Cold Braking

[bstandley1]

Earlier today, I took advantage of the unseasonably warm Northwest weather (60+ Degrees) and took the Cobra out for a spin. This was my first drive in about 2 1/2 weeks. I pulled out of the garage and descended down the road (very steep) in first gear and as I approached the bottom, started to apply the brakes. The pedal was very firm ... but I wasn't getting much in the way of results. As the heavily traveled intersection was approaching, I was literally standing on the pedal and I heard a loud groan as I came to a complete stop just a few feet from getting t-boned. I waited until no traffic was coming in either direction, pulled out slowly, accelerated to about thirty miles an hour and tested the brakes. They worked fine. I repeated the test several times at increasingly higher rates of speed on a deserted backroad and the brakes worked fine. I've never experienced this problem before and was wondering if any of you folks had some ideas as to what caused this and how to prevent it in the future. Thanks!

Bob

One other fact comes to mind ... it was extremely humid today; the windows completely fogged up when I left the garage.

[ralphscott]

Bob, I'd check the rotors for oil or grease easier to look on the garage floor where the car was or the inside of the front wheels. Other option could be stuck pistons in the calipers. My best guesses...

Ralph

[GeorgiaSnake]

I've experienced the same groan in the rear but not the loss of braking. It only happens when the car has slowed to about 15 mph.

Randy

Unique 289 FIA #2899420
Southern Automotive 396
Team III 16's
Brilliant Silver

[eliminator]

If these cars sit up for any period of time the rear Jag rotors will rust up completely. After the brakes are applied a few times it will remove the surface rust and work OK. As Ralph suggested, check for a bad wheel seal, or other things that can contribute to oil or grease on the rotors. If you do get oil or grease on the pads, discard and get new ones, you cannot wash it out, it penetrates the pads[xx(].

Rick
#4279405

[ralphscott]

The groan in the rear could be the posi unit you need to add containers of posilube to your rear end, if it is a posi.

Ralph

[clinck]

Oh Boy, has this hit a sore spot. I thought that I was the only one that had this horrible death sound coming to a stop at about 15 miles an hour. First time the car made the sound I nearly passed out. Man, I thought the rear end was coming apart but for the fact that the car stopped on command. It's really not cool pulling up to a stop light and have your pristine lttle race car make sounds like a 1967 used, worn out Buick Electra 225 on her way to th scrapyard.
I mentioned it to Alan Weaver and he advised me to check the rotors and pads. I did....saw nothing out of the ordinary. What would I expect to see on a car that has a 1,000 mikes on it.
Then I decided that I wasn't driving it hard enough and that the brakes needed exercise. That has helped some but the car will still make that painful sound occasionally [like when I'm stopping]. It's dry here in Arizona so moisture is not an issue. We average 12%humidity.

If anyone knows what's causing this sound from the jag rearend and can fix it for all of us that hear this extremely unique [no pun]tone. he will please a couple of us on this topic.




Sundown

[bstandley1]

Just a quick update:

I inspected the pads and rotors for grease, etc; found nothing. The rotors appeared to have quite a bit of rust on them so I'm inclined to believe the difficulty in stopping was related to the rust. I drove it again today and had no problem. The next time I let it sit for a couple of weeks before driving, I'm going to apply the brakes in the driveway (about a 75 foot straight away), back it up, and repeat the process before I head down the hill. Thanks for your input!

Bob

[Pete W]

I had a similar problem with the front brakes on my car and found that I had metalic front pads. This caused horrible cold weather braking as those pads are designed to operate best when hot. I switched to a soft pad that I found at my local NAPA store and the problem was solved. Rust on the rotors will definately give you some groaning noises on initial braking .

[souzape]

I have pretty much shared Chris' experience... car occasionally groans heavily as it rolls to a stop. I have followed other threads on this topic and pretty much believe that the problem is the relatively hard compound brake linings on our cars and have confirmed this to my own satisfaction by getting out on a back road and pulling several consecutive hard stops from 70-80 mph to heat the pads up. Sure enough, the groaning goes away. When it comes time to replace the pads I will definitely be looking for some softer pads.

Phil Souza

[clinck]

Ok, So what pads come with the car from the Weaver's shop. The pads on my car are the originals. Are these metallics?



Sundown

[souzape]

Chris- I don't know what the exact composition is on the original pads (I'm sure someone out there knows) but they're much more like racing pads than street pads.

Phil Souza

[eliminator]

Most of all the front pads are performance pads supplied by Wilwood.
If your car produces very little brake dust on a 30-40 mile drive then I would bet the pads are HARD.

Rick
#4279405

[clayfoushee]

Yep, they are Wilwood and marked "off road use only." They are designed for racing and high temp applications. On the positive side, they don't fade................

Wilwood does have several different compounds, but they're probably all harder than typical street pads.

Clay

'98 Unique #9299, 427FE side oiler (452.1-stroker), top-loader (close), 3.31 rear

Annapolis, MD

[eliminator]

You can check with Maurice on the pads, pull your pads and they have the info on them, Wilwood Numbers. Go to Wildwood's web site and you can get pads that are a little softer. I think Uniwue may have some in stock, if not they can get them for you.

Rick
#4279405