After finally getting my instrument panel issues sorted out, my vette has been fine for the past 2 months. It's been a daily driver up until a week ago.

Yesterday, after sitting for 5-6 days, the brakes were hard to apply. I pulled the vacuum line off the front side of the booster (at the check valve?) and verified vacuum was present at idle. The sun went down, it got cold, and I quit for the night.

I've read about others having bad check valves, so I'll check that next. Is that the only vacuum connection on the booster assembly, or are there others under or behind it? Assuming the check valve is good am I looking at a definite booster replacement?

It just seems odd that everything was fine one day, it sat for a few, and now the brakes are giving me fits.

Addendum...

I forgot to mention that I noticed fluid leaking at the rear of the master cylinder onto the front side of the brake booster, let me guess, I've got a back M/C as well, and it leaked fluid into the booster?? :-(

I recently had a booster issue. Replaced the check valve hoping for a quick fix. No luck. Had to replace the booster. Should have just done it in the first place. And yup, it just happened overnight. One day fine next day stiff.Hopefully a booster guru will chime in soon and help you a little with more in depth analysis.

The two could be related... or not... there is a chance that the fluid go in there and damaged the diaphram...

I would suck it up and replace both components...

Also, consider the bias spring whilst you are at it.

Thanks for the insight guys. Andy, I've heard of the bias spring somewhere along the line. I'll do some digging on that as well. Merry Christmas to all!

Do you have headers? The #7 cylinder throws allot of heat at our LT1 plastic booster and cracks them. I put heat shield cloth on my booster to keep the header heat off of the booster. I lost my brakes on a rather large hill, called Tantalus here in Hawaii. Was not fun.
Probably overkill on how far I went, but you can kinda see in the picture what I did.
[IMG]http://i33.photobucket.com/albums/d80/Steve40th/Engine12.jpg[/IMG]

If you do replace the booster, get a metal replacement - that's the way to go unless you care about NCRS, etc.

Also the bias spring like Andy said - you can get it from Doug Rippie Motorsports.

Matthew

No, I don't have headers. Save for the Opti-direct ignition system, she's all stock. I was doing some work in Kaneohe Bay a couple years ago. The roads out there were awesome, wished I had my vette with me instead of the Pontiac G6 rental. :tongue10:

Glad to hear nothing bad happened when you lost your brakes!

Quote:

I couldn't agree with this more. I replaced the booster twice only for it to go bad again. I now have a metal booster and have no problems. Just order a brake booster for a 1984 corvette. They are metal. If you order one for 1985 on up, it will be plastic.

The DRM brake bias spring is also a nice upgrade, I'm glad I did mine.

My oem plastic brake booster is 25 years old and still running strong. It's seen a few track days and countless canyon runs.

305*F+ oil temps and no heat shields on the stock headers but I haven't fried it yet.

Well, Kevin, I'm glad yours has held up, but there are thousands that haven't. And heat doesn't help them survive.

I ordered my metal one off the internet, I think from piratejack.net for around $125.

Matthew

After reading all of the advice to order a metal booster, I special ordered (ahem...a non-metal one I'm afraid) from Autozone (part number 54-71405) on Christmas Eve thinking it would get here by the following Monday. Between the shipping delay and unseasonably cold weather in north Florida, I didn't get started on this project until this week.

Getting the old unit out was tougher than I thought it would be thanks to the diagonal-running brace right in front of the booster. Getting the studs of the new unit to go through the firewall bolt holes was a royal PITA thanks to the metal plate under the dash dropping down about half the width of the holes in the firewall.

I bought a set of metric swivel sockets (part number 34446, well worth the $54 price for a set of 7) from Sears this afternoon. A 13mm swivel socket and a drop of cyanoacrylate (aka superglue for RC planes) held the nut in place on the socket and went on the interior booster studs with ease.

Hooking up the booster rod linkage to the brake pedal is another matter entirely. It appears that the Autozone booster's linkage rod is approximately 1/4" shorter than on the old unit. I also wasn't able to get the rod to slip completely over the peg on the brake pedal.

I didn't see anything in the instructions regarding adjusting the length of the linkage. I gave it a rest for the night and wanted to see if anyone else has encountered this issue and if I'm overlooking something simple. Aside from, "next time buy a metal unit :-)", does anyone have a helpful hint or two?

Thanks,
Rick

Quote:

Yep, I agree. Don't think the plastic v.s. metal makes much difference. Problems are usually internal.

The linkage rod is adjustable by screwing it in or out. At least on my booster it was. You need to install the booster and then, if the rod isn't the right length, screw it in or out to get it where you need it. You want the brake pedal to be all the way up or almost all the way up when hooked up to the rod. Rod too long and it will be applying brakes even when you aren't touching the brake pedal. Rod too short and your brake lights will be on all the time. Not an exact science, being within a few turns either way should be fine, just make sure what I mentioned above isn't happening.

If you work at it a little and pry fairly gently, the rod should slip over the peg. A touch of soap or liquid dish detergent on the peg will help it go on just a little easier.

I think he's referring to the rod on the pedal side, that's a different part.

Quote:

being in Calif, your not running long tubes though right?

stock headers. If anything, coated long tubes would put off less heat.

Quote:

You are correct, I don't know if the hole in the booster rod is too small, but I have been getting my butt kicked trying to put it on the peg on the brake pedal. I've removed the nuts to give myself some more play and still can't get the dang thing on. Plus, I'm having a much harder time removing the replacement booster thanks to the diagonal running square tube in front of the booster.

In all the threads I've come across, no one else has made mention of this tube, I'm beginning to wonder if the "minor" accident my vette was in with a previous owner bent something out of shape. I'm an experienced shade tree mechanic but I'm ready to have it towed to a shop to pay someone else to get frustrated with it.

I'm pretty sure that brace is removeable.

It took a 16 year old flexible step-son to get the rod back on the pedal. If I EVER have to replace the booster again I'll be taking it to the shop.

It was a royal PITA to get the nuts back on.

Good luck. Right now I'm trying to figure out if I want to tackle the clutch master and slave or take it to the shop.

I was able to reach one of the mounting bolts on the bottom of the aforementioned brace. Removing that bolt made all the difference in the world as far as providing more room to reposition the booster.

I tried in vain to install the rod on the brake pedal with the booster bolted in place. I finally relented and pushed the booster studs back through the firewall and managed to get the pedal connected. This was after beveling the edge of the hole in the pushrod a bit and it was still a PITA to get it on the pedal.

The 13mm swivel socket from Sears was a lifesaver to get the nuts back on the booster studs. If it ever needs to be replaced again, I'll still do it, but I won't like it a bit. Thanks to all who offered help and listened to my rants along the way.