Alright, this seems crazy but I'm gonna ask the question anyways. I know that this is a lot to read but when you get to end you will understand why I have given all of this information. Please bear with me.

I recently bought a 1970 Cutlass Flat-Top Wagon. In 2012 it had a front disc brake conversion, new master cylinder and power booster.

I noticed the following problem when I test drove the car but I figured I could fix it so I bought it anyways. When I step on the brake pedal the pedal feels like it should and the brakes work like they should until the pedal reaches about half of what should be it's normal travel. After pushing the pedal about half way down the pedal feels like it hits a brick wall and you can't push it any further. At that point the brakes have not achieved full effectiveness. So, the pedal feels like it hits a wall when you step on it and the car will not brake hard. This makes for some uncomfortable moments when trying to stop the car because you start to panic when the pedal stops and the car doesn't. Actually, the car stops but more like a rolling stop. Not good if you need to make an abrupt stop.

So, I took the car to the mechanic that I have been taking all of my cars to for the last five years. He owns a reputable local auto repair shop and works on just about every kind of car. I know him by name and he knows me by name. My kids sale fundraising candy bars at his shop and he lives in my neighborhood. I say all of that just to let you know that I trust this guy. He's a good dude.

The mechanic discovered that the rear cylinders and drums needed to be replaced so I had him do it. The brake shoes were okay though. He also adjusted the emergency brake. The vacuum suction going to to the power booster was great, the master cylinder checked out okay and the linkage to the pedal from the master cylinder/ power booster was fine. The proportioning valve was stuck when he took it off and inspected but was able free up the valve and get it in good working order (I guess there's a little valve inside that moves. I've never actually seen what one looks like other than when it's mounted on the car).

At that time brake fluid pressure at each wheel checked out good.

After all that I still had the same brake pedal/ brakes not achieving full effectiveness problem. All of that fixed nothing.

The mechanic had my car for about three weeks (he's not charging me for any of his trouble shooting or anything past the cost of the rear brake cylinders and drums). He spent time over the last three weeks trying to find out why the problem still persisted.

Good news! He called me yesterday and said that he fixed my brakes. The pedal feels good now like it should and the brakes stop like they should. Sounds great right? Well, it is great but the cause of the problem has me scratchin' my head. When the mechanic called me he said "you're gonna think that I'm crazy but it was an engine timing issue". He said that he called an old timer that has worked on many of Cutlass' and the old timer told him to check the engine timing. The old timer said that engine timing being off can cause that problem. He thought that the old timer was crazy but figured he would give it a shot. Well, the timing was off a little bit. So, he adjusted the timing and sure enough it fixed my brake issue.

That sounds crazy to me so here's my question;

Has anyone heard of brake problems being cause by the engine timing being off a little in an old Cutlass?

 

If the timing was declined it possibly would not provide the vacuum necessary to keep the brakes operating properly. So yes it's possible. Another indication of lack of timing, is the engine would be a complete dog and lacking power.

 

I'm skeptical.

- Eric

 

It's the original 350 that was rebuilt two years ago so I don't think it's dog. The car moves out pretty good. I took my buddy for a ride who also owns a Cutlass and he was impressed with the cars acceleration. Prior to the rebuild it had about 90,000 miles on it.

I never would have thought that the timing would affect the brakes. You learn something new everyday.

 

Let me rephrase my statement, if it does not have more power than it had before, it was not the timing that corrected it. I'd, for grins and giggles, ask what the timing was before and where it is set now.

 

The power booster retains sufficient vacuum to provide power brakes for at least two applications of the pedal even after the engine is turned off (or stalls), so unless there was insufficient vacuum to start, I can't see the vacuum being insufficient once you start to press the pedal. It's possible that there is a leak somewhere or the check valve on the power booster is not working properly, but the reality is that even with no vacuum in the booster, you should be able to fully apply the brakes by pressing harder on the pedal. Was this not the case?

 

On my engine, I have seen reduced braking performance with the initial timing set to ~10º compared to with it set to ~18º (I have a factory 78-79 HEI distributor).

This is related to the amount of vacuum the engine produces: at 10º initial timing there is ~14" vacuum and it is erratic (bouncy), but at 18º initial timing the vacuum is a steady 16", which translates to increased braking performance.

