I am about to service the rear brakes on my truck, since the left rear wheel cylinder is sticking... I understand that to complete the job I would need the following:
1- Rear Wheel cylinders: /
2- Rear Hub Seals:/
3- High temp Wheel Bearing grease:/
4-DOT 3 brake fluid:/
5- Gasket material for rear diff cover:/
6- 80W/90W diff. Oil: Any specific type needed?
7- Gasket sealant: Permatex Ultra Grey/
As for any other brake parts, I have not been able to obtain any return springs or additional hardware... I have never done these before (Huck brakes) so I don't know if a special tool is required... Please see photo. Additionally, one very important detail, what is the required thickness of the rear brake shoe linings? Unless you know of anyone selling good quality rear brake shoes... Thank you.
That tool is to compress the brake shoe link pin spring so you can remove/replace the pin lock. Makes it an easy job but not necessary. Remove the locks carefully because you want to reuse them. They are made with soft malleable metal and bend easily, but also break. They are available from some vendors and also on Ebay occasionally.
If you need to reline the shoes find a brake specialty shop and they will take your shoes, media blast and paint them and replace the lining. Be sure to ask them to use the softest lining material they have. If you replace the linings you should have the shoes arced to the individual drum. To do this they would need the drum, as well, and don't mix up the shoes with another drum.
The bearings are lubricated by the diff. oil. It is a good idea to use wheel bearing grease upon assembly so they are not running dry before the diff. oil sloshes out to the end of the axle housing. I lightly lube them and I don't think high temp is necessary.
Ideally, you would have, or make, an axle nut adjusting tool. You can use a punch to loosen and remove the lock nut and axle nut but on reassembly you want to be able to set the bearing preload correctly and that is difficult to do carefully with a punch.
If your seal is not leaking, and looks intact I would leave it alone. Be sure the area of the spindle it rides on is not corroded. If it is corroded I would try to reduce pitting with emery paper and then replace the seal with a new modern one.
Good luck, Kent
Last edited by Lightholder's Dad; 05/22/201910:26 PM.
Thank you for your reply...As for the tool, are you referring to the springs at 3 and 9 o'clock or the lower anchor spring? Would you have the original GM numbers on the locks? Thank you for the tip regarding the brake shoes, I know that the devil is in the details...
As for the rear bearings, I had no idea that they were lubricated by the differential oil. So there is no inner axle seal on these trucks then... Interesting, I thought they were set up like the old WWII jeeps...
Ummm.... As for this axle nut adjusting (tool) is there a basic parameter to start with, such as, go all the way tight until the bearing locks up and the back off 1/4 turn or so? Someone must know what the starting point is...
I have replacement seals, I was going to replace them regardless since I have to repack the bearings with grease, but if not I save myself $$$ by not replacing them...Lets hope that the spindles are in good shape and free of rust...
Philippe, You need to access a shop manual at the Old Chevy Manual site. Here is a link that answers how to adjust the bearing preload from the 1941 car and truck manual. http://chevy.oldcarmanualproject.com/shop/1941/41csm096.htm So basically, you tighten the axle nut and back off 45 degrees (one eighth turn).
The tool is helpful for both the shoe and anchor pins. You could use large pliers or vice grip adjusted to compress the springs. I have done it without that funky tool but since I have 3 trucks with Huck brakes I thought I would treat myself and get one. It is out on loan right now to a friend who is working on a 1940 Chevy car. PS I don't have the GM numbers for the locks but if you look at the Old Chevy Manual Project site you can find parts books that will have that. Kent
Last edited by Lightholder's Dad; 05/23/20192:25 AM. Reason: post script
I will have a look at the manual, thank you..Must say this big stuff can be a little intimidating...Hopefully there are no more special tools needed... I just bought the tool on Ebay. There is no sense to fight with pliers or screwdrivers and risking damaging something else on account of not having the right tool... $25.00 shipped to me-could not pass that up. I hope it will make my life easier... I will try to find the numbers for the looks with the link you provided.
