51 M38

[jake138]

Thanks Brian! I'm really starting to get back into it now and I'm having fun again, remembering why I started this project in the first place!

The steering damper is already gone, that came off when I started doing the tie rods. I had the early tie rods with the smaller threads and both my steering tubes were bent like pretzels. I swapped in the larger thread tie rods, larger diameter steering tubes, and I changed the setup to be like the CJ5's. If I remember correctly, this is referred to as the Inverted-T setup where the driver side knuckle is linked to the male end of the double-tie rod on the passenger side knuckle with a 35" long tube, then the socket side of double-tie rod goes up to the bell-crank with a 17" long tube. I will post that project soon in another post with pictures and explanations as to why I did what I did.

The Bendix joints are on the long list: I will be diving into the knuckles later once I'm ready to dedicate the time to keeping it on jack stands for a while. I'm trying to keep the frame rolling for now so that I can get the majority of the Jeep back into once piece. We're planning on selling the house and moving within the upcoming months and I'm doing my best to keep everything portable. You are absolutely correct though, I'm worried that there were some worn components that I will need to address once I'm closer to getting it road worthy.

For right now, the biggest hurdles are general well-being: stop the rust, fix the worst of what's been damaged, and get it back in once piece again. The long-list includes improving drive-ability and road worthiness.

~Jake
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Jake, Central CT
51 M38 s/n 35627

[jake138]

Replacing the shocks went flawlessly for 3 out of 4 corners. For the first three corners, I didn't even attempt to loosen one of the nuts without heating it first. I gave each nut a minute of the MAP gas torch, and they all came off nicely. By the time I got to the fourth corner, I got a phone call from my father, so rather than deafen the call with the torch, I tried to remove the top nut without heat.

Mistake one.

After snapping the threads clean of the shock mount, I wondered, was it just bad luck with this one, or would the bottom mount need heat too? As I was still on the phone, I tried to give it a gentle tug without heating again.

Mistake two.



So now with both threads missing, I took a look at how much work it would be to replace the entire mounts. After determining the amount of cutting and welding necessary, and that the rest of the shock mounts were solid and did not need to be replaced, I formulated a plan instead for replacing the threads.

I measured the thread size and bought 2 bolts at the hardware store. After cutting the heads off with a hack saw, I chucked them in the lathe and turned a small diameter on one end that was just under the minor diameter of the threads. The picture below shows the top bolt finished and the bottom bolt before I turned its small diameter.



Back out in the garage, I used the angle grinder to grind a nice clean, flat face on the end of the shock mounts. Using a prick punch, I gave myself a nice spot in the center, and then center drilled both shock mounts with the cordless drill.



I then stepped up to a drill bit diameter that would give me a nice press fit for the diameter that I turned on the bolt.



Being a machinist, not a welder, I wanted even just a small press fit to give myself that slight bit of assurance that the threads would be less likely to snap off. Also, by my assessment of the shock mount itself, there should be minimal lateral forces applied against the threads, as the larger arbor diameter holds the force of the shock vertically, and the threads serve merely to hold the shock from sliding off the arbor.

As the adage goes, "a grinder and paint, make me the welder I ain't," so after welding and a quick touch of primer, both shock mounts were ready for their new shock.


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Jake, Central CT
51 M38 s/n 35627

[Ryan_Miller]

I had a similar issue with my frame. I ended up getting cutting the spots welds on the bolt to remove just the threaded bolt from the frame bracket.

I then took a grade 8 bolt the correct size, took it to a friends machine shop and made the threaded part to fit the original and cut the head off to the proper length.

I then put the new part I made into the bracket and welded it like the original.

My only reservation with the way you did it is there is a weak spot toward the end.

However if it fails it is not a catastrophic issue so I would probably continue with what you have done and see how it works out.
It looks like you did a good job.
_________________
Ryan Miller
MVPA # 22010

[jake138]

[Ryan_Miller]

I think you are right. You are probably not going to be rock crawling or other extreme ATV sports with it.
_________________
Ryan Miller
MVPA # 22010

[jake138]

Since my tie rod ends were destroyed from lack of regular maintenance, I ordered new tie rod ends from Kaiser Willys. When they arrived, I quickly primed them and began to remove all the old ones. As soon as I tried to thread the new tie rods into the old tubes, I discovered what I'm guessing is one of the differences between an "early" M38 and a "late" M38: the early MC's came with tie rod ends and steering tube threads matching the CJ3a with 11/16" major diameters, whereas the late MC's had the larger threads like the M38A1 with 3/4" major diameters.

