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In Appreciation of John Hinckley -
Re: Dual master cylinder bench bleed
My wife and I did the plant tour at Bowling Green in May. After the car is fully assembled, they go through an area where all the fluids are added. You can't see what goes on, as the area is semi-blocked off and has warning signs for inflammable materials, etc., but brake fluid, coolant, engine oil (all 9.8 gallons of Mobil 1), and 4 gallons of gasoline are added.
I asked how the brakes were bleed as this whole process took all of about 5 minutes. Our tour guide said they attach to the master cylinder and evacuate all the air out. Then they add the fluid to the evacuated system. I would think they would also do a pressure decay test to the evacuated system to check for leaks, but I did not ask that question.
Very interesting experience. I would highly recommend it. The public tour is only $10 - almost 3 hours long.
-Dan-Comment
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Re: Dual master cylinder bench bleed
Very interesting! Would like to see how all the hoses etc are hooked up to fill all the systems. I imagine one or two guys hooking up a lot of hoses and then just turning on one switch and like magic all is complete.Comment
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Re: Dual master cylinder bench bleed
All under hood work is done beforehand. Engine compartment work is completed before the front fenders are installed. Easier access that way and no chance of dinging up the paint.
Throughout the entire build the line moves at a steady pace. Each work station has 3 minutes to do their job. If they need to build more or less cars in a day, they work more or less hours. The line speed does not change. They were building 168 cars the day I was there.
The engine compartment work involves workers on both sides of the car, and may have been a double work station as it seemed to take more than 3 minutes. Don't forget the line is continually moving.
I think the fluid station was much the same, except you could not see what was happening. I believe that all under hood work is complete before the car makes its way to the fluid area. All they do in that area is add fluids. I visualize one person doing the brakes, and the next person doing coolant or gas, or whatever as the line moves on down.
It was very interesting at first start up, which is just after the fluids are done. A computer test is initially done, then an operator gets in the car and starts it up for the first time. And they start right up. After a short delay as additional systems are tested, the operator turns the steering wheel in both directions to make sure it turns - it does. Then he puts it in gear and moves the car forward a few feet and applies the brakes to make sure they work - they do. Everything works the first time - very few rejects for anything. This place is a very well oiled machine. Then he drives it over some speed bumps at a fairly good speed and directly to the alignment pit. Complete alignment in under 3 minutes. The speed bumps center the suspension system, as at this point the car has not been moved since it was released from the overhead carrier and sat on its own wheels for the first time.
You gotta see it. A real learning experience. You are only about 10 or 15 feet from the car throughout the entire build.
-Dan-Comment
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Re: Dual master cylinder bench bleed
It just dawned on me that I have hijacked this thread. Sorry.
I will not post any more. Will start a new thread if necessary.
-Dan-Comment
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Re: Dual master cylinder bench bleed
Yes Leif -it is 9.8 quarts. My bad. I must be getting old.
-Dan-Comment
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Re: Dual master cylinder bench bleed
Joe -
That's correct - the brake system is processed with an "evacuate-and-fill" system, without touching any of the bleeders. A mechanical probe enters and seals the compensating port in the bottom of each section of the reservoir, vacuum is applied to the probes to pull the system down to near-zero, a brief decay test checks for any gross leaks, and brake fluid is injected through the probes at about 60 psi into the system while it's at a very high vacuum level. This is followed by a series of tests run by pressurizing the master cylinder at 2,000 psi via its rear piston to verify lack of entrained air and adequate pedal travel based on applied pressure.
This is how the brake process has been done since the early 60's - but today's equipment is far more sophisticated and capable. All brake fluid work is done on the Chassis Line, before any painted body panels are installed. See photo below of a late C3 chassis at St. Louis just past brake fill, with a temporary fixture supporting the master cylinder from the steering gear so it wasn't damaged at Body Drop (the master cylinder was bolted to the brake booster [which was on the body] right after Body Drop).
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