If this is a full floater hub type rearend, you don't pack the bearings with grease. When they have been all apart and completely cleaned of grease, you would need to put a little grease on them until the rearend fluid works it's way in.
There is a seal inside the hub. It rides on the support tube. You will need new metal gaskets to install between the axle end and the hub. I would suggest using RTV on the rear cover. If this rearend is of the hypoid design then the fluid should be hypoid high pressure lubricant.
As I said, I am used to the WWII jeep full floating axles and they get packed with grease... As for new metal gaskets you mean 2 aluminum gaskets? What kind of RTV do you recommend? why are you opposed to having a gasket in there?
Back to the rear end lubricant question, I understand it should be a Hypoid SAE 90 to 140W/160W (for extreme use) GL-1 mineral based which it seems impossible to find... Just by looking around I have found the following...
1- NAPA 65-201 (90W) GL-1, Mineral based. NON EP lubricant = Not Hypoid lubricant... So it is out. This would be good for the crash box and driveshaft***
2- NAPA 75-210 (80W-85/90) GL 3, 4, 5.. Blend? EP = Hypoid lubricant, not mineral based as I understand... Out.
3- PARTS MASTER # 5831 (80W-90W) GL-5, MT-1.. Blend? EP = Hypoid lubricant, not mineral based as I understand... Out.
4- VALVOLINE # VV825 (85W-140W) GL-5, MT-1.. Blend? EP = Hypoid lubricant, not mineral based as I understand... Out.
5- LIQUI-MOLY # 20016 (85W-90W) GL1- GL-4, Mineral based. NON EP lubricant as I understand, so it is Out as well...
As you can see, it is a challenge to find the correct oil...Maybe someone can make specific recommendations, since oil is not oil and there are many brands out there that may work but also cause other problems because they're really not suited for older machines...
*** Back to the driveshaft lubrication, it is specified to use the same oil as in the gear box... The driveshaft tube has grease fittings, how to you fill it with (1 pound) of 90W transmission oil? Remove the grease fitting and use an oil can?? Thanks you.
Just found 2 possible candidates for the rear differential oil that would appear to meet the required specifications...
1- Mobil 600 XP Series (EP) mineral based oil suitable for spur, helical and beveled gears available in 90 W # 103542 and 140 W #103495. Lastly should I go with the 140 W if I am in a hot climate even though I will not be working the truck hard?
When they came out with the hypoid design, they also made s new lubricant for it. the gear design literally squeezes the lubricant out from between the teeth so that is the stuff you want to use.
I would guess it would take a while to find a paper gasket for your 1 1/2 ton rear cover. RTV made for auto use will give you a more modern complete seal that will never leak.
Yes the axle gaskets are aluminum. You won't find new pins and you may not find the pin locks. The springs would be a rare find too. The best idea is to be as careful as you can taking it apart and only replace what is broken. Most wheel cylinders can be rebuilt. Mine were pitted so I had them done by a professional shop who installed stainless sleeves.
For the rear brake cylinders, try NAPA UP 3677. I found them to be identical to the rear cylinders in my '37 SD.
The rear wheel seal is a SKF 31870. If you need new locking plate for the axle nuts, the part number GM 473629 is a current number and is available from GMPartsDirect.com
Jim
Last edited by neonman; 05/23/20196:47 PM.
1935 QD 1.5 ton stake bed 1937 SD 1.5 ton stake bed 1944 MS 1.5 ton stake bed 1946 PW 2 ton stake bed
Thank you very much for the additional parts information, one less from the list.. On the cylinders, Raybestos WC3677 is the same thing and cheaper w/Amazon for $40.59 each. As for the oil seals, National 6358 $6.58 each with them also. Don't pay $40.00 each per seal as I did. Will reserve my comments for the abusive pricing. I am learning at a very high cost here...
