I'm really debating

[Deadguy]

whether or not to do the disc brake conversion on my jeep. I have to put 1 1/2" spacers on it, which is the main thing I'm thinking twice about. I know that heat buildup reduces the efficiency of brakes, and that is part of the reason disk brakes work better than drum brakes. I live in Texas, it's usually already hot, and my brakes, even though supposedly new, have little stopping power. I have drill on slotted rotors, on a disc brake conversion, and I was hoping that would help solve the problem.

[swat]

I really hate to see modifications made to a vintage vehicle. However, it is your jeep and you can do whatever you want to on it. That said, the old military jeeps do not operate at the speeds of modern cars, and brake heat build up should not be a major problem. I believe the problem with your drum brakes lies in another area. Paragraph 242 in TM9-8012 outlines the procedure for adjusting the drum brakes. It is critical that both ends of the brake shoe be properly adjusted, using the shoe anchor pin and the eccentric bolt. If it were my jeep, I would go through the adjusting procedure before investing in a costly disc conversion. Also, first make sure you dont have any restrictions from pinched brake lines going to the wheel cylinders. Bleed a little fluid from each wheel cylinder to see if you are getting a good flow. Good luck with your brakes.

[BullRun]

On some other old 4x4 vehicles if the brake lining material is only about 1 mm off from spec it causes all kinds of problems with brake function.

Genuine Willys brake liners for shoes are probably not available but maybe a different brake shoe liner would work.

In the other cases the liners were off brand materials that are different in thickness and composition.

I would say if your brakes are so bad that your contemplating a conversion there must be something not adjusted right ot worn beyond specs.

If your doing over 45mph I think the original brakes are not sufficient for modern traffic. I like to drive around 35 to 45 tops just to play it safe.

[wesk]

So far you have made it pretty clear that in your jeep rebuild money is not an issue. So the decision is all yours.

But you did come here fishing for opinions so I'll offer mine as well.

First ascertain the brake system condition. Have an experienced Willys jeep guy drive the jeep and evaluate it's brake system performance. In all my 50 years around these jeeps at least 50 % of poor brake performance has come from folks who have never driven a manual brake light weight vehicle. I would hop in, take her for a spin and come back and tell the troop, "sorry but I can find nothing wrong with your brakes" and you can just imagine his reaction to my statement! I have the same thing happen with complaints like no real power in third going uphill. I drive it and it climbs hills in third just like a 2200 pound, 60 HP jeep will.

If the evaluation indicates poor brake system performance then if you are an experienced mechanic pull out the troubleshooting guide and follow it.If you are not an experienced mechanic then I strongly suggest you take it to a reputable shop and have them assess the system and give you an itemized inspection report and quote.

Now you are in an informed position to make an educated choice of weather you want to repair your brakes or install your new disc system. Make sure you consider the changes that will result from the conversion such as wheel offset and decide how much that is going to affect the jeeps appearance and steering/handling.
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

[Deadguy]

It's not that money isn't an issue, it's that I had a budget. I had a 2007 FJ Cruiser that I sold, and I didn't mind putting up to all of that money into the jeep. In my mind, I was essentially trading one vehicle for another. I don't need a daily driver, I bike to work, but I would like a reliable, well running truck. Problems have arisen, and I am ending up spending all of that and maybe even a little more on the vehicle. I sometimes go for short stretches on the highway, at 50-55 miles an hour, and in 100 degree Austin Texas heat, it makes it difficult to stop the vehicle. Even on the local streets, I need to really plant my leg down on the brake pedal at more than 30 mph.
I am trying to keep the vehicle as original as possible. I got a winter top from Beachwood Canvas, the 1954 military 24 volt turn signal upgrade off ebay, and the 1954 cab heater from Midwest Military. The only real modern modification I've made is installing seat belts.
If I make the upgrade, I will keep the original drum brakes, it will be a bolt on modification that is essentially just for safety, like the seat belts. I had a CJ7, and I switched the drums to disc brakes, and the difference was remarkable.

[wesk]

I never said there would not be a remarkable improvement in performance.

I would really like to know what you are comparing the brake system performance to. Do you actually have a lot of driving time in vehicles from the 40's with manual brakes? I think from reading your posts that you are comparing the quality of the braking in your M38A1 with the CJ7 and what you feel is the need to use leg muscle that you have never needed to use before but was a common requirement in the 40's and 50's. Obviously you are not comfortable with this amount of energy requirement and I believe you will without any system evaluation just install the kind of braking system you are used to. I drove my A1 20 miles each way to work on I90 in Rapid City SD for 4 years at 60 + MPH with stock brakes and never once felt that the jeep's brake performance was not adequate. But I had been driving those type vehicles for over 25 years and that was in 1986. You will still be surprised at the braking effort with front disc and no power assist. Don't forget the proportioning valve cause that A1 is very light in the rear.
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

