DOT4 or DOT5 for my brakes?

[Cortez]

While this might be better suited to a tech section of the forum
(and please move the message if needed), it's related to my scoot so..


To make a long story short, my manual and brake fluid reservoir caps
say "use dot 4 only".

My mechanic (...) says "You got ABS brakes, you should use DOT 5."

Should I really?

I can obviously google the differences, but WHY does he insist on using
DOT 5, and again, why does the manual stress the importance of using
DOT 4 ONLY more then once?

What could happen?

[S/W]

The manufacturer is the expert of choice, use Dot 4.

[Cortez]

Originally Posted by S/W

The manufacturer is the expert of choice, use Dot 4.

I forgot to mention that I'm, of course, gonna trust the manufacturer on this
one, but I'm curious to the exact differences and possible issues if going with
the DOT5.

Just like with the oil recommendations in the manual, most will use "better"
oil then the manual calls for (which again might not be a good idea but
we'll never know for sure).

[ragtoplvr]

You need a new mechanic, NOW

Dot 5 is silicone, and will mess things up. There is a Dot 5.1 that is glycol based like dot 3 and dot 4. It can be used BUT

it is different
It does not meet the same specifications.

If there is silicone Dot 5 in there you need to start to flush it all out NOW

Rod

[Cortez]

Originally Posted by ragtoplvr

You need a new mechanic, NOW

I've heard that one before.

Originally Posted by ragtoplvr

Dot 5 is silicone, and will mess things up. There is a Dot 5.1 that is glycol based like dot 3 and dot 4. It can be used BUT
it is different
It does not meet the same specifications.
If there is silicone Dot 5 in there you need to start to flush it all out NOW
Rod

I'm the kind of person that'll ask before doing anything, so, there's DOT4
in the brake lines still..

Waiting for EBC HH pads to arrive and will do the fluid at the same time so
I just wanted to make sure.

Thanks!

[Cortez]

My manual also states that I should use the same tire pressures when
I'm riding alone, and when with passenger or both + fully loaded up
which makes no sense to me, so that's why I'm questioning everything.

[MotoRandy123]

Why the heck did they call it DOT 5 and DOT 5.1? Seems easy to make a mistake.

Very few vehicles use DOT 5, I think some Harley's do...

[Cortez]

Originally Posted by MotoRandy123

Why the heck did they call it DOT 5 and DOT 5.1? Seems easy to make a mistake.

Very few vehicles use DOT 5, I think some Harley's do...

That's also a valid WTF.
Maybe my mechanic meant 5.1.

[JerryH]

Never use DOT 5 in anything it didn't come in. It will mess up the entire braking system. The differences between DOT 3, DOT 4, and Dot 5.1 are the boiling point. They are all interchangeable. Unless you are racing, you are unlikely to ever overheat even DOT 3. I use DOT 3 in my '95 Goldwing, for both the brakes and clutch, and have never had an issue with it, even though Honda recommends DOT 4. DOT 4 is a LOT more expensive than DOT 3, and when I first got the bike it needed some brake work. While doing that I went through about a gallon of DOT 3, and then intended to switch to DOT 4 after I got everything rebuilt, but never did. DOT 4 should be good for any kind of street ridden scooter or motorcycle.

[Cortez]

Originally Posted by JerryH

Never use DOT 5 in anything it didn't come in. It will mess up the entire braking system. The differences between DOT 3, DOT 4, and Dot 5.1 are the boiling point. They are all interchangeable. Unless you are racing, you are unlikely to ever overheat even DOT 3. I use DOT 3 in my '95 Goldwing, for both the brakes and clutch, and have never had an issue with it, even though Honda recommends DOT 4. DOT 4 is a LOT more expensive than DOT 3, and when I first got the bike it needed some brake work. While doing that I went through about a gallon of DOT 3, and then intended to switch to DOT 4 after I got everything rebuilt, but never did. DOT 4 should be good for any kind of street ridden scooter or motorcycle.

Cool, thanks.

I'll probably stick with DOT4.

It's a heavy scooter, I'm heavy, and it has a small single disc up front
so any kind of help is nice, and I like being able to do a "sporty" ride when
I feel like it without having to worry about cooking up the brakes.

Waiting for EBC HH pads to come and I'll do the fluid swap then.

Thanks everyone!