Thank you very much for the information and photos, will contact them tomorrow for pricing and check Ebay... I have also updated my list on top of this thread. In the meantime, I hope I can come up with the other part numbers...
Phillippe, Why are you looking for all the those parts? Do you not have any parts to start with? To rebuild worn out brakes you will re-use the vast majority of the parts. If you are lucky you may not even need new cylinders, just the rubber cups. Perhaps I don't understand your situation or what you are trying to do.
Regarding the lubricant, any multiviscosity hypoid gear oil will work, including several you listed above as "out".
Enlighten me as to what you are doing, Kent
Last edited by Lightholder's Dad; 05/24/20196:32 PM.
Maybe I am overreacting a little since I never have dealt with Huck brakes before and I am expecting that most everything is beyond being usable due to its age... I have 2 new cylinders and seals. I suppose it is reasonable that I could re-use the outer nut lock and just get new axle gaskets and be Ok. Be Ok with all the pins, locks and springs... Just run them through a wire wheel and paint them with red oxide primer and assemble with never seize... Am I over simplifying it now? That would be the best case scenario, and I am hoping for that... On the other hand, I was trying to do some homework and find the part numbers for most of the stuff that I imagine would wear out, rust, or be a problem over time...That's where I'm at. Tomorrow I will start the disassembly process and will know for sure in which direction to go. Do you have any suggestions to avoid any pitfalls?
When they came out with the hypoid design, they also made s new lubricant for it. the gear design literally squeezes the lubricant out from between the teeth so that is the stuff you want to use.
I would guess it would take a while to find a paper gasket for your 1 1/2 ton rear cover. RTV made for auto use will give you a more modern complete seal that will never leak.
Yes the axle gaskets are aluminum. You won't find new pins and you may not find the pin locks. The springs would be a rare find too. The best idea is to be as careful as you can taking it apart and only replace what is broken. Most wheel cylinders can be rebuilt. Mine were pitted so I had them done by a professional shop who installed stainless sleeves.
Hello there,
I understand that the Hypoid lubricant needed for the rear end is supposed to be mineral based...The only one that I have found that is Hypoid and (EP) is the Mobil XP 600. The others seem to be incompatible since they lack either one of the requirements... I Imagine it is acceptable to use RTV for the rear cover, but which specific brand or type really works? As for the axle gaskets, GM 2310537, anything found so far is made of a fibrous material similar to most modern gaskets...If you can share photos of originals it would be great...
Philippe, Unless your brakes and axles have been buried in mud for a long time, I think you will find the hardware will be remarkably well preserved. Study the manuals so you don't break something disassembling the items and then wire wheel or media blast to clean them up. Since you live in FL you may want to paint them but some uncoated primers actually attract moisture like a sponge so be careful. Clear coat with spray can lacquer works pretty well for the protected area you are working in.
I may be wrong but I think you are mistaken regarding lubricant. Original instructions for the transmission and differentials of the older trucks noted that mineral oil lubricant was required. This is not correct for hypoid differentials and any modern hypoid gear lubricant should work. I hope that someone will correct me if I am wrong.
I would use Permatex "Right Stuff" to seal the axle caps. I don't think the gaskets you linked are the correct ones. Don't you have 10 studs on your rear axles? The Right Stuff is a rubber compound that works great without oil seepage and no gasket is required. It is somewhat adhesive and holds up much better than RTV. The lock pins you linked are what you are looking for. You have to bend them slightly to remove them but if you are careful and the previous mechanic has not ruined them already you may not need new ones.
Thank you for your reply and advice regarding the hardware... I will paint instead of prime not to get in trouble. As for the lubricants, things can be confusing since much has changed in 80 years and what was available then is not available now... Can we start by saying that the rear end axle and bearings needs:
which seems to have both characteristics... There is also a SAE140W if better suited for the rear end and bearings in a hot climate. I'm just trying to select the right oil for the truck which it is not easy...
