Bond007

Hello Vetteheads, As promised here is my experience with Dot 5. Two weeks ago I asked people about their experiences with silicone based brake fluids and also the Dot 3 users and struggled with which way to go , it was difficult to decide because of the conflicting opinions and past experiences, however, I decided to go with the Dot 5 only because:

1. I replaced all the calipers, pads,rubber brake lines, rotors, master cylinder, so I essentially started with a new system.

2. Also I was drawn to the opinion that it would preserve the piston and sleeves better when stored in an unheated garage like I do during the winter months.

I ran air and alcohol through the steel line and proportinate valve. Before I ran Dot 5 through the calipers I bench bled the master cylinder hooked it up,then let it drain through the rubber hoses into glass jars via gravity until I saw no moisture seperation between the silicone and any foreign material or residual alcohol in the glass jar, I did NOT reuse the silicone. I then hooked up the lines to the calipers and bled until I got a steady stream of drops and no air. I MUST admit to all of you that I am NOT very happy with the firmness of the pedal as I was warned by some that this would happen. It is not that I have any concerns about stopping, however,but with a complete new brake system I am disappointed with the results. I expected to be able to SPIKE the brakes and get rubber if needed to but it doesn't happen ,but it will stop but not as soon as I had expected it to. So now that I have bared my SOUL if anyone can maybe help me improve on what I have, by doing something I haven't done, I would certainly appreciate it. I really do no want to drain my $40 brake fluid out and have a hellacious time flushing through everthing to try and get it out , then put DOT 3 in and still have a problem. I just may have to live with it, and chaulk it up to a weak moment in judgement. Thank All of you for the help.

Peter :flag


[Modified by Bond007, 9:41 PM 7/5/2002]


[Modified by Bond007, 3:11 AM 7/6/2002]

Bond007

No takers??????

mrvette

Bond, make sure you have checked for true running rotors, especially in the rear, because if you left the spring in place behind the caliper pistons, they will 'pump' with the excessive rotor wobble, and induce air in the system....
so I am told dot5 will hold air in suspension....frankly I can't see HOW, but that's what I"m told....MY car has what I"d call significant rear rotor wobble, allways did, I left out the springs and everything has been fine...for 6+ years now, redoing the stainless calipers I bought the car with...
I have found the pedal to be a bit softer, but in fact it's still enough to lock them up in a panic on dry roads....I know this....

GENE

jerryp58

Sounds like you were very careful & precise with the whole process, but all I can think of is: Did you follow any break-in procedures for the rotors / pads? The last set of pads I had put on a Toyota, I was told to baby them for the first 100 miles with slow, smooth stops. I did and have had no problems with them. I can't remember how I broke-in the pads I put on the Corvette :crazy: They'll stop on a dime but they squeak like mad.

I'm sure you don't want to, but you could always try another bleeding.

Good Luck.

Matt Gruber

Bond
i had negative comments, but Tom454 offered good advice and i am now neutral. It seems the previous owner blew unfiltered air thru the lines, causing water to collect in my calipers, and doing damage. Had tom454 installed the dot5, i'm sure it would be OK.
To get a harder pedal my car has SS braided brake hoses; they are said to expand less and give a firmer pedal.
Also, i would let the car sit and re-gravity bleed the next day to get more air out. Do not touch the pedal; don't churn things up.
The pedal was OK when i had dot 5, after the 2nd bleeding.
Whatever you do don't switch back to dot4. i did that and it was awful 'cause it caused a green slime to collect in the calipers even tho i rebult every caliper, andflushed 1 gallon, the old lines could not be cleaned out; but you could try roto-rooter :lol:

Tom454

Quote: 1. I replaced all the calipers, pads,rubber brake lines, rotors, master cylinder, so I essentially started with a new system.

Master Cylinders can be junk right out of the box. Several members have posted recently about receiving both new & rebuilt M/C's that did not function correctly. This includes multiple products from the same vendor and/or source. I, too, have had this happen many times.

I also took some DOT 5 and shook it up to induce air bubbles... they do seem to stay suspended longer than in DOT 3/4, but they still float to the top and dissipate. They do not STAY suspended.

I have DOT 5 in my 66 manual brake (single cylinder) Vette.... and it has a harder pedal than my 70 dual cylinder brakes with DOT 3. The DOT 3 70 had a MASSIVE amount of sludge in it, as compared to my DOT 5 66 which had virtually none after 16 years of service.