So I can believe that if your timing was way, way off on a stock engine that the vacuum could be low enough to affect the power brakes. Note that I said way, way off. I never experienced that on my engine when it was in stock configuration, but it could be possible even though I never experienced it. Stock vacuum on my engine was in the 20-22" range, which is more than sufficient for the power brake system to work at optimal levels.

 

A few things here.
You have a great mechanic to take your car to. You are one lucky guy.
He wasn't embarrassed to tell you that he he asked for outside help when he came across an issue he couldn't figure out. It happens to us all (even me ), another point in his favor.
Your brakes work properly now. Not only that, your mechanic charged for the work he had done, and didn't demand payment for trying to figure out the problem.
All good.

Several guys here who have a great deal of knowledge and experience with Oldsmobiles, whos' opinions I respect, say timing shouldn't make a difference.
But in your case it did. Unless your mechanic has told you a pack of lies about how he fixed your car. I think he has been honest with you.
But has he previously done any tuning work on your car?, if so the timing should be right anyway. Unless he was working to the wrong settings by mistake.

Perhaps you drive your car gently most of the time, in which case you might not realise the timing was off. Do you have much experience of old American V8 iron?, perhaps you thought your car was supposed to run like it did.
Have you noticed any difference driving it now, like a smoother take off, better gas mileage, or perhaps it climbs the hills a bit easier?.

To answer your question, it seems most of us haven't heard of bad timing causing bad brakes. But we have now . Perhaps .

Roger.

 

Alright, here's what I found. My problem is all vacuum related. When I brought my car to the mechanic it was producing 10Hg of vacuum thus the hard pedal. I just didn't know enough to identify what I was feeling. After advancing the timing I now have 15Hg of vacuum. I should have between 18-22Hg of vacuum. With the cam that is in the engine I can't produce anymore vacuum. So I was right when I said that my brakes don't feel like I think they should. Now my brakes feel better (still not perfect but better) then they did and they stop the car like they should. I got cutoff in traffic while driving my car yesterday and had to lock up the brakes. They indeed did lock up and worked well.

Everything in the system tested good and is working as it should the brakes do feel good enough to drive the car. Also, after the mechanic tuned up the car and advanced the timing it runs noticeably better. There is a definite increase in performance. The car is running very good.

The way I see it I have two choices. I either buy an electric vacuum pump like the SSBC pump or I live with what I've got. For now I think I am gonna live with it.

Thanks for all or your input everybody. I am new to owning a car like this and I really didn't/ don't know much about these cars. I've had this car for a month and three weeks of it the car was at the shop. I am learning though. I'm just glad that these cars don't have computers.

Now I've gotta figure out where I am gonna put speakers in the car. The one dash speaker sucks. I'll leave the original am radio and speaker but I gotta figure out where to mount better sounding tunes. Anyone know where I can get a good working 8 track player?

 

All of that makes sense.

If you've got a high-duration cam, it will kill your vacuum, it will need a lot of advance, and it will run better when properly tuned.

We would have had much more to work with if you'd told us any of that at the outset.


Three, actually. You can install a HydroBoost system from a GM diesel pickup (the aftermarket makes fancy chrome plated ones, too).
They work great, and if you get all the parts in the junkyard, they're not expensive.

- Eric

 

I have a set of Custom Autosound kick panel speakers for up front and a set of 6x9 coax speakers is boxes in back. Since you have no rear package tray to mount speakers (but LOTS of rear cargo space) you could be creative with rear speakers.

 

Glad you got it mostly ironed out with a good explanation on the repair.

 

I recommend you take up on of the options other than living with your brakes as they are.
No reason to have brakes not working as well as they can.

And it seems your mechanic will do the job properly for a fair price if you don't want to tackle the job yourself.

Eric raised a fair point, the more information you give us, the the better we can help.

Can we have some pictures please?.

Roger.

 

Oh, and a fourth option (duh.): You can change your wheel cylinders and master cylinder and dump your booster and go to manual brakes. You hav enothing to lose, as now you have a heavy pedal sometimes, unpredictably, and manual brakes would give you a less-heavy pedal, consistently.

- Eric

 

Beat me to it. My 70 W-30 has factory manual disk brakes and I've never had a problem stopping it. Yeah, pedal force is higher than with power brakes, but not unreasonable.

 

Sorry about not providing information about the bigger cam but I didn't know about it myself. I didn't know the cam wasn't stock until my mechanic told me.

