Vintage Jeep V-6 CJ-5 Bronze Brake Pedal Arm

[snoopy2x]

 

I sent what I believe to be my jeep's original brake arm to a machinist in Alabama who rebushes a lot of them for members of the Early CJ5 site.  As it was being cleaned and then glass-beaded, he realized that unlike any others he had previously seen, this brake arm is made of bronze rather than steel.  He started a thread about it with this photo:   http://www.earlycj5.com/xf_cj5/index.php?threads/strange-brake-arm.129750/

 

 

Apparently, these solid bronze brake arms have been found on a number of '66 & '67 CJ5s (http://www.earlycj5.com/xf_cj5/index.php?threads/brass-brake-pedal-arm.89095/#post-951636), so it's likely an OEM jeep part. 

 

My question is, why would Kaiser Jeep have made some brake arms out of bronze instead of (less expensive) steel in the first place?  Do you have any insight on that?
 

The vast majority of the wear on mine was to the (also likely original) steel cross shaft, rather than to the inside diameter of the bronze brake arm pivot.  I've always thought that steel is harder than bronze, and would think that the bronze would therefore wear out faster than the steel.  Am I wrong about that?
 

Maury

[Moses Ludel]

Wow, Maury, this is something!  News to me but obviously original equipment on your Jeep.  Is it not just bronze-plated?

Whether truly bronze through-and-through or just bronze plated, there may be some M38A1 history involved.  Kaiser/Jeep did produce this military model for some time into the 'sixties and may have had an abundance of extra parts from those models.  The bronze could have to do with water fording capability or the operation standards for a highly humid environment like SE Asia. 

Risk of a brake pedal rusting through is highly unlikely but there must be an explanation.  Resistance to salt brine beneath the vehicle is also a possibility, I received a Model 18 transfer case parts donor from a friend in Ohio.  The vintage CJ-6 was stationed on a salted runway and used as an emergency vehicle.  The iron case had salt damage so deep into the casting that it was worthless, a sign of what road salt can also do.  The casting had a weird look to it, the case looked "wet" where the damage was apparent.

Should this be the case, it would be interesting to see whether an M38A1 connection can be made.  You do have an interesting brake pedal arm!

Moses

[snoopy2x]

The guy installing the bushing for me is an experienced machinist, and he had the same question about it possibly being plated, but concluded after some additional investigation that it is a solid bronze cast piece.  I was intrigued by your thought that the bronze arm might possibly be a leftover M38A1 brake arm, and did a bit of investigation about this possibility.
 

It turns out that though they are indeed very similar, the M38A1 brake arm is not identical to the CJ5 V6 brake arm.  The two have different part numbers as well.  Below is a shot of an M38A1 brake arm above a (cast steel) brake arm from a '71 V6 CJ5. As you can see, the "bends" in the castings are slightly different between these two parts:  




Note that the brake arm from the '71 has exactly the same shape, and also the same part number as the one off my '67 jeep.  However, like the M38A1 brake arm, the one from my '67 has the smaller pin for the early single-reservoir master brake cylinder.  The one from the '71 has the larger-diameter pin to accommodate the later double-reservoir master brake cylinder.  (Why Jeep would make brake arms with two different pin sizes but not change the part number is a mystery to me.)

 

Did any other thoughts occur to you as to why the one on my '67 was made of bronze?  As you say, there must be a reason, but so far it has been an elusive one to figure out.

 

Maury

 

[Moses Ludel]

Hi, Maury...You hint that the V-6 models were a one-off brake arm design.  If this brake arm has features to allow the arm to clear any V-6 components or position the brake pedal differently, that might explain the variance.  If the arms were limited production at the onset of the V-6 models, Kaiser may have done short orders (small quantities) of these arms, and maybe they were easier to manufacturer in bronze at those smaller production numbers.  It would be worth comparing the cost for limited production iron versus bronze.

