Need new wheel cylinder , which size ?

[badmix]

1984 k5 , 305 cid , 700r, 10b rear.

Have a leaky wheel cylinder, but everywhere lists 2-3 diff sizes;

11 5/32 x 2 3/4

11 x 2

15/16 bore

 

[diesel4me]

You can measure the drum diameter & width to determine which brake shoes it has (or just the width of the shoes themselves)--or measure the bore of the old leaky one,they are only 1/16" difference in bore sizes and the bigger shoes take the smaller bore size according to the listing I looked up..

It's best to match the old cylinder bore up,because if you put two that aren't matched you'll get a pull to one side..and someone may have replaced the rear end in the past too,so the "correct" listing going by the vehicle may not net the right parts..

 

[badmix]

Yea, i gonna buy both sizes from napa and match whst ive got and return one i dont use

 

[badmix]

Well, got wheel cylinder installed, sprayed PB Blaster on back plate.

Bolts and brake line came right out.

Now for the weird part, i only removed the top springs by the shoes, i did not take the shoes out nor mess with anything else, i did hose down the area with brake cleaner. The install went well but once i out it all together and drove it, the patking brake went to the floor it seems, its grabbing but not crazy like it did before, i didnt touch anything related to parking brake.

I adjusted it at the pivot point on frame rail, its better ( will keep truck from moving when in drive )

My only thought is that it was actually gunked up and bound up before and now its “normal” , ive never changed rear brakes in forever, they look good, and truck stops well, and had good peddle too

 

[diesel4me]

I replaced a wheel cylinder in my truck a few months ago (Autozone ones I replaced about 2 years ago,one leaked after 4000 miles they refused to warranty it,and the new one I had to buy only has a 90 day warranty,costed $4 more too!..)..

When I did mine,I used the same method,I just removed the top springs and was able to get the cylinder in after some fiddling,had to pry the shoes away a bit before it would go into place--I hate dealing with drum brakes ,and avoid fully removing them to do a wheel cylinder,I always try to cheat that way first!.
--that "strut bar" under the cylinder with the slots on each side,that goes over both shoes was a pain,it kept wanting to drop out of position..

If that bar didn't get put back right,it might have caused the E-brake issue..but so could several other things,like if you had to back off the adjustment at the star wheel to get the drum off,and didn't re-adjust the brakes after the drum was back on--or maybe the old cylinder was seized and held the shoes out further,now with the new one in,they retracted in all the way..those little "feet" that stick out of the wheel cylinder have to be in correctly over the shoes also..

You may need to adjust the star wheel until the wheel is hard to turn,then back it off a few clicks till it spins freely again..then if the E-brake still is too low,you will have to adjust the cable at the center of the truck where the threaded rod on it is..

 

[badmix]

Yea i pulled brake drum earlier and double checked, parking brake hardware is whereits all suppose to be. Im guessing it was all bound up and now its freed up.

 

[badmix]

This is where locker in back an issue, lol, i cant turn one side only, lol

 

[badmix]

Ran into an issue today - got drivers side wheel cylinder from napa # 37080 , same part number for pass side but when i went to install it, its too long. This one is 3 3/8” long and oem is 3” , there isnt room for the napa one.

The other part # for napa is 37048 but that one didnt fit pass side.

Can it be both sides are diff ?

 

[badmix]

Looking at pics both on napa and rock auto,someone put wrong part on box

 

[diesel4me]

Boxed wrong would be my guess--there may be "slight" variations in aftermarket cylinders VS originals,but they would have to be very minor in order for them to fit and work as intended..

I bet someone else bought "both size possibilities" and intended to return the "wrong" one,but mixed up the boxes they came in perhaps,or it was a goof as the packaging part of the manufacturer ..

Unfortunately it is not uncommon to get parts that aren't in the correct boxes nowadays..we used to have troubles with GM small block water pumps in the 70's,they all "look" identical,until you find out there is several minor differences among them that wont allow the belts to align,or the P/S pump bracket to bolt up properly..