Since this mismatch caught me off guard as I had not read anything about this previously, I started doing more research and eventually decided I wanted to keep the larger thread size tie rods: 1) I had already purchased and painted them, and 2) the larger threads and steering tubes must have been deemed an "upgrade" for the military at some point, so I might as well stick with them. I was also able to suppose that the CJ3a size steering tubes lacked strength, as evident by the facts 1) both my short tube and long tube were bent, and 2) internet research showed other people also complained about bent tubes.

In the midst of my research about the steering tubes, I found that many people also chose to upgrade their steering to a more stable configuration. The factory configuration, where each front wheel connects to the double-tie rod at the bell crank, seems to create a toe-out condition when under heavy braking applications. As the suspension compresses during braking, this decreases the vertical distance between the bell crank and the steering knuckles. However, since the steering tubes are a fixed length, and the pivot points of the knuckles are fixed on the axle, this causes both front wheels to toe-out.







Having driven a lifted YJ for a few years and already having a full appreciation for bump-steer from incorrect steering geometries, I decided that now would be the perfect time for me to address my concerns with the factory MC configuration.

By installing the double tie rod end in the passenger side knuckle, I would then link across to a single tie rod end on the driver side knuckle using a 34" long steering tube, similar to what I believe eventually Willys would install on the CJ5. Going from the socket-side of the double tie rod end, I would use a 19" long tube with two single-ended tie rods ends to link back up to the bell crank. I would be able to use all four of the tie rod ends I had already purchased, and now I simply needed to order steering tubes. I measured the lengths needed by installing the new tie rods ends into their sockets and aligning the steering knuckles as close to parallel to the frame as I could get by eye. I then found someone online that had measurements within 1/4" of mine and decided my procedure worked.

Looking on Summit racing, I found that I could order steering tubes with many thread sizes, in a variety of materials, with some lengths in increments of a quarter inch! Since I had already seen that the factory diameter steering tubes will bend, I decided I wanted thicker wall tubing and a larger diameter. Summit did have some aluminum tubes available, but since this isn't a race Jeep and I'm not worried about weight savings, I went with some nice looking zinc plated steel tubes, made right in Coopersville, Michigan. The 34" tube was $29 and the 19" was $20, so for a total of $49 I had some quality, American made, heavy duty steering tubes that wouldn't bend.

19" tube
https://www.summitracing.com/parts/kys-100t421901a

34" tube
https://www.summitracing.com/parts/kys-100t423401a
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Jake, Central CT
51 M38 s/n 35627

[jake138]

The configuration I built is what's known as an "inverted T", as the tie rod steering tube attaches knuckle-to-knuckle, and the steering tube from the bell crank then links to the passenger side double tie rod end. Once my parts had arrived, I test fit everything together and confirmed a suspicion I had while measuring for tube lengths: the larger diameter of the tubes would not give me enough clearance to the leaf springs.


The gap in this picture disappears entirely once the wheels are cut to either side, and this would not actually allow full range of steering.


The wheels actually were slightly to the right of center in order to even get everything to fit, and I could not turn the wheels to the left of center at all without completly stopping against the passenger side leaf springs.


Even if I had used smaller diameter tubes that cleared the leaf springs, the angle between the bell crank and tie rod tube would have given terrible bump steer.

Luckily, since I had already seen that these issues would arise when I was making my measurements for the tube lengths, I had already researched my next modification: flip the tie rod ends to the top of the knuckles. By doing a tie rod flip, I would give myself the clearance needed for the leaf springs, as well as reduce the angle between the tie rod tubes to almost nothing.

After some time on the internet, I found a company that sells a kit with the automotive reamer needed to ream out the steering knuckles and the three steel inserts that would be installed to make up the gap between the new taper and the existing taper. However, I honestly did not like the way they install their inserts, and also they currently ask $190 for the kit, which I found to be rather pricey for 3 small tapered sleeve inserts and a $40 reamer. There are other kits available that are straight diameter sleeves, but those usually required welding the sleeve to the knuckle, and I just found that to be unneccesary additional work. Instead, I decided to design my own tapered sleeves that did not require welding and would not be easily removed.

When reaming the knuckles from above, some type of insert is required in order to make up the gap between the large opening on the bottom from the original taper and the new taper from above.



There's two things I don't like about this: 1) since you're using a reamer that has the same taper as the tie rod end, you need to take out quite a bit of material from the knuckle in order to completely fill the gap in the middle drawing. My drawing is quite a bit exaggerated obviously, but there is still a significant amount of additional material that needs to be removed. And 2) since the taper on the outside of the insert matches the taper of the tie rod end, if you ever need to remove your tie rod ends, there's an equal chance that the insert will come out of the knuckle and be stuck to the tie rod end. I didn't want this: I want to know that the insert is permanent to the knuckle, without having to weld or braze it.