On that note, you're calling the iron/steel arm a casting, right?  Neither are forgings?  Is the '71 bushed type arm showing a factory bushing at the big end?  Is the larger brake rod pin just the same arm and pin as yours but with a pressed on bushing for the master cylinder rod?  If so, does the bushing resize the pin to accept the dual master cylinder rod while the arms remain the same part (number)?

Some thoughts...

Moses

[snoopy2x]

 

I asked the machinist working on the bronze arm if it was cast or forged, and he's pretty certain it was forged, as there are no inclusions as would be expected with a casting.  He also said it is definitely solid bronze, as opposed to being plated. 

As best I can determine, the CJ5 V6 brake arms were a one-off modification of the earlier brake arms used on other CJs and the M38 and M38A1.  As NOS brake arms for the V6 are no longer available, a good fix for worn arms is to have them bushed.   As you're well aware, the inevitable wear to the inside diameter of these arms causes brake pedal side-to-side wobble. The bronze bushing in the '71 brake arm isn't factory, but was installed as a repair to correct this problem.         

Below is the (dirty, still unpolished) bronze brake arm from the '67 (top) and the one from a '71 (bottom).  Like the M38A1 brake arm, the one from my '67 has the smaller pin for the early single-reservoir master brake cylinder. The one from the '71 has a larger-diameter pin to accommodate the later double-reservoir master brake cylinder.  This pin is a longer, larger diameter one-piece pin, rather than a sleeve pressed over a smaller pin. 





However, despite the significant difference in the master cylinder pins, which are more or less specialized rivets permanently attached to the arms, these two brake arms have the same part number, 941416. Why Jeep would make them with two very different pin sizes but not change the part number is an interesting question.
 

Maury 

[Moses Ludel]

This is interesting, Maury.  Our exchange could be valuable to others...Nice piece of history!

The shared part number could simply be an accident.  Perhaps an iron arm was supplied to the job shop for duplication in bronze with a request for a new shape to the bronze arm.  The iron arm/pattern had the part number embossed, and perhaps the supplier (or Kaiser/Jeep personnel) took it for granted that the short run of bronze arms should be the same part number.

The pin in the re-bushed arm is clearly a press-in or fitted item, so it may also be that the arms are considered the "same part".  In this case, the arm's press-in master cylinder (pushrod) pivot pin determines the application.  If I'm guessing right, the arm came alone with a separate part number for the stud.  The installer would press the correct pin into place.  Replacing the arm would be an alternative to your re-bushing an OEM arm.

I have an original 1962 edition of the Jeep Universal Parts List. In that era, the parts guide shows a common part number 637408 Brake Pedal Stud for the CJ-3B, CJ-5 and CJ-6 (plus the DJ-3A).  The brake pedal "Assembly" is part number 800527, again common to all of these 4-cylinder models.  Likely the pin ("Stud") was a service replacement part installed on the original arm.  We know that the arm's pushrod pivot pin is wear prone.

Moses

[snoopy2x]

Moses, your theory very well may be correct.  The brake arm and the associated pin may have been differently numbered parts in the Kaiser Jeep Parts List.  If so, this would explain the apparent discrepancy that the brake arms with the earlier smaller pins have the same part number as those with the later larger pins.

Thanks very much for your feedback! 

[Moses Ludel]

Maury...Perhaps someone has a 1965-71 era factory parts manual to verify whether the brake arm pushrod stud was available as a unit part like earlier models.  On the cusp would be the 1966-67 models, the transition from single (1966) to dual (1967) master cylinders, which coincided with the introduction of the CJ V-6 Dauntless models...Comparing 1965, 1966 and 1967-1971 OEM brake arm and stud numbers, V-6 versus 4-cylinder models, might prove interesting.

Keep in mind that the early Jeep CJ V-6 models were in flux, factory modifying and substitution of parts was not unusual.  Transmission to bellhousing and other "adapters" changed course several times.  Some anomalies were introduced by dealers and owners, like ditching the V-6 Prestolite distributor and installing a reliable Buick/Delco-Remy unit.  Then there were the 4-speed V-6 CJ ghosts.  Some say that the V-6 models never offered the compound low gear 4-speed truck type transmission (T98A/T18 type), others have owned them.  Most do have a 3-speed.  We could carry that discussion to the last CJ-3Bs.

