padgett Posted September 27, 2001 Share Posted September 27, 2001 Ok Canadian girl - I have an '88 with 72k miles. Only had since June but have had NO problems with brakes. Did replace accumulator <BR>based on "six tests" and slow light. But never manifested in any way.<P>Looking at most of the posts and thank you Skip for a very informative post on no boost, I see that there are a lot of different things happening but most seem to have had warning (sudden pull, warning lights) prior to complete and catastrophic loss of the type Tulley's wife had. From the post:<BR>"Braked and pedal went all the way to the floor. Pedal came back up and locked."<P>I interpreted this as the pedal suddenly went to the floor. When released it came all the way up but when pressed again it did not move and had no effect. Am assuming no prior warning lights.<P>Today I received a copy of the GM-Teves training manual dated 1987 and with Reatta specifically mentioned (GM Product Service Training 55205.02-1). It has extensive hydraulic circuit diagrams (like those for the transmission) showing different modes of operation that are not in the FSM but may be seen at <A HREF="http://www.reatta.net/brakes/brakes_pictures.html" TARGET=_blank>http://www.reatta.net/brakes/brakes_pictures.html</A> ).<P>Some people have said that a main valve (uper left in diagram) stuck open can cause a hard pedal - looks to me more like the pressure in the m/c would just equalize resulting in a "no boost" condition and pressure would still be applied to the rear brakes.<P>Am comming to the conclusion that the failure was probably mechanical and not electrical or hydraulic - at least I am having trouble finding a mode that would match the symptoms.<P>Not saying the ABS cannot do oddball things such as locking one wheel on application or sudden loss of boost, just not catastrophic sudden failure.<P>What would match the symptoms would be a mechanical failure in the pushrod (breaking and jamming) or the mounts (two bolts not readily checked and in an aluminum bracket - just checked mine and are tight). The oddball multipiece pushrod design and intermediate bracket with bolts in shear may contribute.<P>Anyone who ever had a clutch rod pop off the arm and jam somewhere during a shift has probably experienced this (what got me thinking about it).<P>What I would like to know is if anyone ever experienced this specific catastrophic failure:<BR>a) no warning<BR> on braking pedal went to floor<BR>c) on release/reapply pedal jammed "rock hard" and had no brakes.<P>One scenario I would like to test would be what happens if for some reason the TEVES assembly was R&R'd and the "hidden" bolt was not replaced.<P>Another would be a failure of the push rod-booster piston link which also activates the control valve (schematic must not be very representative, would like to see actual parts). If could jam push rod control valve would never open and push rod must move in about half way to be able to activate manual front brakes.<P>Sounds like someone could spend an interesting day with a Reatta, some jumpers and switches, and wide open spaces.<P>Note: Going back to Dan's similar incident last year I found this:<BR>"When I went to look at the car Saturday, the reservoir level was correct, the pedal was still hard as a rock, so there was no way of pumping the pedal, I am assuming the system is still depressurized. The pump still ran when the ignition was turned on, and believe it or not , both lights STILL go out after about 30 seconds." <A HREF="http://www.aaca.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=001817" TARGET=_blank>http://www.aaca.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=001817</A> <P>Either we have a system that can keep up the pressure for several days or this was a mechanical failure, possibly inside the master cyl. It really bears looking into.<p>[ 09-27-2001: Message edited by: padgett ] Link to comment Share on other sites More sharing options...
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