So, I designed and machined my own tapered sleeves.


The left most sleeve is right-side-up and shown as it would be installed into the knuckle, the other two are upside-down to show the difference between the external and internal tapers.

The external taper of the sleeve is 1/4" taper per foot, as opposed to the internal automotive taper of the tie rod end which is 1 1/2" taper per foot. This much shallower taper on the outside will force the sleeve to be a much tighter press fit into the knuckle and will prevent the sleeve from being removed if the tie rod end ever needs to be removed. I practiced reaming the new taper in my old double tie rod end, test fit some prototype sleeves, and found dimensions that worked. After a few iterations, I found one that worked perfectly to my liking.

By using a more shallow external taper, I also reduced the amount of material that would be removed from the knuckle:



With a taper coming from the top and bottom, here is what the tie rod end would look like if the tapered hole did not have an insert:


You can clearly see the gap all around the tie rod end.

Here is one of my sleeves loosely inserted into the freshly reamed hole:


Once the tie rod end is tightened down, the sleeve becomes fully seated, and the tie rod end can be easily removed, leaving the sleeve in place:

_________________
Jake, Central CT
51 M38 s/n 35627

[jake138]

To ream my knuckles out for the 1/4" taper per foot for my sleeves, I started with a Number 9 Gammons Hoaglund taper pin reamer.





Using the cordless drill, plenty of cutting oil, and a good amount of patience, I gradually reamed out the passenger side knuckle first.


The reamer looks like it's sitting at an angle because it was just loosely sitting in the hole as I staged this picture. I was very delibrate to ensure the new tapered holes were as parallel to the existing holes as possible.


Making sure everything was clean before test fitting.


Not deep enough yet!

As I gradually got deeper, I was cutting higher up on the reamer until I eventually had to step up to a Number 10 reamer. Unfortunately, the shank on Number 10 reamer was too large to fit into the chuck on my cordless drill, so back in the shop, I set the reamer in a spin fixture and ground down the shank with the surface grinder.




Starting to reduce the shank diameter.

Back in the garage with the modified reamer, and after some more reaming, cleaning, and assembling, the passenger side looked good, so I moved to the driver side.



Once all the nuts were tightened down, I installed the steering tubes and lock nuts for the final result.


Plenty of clearance to the leaf springs now!







This flip greatly reduced my steering angle so that both tubes are as close to parallel as possible. There will be plenty of adjustments to be made to the alignment later down the road once the body is installed and the wheels are back on the ground, but the angle can only improve from here.
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Jake, Central CT
51 M38 s/n 35627

[Mike_B]

Lots of nice machine work going on here!

What keeps the tie rod from hitting the bottom of the bell crank when the suspension travels up? If you measure between the top of the axle and the bump stop on the frame you have a lot more clearance than between the tie rod and bell crank...

Mike B
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Mike B
1953 M38A1 Brush Truck
1952 M38
1951 M100 Trailer

[jake138]

[Ryan_Miller]

I like the reamer.
I had some 1st style battery terminals cast of brass years ago and that was the last step I never got around to so they would fit on the tapered battery terminals.
Where did you get those ?
_________________
Ryan Miller
MVPA # 22010

[jake138]

[jake138]

When it came time to tackle the brakes, I had to weigh my options:

1) Rebuild the factory 9" brakes
2) Upgrade to 11" drums in the front from a CJ5
3) Upgrade to front discs with a GM caliper adapter

When I researched these upgrades to improve braking performance, I found that the amount of work involved in an 11" drum conversion is #@$%@ near just as much work as doing the disc conversion. If I were going through that much time and effort, I would rather have the disc brakes in the front for the additional stopping power. The only advantage to the 11" drums is that the discs require wheel spacers in order for the calipers to clear the wheels. After pricing out all 3 options, and after a lot of hours of researching on the computer, I decided I would stick with rebuilding the 9" drums. I'm building an old Jeep, and it's going to drive like an old Jeep. From my time researching, I feel confident that with a factory powerplant and properly adjusted 9" drums, I should be able to safely drive my Jeep around town while remembering that I am, in fact, driving an old Jeep without power steering and 4 corner drums that require some additional stopping distance.

