Master cylinder

[D-a-n-i-e-l]

Once again I noticed a colplaint about our Teeves system. I had to replace mine less than a week after buying my Reatta. Ouch! these things list for as much as I paid for the car. Well I pulled one out of a junk Caddy. After two or three evenings I finally construced a woring system.

So has any one tossed around the idea of using a diffrent mastercylinder/ABS system? If I remember correctly the Teeves was replaced in the 90 Reatta, but the 90 Reatta still used the same ECM as our 88/89s. I am sure that there is a way to mod and replace our system with off-the-shelf GM stock parts or system. With my plans of a calipier upgrade I think it may be a good time to research a change in the sysetem.

Any ideas on this topic?

[Barney Eaton]

There have been people that have converted their Reatta to a conventional system from a Riveria....but you loose the ABS.

The reason the car was for sale was probably the former owner had some brake problems and got it working enough to sell.

The Teves system was used from 1988 till 1990 on the Reatta and other GM vehicles. It is a good system but misunderstood. I talk to people every week that have taken their car to a dealer and they want to start replacing parts.

Usually they can fix the problem themselves.

The most common problem are (1) the accumulator that fails more with age than usage (2) the pressure switch (3) the relay. If a motor fails, it is usually because of a bad pressure switch or relay.

For the time and money you will spend on retro-fitting another unit, spend that time reading and understanding the Teves unit.

If you do the brake test every 6 months, you can avoid brake problems.

[D-a-n-i-e-l]

I understand our system and agree it is very misunderstood. But I am planning on upgrading all four corners of the brake system when I return to the states.

To go along with that I thought why not try to upgrade to a newer mastercylinder and try to keep an ABS system.

The biggest downfall of this system is lack of brakes when the pump and accumulator got out. I am amazed that no one has convinced GM to replace the system by recalling it. Every one here can probably agree with that.

On vaccuum boosted systems you do not completely loose use of brakes you just get a hard pedal, and can still stop pretty well. Any way I am just starting to kick around a few ideas for upgrades/replacements

[Barney Eaton]

The Teves workes the same way... you still have brakes but you have lost the mechanical (hydraulic) advantage of the boost. I will agree that it is scary, but it is very similar if you loose vacumn on a conventional power brake system. Same with power steering if the belt comes off.

[Ronnie]

This discussion on loss of braking power due to loss of boost might be a real good reason for upgrading to larger brakes. (discussed in another thread) With larger, upgraded brakes, you would have more stopping power (when boost was lost) and make stopping in that situation much safer.

BTW, before I installed a new brake accumulator, which was completely shot, my car still stopped just fine. IF the pump had gone out with a bad accumulator that would be a different story. Maybe even a scary story.

[D-a-n-i-e-l]

The way I remember the brake system works with out boost is: you have limited front and no back braking, with the loss of boost. I have driven my Reatta (30 miles the night I bought it) without boost and it would not stop in any kind of a reliable manner. At least with a normal vaccuum boosted system all brakes still work and will stop the car in a much shorter distance.

But back to the purpose of this post. Does any one have access to pinouts for the ABS computer in the Reatta and any other GM ABS systems. I know it is a long shot but I am hoping for just a bit of rewiring or even a matching pinout from an other model GM ABS. The other question I have is: does the ABS computer comunicate with the BCM or ECM?

[Guest F14CRAZY]

Hmmm...I know the '89 FSM at reatta.net has pinout diagrams and such. I don't know what part its in though, but I think it's electrical diagnosis

[JWC]

I agree, the Teves system is a real pain to fix, my problem with this system is only when it's cold out, I get a VERY hard bake pedal with NO braking power, and the brake test will not work when the pedal is hard, they do start working after the car has warmed up. I have asked for help and tried what the members say but as to this date no one can really tell me why I have this problem, I think it's in the valve body, but I will have to wait until the cold weath returns.

