laotsu Posted June 14, 2013 Report Share Posted June 14, 2013 doing a total overhaul of the brakes on my '71 521 and I ordered all new cylinders, flex lines, and a new master from Rock Auto. well I got two different rear cylinders under the same part # one is a 13/16 and the other is a 3/4 the part description calls them out as 13/16 which is what came off of the truck. I call Rock Auto and they send me a new part right away, gues what... it's another 3/4. So right now they are trying to figure out why they cant seem to send me another right sized cylinder and my truck is out of commission until I get the new parts. my question is, can I just install the 3/4 cylinders? What is the difference between the two? On a side note, what size are the stock hard lines and flare nuts in my truck? I have read elsewhere on here they are 3/8 but the flare nuts are larger more like 7/16 or 11 mm. do either of those sizes seem right? Quote Link to comment
DanielC Posted June 15, 2013 Report Share Posted June 15, 2013 The difference between 13/16 and 3/4 is 1/16. Use the same size on each side, it really does not matter which. 13/16 will give you slightly more pressure on the back wheels, and all other things being equal, would tend to lock up the rear wheels slightly sooner under hard braking. Stock flare nut size is 3/8-24. You measure bolts on the threaded part, not by the side of wrench that fits the hex, which for the stock flare nuts is 7/16. Body fasteners on your 521 are all SAE, from the factory. Engine and transmission bolts are metric. Fluid fittings on the engine are BSP 1 Quote Link to comment
Jayden71 Posted June 15, 2013 Report Share Posted June 15, 2013 I just did rear cylinders on mine. The hex head on mine was 11mm. Simple repair. Except the old 43yr old cylinders did not want to come off at all!!!!! Took a bit of pounding and workin to get them to separate from the backing plate Quote Link to comment
laotsu Posted June 15, 2013 Author Report Share Posted June 15, 2013 I just did rear cylinders on mine. The hex head on mine was 11mm. Simple repair. Except the old 43yr old cylinders did not want to come off at all!!!!! Took a bit of pounding and workin to get them to separate from the backing plate same here, but a drift punch made it all cake. I'm having a bitch of a time with the hard lines, I will definitely have to replace the two fronts and might just go for doing all the hard lines. Quote Link to comment
laotsu Posted June 15, 2013 Author Report Share Posted June 15, 2013 Body fasteners on your 521 are all SAE, from the factory. Engine and transmission bolts are metric. Fluid fittings on the engine are BSP Really? I thought the whole truck was SAE. Good to know. Quote Link to comment
laotsu Posted June 15, 2013 Author Report Share Posted June 15, 2013 oh and thanks to my ratty brethren for the quick info Quote Link to comment
Jayden71 Posted June 15, 2013 Report Share Posted June 15, 2013 same here, but a drift punch made it all cake. I'm having a bitch of a time with the hard lines, I will definitely have to replace the two fronts and might just go for doing all the hard lines. I used my 1/2 inch drive 2ft long extension through the cylinder and worked it back and forth. Took a while but it worked. I got lucky with the hard lines. Mine are all in good shape not stripped Quote Link to comment
laotsu Posted June 15, 2013 Author Report Share Posted June 15, 2013 I got lucky with the hard lines. Mine are all in good shape not stripped mine weren't stripped, until I got to 'em, just fucking frozen. PB blaster for two days and a quality pair of vise grips finally freed 'em. Heat and WD40 did nothing. Quote Link to comment
oldskoolvws Posted June 15, 2013 Report Share Posted June 15, 2013 Kroil is king in the help me get rusty shit off world. I'm not looking forward to seeing how mine are.... Quote Link to comment
laotsu Posted June 15, 2013 Author Report Share Posted June 15, 2013 never heard of Kroil Quote Link to comment
oldskoolvws Posted June 15, 2013 Report Share Posted June 15, 2013 Only one thing I know of that WAS better, Evergreen. Haven't seen it in years and years. Kroil is $$$, but it is your bestest friend ever. I buy it in the gallon. Lasted over 3 years for me now ans still have about 1/3 left. http://www.eastwood.com/aerokroil-16-5-oz-aerosol.html Quote Link to comment
Laecaon Posted June 15, 2013 Report Share Posted June 15, 2013 I just did rear cylinders on mine. The hex head on mine was 11mm. Simple repair.7/16th is just a hair larger than 11mm. Most of the time 11mm will fit on a 7/16th hex, but will be very snug. At work the 11mm socket will stick to the bolt, than come off with the ratchet. 7/16ths is a better fit. Quote Link to comment
DanielC Posted June 15, 2013 Report Share Posted June 15, 2013 For penetrating oil, I use 50/50 acetone, and ATF. Quote Link to comment
Jayden71 Posted June 15, 2013 Report Share Posted June 15, 2013 7/16th is just a hair larger than 11mm. Most of the time 11mm will fit on a 7/16th hex, but will be very snug. At work the 11mm socket will stick to the bolt, than come off with the ratchet. 7/16ths is a better fit. didn't have any trouble whatsoever. Used a flair wrench and they twisted right off. Didn't even have to use any penetrating oil Quote Link to comment
laotsu Posted June 15, 2013 Author Report Share Posted June 15, 2013 didn't have any trouble whatsoever. Used a flair wrench and they twisted right off. Didn't even have to use any penetrating oil Well lah tee fuckin dah! Aren't we Mr. High And Mighty? " I can get flare nuts off with nooooo problem." :sneaky: <_< :angry: :fu: Quote Link to comment
Jayden71 Posted June 15, 2013 Report Share Posted June 15, 2013 Well lah tee fuckin dah! Aren't we Mr. High And Mighty? " I can get flare nuts off with nooooo problem." :sneaky: <_< :angry: :fu: Someone needs a diaper change and a nap Quote Link to comment
laotsu Posted June 16, 2013 Author Report Share Posted June 16, 2013 Someone needs a diaper change and a nap what, no cookie? Quote Link to comment
banzai510(hainz) Posted June 16, 2013 Report Share Posted June 16, 2013 DOING BRAKES ALSO BUY A SET OF FLAIRBUT WRENCHES. buying rear wheel cylinder I have a mistached set they both work fine wasnt going to wait for the correct one or was out of stock at NAPA at the ime or NLA Quote Link to comment
laotsu Posted June 16, 2013 Author Report Share Posted June 16, 2013 DOING BRAKES ALSO BUY A SET OF FLAIRBUT WRENCHES. are flairbut wrenches what you get after a ten jalapeno taco? :rofl: Quote Link to comment
laotsu Posted June 16, 2013 Author Report Share Posted June 16, 2013 (edited) what sort of flares are stock on the 521? Double? answered my own question with google. Double. Edited June 16, 2013 by laotsu Quote Link to comment
DanielC Posted June 16, 2013 Report Share Posted June 16, 2013 The 521 uses a very common 3/16 steel brake line, with the 3/8-24 flare nuts, and like you found out, a double flare. Available at just about any auto parts store. Quote Link to comment
laotsu Posted June 16, 2013 Author Report Share Posted June 16, 2013 now what are the stock lines made out of? Velveeta, swiss, or cheddar? Quote Link to comment
Jayden71 Posted June 17, 2013 Report Share Posted June 17, 2013 what no cookie? you'll spoil your dinner Quote Link to comment
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