First step is replacing the brake drums as all 4 of mine were already cut to the max size of 9.060". Replacement OEM brake drums are $60 each from Kaiser Willys or Walcks 4WD, however, a thread on this site by Brad (Southpw) had found that the Raybestos 2300R brake drum from a 1959-1969 CJ5 had the same specifications as an M38:

http://www.willysmjeeps.com/v2/modules.php?name=Forums&file=viewtopic&t=10815

Brad's original screenshot from September 17th, 2016, shows a Nomimal diameter of 9.00" and a Discard diameter of 9.06", which means they would be the perfect diameters for replacing my M38 drums. However, once I found the drums on Raybestos website, and current as of the writing this post January 18th, 2021, these drums are specified to have a Nominal diameter of 9.06". The Raybestos website now shows the dimension listed as MM and the metric equivalent as IN, and although the units are inadvertently swapped, the numbers are correct.

https://www.brakepartsinc.com/raybestos/catalog-part-search/catalog-interchange.html

Finding these drums on Rockauto was easy enough searching by part number 2300R, and after shipping, all four drums were delivered for just under $100.


Taken before painting, after drilling the countersinks deeper for the hold down screws, and after degreasing.

Now that I had the drums in my hands, I measured their Inside Diameter, and they did infact match the current specs on Raybestos' website. With an ID of 9.060" this meant I would need to do either one of two things:

1) Shim the factory thickness liners out to match the ID of the drums, or
2) Install oversize thickness liners on the brake shoes to match the ID.

If you read my posts in Brad's thread about the drums, you'd see that I called a shop that previously used to install oversize thickness liners, however, they no longer do the shoes themselves in-house. Rather than paying for a middle-man, and after not being able to find any other shops that installed oversize thickness liners, I ventured off to the internet to find another option. Eventually I had found a walkthough on how to make my own liners from scratch, and as much as I would like to give the creator credit for their excellent knowledge, pictures, and descriptions, they did not put their name on the walkthrough anywhere. I will use my own pictures and describe my work to the best of my ability, just know that this process is not my own, and that the credit goes to the creator of that original walkthrough I found online.

Making new shoe liners started with ordering a 6 foot length of 2" wide, .250" thick brake lining material from McMaster Carr. If you follow the TM 9-8012 specs for the factory thickness of the brake shoes, you would see that they were 7/32" thick, which means that by using 1/4" thick liners, I would be adding 1/32" per shoe, for a total of 1/16" additional diameter across both shoes, matching my new drum ID of 9.060" perfectly. Also by following the TM for the length of the liners, I calculated that I would need just under 6 feet total of liner. I did not buy extra. While researching brake liner materials, I decided to use a non-metallic liner. Although my research suggested that the semi-metallic liners might last longer, they are made with an integral woven brass mesh that reportedly causes the liners to run hotter. At the expense of longevity and possibly requiring more frequent shoe adjustments, I elected the non-metallic liners for cooler brake liner temps that would hopefully reduce braking fade. At the additional cost of possibly adjusting the shoes every 500 miles, this will likely be once per year in the Spring time before a driving season starts. In order to help possibly visualize any rapid deterioration in brake liners, I chose to paint the drums with a very reflective, vibrant chrome colored high temperature paint.


I'm terrible at remembering to take pictures, and it is just now that I realize the only picture I have of the drums painted is as they sit on top of the empty dog food bag I used to keep the snow off them .

When ordering the brake lining material, I also ordered the 5/32" diameter rivets I would use to hold the lining material to the shoes. By using copper rivets with brass mandrels, my hopes are that if the liner ever wears down to the rivets, the softer metals will minimize any damage done to the drum ID. I ordered the rivets from Hansen Rivet Company in California, whose excellent customer service I could not speak more highly of. The rivets I used have a gripping length of .126"-.187".

I got to work on cleaning up the old shoes. Five out of eight shoes say Bendix, the other 3 are unbranded. The old liners were held on with adhesive and required extensive chiselling to remove.



One of the unbranded shoes did not have any holes, so after following the template of another shoe, the new holes were laid out and drilled.


You can see a faint scribe line for the location of the holes on the right shoe. Excuse the blue layout fluid explosion that previously occured on the height stands, that stuff sticks to everything...

After all the old adhesive was removed, the shoes needed to be media blasted clean.



Once the shoes were cleaned, they received a nice coat of high-temperature flat black paint, which I never photographed .

With the drums on standby to check fitment, the rivets and brake lining material in hand, and the shoes dry, they were ready for their new liners.



I started at one end of each shoe using a C-clamp to hold the liner in place. From the inside of the shoe, I pilot drilled the hole for the rivet body through the lining material. Moving to the wear face of the liner, I counterbored the rivet hole.


Using electrical tape wrapped around the body of the counterbore bit as a depth marker, this picture shows how deep the rivet heads are from the liner face. I approximated around .100" of the liner is below the rivet head.