[Deadguy]

I know there is no power assist. Even without that, I am willing to bet there would be a big difference. I installed a vacuum booster on my CJ7, but I won't do that on the M38A1. I'm also not swapping out the generator for an alternator, or trying to add power steering. I won't be cutting a hole in the dash and adding a cd player and speakers. I just want the jeep to stop better. People are bad drivers, Austin is almost all hills, and if I get in a wreck, I am sure I will have to pay way more than the disc brakes cost me.
I listened to you guys in not swapping the tranny for a T18. I'm replacing, but not changing any of the worn steering linkage. I will change the kingpin bearings and wheel bearings, and not add a steering stabilizer. I am installing an overdrive, if nothing else it will take some wear off the engine, and make it easier to get out to those camping and hunting spots.
And no, the oldest vehicle I had was a 1973 CJ5. It had full drums, 35" tires and a V8, and was a pain to stop. That was when I was 18 and had no money, or else I would have done something about it.

[ZeroGs]

I concluded for me better braking was more important than the brakes being stock. The wheel clearance was a problem for me when attempting to install the calipers for a disc conversion. The larger drums work much better than the smaller drums and suit my needs and preferences.

[oilleaker1]

It will be alot of work to change to disc brakes. I've found the stock brakes are fine if the drums are within spec ( not turned too far ) and the linings are the correct thickness and all adjusted correctly. I've also seen 11 inch Jeep pickup brakes bolted on for more brake surface than the stock 9 inch. If you are driving over 50 in your Jeep I personally think you are not that safe if a quick action is needed. I drive a 2000 Jeep Wrangler for year round use and use my old Jeeps for the slow life. They are suited to it. V8 engined old Willys Universals are frankly scarry. They can sure twist off a axle with the big mud boggers on them. To each his own. John

[ocwd]

My buddy has 11" drums on the front axle of his CJ2A. He is extremely happy with the braking performance from just having them on the front axle. I would love to do that to my M38 but I am staying as stock as possible.

There is a pretty rough looking M38A1 on my side yard. That one will get 11" drums all around if I can find them reasonably priced.

[skyjeep50]

Mindset change? Having an agricultural background, I think of my M38A1 as a high speed tractor rather than a car and drive it as such. Or you can think of a military jeep as a large ATV that can be licensed for the road. I bet some of those newer car-like ATV's could pass me! I would get the original brake system adjusted and working properly then evaluate. I really try not to drive my jeep over 50 and usually a max of 45 but I'm not driving in traffic either. No cab, no top, no heater and that's the way I like to enjoy my jeep. To each his own.
_________________
1951 M38

[RimfireJim]

I think your concerns about the temperature around Austin and it's effect on your braking are unfounded.

First off, the issue with brakes and temperature is either a) fade, which is caused by outgassing of the brake lining due to overheating from prolonged use, resulting in low friction between the lining and the metal, or b) fluid boiling due to heavy use of the brakes pumping heat into the fluid, resulting in spongy brakes. Your description doesn't match either of those (if it was fade, you wouldn't be stopping). Yes, disc brakes dissipate heat better than drums, but needing "to really plant (your) leg down" doesn't have anything to do with that, it's just a mechanical advantage issue.
Secondly, the difference between 100F in Austin and 50F in Wisconsin or wherever is insignificant to the temperatures generated at the brake drums, which can be in the multiple hundreds of degrees Fahrenheit.
_________________
Jim M.
1952 M38 son-father project
Discovering more worn out parts, one assembly at a time

[Deadguy]

Maybe that theory is unfounded. It is, however, not unfounded that the disc brakes will stop my truck better than drums. It's also not unfounded that where I live in Austin is nothing but hills, and there are plenty of bad drivers. I have the disc brakes. They are in my garage. I could return them, get my money back (minus the shipping), find a set of 11" drum brakes, install them, the pads, the springs, and all that, and try them out, but why? 11" drum brakes are not stock either, and with me eating all of the shipping charges, I probably wouldn't save any money at this point. I've rebuilt drum brakes before, and it is much more of a pain in the ass than disc brakes. I'll keep the original 9" drum brakes, just in case, and it will be a very easy swap to restore it to all original.
I have gamma goat rear tail lights, amber lenses to turn my marker lights into turn signals, and the 1954 turn signal upgrade. That isn't exactly stock either, but I live on the edge of a city, not way out in the woods, and it's a safety issue.

[ocwd]

I only mentioned 11" drums because they are less noticeable and probably less work to install than disk brakes. If you install 11" drums, you will also need new rims and tires. My M38A1 already needs rims and tires. I have a feeling that you will enjoy your Jeep more if you install the disk brakes. Plus, you already got the stuff. Why return it? Enjoy your Jeep and don't worry about the "Jeep Police."

[wesk]