View Full Version : Brake Light came on (not tail lights)

03-20-03, 06:29 AM
Was driving around Galveston, TX when my Brake Light (warning light) came on. Read the manual, and this means I lost my power assist function. I drove the car back to Louisiana, the brakes worked fine manually, but you could tell they were a little weak. Putting the car in neutral at a stop light then back into drive would not create that drop down of the rear affect, just a flat push forward of the whole car. I really had a problem. I like the drop down affect!

Well, I checked the master cylinder, this was full, front and rear. I stuck my head under every wheel well, saw NO leaking. About 2 days later I had time to bring it into my mechanic I started using. At the mechanic we checked the master cylinder again, the rear was low. This is good, means the problem is probably in the rear. My wife needed me at the house so I left the car and waited for their report. Later that day I get a call, the master cylinder is bad going into the booster. Great, lets change it, cost is going to be $189 parts/labor. The master cylinder I had was only 3 years old. But you never know I guess. About 2 hours later I get another call, we found the left rear caliper bad, it is leaking fluid all over. Another $200. OK, can't argue with that, but what about the master cylinder? Didn't question it at the time, but after thinking about it, is the master cylinder really bad if the leaking is coming from the caliper? To me the master cylinder is just a resevior, and does NO mechanical function, I'm guessing here, am I right?

My question, how do I find out if my master cylinder was "shot gunned" changed and then the real problem was found and fixed when they started to bleed the system? I really hate throwing $200 away. So, what is the best way to go about it?

Next issue, the mechanic then tells me, "I noticed a funny sound coming from your left rear tire. Might be your U-joint." I have never heard a sound coming from this area, I drive the car everyday. But he tells me, "the sound begins when you step on the gas." Still haven't heard this while I drive it.

My left front brakes have been sticking sometimes and I get a "shhhick, shhhick, shhhick" driving through a parking lot and probably even at high speeds, but I have taken this wheel off and spun the rotor and verified it is the brakes sticking a little. (how do I fix this? I just chalked it up as too small to worry about)
Although I would like to have a quite ride when driving close to spectators.

So how should I treat the U-joint case? How do I verify that this may be an issue? I really do not want to spend another $400-whatever on something that the mechanic knows he can scare me with. As we know these older cars have all sorts of, "well, those front whatever always go bad, and when they do, look out to your pocket book. or Those back (inertial dampers) don't look too good, you may want to replace the flang bolt flaps with newer graybar tork handle loops." You get my picture. I thought I could trust this mechanic, and maybe I can, my father has used him for years, about 15. But I do understand this car can be a money maker in fixes for the right mechanic. But also remember my car has been frame off restored pretty well about 5 years ago. Everything under the car was replaced new. And only about 20,000 miles have been put on it since. But it did sit during winters in Wisconson.

What do you think I should do about the master cylinder? How do I verify the U-joint problem so that I don't chase a dog up the wrong tree? Any good mechanics in the Lafayette, Louisiana area that you know of?


03-20-03, 07:07 AM
1981 --- I really do not want to spend another $400-whatever on something that the mechanic knows he can scare me with.

I suggest finding a new mechanic. $400 for the master cylinder and 1 caliper + labor??? The master cylinder from the local AUTOZONE is $18.99. Why didnt your mechanic check out the front brakes as well??? He should have for $400.

Are you 100% sure that this car had a complete frame off restoration??? If so I dont think you have to worry about too much.

If you dont notice any noises from the "u-joint" hold off for a little while.

Good luck on finding a knowledgeable and trustworthy mechanic in your area. The PO's mechanic/restorer would be a good bet if local.



1979 L-82

03-20-03, 07:23 AM
If your master cylinder was leaking, it leaks from the seal where it bolts to the booster. Mine was leaking, and my mechanic found it because it leaves a trail of fluid down the booster front. Check that area, if they wiped it dry you should still be able to tell if it was leaking. First my MC was leaking, replaced that, then last inspection my mechanic found the front calipers were leaking. I am doing that job now on all four wheels, and while I have it all apart on my 75 I am also replacing the front wheel bearings. Maybe in the future, if you are mechanically inclined, when they find a supposed problem, refuse their fix and tackle it yourself, helluva lot cheaper!!!!!!!

