The SX/4 money pit

[IowaEagle]

I thnk he did.  But he said even then during install air would sneak in.

[Smitty]

I really think I have bled it all out.  The rear shoes move and now I am thinking there may be an issue with the calipers.  Maybe they are not on right and sliding up on the caliper bolts instead of pushing on the pads.  have to check it out tomorrow.  Brand new MC came yesterday and I put it on last night - no change.  Pulled the rear drums again and everything there is fine.  Always thought the issue was with the rear brakes but now, the only area I have not done or checked at least twice is the front brakes.

[Route 66 Rambler]

  Worked on a Ford LTD once that had the incorrect wheel bearings in the rotors.  When the calipers applied, the rotor would just move over, no real brakes.
mike

[IowaEagle]

I had to polish up the bolts with my Dremel tool to get them to slide right as they were really pitted and corroded on the outside.  Finally, got a brain and to new bolts to make sure they don't bind up.   So, you could have found the issue.

[Smitty]

The caliper bolts are new.  I took the fronts apart this morning and there was nothing wrong.  It all seems to be in the booster/MC area so I am going to lenghten the rod from the booster to the MC and see if i get braking action sooner in the pedal throw.  First I have to finish putting the wagon back together so maybe tomorrow I will fool around with it some more.

[IowaEagle]

Dang!  I wonder what is missing from this equation.  It seems you have examined it from every possible angle.  Is there a pinched supply line some where?

[Gil-SX4]

Any chance you might have goten some water in there or the wrong fluid?

[Smitty]

The entire brake system is new and I have used new brake fluid thoughout so I doubt there is a contamination issue.  Skeezix has become quite the authority on braking systems now   She has done a lot of on line researching for me.  You know, it really is a simple system.  The problem is that not enough hydraulic pressure is being created to engage the brakes fully before the pedal hits the floor.  We have compared pedal heights and structural dimensions with the wagon and find no difference so the hardware is correct and installed correctly.  My thoughts now are that the rod from the booster to the MC is not long enough and the MC is not building pressure until the pedal is too far down towards the floor.  The rod from the booster is adjustable and I have left it alone from the factory setting.  I got another booster/MC assembly from Ted354 and the rod lengths are the same so I figured it was good to go.  Skeezix found out that the pedal to rod ration is 6 to 1 so adjustments should be minor.  What that means is that it takes about 6 inches of pedal travel to move the rod in 1 inch and since the MC only needs to move about half an inch to build full pressure I should have full braking with 3 inches of pedal travel. 

After I get the wagon done today I will play with this.  The day is delayed tho.  One of the girls wants to come home from college for a few days so we are headed down to get her.  She will be doing a semester abroad at St Andrews University in Scotland this fall so it will be nice to have her home for a few days.  Means no wrenching till about 2pm

[OntarioEagler]

This is a really interesting thread for guys like me, because it is so well written and descriptive.  Lots of good stuff to learn about.

It is really presumptious of me, a wrencherwannabee, to suggest things to you Smitty.  But in the unlikely event that you haven't already checked these out, here are some things that I would try:


1   Try brake application with engine on and off.  You might be able to learn something from the feel of the booster.  (I have learned the feel of no-vacuum boost on the brakes when I have problems with the idle circuit of the Carter.  Not a recommended procedure!)  You will get a good idea of the pedal travel/pressure ratio with and without boost.



2   Make sure that you are not pushing the master piston through the primary circuit into the secondary.  That will, I think, give you excess master piston travel and consequent excess pedal travel.  None of your brake lines are crossed from primary to secondary or vice versa, eh?  (Actually, I don't even really know where and if they can!  Maybe at that little ball valve signalling that you are on secondary?)



3   While she is still here you might want to put your daughter to work for 5 minutes applying the brake pedal while you go around the car with the wheels off to see what sort of brake pressure you have on each wheel.  She should be able to feel, on the pedal, you pushing and prodding on the wheel cylinders or the calipers.... Especially if you have the vacuum off.  That might give you an indication of where the problem is located.



The above are pretty obvious, but you never know.

In any event we are all waiting to find out what is causing this mysterious delay to the roadworthiness of the money pit!

[Smitty]

Don't ever think an idea is too simple to mention or that it is not worth mentioning.  I am the first one to admit my limits and if I had all the answers then the car would be on the road by now   I like your idea on the the rod maybe being too long and I will try to lengthen it and shorten it to see the difference.  My plan is to size it so I can just feel resistance against the MC when I hold it flush against the booster.  That way it should be right at the point to start the pressure stroke.  Anyway, have to go finish the wagon now .  Then the money pit

Did you ever remember to run down the road and see about that sundancer?  That guy is a little strange

[OntarioEagler]

Don't ever think an idea is too simple to mention or that it is not worth mentioning.  I am the first one to admit my limits and if I had all the answers then the car would be on the road by now   I like your idea on the the rod maybe being too long and I will try to lengthen it and shorten it to see the difference.  My plan is to size it so I can just feel resistance against the MC when I hold it flush against the booster.  That way it should be right at the point to start the pressure stroke.  Anyway, have to go finish the wagon now .  Then the money pit

Did you ever remember to run down the road and see about that sundancer?  That guy is a little strange

Good advice. 

I suspect that it applies to quite a few of us here who are somewhat awestruck by the "wrenchers" who really know their stuff.  I know that I feel reticent to comment on some of the stuff because I am such a newbie at this game.

Thanks for the reminder re the Sundancer.  I have tried to call him a couple of times since I got back from the last trip with no result.  A friend has  recently (a week ago) reported that the Sundancer is still there.  It is visible from the highway. I will try to get over there before heading out to BC.  It is a out of my way but I might take that route on my way back from Toronto in a couple of weeks.  I seem to recall that he has an email address but I don't know what it is off the top of my head.  Back to the drawing boards!!

I saw the Sundancer about a year ago.  It was parked on GRASS.      A terrible thing to do to a rare car!

Anyway, I hope to get some more up to date info to you in the next two weeks.

Tom

[OntarioEagler]

Couldn't get over to see the 'dancer on the weekend, Smitty.  Traffic to cottage country was heavy and I got delayed.  Sorry.  Can't find the owners name, but I know where he lives.  Maybe I can get over there when I get back from BC at the end of Sept.

Did you get the brakes working on the money pit?  Very interested in what you  learned/did.

OE

[allend]

have you checked the metering valve (proportioning valve) it could be malifunctioning to the point its not letting fluid go to the front.

[Smitty]

have you checked the metering valve (proportioning valve) it could be malifunctioning to the point its not letting fluid go to the front.

I pulled the brake valve and cleaned it out.  No change.  I think that if the brake valve was at fault I would still have a hard pedal, just no braking action.  All four wheels have brake dust so thay are getting some pressure.  My understanding is that the brake valve is really only for the brake light switch and that the metering is done by the MC. Hence why the resevoirs are different sizes.   There has been a lot of discussion on this on the AMC list and the manual is clear to call it a brake valve and not a proportioning valve.  Since these are made from unobtainium I may try to adapt an XJ unit.  The issue is a lack of full pressure before the pedal throw reaches its limit.  The hydraulic system for the brakes is a closed system so a stuck valve or caliper etc should not cause a lack of pedal pressure.  I think

[IowaEagle]

Sorry if this was asked before, too lazy to look back, if you had the MC rod off the pedal did you put it back in the right mounting hole?  There is one for Power and one for Manual brakes.  From memory the lower one is for power brakes but you may want to check my memory.