Getting to the rest here, my axles are held by 8 bolts, but the hubs have 10 bolts... I will give the "Right Stuff" a try since it sound pretty good... As for the lock pins, I have a feeling they're going to be tricky... The small shop manual I have for 1938 (Cars and trucks) doesn't specifically tell you how to remove them at all...
I finally took the brakes apart today and the biggest problem seems to be the frozen adjusters on the wheel cylinders causing a problem with one shoe getting hot on one side... I snapped one of them while trying to turn it. It is going to be a joy to pin the new one in on the plate... The one that came undone was braced, the others are pinned with a hammer and punch...
Don't know what the proper procedure for securing them is... The shoes are actually fine...
I have a few other questions and nervous about breaking something else... Is it better to try to remove the entire backing plate to work on the broken adjuster?
While I have this apart it is probably a good idea to replace the hub seals, any tricks to getting them out? I am trying not to mess with anything else.. The bearings have plenty of grease and oil, I don't want to touch them to avoid any problems...
Lastly, if anyone can help with part numbers for:
1- The special hollow bolt that goes on the brake junction block that mount to the wheel cylinders and the copper washers..
If your brake system is like I think it is...are the rear adjusters a 5/8 bolt that rotates a little disk that moves the wheel cylinder screw in/out? Pictures would help. If so, the adjusters can be sourced. The disk portion is swaged onto the bolt. Careful mig welding will accomplish the task, just don't get any heat on the tensioning spring behind it. It can be done while on the vehicle but it sounds as though you nearly have the backing plates off at this point.
1) the banjo bolt and copper washers are still common items found in a true auto parts store or online if you only have the big box auto parts stores. The bolt can be reused if still serviceable. 2) the terne plate "gasket" should be used as the soft tin helps to cushion torque transfer while sealing. Get a good part number and go on the hunt. 3) if the axle shaft to hub lock plates are not present or impossible to find, you can run without them. I use good new locknuts and a little bit of the soft setting locktite...and frequently check them. I had some of the lock plates you are looking for, so they do show up once in a while.
Hello Paul, you're right about the description of the system...I have located the adjuster (Pinion kit) GM 3705288. I am considering MIG or TIG as soon as I remove the backing plate...Unfortunately there are no real auto parts stores near me, so that is that is why finding original factory numbers is so important to locate the parts that I need... I have a few photos of the stuff as requested...
Curiously enough, the wheel cylinder caps are marked FC 4665 "Ind. Arg." (Industria Argentina/Made in Argentina) and the body is marked FD 3677 C3...It is the second component on the truck marked that way... The front grill is marked Gavila, M. R. Industria Argentina... Sorry to get off topic, but thought it was odd and interesting.
Getting the factory part numbers is crucial in sourcing parts for vehicles so old, it is especially so with larger trucks as there is little aftermarket support. Securing a parts manual should be high on your wish list. I hope you have found a brake spring pliers as those springs are quite difficult to install without one...unless you have Popeye like forearms. The wheel cylinders look to be relatively new as the first time I noticed Argentinean brake parts to come on the market was only about 5-6 years ago. Hopefully chemists in Argentina are better at reproducing rubber components than those in China. The axle to hub terne plate seal on your truck may be the same as used on military trucks of similar age. Give me some dimensions and I can compare. If so, I have very reasonably priced sources.
If you had the chance to buy some of the main brake spring then that would be good for your stash. They sometimes are brittle and break when working with them. I think the biggest hurdle for you is the condition of the drums. Hopefully you will be lucky.
I once bought an NOS gasket set for my transmission. I dumped them out from the envelope on my bench and they shattered!
Trying to compile most factory part numbers that may be needed for the job... The measurements for the outer lock plate are also provided below, as well as an updated list and a better photo of the parts breakdown. If anyone with a parts book can fill in the missing blanks it would be great...Thank you.
1- Rear Wheel cylinders: GM 5300885 Casting #5300892. Raybestos WC 3677 or NAPA UP 3677
