twinarrow99

Borrowed a Motive Brake pressure bleeder, about to use to replace/ flush my GrandSport. Noticed each caliper has two bleeder screws/nipples. Does it matter which one to use- do you use both? If no difference or minimal gain using both, I would use the outside one, easy to get to. Second question, what DOT3 brake fluid / brand to use for standard street use? TIA.

twinarrow99

Called Motive this afternoon, their recommendation is to bleed using the inner nipple first, outer nipple second for each caliper. Going with that!

jimijam

Inside to outside in the following order
RR
LF
LR
RF

jimijam

Oh yeah, clean DOT 3. Brand means nothing but how much you pay at the counter.

05 Wreck

Always thought farthest to closest to master cylinder was correct order?
RR
LR
RF
LF

twinarrow99

Yep, I thought same 05Wreck!

jimijam

Not on these, but that works for my two 69s.

Jfryjfry

Not exactly true, but not terribly important on a street-only car with appropriate and regular brake fluid changes.

Mike's LS3

Brands do make a difference because some will have higher wet and dry boiling points than others. I use Prestone Dot 4 brake fluid.

Bleed inner then outer for calipers with two bleed screws.

oemtech

Although it has a higher boiling point Dot 4 tends to absorb water at hiher rate than Dot 3.

jimijam

And for the OP's "standard street use" car, DOT 3 is just fine.

Purple92

So - out of curiosity - any particular reason you want to stay with DOT 3 fluid ? DOT 4 fluid is compatible with DOT 3, and has higher wet and dry boiling points than DOT 3. I generally get the Prestone DOT 4 at Wal Mart - it's a bit more expensive than the DOT 3 stuff, but if the cost of brake fluid is really an issue for you - perhaps you might want to reconsider owning a Vette - the tire bill alone is going to be quite unpleasant.... Yes, DOT 3 is perfectly acceptable for normal street use - hence the reason it's a factory fill, but I truthfully can't remember the last time I bought DOT 3 fluid ...

twinarrow99

Purple, no specific reason for sticking with DOT3 here, other than it is what owner manual specs out. Price is not the issue. As for tires, already replaced the RF's with PilotSuper sports along with a few mods. This is my 2nd Vette, well aware of the cost of ownership. Thanks for your sage advice.

Seadawg

The main reason most people stay with DOT 3 is that they only use their vette on the street, and it will last longer (meaning absorb moisture slower) that DOT 4. For street use, I've never heard of anyone "boiling" the brake fluid either, which could happen if you really push it on HDPE events.

I just changed the Motul RBF600 DOT4 with the Prestone synthetic DOT3, since I don't plan on tracking mine anytime soon. I have the Motul pressurizer, and the small bottle that you use at the wheel. I've never put fluid in the Motive bleeder, I just fill the reservoir full, then each time I empty a bottle of dirty fluid, I refill the reservoir.

twinarrow99

Hey Seadawg, many thanks for your post! Exactly my thoughts here, have seen threads stating what you have stated. Going to use the Motive the same way... Appreciate your input!

Purple92

So - I've seen a few instances of brake fluid boiling - it can happen on the street !!! If a caliper piston sticks - the pad rubbing the rotor generates a fair amount of heat, and that heat is transferred thru the piston to the fluid. It happened to me once on an ancient VW - I knew a brake was dragging, but didn't know that fluid boiling was a possibility - or what happens when fluid boils. I learned !!!!!


I guess I've always looked at the higher wet boiling point of DOT 4 as "insurance" in case the fluid absorbs a lot of moisture - and you've been using the brakes aggressively... I'm probably just being overly concerned about nothing, as I try to flush brake fluid in all vehicles every 3 or so years (way more so on stuff being tracked), so the fluid is typically in pretty good shape... But - personally - I'll be sticking to DOT 4....

And yes - I also use the Motive Adapter - but I don't use their pump. I have a 5 gal air tank that I pressurize to about 15 psi - then I just run an air hose to the Motul adapter that I modified to accept a quick connect air fitting.

Mike's LS3

I use Dot 4 for both brakes and clutch master cylinders. GM changed the clutch fluid to Dot 4 from Dot 3. I'll take the higher boiling point for the fun times on the twisty roads and spirited driving. I flush the brake system every 2-3 years so I'm not too worried about moisture, especially since humidity is low where I live. Heck, emergency service vehicles use Dot 4.

BTW: I prefer not to add fluid in the Motive bleeder, just pressurize and add to the reservoir when needed.

pragmatic

What about the new DOT5.1 (DOT5 temperature ratings with a glycol not silicone base fluid)? Its compatible and can be mixed with DOT3 and DOT4 has a higher boiling point and a lower viscosity.

davidfarmer

Preston’s synthetic DOT 4 is my go to fluid. It’s readily available, cheap, and has performed very well for me. I use a pressure cap...I use th pe GM Kent Moore cap...but I bleed with nitrogen.

30 years and I’ve not found the order matters, but the methods above are certainly fine. Important thing is to flush thoroughly and use EVERY bleeder available to get fresh fluid into every nook and cranny