03-20-03, 10:57 AM

There are some really Good past threads on this subject, Here is 1 (http://www.corvetteactioncenter.com/forums/showthread.php?s=&threadid=20047&highlight=Master+Cylinder) for a lot more you can use the "Search" feature. You can find this feature just below the tabs at the top of the page on the right side of the screen.

Just go to this feature then type in the "Search Keywords" **Master Brakes** then check the **C3 Tech Forums (1968-1982)** in the "Search Keywords" box. (you don't need to use the ** ;) )

03-21-03, 08:09 AM
Thanks, I will do that.

One other question:

That noise coming from my left rear wheel is real. I arrived at my mechanics place yesterday to inspect the Brake work and found the brakes to be in good order. I think they put a cheap master cylinder on, it already has some rust starting to form on the iron, my old one had none and it was years old. Maybe I should spray some pam on it to keep it from drying out and rusting.

Well, back to my question...We put the car up on the rack to enable the wheels to hang (couldn't here the noise good enough on the road, my exhaust just sounds to good to overhear
:eek), by doing this I think this put the suspension in a tighter bind to more easily create the noise. Well, while the wheel turns the noise sounds like someone randomly clicking their ballpoint pen, slower as the wheel spins slowly but faster as the wheel spins faster. So proportional with the speed of the wheel. we only lifted the car about 6 inches or so off the ground, so I rolled under it while the back wheels spun at idle. (I didn't really put my ear close, didn't want to make a distance mistake and have something get caught around that turning half shaft), but putting my ear close to each U-Joint on the left half shaft led me to believe the noise came from near the U-Joint at the wheel, not the differential side. Now with that said, the mechanic told me he could not fix this because he was afraid to tear it apart and not be able to get it back together again. What!? Aw man this sounded bad. So I did some research on the web, called around and think the problem may be the U-Joint itself. The clicking can be heard more since I drove the car home to park it until I can figure out what the deal is. It isn't as bad as when it was on the rack with the wheels hanging, but when I change direction, forward to back for example, there are some clicks then everything goes back to normal. The loudness of the clicks are about the same as if someone were clicking the pen while standing normal distance in front of you.

So what do you think? U-Joint, it really sounds like it, but again, this is the same wheel they just replaced the caliper on. Man things just haven't gotten any better, but the noise was probably there all along, I just never noticed it, it really is hard to hear over the exhaust.

Is replacing this U-Joint that hard? The mechanic thought he was going to have to take just about the whole back end apart to get to this one U-Joint.

Once I find a better mechanic to do the work, Should I also replace the bearings while I am at it. Just in case this is the problem and not the $16.00 U-joint? or does this open a new bucket of grease?


03-21-03, 02:53 PM
some frame off restoration


03-21-03, 10:57 PM
Heres the deal on the frame-off restoration.

I bought the car from a guy in Wisconson. Talked to the husband/wife owners of Corvette Sports up there who did most of the work for the restoration. Was sent pictures of the frame with everything off of it after the powder coat, and pictures of the rolling chasis as parts were put back on. The work was done over a 2 year period and was completed about 2 years ago. Everything under the car is brand new or was when it was put in during the restore. Engine rebuilt, and transmission rebuilt. The one concern I have always had is, the guy let the car sit during the winters. And I am not sure if he litterally let it sit, or started it every few days for some time. I live in Louisiana, so I know nothing about what some of you guys do while storing your cars or even for what particular reasons.

I do not know these people at Corvette Sports, but these cars are mechanical and will break, usually when you are out on the town right after dinner.

I understand your comment, but my question to you is, are all frame off restorations perfect and complete? I did not perform the work, I only bought the car which to me, after seeing many corvettes while searching for my 1981 I noticed a trend; original low milage, and none even came close to the work performed on this car. Most sellers when asked, "so what have you done to it to restore the car?" all replied, "nothing, this car is great to drive." and I walked, most wanted way too much cash for a nice used car with low milage and no restore at all. I drive this car everyday, so all this work that was put into it will be used and old by the time I am moving into a new corvette or an earlier model. Everything under the hood and car except the motor and transmission is or was new during the restore. And it looks it still. All the way to the custom stainless steel exhaust. None of this crome plating covers to hide rust, there is hardly any, if any. But it has been about 2 years, 1 of which I have been driving it everyday. Rain or dry, I like driving it. This is not a sit in the garage car, this is a car I even use to drive to Houston and Galveston, 4-5 hour drives for work occasionally. I even drove this car from Wisconson when I bought it. But I do keep the underneath clean. Everyone loves to poke their heads under to see how new the front or rear suspension is. And I like this.