[JerryH]

The boiling point for DOT 4 is higher than I can imagine any non racing bike ever reaching. As for the pads, I'm not familiar with "HH" pads, I use EBC organic pads on all my bikes, including the Goldwing. I found out a long time ago that metallic pads will eat rotors like crazy. I don't know what the rotors cost on your scooter, but they are over $300 apiece on my Goldwing.


As far as the tire pressure thing, all tires have a "max" pressure molded into the sidewall, and I use that pressure under all conditions, no matter what the load. Tire companies are probably the most sued vehicle component manufacturers there are. You can bet they would not recommend something unsafe. There is in fact a fairly large safety margin above that pressure. I have also found tires seem to last longer at the max recommended pressure. There are a couple of dual sport bikes I know about that are known to have weak wheels, mostly due to the materials they are made out of. When you run really low pressures in the tires, it allows the spoked wheels to flex a lot, and they eventually start to come apart. I own one of those bikes, with 30,000+ miles on it, and have never has wheel problems, and I believe there are 2 reasons for that. One, I keep the tires properly inflated, and two, I do not ride it like an MX bike.

Since I weigh 220 pounds, plus gear and cargo, I always keep the tires on all 3 of my scooters inflated to "max" These are small scooters, with 10" and 12" wheels. Two 125s and a 150. I found the rear tires on my Vino 125, with 24,000 miles on it, last about 6,000 miles, while the fronts last more than twice that. I have heard many much lighter people claim tires lasting less than 4,000 miles in the rear. Just guessing, but I figure they were using the tire pressures listed in the manual rather than on the tire.

[Paul Mihalka]

"I don't know what the rotors cost on your scooter, but they are over $300 apiece on my Goldwing."

As I picked up on Ebay a spare rear wheel for my Majesty, I got a brand new EBC rotor to make the wheel complete, for $67 + shipping.
AS I am coming from the BMW world, I love Yamaha parts prices.

[Cortez]

Originally Posted by JerryH

The boiling point for DOT 4 is higher than I can imagine any non racing bike ever reaching. As for the pads, I'm not familiar with "HH" pads, I use EBC organic pads on all my bikes, including the Goldwing. I found out a long time ago that metallic pads will eat rotors like crazy. I don't know what the rotors cost on your scooter, but they are over $300 apiece on my Goldwing.


As far as the tire pressure thing, all tires have a "max" pressure molded into the sidewall, and I use that pressure under all conditions, no matter what the load. Tire companies are probably the most sued vehicle component manufacturers there are. You can bet they would not recommend something unsafe. There is in fact a fairly large safety margin above that pressure. I have also found tires seem to last longer at the max recommended pressure. There are a couple of dual sport bikes I know about that are known to have weak wheels, mostly due to the materials they are made out of. When you run really low pressures in the tires, it allows the spoked wheels to flex a lot, and they eventually start to come apart. I own one of those bikes, with 30,000+ miles on it, and have never has wheel problems, and I believe there are 2 reasons for that. One, I keep the tires properly inflated, and two, I do not ride it like an MX bike.

Since I weigh 220 pounds, plus gear and cargo, I always keep the tires on all 3 of my scooters inflated to "max" These are small scooters, with 10" and 12" wheels. Two 125s and a 150. I found the rear tires on my Vino 125, with 24,000 miles on it, last about 6,000 miles, while the fronts last more than twice that. I have heard many much lighter people claim tires lasting less than 4,000 miles in the rear. Just guessing, but I figure they were using the tire pressures listed in the manual rather than on the tire.

I hope you're not riding aggressively or that might get you into trouble.

Even 10% more then recommended up front on any of the bikes I owned
resulted in less grip in corners and braking.

Bicycle tires for example have a HUGE margin of different pressures that
can be used, and if you like grip and being safe, you don't go to the max.

Of course they last longer, you're riding on a tiny section of it.

[Cortez]

Originally Posted by Paul Mihalka

"I don't know what the rotors cost on your scooter, but they are over $300 apiece on my Goldwing."

As I picked up on Ebay a spare rear wheel for my Majesty, I got a brand new EBC rotor to make the wheel complete, for $67 + shipping.
AS I am coming from the BMW world, I love Yamaha parts prices.

+1

There's a bunch of aftermarket rotors out there that usually cost less then
some bicycle rotors (TSW for example).