[Guest jcc3inc]

When I was looking for a Reatta, I saw one 89 which had the Teves replaced by the conventional vacuum boost system. (Of course the 91's have that as well.) I don't know what problems if any resulted from the change, but the vacuum system sure is a lot more common.

Regards,

Jack C.

[Guest F14CRAZY]

The vacuum system as in like a Riviera of the same era can be used, but you'd lose ABS

[Guest kennyw]

Abs brakes will not stop a vehicle as fast as regular brakes with the right person behind the wheel. I saw this on the history channel. They used a ford truck for the test. The abs system is for the person who panics and grabs the steering wheel with both hands and stands on the break pedel. In that case it will tend to stop the car in a straight line. It is also good for [this] person in turns. That said: I have the abs like everyone else. The light has stayed on from time to time but always has gone out. Now my abs light seems to be on for good. O.K. so you say I now have the breaks I like: True. My problem is if it is on the car I would like it to work properly. Other people drive the car from time to time and they might be the person above. So give me the 1,2,3,as to where to look first to make them work, as abs again. I just replaced the crank sensor for a no run and just finish replacing the instrument cluster for the orginal that didn't light up anymore. I finally got to use one of the expensive parts from the pick and pay yard.

ken

[Richard S]

Now wait. I can recall some horror stories right here in River City and over on the Allante site as well. When the Teves and Bosch systems "go out", you are not just faced with a harder pedal, you are confronted by a rock hard one. It is as though the hydrolic system has turned on you. There was some talk of a small valve that when stuck, may actually reverse the hydrolic effect. A search of the archives will show that some have reported being in an accident as a result. I have never experienced the pedal "backlash" in my Reatta, but I did recently in the Allante, and with two feet on the pedal, back pressed into the Recaro, braking is stll minimal.

[Ronnie]

It's kind of ironic that you brought that up. Just today, after reading this thread about the Teves braking system, I decided to put it to the test without power assist. Near my home here in the hills of Tennessee we have a long, steep grade where you can see for about 2.5 miles and it is all down hill. When I crested the hill and started down the steep grade I was doing about 65 mph (in a 55 mph zone). I could see there were no cars in sight. I turned the ignition off and lightly pumped the brake pedal to relieve all accumulator pressure. The red and yellow warning lights came on. Then I started to increasingly brake harder and harder to test the function of the brakes without any power assist. The final time I really stood on the brake pedal and although the tires didn't slide I felt I could stop in all but the most drastic situations. The brakes did feel different and required a lot more effort on my part but they just seemed like normal power brakes with no power assist.

I really don't see why the brakes should function any different from a normal vacuum assisted brake system. You still have a fairly normal master cylinder if you ignore the motor and accumulator and you still have a good set of calipers that clamp on rotors of ample size. Seems to me unless there is a blockage in the system, the brakes on our Reatta, should function pretty much as a normal brake system without power assist. My test today pretty much proved that out, at least to my satisfaction. I no longer fear the Teves system without the power assist.

Any car that has 4 wheel disk brakes will require much more brake pedal effort than a car with drum brakes if the power assist is not working. The reason for that is because a drum brake has so much more surface (friction) area of the brake lining contacting the metal brake drum compared to a disk brake setup. You never see a car, equipped with disk brakes, come from the factory without power assist for that reason.

I don't mean to be confrontational. I don't doubt your stories. It well could have happened. It just didn't happen to me today. Maybe someone else will give it a try when they have an open road.

BTW, the steering felt like a normal power steering system without the pump running also. No problems steering.

[D-a-n-i-e-l]

dis conect your pump motor wiring then drve to your hill. by the time you get there you will probably have gotten in a wreck or have lost all intrest in driving your Reatta down the hill or any where else for that matter. If you still had brake lights on your pannel that means (on a working system) your pump was still getting power and providing some kind of boost, even if it was minimal. Like I said disconnect the the pump motor wire and then come back and tell me if you have the same opinon.

