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; Wed May 22 2019 10:26 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; Thu May 23 2019 02:25 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?