for the '92 H1 for $38.00 each as well, one would think those would be dimensionally the same to the OE 10.5" rotors on the Hmmwv.

Same fitment, but calipers are rebuilds, and rotors are chinese.

 

[dilvoy]

Get metallic linings.