I just do not have all of the proper knowledge on how to fix cars. So I ask the group.

Whether or not the frame-off was even remotely done correctly, in the end, the noise still needs to be stopped in the left rear wheel.

Any suggestions?


03-22-03, 01:15 AM
1981 --- Heres the deal on the frame-off restoration.

I am not trying to attack you or make you second guess your purchase. If it seemed that way I am sorry.

My understanding of a frame off resto... would effectively take the car back to OEM condition. Having such problems seems to soon in the life of your car. That is all I meant.

1981 --- Once I find a better mechanic to do the work, Should I also replace the bearings while I am at it. Just in case this is the problem and not the $16.00 U-joint? or does this open a new bucket of grease?

Find a VETTE knowledgable mechanic, and replace anything that is questionable. If there is extensive labor time involved in the repair, you might as well replace a few things here and there and sleep at night knowing you wont have a problem with your rear end in the near future.

Sound advice???

:) :) :)


03-22-03, 08:34 PM
The brakes could easily be a two-fold problem, having a bad master cylinder (leaking as mentioned), as well as a leaking caliper or two. I've had it happen to me. I purchased a new (not rebuilt) M/C for $60 and painted it before bench bleeding (otherwise, it will quickly rust). I use DOT5 silicone, so not worried about brake fluid eating up the paint. Here's a link to some pics. http://www.c3vettes.com/chris_81_3.html Sometimes it's hard to know if you've got a leaking problem unless it's serious enough to hit the ground. Best way to check is to pull the pads out and look inside the calipers for wet grunge. There will be some on the pads as well. It's pretty easy to tell. You'll probably have air in your brake system as well, and it's common with older seals. Your warning light is coming on because of lack of fluid and there's a trip switch on the distribution block causing it. Once you get it full and bled the light may still come on until you jam the brake pedal hard one time to reset it. Replacing a caliper yourself is fairly easy. Bleeding can be frustrating (slow), but consider gravity bleeding as your best option.

The noise you hear could very well be the ujoint. Browse around that link I posted and you'll see what can happen. Argh! Again, not that difficult of a job, just time consuming. You will need a 12pt, 1/4" socket to remove the bolts, and you need to be careful not to strip the heads. Once you get the halfshaft out, take it to a place like Fleetpride and they'll install new ones (they carry the Spicer brand). I do my own, but unless you have a press or vise, it can be a challenge, especially if rusted a bit. When putting them back in, I believe the torque is only 15 ft lbs, so it's important to use lock-tite (the blue color strength is all you need, and replacement bolts already have some on it). You can sometimes easily see some slop in the ujoint cups when someone is lifting up on a wheel. If you see anything like this, it's time to replace! Oh, also, be careful when spinning those wheels with the motor when it's in the air. The angles on the shafts are pretty severe and can cause some damage. Also try the emergency brakes (and regular brakes) to see if the ticking goes away when you add some resistance. Could be that too.

03-24-03, 11:35 PM
I will be replacing the u-joints myself on the left half shaft within the next few days. I will let ya'll know how it goes and if it does the trick.

When I put the car into drive or reverse the clicking/popping is heard. When a load is put on that half shaft initially during movement clicking/popping is heard. Will cost me the price of the U-joints to do this, so if it doesn't work I will then opt to have the bearings changed.

I will look into the parking brake too.

Thanks for the help, I needed it, and may still...wish me luck.


03-25-03, 03:56 AM
1981 -- I will be replacing the u-joints myself on the left half shaft within the next few days. I will let ya'll know how it goes and if it does the trick.

Good Luck!!

There is nothing more satisfying than doing the job yourself.


03-25-03, 10:06 PM
Got the half shaft off, and the outer U-Joint had a bad cap. There where NO needle bearings left, just rust! Felt great to find such a bad component. I was guessing it was that U-Joint. Will have pictures up by tommorrow.

