Tight Disc Brakes

[americanmusc1e]

I just finished putting disc brakes on my '70 pickup,
the truck has crossdrilled rotors (SUM-DSEP-5516L and SUM-DSEP-5516R from Summitracing) and stock calipers i bought the rotors and calipers slightly used off of e-bay and the brake pads came with them..........I put the calipers on there this morning and the pistons are all the way back in the calipers but the brakes are really tight, I put the wheel on it and i can barely turn it.........is this normal?????

thanks in advance

[cdowns]

did you use a tool or cclamp to make sure the pistons are all the way in ?

[my67chevytruck]

sounds like you have the Rotors on way too tight then. If you remove the caliper is it still very hard to spin? I cant recall the torque spec for the spindle nut, but they are not much.

[americanmusc1e]

Originally Posted by my67chevytruck

sounds like you have the Rotors on way too tight then. If you remove the caliper is it still very hard to spin? I cant recall the torque spec for the spindle nut, but they are not much.

the rotors turn freely without the calipers on

[americanmusc1e]

Originally Posted by cdowns

did you use a tool or cclamp to make sure the pistons are all the way in ?

pistons are all the way in

[chevy_mike]

I don't know what your setup is but I do recall there being a 1" rotor and a 1.25" rotor. I don't know if the calipers are any different but if they are, do you have the right calipers?

[cparman]

Maybe before taking it back apart loosen the two nuts that hold the master cylinder to the booster or firewall. loosen them about half way. if the wheels will turn then your problem is that the rod in the booster is too long.

what happens if you open the bleeder screw on either wheel?
If the wheel becomes easier to turn, you have a hydraulic problem. possible collapsed hose??

If the wheel is still hard to turn, like someone else said it is at the wheel.

[BluTrukker]

Make sure the pins that the caliper rides on are not rusty inside the boots. I had it happen to me, they would slide a little, but not enough.

[Twisted78SS]

You mentioned these are on your 70? What did the Spindles and disc setup come from? Since there is a difference from the 71 and 72, it would possibly help to diagnose your issue.

Speaking from the 72 spindles I just put together, I know, the calipers are the same. You said you bought these used, I would suggest making sure the cups are all the way in. If there is any corrosion on the cups it could be that they did not fully compress. I have seen some pretty funky cups that at first glance appeared fine on the outside. Beyond that, it is possible the pads are the wrong one's. also as mentioned be sure to spin the rotor with the caliper/pads out of the way to ensure is spins freely.

[americanmusc1e]

the pads on the outside are rubbing and the inside pads have a small gap between them, the spindles are McGaughy's stock height(http://store.summitracing.com/partde...5&autoview=sku) and they are conversion spindles designed for a 1970, the calipers i got off e-bay i think they are from a '72

[Twisted78SS]

Well, that is odd, The caliper for C10s are the same from 71-78, so they should not be the culprit. Back to the pads maybe? Any chance to get some close up shots?

Anyone else have an idea?

[americanmusc1e]

here's a pic, hope it helps


if you want a picture of something specific let me know

[my67chevytruck]

hmmm, it looks correct. how bad is it rubbing?

[americanmusc1e]

Originally Posted by my67chevytruck

hmmm, it looks correct. how bad is it rubbing?

when i put the wheel on it i can barely turn it!!!!!!--it's tight

[Twisted78SS]

I agree, it appears to be correct. Are the rotors freshly turned? if not do they have any ridges on them at all? It could be new pads + rough rotor surface equals stiff to turn by hand.

Did you try moving the truck under its own weight? and how did it feel.. Might be nothing to worry about one you get the brakes operating a few times. The caliper and pads will find their center. I say give it a drive and see how things go.

Let us know..

[americanmusc1e]

Originally Posted by Twisted78SS

I agree, it appears to be correct. Are the rotors freshly turned? if not do they have any ridges on them at all? It could be new pads + rough rotor surface equals stiff to turn by hand.

Did you try moving the truck under its own weight? and how did it feel.. Might be nothing to worry about one you get the brakes operating a few times. The caliper and pads will find their center. I say give it a drive and see how things go.

Let us know..

will do tomorrow

[chevy_mike]

So, looking at your picture, I circled in yellow the slider pin. Do you have the metal sleeve that goes on the pin and slide into the caliper (with the o-ring inside)?

Here is a hardware kit and you should have a large o-ring in the inside mounting hole and the small o-ring in the outside mouting hole, the sleeve on the slider pin and this all bolted to the spindle. It looks like you are missing parts.

Hardware kit (BTW, you should have four small, four large o-rings and four sleeves, the pic is missing a large o-ring)

[Sinisterspeed]

One other thing it could be. With the stock Prop valve the residual pressure in the lines for drum breaks is 10lbs where Disk breaks are only 2lbs. There are a couple ways of fixing this which I could elaborate on if need be. But if you changed the fronts to disk without changing the stock proportioning valve that was for a drum/drum set up, I would be looking there.