ABS to Vacuum Conversion-Revisited

[Ronnie]

This topic was originally started by forum member Coop on October 7, 2001.  You could say this is the condensed version of the old topic.    I have omitted irrelevant posts that were in the original topic and I took the liberty of reformatting the posts to make them easier to read. I did this because the topic of converting to vacuum power brakes comes up here on the forum frequently.

 

As our Reattas get older more people might consider converting to a vacuum assist brake system. Coop used parts from a Buick Riviera without ABS that are readily available.  This seems to be a workable solution if you want to change over to brakes with a vacuum booster.  You will lose the ABS part of the brake system if you choose to do so.  I'm not recommending converting to vacuum brakes if the Teves system can be repaired.   The Teves ABS is an excellent system when maintained and working properly. 

 

Please note: I don't think Coop has been on this forum for many years.  It's not likely that he will answer any questions but other forum members might be able to. 

 

 

[Ronnie]

On 10/7/2001 at 10:00 PM, Coop said:

 

About 6 months ago, after being ripped off by the local Buick dealer 2 times and my girlfriend almost wrecking her 1990 Reatta 2 times, I successfully removed the Evil Teves system and replaced it with a more conventional vacuum assist/master cylinder non-ABS system. The brakes work great and I sleep much much better now.

 

I guess the reason I'm posting this is for 2 reasons. I see a lot of people having problems with the system and contemplating a conversion. I would be glad to help anyone with any questions they may have regarding the conversion or brake system otherwise. I wouldn't consider myself an expert but I'd hate to see any more pictures of wrecked Reattas because of brake failure. And the conversion did work, quite well too. ...

 

 

 

On 10/8/2001 at 12:28 PM, Coop said:

 

For parts I basically used everything that would be installed in a non-ABS Riviera. I did run an extra line to the rear, and I also removed the original proportioner valve inside the rear drivers side wheelwell. The new master cylinder/vacuum booster I just got at a local auto parts store. I think it was about $150 with a lifetime warranty. It didn't come with proportioners or a [fluid] level switch, but I got these at a local salvage yard. The same system was used on Rivieras, Eldorados, Toranados and I think one other car from the same years.

 

It was basically an easy conversion, the hardest part was fabricating and installing new brake lines. Every port on the master cylinder was a different thread. But it was well worth it.

 

 

 

On 10/8/2001 at 2:20 PM, Brolliar said:

 

Coop, I found your post very interesting. If you wrote out a short description of what you did and posted it here I know a number of Reatta owners would be interested. Questions I can think of are:

1. Did you keep the Reatta brake pedal and did it feed into the Riviera master cylinder OK?
2. Did the Riviera vacuum booster fit in the Reatta OK?
3. Did you have to move anything in the Reatta to make room for the Riviera brake system?
4. What brake electrical systems did you disconnect and where?
5. What year Riviera did you borrow parts from?
6. Did you rerun hydraulic lines to all four wheels?
7. Do the brakes now feel like a normal Buick without ABS?

A description of what you did would really be nice.

 

 

 

On 10/8/2001 at 11:24 PM, Coop said:

 

Wow, lots-o-questions... Hope I can answer all, here goes...

 

Before I say anything else I just want to say that before I began this task my plan was to do as little alteration as possible to the car with the exception of the brake system. I kept the original brake pedal, the travel was the same and location of the "pin" that actuates the booster was the same. But the "pin" on the Reatta is larger in dia. than the mating hole in the pushrod of the vacuum booster. Instead of altering the brake pedal I opted to drill out the hole in the pushrod. It didn't leave a whole lot of metal, but it left enough where the actual stress points would have been, and I was also prepared to throw a little weld on it if I had to, but I didn't. (I did rigorously test after the install)-OK

 

The booster was a little tight, but it fit fine and I didn't have to move anything. As far as the vacuum connection, the engine actually has a port that is blocked off with a cap. It's sort of a pipe coming from the plenum/intake on the right hand side going back towards the master cylinder. This provision is actually for non-ABS vehicles.

 

Electrical connections.  I hope I can remember everything. The EBCM I basically just unplugged everything. Then I unhooked A 6 wire connector under the dash called the "ABS" connector.  I did this just to make the BCM "happy" so to speak, and so the ABS light on the dash would not come on. I did have to reconnect one wire in the connector (butt-splice) so the red brake light would work with the new level switch. Wire #33 tan/wht. I then just wired the new [fluid] level sensor connector in parallel with the old one under the hood.

