Brake question

After some seven years, I finally got the restoration finished on my '75 GT and shipped from Alabama to Colorado.

All appears fine and will haul ass with the engine rebuild - thanks to many on the site.

I do see that the temperature gauge is not working but I should be able to track that down. There is also oil all over the intake manifold which will require some investigation.

Now the brakes - disk brakes all the way around - work fine but I have to push the pedal way too far before they grab. The master cylinder is full. Any idea why this? Need to bleed? Anything else?

 

Could be you need a different M/C pushrod. When I converted mine to discs, the supplier told me to re-use my original.

 

No, these are Lincoln rear disk brakes converted years ago and always worked will with the original pushrod.

 

Four-wheel disc brakes have a softer feel and slightly longer pedal travel. I struggled for years with it when test-driving a vehicle with it. So, as long as the car reasonably stops and not leaking fluid, I'd say it has no problem. As far as the oil, check that the PCV is working, and that you don't have a problem with high crankcase pressure. Also ensure the valve covers are properly snugged.

 

Refresh my memory Clark. Are the brakes using a hydro booster or the original vacume operated booster ? If vacume operated, remember that that head and cam shaft combination Mike Osburn combined produces a lower overall vacume number than the original engine did. Your cam shaft is not super radical but it has enough overlap to be felt in the brakes. Might want to re-torque the intake bolts and valve covers even though the engine was run on the stand at least five hours. Master cylinder could possibly be leaking internally but for now I vote lower vacume is the culprit.

 

Thanks Hillbilly. The brakes are solid when engaged. The brake pedal travel to engagement was alarming. And no, 5.0, the parking brake was never used that much but I will try your suggestion. Hmmm, hydro booster would be a nice upgrade.

 

Was anything brake related removed during the restoration? Could possibly the master been removed or replaced? If it's got THAT much pedal travel I'd look at the pushrod/booster distance.

 

Yeah, the hydro boosters hide any low vacume issues. Try 5.0's suggestion too but I don't see any way the rear auto adjusters could retract from good pad clearance to a loose condition on their own. If you have ever replaced the rear pads you will know how hard it is to screw the rear pistons back into the calipers to make room for new pads. Did the kids replace the brake pads ? If they did they may have failed to cycle the parking brake enough to take the slack out. Wish Mike was still living, he had a phenominal memory of every detail on all the engines he built. Did he hit the mark for you on that engine's performance ?

 

Hillbilly - Yes, Runs like a scalded ape! Too bad Mike is gone. I would like to have met him.

But no. To my knowledge the brakes were never touched in any of the restoration work.

 

Thought of something else to check on the brakes. Probably not the problem but have someone clamp down on the brakes while you observe the flex hoses. Have seen a few that swelled up like a football under pressure.

 

Good point! Also wonder if this could be a master cylinder problem. This just seems very odd. Brake pedal is solid, no spongyness but at a good half travel to the floor.

 

I played with the truck some more today. I'm thinking I just need to bleed the brakes. Can this happen if the truck has mostly set for about 7 years? I find, with the engine off, I can bring up the brake pedal solid after a few manual pumps just like a brake system with air in the lines. 'Course it wouldn't hurt to flush new fluid through those brake lines after 12 years.

Also, I found the intake manifold and even the air cleaner covered in oil - red oil - automatic transmission fluid no doubt. The C6 has been replaced. Any chance it could have puked fluid out the fill tube if initially overfilled?

But my gawd what a mess. The under hood wiring now looks like spaghetti! There are connector hooked to nothing. Wires connected to nothing. Wires strung everywhere. What a mess. Still, it runs. Whoo ha!

 

Only two sources of red oil, trans. and steering. Both could puke if overfilled. Steering would be more likely if over filled and someone tried turning the steering wheel with the engine not running. Shipper maybe ? Trans. is more likely to puke out the case vent once it is at running temperature if overfilled. There should be a tiny number of wires needed to run that engine if the MSD all in one distributor is still in it. One oil and one coolant sensor, electric choke, a/c compressor clutch and throttle kicker, distributor feed and tack, and a healthy ground strap from the engine to the firewall. Ignoring the alternator harness as it should still be in the original separate bundle and use the stator wire for the electric choke. I bet you get rid of the extra spaghetti quickly.
Hindsight is 20/20, wish I had confiscated the dyno figures from Mike's files but who knew he would pass so quickly. They were very impressive. How is that engine reacting to higher altitude ? Idle quality still good without being too rich ?

 

My advice, bleed the brakes. As old as the system is, you might also need to replace the master cylinder (because it has been running in the same spot for some time.)

 

Engine runs great BUT knowing the altitude differences, I had it fuel injected with a Holley Sniper conversion.

What? Replace the master cylinder after only 10 years?

 

I had to do that on Babe. Brake fluid absorbs water out of the air, and once it's in the fluid, it not only reduces the fluid's ability to resist boiling, but it corrodes surfaces the fluids touch. Fluid is supposed to be changed once a year if the vehicle sits for long periods of time. And, when I did the MC, I also had to replace the prop valve, for the same reason...interior corrosion.

 

That's the reason I spend for silicone based fluid, doesn't absorbe moisture. I have some units going on over twenty years using silicone brake fluid with no parts failures. Only drawback is you have to remove all traces of the old fluid to get long play results. Dry nitrogen seems to be the best thing to remove and clean out the old fluid in brake systems.

 

Right, I have heard of that, but how many people have the lucre for dry nitrogen? If someone has access to a shop that has a nitrogen concentrator for tire inflation, I suppose, but you still have to have fittings to be able to blow out lines and parts.

 

I was finally able to bleed the rear disk brakes (1976 Lincoln Continental units). However, I noticed afterwards that all the extracted brake fluid came from the front (smaller) master cylinder reservoir. Should that be correct?