That's vintage Jeep®, right?  Willys and Kaiser were known to use up parts until they were gone, and the MB/M38/M38A1 military parts bin was available.  My '55 CJ-5 with factory front spring "reversed shackles" (anchors at the front of the leaf springs) was clearly the M38A1 design, and many four-wheelers wish they had stayed with it...Some early CJ-5/6 models had the military 2-piece windshield.  Visualize a factory with lots of parts and lower volume production.  It's cost effective to use what you have on hand and left over.  Our marvelous Willys/Kaiser era Jeep 4x4s have sweeping parts interchangeability and were produced at a time when Detroit cars went through distinct chassis and powertrain design changes every few years—and parts management became a nightmare for these popular postwar and muscle era cars.

When I conducted the annual workshops for Mopar at Camp Jeep® we used the expression "most personalized vehicle in the world" to describe Jeep® vehicles.  (I might add, "Most cannibalized, too!")  Original parts, whether factory or in the field, were sometimes truly original, even one-off.  The assembly line needed to keep moving...Your CJ is a rare example of "original"!  The bronze brake pedal arm is suitable for framing...

Moses

[snoopy2x]

Hi Moses,

Well, it took me awhile, but I eventually found someone with an AMC 1971 Universal Parts List, and he was kind enough to scan and email the relevant pages.

Below are those including the brake arm from my Kaiser Jeep 1966 Parts List, as well as the pages from the '71 list.  From what I can tell, it doesn't appear that the brake arm pushrod stud had a separate part number in either case.  Do you notice anything along those lines that I didn't?:

 

1966:

 

1971:

 

[Moses Ludel]

snoopy2x...The relevant part numbers for dual master cylinder models (1967-71) are the last section on the 16th (last) page.  There are two LHD pedal assemblies listed under "split master cylinder systems" with self-adjusting brakes:  P/Ns 945546 and 948181, neither a match for your pedals.  From this 1971 parts manual, it appears that Kaiser/Jeep (emerging AMC perhaps) attempted to consolidate the brake pedal parts with two superseding part numbers .  These two numbers, according to the chart, include the V-6 Jeep CJ models.  There is no distinction or information to determine which number fits a particular master cylinder rod eye size, but we assume that the arms differ around this key feature.

From what we can gather here, the service department or retail customer must compare the two available pedal arms with the existing OEM pedal and the master cylinder type.  This catalog is a very poor referencing system offering little insight.  The model applications are too general, there is nothing distinguishing the two pedal arms, and worse yet, neither of these numbers match the OEM numbers for your 1967 model. 

This takes us full circle to Kaiser/Jeep Corporation's on-the-fly fitment of parts during the 1967 transition to the Federally mandated dual master cylinders.  Your bronze arm and the potpourri part numbers make it clear that existing arms (i.e., part numbers) were used as templates then drilled and fitted with a correctly sized master cylinder rod eye pin.  Apparently, the cast bronze arm got its part number from the template part.  Jeep CJ production numbers were climbing with the introduction of the V-6 engines, demand may have necessitated a hasty outsourcing of brake pedal arms, which points toward the expediency of casting a bronze arm.  There may simply have been a parts shortage in need of a quick solution.

The 1971 catalog is a reference to service replacement parts.  This reveals an effort to make these two LHD dual-master cylinder brake pedal arms fit the range of 1967-71 CJ models, both four-cylinder and V-6 applications, accounting for the two styles/sizes of master cylinder rod eyes and so forth.  Until Kaiser/Jeep got this right, the arms were spin-offs from existing parts stock or in your CJ's case the "collectible" bronze stopgap part that kept the assembly line moving.  Ultimately, meeting sales and production demands were the aims.

Moses