The counterbore bit at depth.

Inserting the rivet through the liner, you will see that since the rivet head is below the face of the liner, a standard pop rivet tool will not be able to apply pressure against the rivet face. On the lathe, I turned a small toolsteel adapter with a diameter that protrudes into the liner and allows a larger face to contact the rivet tool.


The smaller diameter on the right end of the adapter fits into the counterbore of the liner and pushes against the rivet face. The small diameter on the left side was a test diameter that I turned off in the next picture.


The adapter fully seated on the rivet face. This allows the rivet tool to press against the larger face of the adapter and not against the liner.

After finishing both rivets on the end of the shoe, I moved the C-clamp down to the next set of holes. By using the C-clamp to slightly squeeze the liner next to the hole I was drilling, when the rivet was installed and the clamp removed, the liner would retract back and the end result was a very nice tight fit between liner and shoe.




No gaps, no need for adhesive.


A finished shoe. I added small bevels on the ends of the liner so that there would not be a sharp transition onto the liner face.

After a few beverages and more hours than I care to admit, I had completed four long shoes and four short.



Back out to the garage with the shoes, I found it easiest to align the pivot pins through the plate, slide the cam washers onto the pivot pins, then hold the shoes onto the cams, all with one hand.



Then, I guided both pivot pins through the holes in the backing plate and installed the lock nuts and washes on the backside with my free hand. It was a bit of a juggling act, but by the time I got to the fourth corner, I was getting "good" at juggling.


Holding the pivot pins in place with my right hand so that I could reach in back and install the lock washers and nuts.

At some point in my time on the computer, I read a post where someone mentioned how their brass cam washers were not as thick as their shoes, and that when they tightened down the nuts for the pivot pins, their shoes would not move. So at each corner during assembly, the first thing I did was fully tighten each nut on the pivot pins to make sure the shoes could move freely.


In this picture, the pivot pin nuts are fully tightened, and as you can see, the shoes are both caught to the point where although I can force them to swing up, they are not moving freely. I forced the shoes up and down a few times to see where the paint would be scratched off, and then disassembled.


Here you can see where the shoe, not the the brass cam washer, was what was being tightened down onto between the pivot pin plate and the backing plate. After polishing the shoe with the sanding drum on the Dremel tool, I cleaned up the faces so that they would not contact the pivot pin plate or the backing plate.

Upon reassembly, you can see that the shoes now dropped down freely on both sides and then could easily swing up to meet the wheel cylinder.



With the rear assembled, I moved to the front.



And after all four corners were assembled, I installed the drums, which I forgot to take pictures of, and then adjusted the brakes to a slight drag, which I also did not photograph. Now the brakes are ready for a light run-in and future adjustment.
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Jake, Central CT
51 M38 s/n 35627

[whydahdvr]

Jake,
Loving your posts on your restoration. Tons of detail and photos! I don't have the mechanical background most of the others and you do but I can appreciate all the work and ingenuity there.

On braking - I've had my 1952 M38 since 2008. Braking, as you pointed out, is different on that than a modern car and that's the biggest difference and thing to remember when driving it.

I mostly drive my jeeps out on Martha's Vineyard. Lots of sandy dirty roads, sandy/dusty paved roads, and mostly speeds below 35-40 mph on the roads. The biggest challenge I've faced isn't being able to brake or slow down quickly it's dealing with the other drivers. Most of them are clueless - like most people (another conversation for another time). Modern vehicle drivers have little appreciation for how physics works and have too many distractions (at least that's the way it appears to me). They're often oblivious to motorcycle riders which is kind of where I put myself as it's a non-standard looking/acting vehicle. Some of the drivers are great though and do give me plenty of room, wave, and appreciate the older jeep.

However, aside from drivers the biggest challenge are the hordes of bicyclist's and moped riders. They're by far the worst (and the people that blindly walk into the street or across intersections and crosswalks).

So, aside from my rant on tourists in tourist spots doing tourist things I think the biggest challenge you'll likely face are those that are blind to their own surroundings and present a challenge to any driver. The brakes have always worked well for my in emergencies. I just do my best to identify my risk vectors as early as possible from our surroundings. The jeep does just fine otherwise.

Josh
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North Shore, MA
Santa Fe, NM
1942 GPW
1952 M38
1964 Apollo 5000 GT

De Opresso Liber

[Ryan_Miller]

Yes, great detail and how to.
I have some over sized drums that were turned too much and every shop I talked to said they don't do that anymore so I had to go with some later military replacement NOS drums that don't have the slit to check the brake shoe adjustment.
_________________
Ryan Miller
MVPA # 22010