 

The master cylinder and vacuum booster were actually new at an auto parts store. I told them I had a 1990 Reatta w/o ABS and that's what they got for me. (even though I'm fairly sure there never was a Reatta w/o ABS). But the Reatta and Riviera are basically the same car mechanically. The new unit only came with the booster, master cylinder, reservoir, and some 'o'-rings. I went to a salvage yard and got the rest out of an '87 Cadillac Eldorado (I think). They sold me the entire complete master cylinder/booster with proportioner valves/level switch and all, I did make sure I got the level switch connector of the harness of the donor vehicle before I left though. I then robbed all the parts off of it I needed (proportioner valves/level switch/etc.) and took this unit back to the auto parts store as a core. I figured for $150 for a new one why use some old crummy thing at a junkyard with no warranty or guarantee.

 

I did have to run new brake lines and this was the most... fun, part of the whole job. I did have the luxury of owning a 1990 Reatta service manual, which also the same manual for the 1990 Riviera. The manual showed the correct connections to the master cylinder (looked exactly like the one I had purchased) and all the proper hyd. line routings. I used this as a guide, but not to a tee. The original proportioner valve I removed, disassembled, took all the guts out of it, put it back together, and plugged the port on the side with a hyd. straight thread plug. Effectively it was an easy way to complete one circuit with no bending or cutting tubing. Then I just ran a separate line back and tied it into the line that was tied into the side port of the proportioner valve. I had to extend one of the front wheel lines a little bit. and the other one I just re-bent. The most "fun" part of this was discovering all the different kinds of brake lines, fittings, flares, and adapters available.

 

The master cylinder had 4 ports and 4 different threads. All flares were ISO flares which is not a very common thing I've found. I adapted all ports to a standard double flare with these cool little screw in connectors. I did have to buy a double flaring tool. (Spend the extra $10 and get a good one, it's worth it!!!) And I got a bunch of brake line couplers, and just put the whole jigsaw puzzle together. This was not an expensive part of the conversion, but it was extremely tedious work.

 

Next came bleeding the system, just the same as any other conventional brake system with this exception: After bleeding the master cylinder, bleed in this order RR LF LR RF, I don't know why but this is the only way I could really get it to work, and it's also the way it's stated in the Reatta manual. Once I made sure all the air was out and drove it, the pedal felt a little spongy. I bled again, got no air, and it felt the same. After about 2-3 days though the pedal firmed up and has been great ever since.

 

I don't know if it feels like a normal Buick w/o ABS because I've never driven one, but it does feel like a normal Chevy Celebrity w/o ABS. (Actually a little better)

 

Wow, that was exhausting but I hope it helps. Good luck, and any more questions feel free.

 

 

 

On 10/10/2001 at 9:52 PM, Brolliar said:

 

Coop, thanks for taking the time to give a excellent description of what you did. I had a few questions, but most were answered when I looked at my 89 Reatta/Riviera manual.

 

At first the level switch you mentioned left me in the dark but after the manual review I believe you are talking about the master cylinder fluid level sensor.

 

I think you took the guts out of the existing proportioner valve because as you say you used the proportioner valves for each rear wheel from the Eldorado parts car. I assume these two rear wheel proportioner valves screwed into the master cylinder as in the Riviera.

 

Did you do some hard stops to see if the proportioner valves worked about right so all the wheels started to lockup at about the same time?

 

I wonder why they used four different threads on the four master cylinder ports. Possibly someone else knows why.

 

Again thanks for your excellent description. It is good to know that a fairly inexpensive mod works. Possibly others concerned about their brakes and considering selling their Reatta will just mod it instead.

 

 

 

On 10/13/2001 at 11:02 AM, Coop said:

 

Brollier:

 

Yes, you are correct about the proportioner valve, and yes, all 4 wheels lock up as they should, I had to test when my girlfriend wasn't around though since it's her car.

 

As far as the 4 different threads on the master cylinder, I'm guessing it was done to prevent getting the lines mixed up on a car that was originally equipped with this master cylinder. Best answer I can come up with there.