[Rawja]

As someone who has experienced sudden catastrophic brake failure, and who has driven a fair amount with "no brakes" in the Reatta I can report that it isn't fun and it definitely isn't safe. Stopping distances stretch out ridiculously, if the traffic around you slows at even their normal rate, you cannot match their deceleration.

I'm sure that is more of a problem for us in more densely populated areas, but it is a serious deficiency that puts you and others at risk when it happens, especially when it happens suddenly without warning.

[Ronnie]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nx2000t99</div><div class="ubbcode-body">dis conect your pump motor wiring then drve to your hill. by the time you get there you will probably have gotten in a wreck or have lost all intrest in driving your Reatta down the hill or any where else for that matter. If you still had brake lights on your pannel that means (on a working system) your pump was still getting power and providing some kind of boost, even if it was minimal. Like I said disconnect the the pump motor wire and then come back and tell me if you have the same opinon. </div></div>

This morning I read your post and did exactly what you suggested. Before starting the car, I disconnected the pump motor. The red and yellow lights stayed on and when I started to move the CRT lit up with ABS warnings. I drove 8.6 miles, stopping at six stop lights to get to the hill. I turned around, waited for traffic to clear and came down the same hill as before. I had the same results as I did yesterday. When I returned home I checked the codes and had a B482, "Anti-Lock Pressure".

I performed the same test with my '99 S-10 Blazer by disconnecting and plugging the vacuum line to the brake booster. The Blazer is a 2 wheel drive with 4 wheel disk brakes. It felt about the same as the Reatta and may have required slightly more effort to push the pedal than the Reatta.

I stand by my statement that Reattas stop like any other car when power assist is lost. You need to press the brake pedal a lot harder. You can't stop fast. You can't slide the tires and you may get in trouble if you have to make a panic stop. You can stop if you use common sense and take precautions that you should with any car that has lost power assist to the brakes.

I don't recommend any one trying the test I did but if you do I would like to know the results.

[Guest Benr98]

I am wondering if anyone has answered the original question here. I am in the process of replacing the Tevis booster for the third time. I took the good booster out of my Reatta for my sons car and have put in 2 reman boosters from Prior Brake Products. Each time it was replaced I had a rock hard pedal. I am getting tired of this and they keep telling me that it is my car, I dont think so since the last one was put in my sons car also and still had the same problem.

If this next unit does not work I will be looking for a way to swap over to the vacuum system and keep the ABS working.

The theory behind the Tevis system is with out a doubt excellent. This system was designed for use on vehicles with high revving engines that create very little vacuum, but why would GM put this on a vehicle that has a redline in the vacinity of 6K RPM's is beyond me, and how often do we actually reach our redline. GM hasn't used this system but for just a few years and honestly how often has anyone heard of a vacuum booster having a catastrophic failure, even if the diapham leaks it is internal and at least still has partial power assist.

[Barney Eaton]

I'm not sure what further assistance we can be long distance.

In some ways I would think Prior is correct, why would you get two bad units?

The first thing I would verify is that the pump works...via running 12v directly to it.

The Pressure switch senses low pressure and turns on the relay (is the relay good?) which sends 12v to the pump motor. I might question the accumulator but I would think the ones from Prior would be completely bad.

If the pump runs, and there is any life in the accumulator, you should not have a hard pedal.

[Guest Benr98]

Well they are fixing the same unit, I am assumeing that is why the problem persists. Also both times the box showed up damaged, I am not sure if this has anything to do with it or not but they are aware of that as a possible problem.

Now the pump works and cycles like it is supposed to. The rear brakes bleed just fine however when I try to bleed the front brakes there is absolutley no pressure and this is the same problem I had with the first unit also. The pedal is rock hard and has just enough movement to bleed the rears.