Here's how that miss-information happened. I bought the car a month ago from a girl that thought having a classic wagon would be fun for her and her two kids. She bought the car in October. She found out that she didn't have the time or where-with-all to keep the car running like it should. She decided to sell it and buy a minivan. She didn't know (or didn't tell me) that the cam wasn't stock. She said that she would give me the guys contact information that restored/ built the car but she didn't get me the contact info. for about a week.

When I bought the car I took it to my mechanic right away and he started digging into the problem. He went through the brakes and couldn't figure it out. After a week went by I got the phone number for the guy who built the car. I called him and he told me all of the stuff he did to the car but never mentioned the cam. I didn't know enough to ask him.

So, two more weeks go by and my mechanic figures out that the cam in my car is not stock. I called the guy back that built the car and he confirmed that he put a bigger cam in it. That's when I posted above that the car has a lumpier cam than stock.

So, it may have seemed like I was keeping that information from everyone but I wasn't. I didn't know it until this last week.

I really appreciate everyone's input though. When I first got the car I couldn't effectively stop the car even by standing on the brake pedal. So, having my mechanic go through everything was a win-win for me.

I think I like the idea of going to manual brakes. Any recommended parts dealers out there for the master cylinder and wheel cylinders? Would I need to replace anything on the front disc brakes or just the wheel cylinders on the rear brakes?

The Hydroboost master cylinders do look nice but they are expensive. Next time I go to the U-pull it I'll keep my eyes out for a GM diesel truck. I'm assuming that those are pretty much a direct bolt on without much fabrication to make them fit?

As far as speakers go, I am totally on board about making a speaker box for the cargo area. I've built many of speaker boxes in my time. I'm actually going to combine the subs and full range speakers in one long box that goes from one side of the car to the other that sits behind the back seat. I'll divide the box up internally and baffle it to get a clear sub sound. The big deal for me is to be able to remove the speaker box so that I can present the car in it's stock form when I want to. I'll put an amp or two under the front or back seat. I haven't decided yet but I've thought about building a console to fit up under the dash on the hump (transmission well) to house a stereo. But I also like the idea of an old am/fm/8 track player that will fit into the original radio mount. I would never cut my dash. The modern stereos that look old are pretty cool too but I really like the idea of playing 8 tracks. Of course, fidelity sucks with 8 tracks but the vintage cool factor is hard to beat. We'll see.

My big problem are the front speakers. I will not cut my kick panels or door panels so now what do I do. I know that I could replace the dash speaker with a modern one that they make for that but I really like having a true left and right speaker. I'll figure it out. These are fun problems to have.

I don't have a lot of pics but here are a few. My favorite part of this car is the undercarriage. Underneath from bumper to bumper looks damn near like a new car. I don't have any pics of the underneath but it's really clean and completely rust free. Actually, the whole car is rust free. I also like that the car was bought new from Bolen Oldsmobile here in Oklahoma City and still has the Bolen sticker on the front bumper, Bolen emblem on the tailgate and the Bolen license plate frame. It's only letting me attach a few picks so I'll reply to this post a couple of times so that I can include the pics that I do have.

Thanks again for everyone's help.

 

More pics.

 

More pics #2.

 

Wow very nice wagon! I dont think the kick panel speakers Fun71 was talking about requires cutting holes in the metal behind the kick panels. You just buy the new panels that have speakers built in. They stick out a little farther, and some have had to move the emergency brake pedal over an inch or so, but no big deal. I plan on buying some for my 67. Again beautiful wagon. Green is my favorite color.
Steve

 

Actually, all GM one-ton pickups use hydroboost, gas or diesel. Unfortunately, it won't be a bolt-in, there will likely be fabrication. You'll need the higher volume PS pump and custom hoses.

 

Nice ride man!! I'd drive that anywhere.

 

Very nice wagon.

 

I'm not familiar with every application, obviously, but my '90 GMC has the P/S pump on the left, it's the same style as the '68-forward pumps, and the hoses run along the left side of the engine to the M/C. It may not be exactly "right" for an Olds A-body, but I bet it'd either fit or come really close.

- Eric

 

Why would he need to change out the wheel cylinders going from power to manual drum brakes?

 

Because most cars (no, I can't quote make and model off the top of my head) used different diameter wheel cylinders for manual and power brakes (as they did for M/C's as well). The point was to change the mechanical advantage of the brake pedal - power brakes do more work through less pedal travel, while manual brakes use more pedal travel to get better leverage.

- Eric

 

Correct:

http://www.classiccarstereos.com/cat...ck-Panels.html