I also inspected the other 4 U-Joints (I will be replacing the 2 on the removed half shaft with Spicer Life series. I believe the part number is 5-799X, if someone can check that for me). The U-Joints on the removed half shaft are greasable no name brand. They are not original since they look too new. All of the others are Spicer non-greasable with Spicer Side Yokes. I can tell because they say Spicer right on them. Why did this guy not replace these U-joints with Spicer too? Makes me wonder what other problems I may see in the future for other systems.

I will be adding pictures to my web site of a side yoke in question. It is a Spicer side yoke which looks to have been molded and in one place is very thin, as if the mold was not injected with enough material, which would weaken this side yoke. I compared it to the other side yokes and it does not look the same. It is the side yoke for the other rear wheel. I don't want to shear this thing one day in the future and have major cosmetic and mechanical problems when that half shaft starts flopping around making my deffirential cry momma. So I will be asking you guys what you think about it. I would spring for replacing it, but maybe it is still good, I'll leave the link to the pictures as soon as I get the site up. Probably by tommorrow.

In the mean time I am waiting for the Spicer U-Joints and the two strap kits to arrive. Then I will put everything back together.

By the way, the bolts were 5/16" and not 1/4". I have an automatic. So I guess I will be putting the 1/4" back in. I really see no need to move up to 5/16" if I am only going to torque them down to automatic specs.


03-26-03, 05:44 PM
Wow... looks like you caught it just in time! The first time it happened to me, it was also the needle bearings either gone or fractured due to a cracked cup. Second time it happened, I didn't catch it in time and wham! Guess you saw the pics... I didn't replace them all the first time, and also used greaseable ujoints made by Federal Mogul. I tried to reach them to complain, but impossible... Then I went to Brute Force solids, but after hearing a few stories of those snapping, I changed to the Spicer solids (along with changing everything to the 4-speed version with larger ujoints). The Brute Force may be OK with stock motors, but in my case, that 405 ft lbs of torque is a killer, especially with a hard hitting 700R4!

You mentioned 5/16th, but the bolt is still 1/4", and the head takes a 6 point 5/16th socket. The 12pt heads were original, so it may have been changed at some point. The first time I replaced mine, I ordered replacement bolts, and the 5/16th (heads) is what arrived. Probably a better head than the 12pt 1/4". Either way, the torque is the same. The 4-speed cars have 5/16" threads and heads.

The part number on the spicer's for the automatic cars is SPL25-1X, but one of the boxes had a hand written # of SPL22-1X, so I'm not positve which is right. I heard Spicer did make some part number changes though.

Guess the only other thing I'd recommend is that you replace all the ujoints... Now. Never know, ya know....

03-26-03, 08:25 PM
My Spicer parts came in $56.46 for two U-Joints and two strap kits (each has the two straps and the four bolts, all are 5/16" heads). When I ordered the two U-joints I did not know what part number to use, so I let the sales guy tell me what I needed for an 81 corvette. He came back with a part number of 5-799x for the U-Joints. I have looked everywhere, on Spicer's web site, Dana's web site, and can not find this part number. I called Spicer in Toledo and a guy told me that 5-799X is a part number for a U-Joint. But are these correct, I look on Spicer's spec sheet for these part numbers, for the Spicer Life series U-Joints your part number of SPL25-1X shows up.

They look like Spicer Life series U-Joints. On the box the printed 5-799X part number is there, and the bar code with 5-799X is there. Pictures will be up in about an hour.


03-26-03, 09:48 PM
Here'a a link to a pic I took of the Spicer solid ujoints http://www.c3vettes.com/spicer_man_auto.jpg You can see the difference between the manual and auto tranny versions. The smaller one was only used on the 80 & 81 automatic cars. The '82's went back to the larger ujoints. When I replaced mine to use the larger ujoints, I had to replace the side yokes, halfshafts and the one-piece flanges. I found used flanges and halfshafts that I reconditioned, but went with reconditioned side yokes that had new hardened tips. I also replaced the diffferential center pin with a hardened unit.

