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sondat

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I almost skipped checking this....guess it's good that I did.  Looks like Mike and Wayne have covered it already.  As Mike said, discs are designed to rub normally......but only a small amount.  the square seals in the caliper piston don't really slide when they activated, but "give" a bit.....then when pressure is released, they pull the piston back slightly.  The hit/miss, as Mike said is either a thickness variation in the rotor or some runout.  You can pull the hub off again, remove the rotor.....make sure that the mounting surfaces between the two are clean and smooth.  Most likely, it would be on the hub if the rotors are new.  If that's good, you could swap the rotors from side to side....keeping the hubs one the same side they are now....that would let you know if the "wow" is in the rotor or the hub. I wouldn't bother with that if you find debris on the mounting surface.  

The brackets should have mounted the caliper bracket(not the caliper) centered over the rotor....or really close.  As long as it's not close to rubbing, the caliper will "float" on the pins(which need to be lubricated so that they don't stick) and center themselves.  Things will also change just a bit as you get the pads bedded in.  You'll want to make sure you do that.  There's plenty of info on how to on the internet.  I should get some info posted on my site, too. lol  

 

If you had a mechanic mount everything up and he thinks it's all fine, I wouldn't worry about it unless you still have issues after you've driven the truck for a bit and gotten the pads bedded.  

 

If you post something for me on ratsun and I don't respond, you can always email me directly through the contact page on my site, but you probably already have my email.  I don't view/follow/post much here.....just don't have the time these days.

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Thanks for all the input fellas and I should have PM’d you originally Mike K. I believe the rotors are seated properly and that does make sense on the passenger rotor, must be slightly warped. As for the constant harder drag on the drivers side I will confirm proper seating of rotor and if still a problem will get a professional to look at it. It is my kids breaks after all.

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PM's are better.....I get notifications in my email for them. :)

 

With the wheel on the driver's side and it raised off the ground, you should be able to spin the tire by hand and it should spin fairly easily and continue a bit after you let go.  If you have to use too hands to rotate the tire or it stops immediately, it's too much drag. Typically, the drag is more audible than "feel-able".  It will definitely be more noticeable with the tire off since you'll be trying to spin it by the studs.  Putting the tire on gives you a lot more leverage to spin it and the weight should carry it a bit.  If you still have it apart, maybe some pics looking right down from the edge of the rotor with the caliper out of the way.  Hmmm....just to be clear....everything spins easily when the brackets are on but the calipers are off.....right?  

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On 11/20/2018 at 9:29 PM, sondat said:

Thanks Mike, we have new bushings. Did some reading that new rubber bushings are better than the urathane because it needs some give as not to bend the tension rods, this may have been a 510 issue though not 521’s. So I don’t see a need to mess with freeing up the large nuts if there not required for adjustment, will install and tighten new bushings/washers up to them.

This is a truck issue too with the urethane bushings.  Those nuts......if I remember right.....aren't so much for adjustment of the rod, but for adjustment of the "squish" of the bushings.  I'd have to look it up again.  You can use urethane if you "relieve" them a bit.  I've got pics or vid online somewhere of doing it. 

 

I looked it up. lol

 

Edited by mklotz70
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The hubs/rotors spin freely with the aluminum brackets on, its definitely the pads that are rubbing. And thanks for the link about the tension rods because I was wondering how much to squish the rubber bushings. The nuts tighten down pretty easy and I thought if I tightened to much once the truck is operating over bumps I could see them splitting.

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I wasn't worried about the aluminum brackets hitting/rubbing.....that comment was for the bracket that comes with the caliper...that wraps around the rotor.  The caliper can be removed from the pins/bracket with the two smaller, 14mm headed bolts.  The larger bolts that I provided remain mounted, holding the steel bracket.  If that is centered over the rotor, then it's probably just that your pistons aren't seated all the way back into the caliper.  When the calipers were reassembled after the powdercoating, were the seals "wetted" with brake fluid before the pistons were installed?  If you had the work done, you may not know.  If not, the pistons can stick and be a lot harder to move.  

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I reassemble the callipers after powder coating, I didn’t use any break fluid on the piston but did ensure there was lube on the slides. They seemed to move with a far squeeze by hand. I’ll look into that. 

Edited by sondat
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Just in case never use petroleum greases around brake parts and seals. I think a silicone based lube is preferred.

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Thanks datzenmike, I used the grease that was already on the slides, just spread around to ensure still lubed.

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Onto wiring, ugh. printed off the 9 pages of schematics that were posted on Ratsun, big help. The under dash harness is untouched and in decent shape, the engine bay harness was tampered with a little around the voltage regulator and some of the leads in and out of the fuse block were broken off.

 

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Dash harness

 

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Engine bay harness

 

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Toned out leads to fuse block, added new connectors. Fuse block isn't internally bridged where required so we will bridge externally on the source side of the block.

 

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Some of the loom between the voltage reg and the starter/alternator got quite hot at some point, the leads were melted together. Replaced leads with new wire and connectors.

 

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A little more taping the bundle once the harness is placed in.

 

 

 

Edited by sondat
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Question on the relays, there are 4 relays under the hood. The 3 on the passenger side front of truck to rear are Horn relay, light relay and I don't know what the third relay is for. It has 3 leads to it, a blue with red tracer and 2 light green leads. the 4th relay is on the drivers side and I'm unsure what this relay is for either. The schematic I printed off only shows the 2 relays (light and horn). I checked the wiring diagram in our Haynes manual and it shows a third relay labeled EI, unsure what that stands for and which one it is, drivers side or passenger.

