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1980 Chev 20 Other - Chassis, Suspension & Steering
Question: when brakes are applied softly comes to nice stop, but when applied slightly more strongly the rear brakes seem to lock up
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Technican: Hello, Remove the rear brake drums and look at the wheel cylinders for leaks. Rebuild or replace as needed and if the brake shoes are fluid saturated, replace them as well. Have the brake drums turned on a lathe.
Also, while you are in there, look to see if the rear axle seals are leaking. Replace as needed.
Fluid saturated brake shoes tend to grab and lock-up. If the wheel cylinders need attention, rebuild/replace both sides even if only one shows signs of a leak.
You will of course need to bleed the rear brakes when you have repaired the mechanical problem.
Technican: How are you doing here?
Owner: Thanks for the info Im sure you are right, just being a "newby" to trucks I did not realise that I would have to take out the shaft to get the brake drums off, so have not had the time to do this.
Many thanks again
Kevin
Technican: You lost me. If you are thinking about pulling the rear axle shafts to remove the brake drums....time-out!
Where did you hear that info? The drums may be grooved from shoe wear and have a ridge at the outer edge of the drum wear surface. The brake shoe adjustment may have to be backed down to allow the drums to slip past the shoes.
The drums may be rusted to the axle flanges and require a couple good smaks with a ball-peen hammer to free it.
Where have I missed it for you?
Owner: the drums have no holes in them to allow me to adjust the brake shoes, I will go give it a hammer to see if it will come loose, so what you are telling me is that you dont need to take out the axle shaft to remove the drum ie the drum pulls out over the axle flange and is not joined to drum itself.
Please excuse my ignorance
Technican: Correct! To pull rear axles one has to open the differential case. Don't do that.
Holes for shoe adjustment are usually at the bottom of the backing plate behind the drum. Some styles are open, some styles have a removable rubber plug. If you do not see an opening provision on the backing plate there may be a "knock-out" place in the plate or even the brake drum.
There is a "self adjuster" metal arm you will need to lift away from the star adjuster wheel to facilitate backing down the brake shoe adjusted setting.
Let me know what you find,
Owner: Well there is no way the drum/hub will come off with out first undoing the 8 bolts on the axle flange, this part seems to be machined as part of the drum itself, it reminds me of a bus/large truck back wheels where you can see the wheel nuts and the flange nuts as well.
Thanks for your help.
Technican: I'll look for more info. I've missed it here somewhere. I'm not one to quit, hang in there.
Technican: Here is what I've found regarding removal of the rear hub and drum on Chevy trucks depending on the size of the ring gear in the differential. please tell me what you think. I'm believing you can do the brakes once you are comfortable with the hub/drum assembly removal/reinstall.
HUB AND DRUM ASSEMBLY REMOV/REPLACEMENT
REMOV PROCEDURE
TOOLS REQUIRED:
J2222-C WHEEL BEARING NUT WRENCH
1. Raise the vehicle until the wheel is free to rotate.
2. Remove the wheel and tire.
3. Remove the axle shaft:
A. Remove the axle bolts ( if 10.5” Ring gear differential) or; Axle cap bolts if 11” Ring gear differential.
B. Tap the axle shaft flange (or cap) lightly with a soft-faced hammer to loosen the gasket.
C. Grip the rib on the axle shaft with a locking plier and twist to start the axle shaft removal.
D. Remove the axle shaft from the tube.
E. Remove the old RTV or gasket.
F. Clean the hub assembly.
G. Inspect the shaft to see if it is bent.
H. Inspect the shaft splines for chips, burrs, cracking, or excessive wear.
I. Replace any damaged components.
4. Remove the retaining ring.
5. Remove the key.
6. Remove the adjusting nut using the J 2222-C.
7. Remove the washer.
8. Remove the hub and drum.
INSTLATION PROCEDURE:
1. Install the hub and drum on the axle tube.
A. Be sure the bearings and the oil seal are positioned properly.
B. Apply a light coat of high melting point EP bearing lubricant to the contact surfaces and the outside of the axle tube.
2. Install the washer.
3. Place the tang into the keyway.
4. Install the adjusting nut.
5. Adjust the bearing preload.
5 A. For 10.5” Ring gear differential:
1. Tighten the adjusting nut to 50 lb ft while rotating the drum in the opposite direction as the adjusting nut turns.
2. Make sure the inner bearing roller assembly is seated against the spindle shoulder.
3. Adjust the nut as follows:
a. Back off the adjusting nut ¼ turn.
b. Retighten to 13 lb ft.
c. Align the closest adjusting nut slot with the keyway in the axle spindle.
5 B. For 11” Ring gear differential:
1. Tighten the adjusting nut to 50 lb ft while rotating the hub.
2. Make sure the bearing cones are seated and in contact with the spindle shoulder.
3. Back off the adjusting nut and retighten the adjusting nut while rotating the hub.
4. Back off the adjusting nut.
5. Retighten the adjusting nut (while rotating the hub assembly) to 35 lb ft.
6. Back off the adjusting nut 135-150 degrees.
7. Install the lock washer.
8. Bend one tang of the lock washer over a flat of the adjusting nut to a minimum of 30 degrees.
9. Install the outer retaining nut and tighten to a minimum of 65 lb ft.
10. Make the final bearing adjustment 0.001-0.010 in.
11. Bend one tang of the retaining washer over a flat of the outer nut to a minimum of 60 degrees.
12. Add wheel bearing grease in the bearings.
6. Install the axle shaft with a gasket or RTV applied.
a. Be sure the shaft splines mesh into the differential side gear.
b. Align the holes in the axle shaft flange with the holes in the hub.
7. Install the flange bolts and tighten to:
a. On a 10.5” Ring gear differential tighten to 110 lb ft.
b. On a 11” Ring gear differential tighten to 15 lb ft.
8. Install the wheel and tire.
9, Lower the vehicle. Here's How To Get Guaranteed Solutions In Minutes
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