Is it the car? I dont think so since my sons Reatta has the same problem with the unit when we tested it in his Reatta. Next time I will test both units (the reman and the one from my sons Reatta) in both Reattas to see what happens. Honestly I hope that they send a completely different unit and not try to fix the one that we have been sending back and forth. This is getting old and if this one does not work I will be switching over to a vacuum system as a new Tevis system is just way to costly to purchase. And I will be requesting a refund and my old booster back.

Heck the old booster worked better than the reman unit they have been sending me. The only problem was there was an internal leak inside the master cylander but at least it worked.

[Guest F14CRAZY]

Benr: may I ask where you're at? It sounds like you're close to me and perhaps we could try some of my parts and see if there's any way I can be of assistance

[D-a-n-i-e-l]

I AM BACK IN THE STATES AND WILL BE RESERCHING THIS IN DETAIL. I WOULD LOVE TO MOVE TO A VACUUM ABS SYSTEM BEFORE I PUT THE F-BODY CALIPIERS ON

[Richard S]

I am wondering if there is a third alternative out there. NX suggested he was going to look into the wiring of our Teves system. He also said he got a unit out of a Caddy. As I recall the similar era Sevile or Eldo came with the Ate system that looks like our Teves. I don't know if one company supplied the units to both Teves and Ate, but I have not heard similar stories of brake failure on those Caddy models [Caddy brake horror stories seem to be limited to the 87-92 Allante with the very different Bosch system]. I think Teves also made a similar system for Saab, but I could not see the brand name on the one I looked at. When I pulled the accumulator off the Saab, the threaded part was different than ours. I am wondering if the Ate system is any more reliable, and whether it is a viable alternative. It would have to be plug-n-play to our cars.

[Guest jcc3inc]

Good afternoon,

I remember reading of an Ebay listed car, a 90 Reatta that had the Teves replaced by a Riviera vacuum type system. His comments were that the braakes now worked great. His comments on things that now don't work are: ABS warning light stays on, and the ABS system now doesn't work.

Regards,

Jack C.

[Guest F14CRAZY]

The vacuum brake system does not have ABS, unless it's from '91+.

[Ronnie]

What are the odds that the ABS would work on a Vacuum boost system if the pressure switch circuit from the Teves system was modified to simulate a constantly pressurized brake system like the Teves system? As far as I can tell by looking at the wiring diagram the pressure switch is the only sensor used by the ABS that relates to the booster pump of the Teves system.

There should be a fairly easy way to tie in the ABS system with a vacuum boost system. It might take a little engineering but I believe if the people on this forum put their heads together we could overcome the problems that would be encountered. All we need is someone with a bad Teves system that is willing to round up the parts and tackle the job. I would certainly be willing to help solve any problems.

I have no problem troubleshooting and repairing my Teves system but I would like to see an alternative developed in case repairing my Teves system becomes too expensive.

[Guest alex_houston]

The ABS light being on can easily be ignored. I still have the Teeves on my daily driver and I have never seen my car on without the orange light on. I may as well put on one of the Riviera systems I have laying around. It would be just the same.

I am getting ready to do a brake job and maybe fix the orange light issue but it would be nice to turn it off in the meantime. Does someone know how to do that without much trouble?

[DAVES89]

I went to REATTA.NET and went to the brake section. Then at the brake I looked up troubleshooting and they spoke about a brake resevoir sensor. I am not sure what that part looks like. According to REATTA.NET the only 2 things that will make the ABS light come on is either the MAIN BRAKE RELAY or that BRAKE RESIVOIR SENSOR. I am going to toss out another idea, the front wheel ABS sensor lead. My light is also coming/then staying on. On my front leads the insulation are bad. I tried taping them up w/electric tape but I think they are now shot. Any thoughts?

[Ronnie]

Alex, I was thinking that if the correct changes were made to the pressure switch (reservoir sensor?) circuit the ABS system might still function as it did with the Teves system in place, assuming it was working before the changeover.