Since I am currently converting my 70 to DOT 5, I am also in the middle of a "mushy" pedal situation with this car..... but I do not attribute it to DOT 5 since my 66 has a pedal that is as hard as a rock.

The 70 had one front hose that had a bulge, and one rear hose that was collapsed internally. Gravity bleeding didn't work, tipping me off to the collapsed hose.

I also had one leaky stainless sleeved front caliper piston.

I tried to use a honed M/C, but it won't hold pressure (mushy pedal) so I am obtaining another M/C or having the original sleeved in stainless.

I replaced all 4 brake hoses with new rubber hoses, rebuilt all 4 calipers, disassembled the proportioning valve and cleaned it out. With the M/C I used (the original 1970 unit) with new internals (Bendix), and I still had a mushy pedal.

I fabricated plugs for the ports on the master cylinder out of brake tubing & fittings bought at a local parts store. Cut off a 2 inch end, leave the fitting on it, and flatten the tubing in a vise to seal it off. The two M/C ports have different sizes on a 70, so two different size plugs had to be made. Using theses plugs, you can isolate the M/C from the rest of the system to see where the "mush" is coming from. Bench bleed the master cylinder, install the plugs instead of the brake lines, and test the pedal. This test will also show you how hard the pedal can feel when the rest of the system is up to par.
If the pedal is hard, then the M/C is not at fault. Remove one plug and connect the line. Bleed & test that side of the system. By this process of elimination you can narrow the problem down.

I also noticed that the front caliper sleeve work is of extremely poor quality. The rears (done by SSBC and returned to me) are of much higher qulity workmanship than the poorly done fronts. I don't know who did the fronts because they were on the car when I bought it. I may trash them.

And finally, I bought the caliper kits at Auto Zone for $8 front, $7 rear (el cheapo) and compared the quality of the parts to NAPA parts. The NAPA parts are much better quality... seals more pliant, and dust seals fit tight in the bores. One Auto Zone dust boot fell out.... the NAPA one stayed in.

I'm also working on an 80 Vette with the same mushy pedal. I expect to have that one in my "shop" all of this week. It has a new M/C (not rebuilt) from ZIP, new hoses, and new sleeved calipers... with DOT 3. We shall see.
It has new rear bearings etc & new rotors, but much runout, so I am shimming them this week.
Bottom line... from my experience, DOT 5 will produce a very firm pedal and will not permanently retain air bubbles. The trick is finding parts that are manufactured properly with tight tolerances. This seems to be next to impossible. There is junk on the shelves everywhere.

Paul L

My experience with DOT5 has been excellent. And it has been three years since the job was done. I started with the SS caliper and new hose kit from Eckler's. That kit included the DOT5. I purchased SS brake lines and brass junction fittings from Mid-Am. And finished off with organic pads from Muskegon Brake to eliminate squealing. BTW, this after much good advice from Forum members.

No flush was needed as all parts were new. Bleeding was done in an order suggested by a member but I forget the sequence. My pedal is firm and the fluid in the master cylinder remains crystal clear. I can certainly lock up the wheels as some yahoo in a Toyota Corolla who ran a red light can attest to! Missed him by that much....In other words I am very pleased with DOT5. And it is not hydroscopic nor does it damage paint.

Barry's70LT1

Just another supporter of DOT 5. Original MC (rebuilt), new rubber lines and SS calipers about 12 years ago. FIRM brakes !!

Something I do when bleeding, is to use a small rubber hammer to gently tap all lines and calipers. Air bubbles like to attach themselves to things and this will dislodge them.
I don't really know if it does any good, but figure it can't hurt.

Look inside a glass of beer, there are many tiny bubbles attached to the glass. Tap the glass and they float to the top.

yellow 72

The post by Bond007 could have been written by me. I've been chasing the mushy pedal gremlin for years, but recently I put this thing up on stands and decided I'm going to leave it there till it's right.
I too thought the soft pedal was due to the dot 5 but after reading some of these testimonials I see that's simply not true. I have bled them in every posible way...three times.
I will be watching these threads for any help and if I happen to make any discoveries I'll pass them on :cheers:

Bond007

Thanks everyone, any updates I come across will also share.

Peter :cheers: :flag