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I think they are for the dual points distributor. The one above coil for the retard points.

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The other is probably the electric choke relay... did the carb have an electric choke? I'm not sure what year that started... .. my 72 had it....

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Ok the relay above coil makes sense it’s for the points. We are changing to electronic distributor with remote matchbox (using 77 Camaro ICM) since we don’t have the remote matchbox. Will have to look up the wiring for the matchbox again, I know it’s on the forum. Will see if that relay is just deleted. As for the electric choke relay, I’ll have to look at the old carb to see if that’s what it had. I think the choke was manual though, I recall the manual nob pull in the cab. We had the hitachi off the L20b rebuilt, so if electric choke on that would the relay come into play then?

Edited by sondat
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Ya so not sure what the 3rd relay passenger side would be for

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3 hours ago, sondat said:

 I think the choke was manual though, I recall the manual nob pull in the cab. We had the hitachi off the L20b rebuilt, so if electric choke on that would the relay come into play then?

 

I had a '71, Manual choke.

 

The L20B carburetor uses an electric choke and an idle cut solenoid. They would need to be working in order for the engine to run. You would only need a switched source of power from the ignition.

 

 

I agree it's the dual points relay. During certain emission conditions the engine is run on a later opening (retarded) set of points. I would definitely not want to run at  less than full advance. Disconnect it and time the engine to be sure it's running on the advance set.

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I used that exact same fuse holder. If you trim the plastic away on the bottom, a thick gauge wire can be soldered across the bottom terminals to jumper it like the factory one. That’s what I did with mine and it cleaned it up significantly. I then trimmed away the ribs on the bottom cover so that it fit, even with the jumpers in place. Just an FYI.

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page BE-5 of the factory 521 manual shows 4 relays.  Lights, horn and E1 and E2....I would guess emissions.  Both E1 and E2 are used for the weird 3rd gear coasting? trigger for the second set of points.  I know it explains it in the manual, but it's been a long time since I've looked at it.  If I remember right, they don't switch between the two sets of points, they simply add the second set which changes the effective dwell.  One relay is involved with the throttle switch, the other is connected to the trans switch and the ACC switch.....which is also mounted near the clutch switch....I think.  

Everyone always wanted to connect the second set of points in parallel with the first so that they could run a lot more amps through it to get a better spark. It doesn't work because the 2nd set is not physically mounted 180 degrees from the 1st....they're off a bit.  Anyway....

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E might be for emissions?

 

There was a temp sender in the cab by driver's left knee, transmission switches for 4rd? and a throttle switch for detecting idle and over 60% to full. The intent was to run retarded under certain conditions to improve the emissions produced by using a second set of points that opened about 4? degrees later. It's just easier to unplug the relay and run full advance at all times.

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All great info Mike, Mike and Mainer311. I will look at bridging under the fuse block, excellent thinking. Last night with harness still laid out on the basement floor I traced/toned out all unknown leads (to me) temporarily labelling, including both relays. The drivers side relay makes sense it is for dual points, it has 1 lead to distributor, 1 to coil and the third goes to pig tail at mid fire wall right beside lead for engine bay light switch. That lead must tie to the unknown relay passenger side because it has 2 leads to mid fire wall also beside engine bay light switch. Passenger side relay has a third lead to multi connector that connects to harness to back of truck, this one is confusing. What reference would emissions relays need to the rear of the truck? Probably the 3rd gear coasting you mentioned Mike K. So we are learning a lot, a little out of our element with vehicle wiring and components but getting there. The switched power you mentioned datzenmike, it would need to feed both electric choke and idle cut solenoid? I’m assuming when turning key on ignition there’s the accessories on position before cranking starter and it would be this first accessories on position that I need to feed to choke and idle cut solenoid?

Edited by sondat
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There was often a switch at back of carburetor. Car L16s were on the firewall at the throttle linkage but the 521 uses a throttle cable so it might be on the carburetor.  

The transmission also has a top gear switch or maybe both 3 and 4th. I assume no retard in the higher gears and sometimes retard when above idle with temps above 50F and not floored? Again just unplug it.  

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If you go into my thread “Just bought a 521” there is a little bit of banter about the “idle cut” solenoid and some of the emissions stuff.

 

Page 21, DanielC posts on August 12th about the “idle cut” which is not actually an idle cut, by rather a large solenoid that also has something to do with emissions. It basically opens an auxiliary port in the side of the carb when you aren’t pressing the throttle, but the engine is being revved higher than idle by coasting downhill. It supplies extra fuel. 

 

The relay on passenger side that leads to rear of truck is indeed for the switch on the trans. That can all be disconnected and removed if that’s what you wish to do. The same for the throttle switch on the side of the carb, and the relay on the driver’s side. A lot of that system used a green wire with a red stripe if I remember right (I could be wrong). A lot of the emissions stuff isn’t shown on the wiring diagrams, so some wire following needs to be done.

Edited by mainer311
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I applaud you for all the work you are doing on his truck, how much of it does your son actually do?  My son's mother says he won't be allowed to drive my 521 because it isn't 'safe'  and not even sure he would be into it when he is old enough to drive anyway.  

 

 

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Safe is a relative term. It isn't safe compared to today's cars. But it doesn't have blinding acceleration and a top speed over 100. It does have a frame though.

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