Let us know how it turns out! :beer

03-26-03, 11:40 PM
The new Spicers are the wrong size, too big for my small 81 automatic. I put the Spicers up to the originals I just pulled out of the car and the Spicers are a little bigger, :( . I knew when I relied on the service guy's knowledge over the phone it would be wrong. Now I need to ship these back and get the smaller ones, I will be shipping one of the original end caps with them so he gets it right. Well, it really was my fault for not questioning how he knew these would fit my car.

Man, it was going to be a great weekend for driving too. Now I'll just have to get a six pack and hang out in the garage.


03-27-03, 07:41 AM
Go here to see pictures of what I am talking about,


I will be sending these Spicers back to get the correct size. Hopefully by tommorrow I will be up and running.


03-27-03, 09:15 AM
hmmm I went to BZ Auto here in Modesto, (it's been around since Moby Dick was a minnow) and got "Brute Strength" U-Joints they carried them in stock.. I would venture a guess that NAPA or most of the other local Parts house's carry the size you need in stock..

Just a thought ;)

03-27-03, 01:41 PM
Thanks, I have looked into it, and could get my U-Joints from local Autozones/Napa type outlets, but after researching I kinda became partial to Spicer. Not that any other U-Joint wouldn't do the same job, I really want to see how these hold up over time. I have Spicers everywhere else I noticed.

I am waiting to hear back from Heavy Duty Parts and Equipment in Harrahan, LA. The local Spicer vendor.

03-27-03, 07:58 PM
1981, I replaced all the u-joints in my 4 -speed - driveshaft & halfshafts not to long ago. I got mine thru the local NAPA and they were the SPICER brand, so you may want to check with them. If they don't stock them , they should be able to get them within a day or two. Zane

03-28-03, 07:45 AM
Thanks, next time I will probably go that route. Would be easier.

I heard back from the local vendor and got everything straight. Gave him all measurements so that he could properly get me the right Spicer Joints. I should get the new Spicer Joints today. In fact the guy told me that these were only $17.90 each rather than the others being $22.60. So there will be a credit to my account! The confusion was that he thought 1981 only had one type of Joint like the '82s. Well, she ought to be back together by tommorrow, I am having a local corvette restore shop press the old/new joints out of/into the half shaft. Man, I really don't like having my car 4 pointed in my garage this long. It just ain't natural ya'll!


Paul Borowski
03-28-03, 08:56 AM
Just the opposite happened to me doing the u-joints on my 4spd '80. I was given six of the "smaller" automatic u-joints. Went back to the Corvette shop where I bought them and was told "no Corvette ever came with two different size u-joints":duh So much for Corvette "experts":( I believe the gymkhana suspension option cars of '81 & '82 MAY have also come with the larger half-shaft u-joints.

03-28-03, 09:06 AM

My 81 has smaller U-Joints on the propeller shaft than on the two half shafts ;) (it's a 4-speed)


03-30-03, 10:47 AM
My 79 auto., gymkhana susp., also has smaller u-joints on the propeller shaft than the half shafts.
The corvette mechanics up here ( Canada ) recommended greasable u-joints. Used TRW heavy duty from NAPA (there house brand is made by TRW). I see alot of people here prefer the solid or non-greasable type.

07-07-04, 09:57 AM
Brake system contamination

The single most common brake system failure caused by a contaminant is swelling of the rubber components (piston seals etc.) due to the introduction of petroleum based products (motor oil, power steering fluid, mineral oil etc.) A small amount is enough to do major damage. Flushing with mineral spirits is enough to cause a complete system failure in a short time. I suspect this is what has happened when some BMW owners changed to DOT 5 (and then assumed that silicone caused the problem). Flushing with alcohol also causes problems. BMW brake systems should be flushed only with DOT 3 or 4.

If silicone is introduced into an older brake system, the silicone will latch unto the sludge generated by gradual component deterioration and create a gelatin like goop which will attract more crud and eventually plug up metering orifices or cause pistons to stick. If you have already changed to DOT 5, don't compound your initial mistake and change back. Silicone is very tenacious stuff and you will never get it all out of your system. Just change the fluid regularly. For those who race using silicone fluid, I recommend that you crack the bleed screws before each racing session to insure that there is no water in the calipers.


07-08-04, 09:36 AM
I had the exact same problem and my guy at that time charged just as much.