If your ABS has not been functioning it would be nice to know what is involved in a changeover to a vacuum boost system and have it documented here on the forum. I personally am not a fan of ABS so if I changed to a vacuum boost system it wouldn't matter to me if the ABS worked or not. I think the ABS system is too hard and expensive to maintain for the 5 seconds you might need it once in a lifetime.

For the fans of ABS that might be interested in changing to a vacuum boost system, it would be nice to figure out how to make the ABS work.

[Guest alex_houston]

I also am not a fan of ABS and therefor my lack of concern about the orange light. Only at night that light gets awfully bright. It would be nice to turn it off.

I have never really considered swapping to non-teves mainly bacause I don't have a brake problem as I see it. I did change my accumulator a year ago and what issues there were at the time went away. I have never checked the leads or other components mainly because I just not concerned enough to do so. I am sure I have plenty of replacements so that is not my issue.

I am not likely to change to non-teves but if anyone ever does it and gets rid of that awful light, please let me know how they did it.

Thanks

[Richard S]

Though you might imagine that I revel in coming along late in a thread to display my shocking ignorance of basic facts, that is really not so. My ignorance is shocking, I just don't revel in it. Am I to understand that the 91 Reatta had ABS with a vacuum boost system? I am also befuddled as to how we could eliminate the Teves "block" in favor of a power booster, and just by leaving the sensor, simulate the pulsing pressure that [i think] is the essence of ABS. The sensor might suggest that pulsing take place, but what mechanism would accomplish it?

[Ronnie]

Yes, the '91 has vacuum boost and ABS.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">and just by leaving the sensor, simulate the pulsing pressure that [i think] is the essence of ABS. The sensor might suggest that pulsing take place, but what mechanism would accomplish it? </div></div>

The "sensor" that I was referring to in my previous post is the pressure switch that screws into the Teves system. The pressure switch serves dual functions of sensing pressure to control operation the pump that is part of the Teves system AND supplying a signal to the ABS computer that there is sufficient pressure for the ABS system to operate. Many things can cause the yellow ABS light to come on. Low pressure in the braking system is just one of them.

The pressure switch has nothing to do with causing the pulsating you refer to as far as I know. The pulsating is felt as a result of the rapid opening and closing of valves that apply and release pressure to each wheel many times a second to keep the brakes from locking and sliding the tires. The valves are controlled by the ABS computer based on information supplied to it by sensors on each wheel as well as other factors.

Yes, there is more to the ABS system than what I describe here but that is basically how it works. There is probably more to changing over to a vacuum boost system than "just leaving the sensor" in order for the ABS to function properly. I was just throwing that out as a starting point for getting a vacuum boost system to work correctly with the ABS system on the Reatta.

[Guest F14CRAZY]

Can we retrofit a '91+ master cylinder?

[Richard S]

Well, here's a picture of the 91 unit. Wiring sure looks a lot different but I can't tell if mounting is the same. I wonder if the 91 had a brake control module. If so, would have to retro that unit as well. Maybe someone with a 91 shop manual can show us the mounting system and the the wiring diagram?

[Guest ChevroletR]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: alex_houston</div><div class="ubbcode-body">I also am not a fan of ABS and therefor my lack of concern about the orange light. Only at night that light gets awfully bright. It would be nice to turn it off. </div></div>

There should be a bulb you can go in and remove? Never had the cluster out, but I've had the vents and switches around it out.

Ryan

[Guest DTerry]

Yep. When I bought mine - almost 5 years ago - the bulb was removed. I didn't even notice it for two years, and then one day I realized the ABS light didn't come on during the test. Fool that I am, I replaced it - planning to repair the system soon. That was nearly three years ago, and I'm still covering the light with a piece torn from a 3x5 index card every morning on the way to work. Real men don't need anti-skid, right?

...and yes, you do have to remove the cluster. It's not brain surgery, but be careful not to drop the screws behind the dash. They evaporate back there, never to be seen again.