Has anyone tried using the Valvoline synthetic DOTt 4 brake fluid in their hydo. brake systems? This fluid exceeds the current DOT 3 & 4 federal standards and has a higher boiling point. I am just getting set to bleed my Hayes brakes after installing some Goodridge lines and wanted to see if there was any feedback on this. Thanks in advance.
I put them in my Avid Juicy's and seems to work fine.
Honestly I bought it because the auto parts stores really don't carry a wide variety and it seemed closest to what Avid requires (dot 4 or 5.1).
I put them in my Avid Juicy's and seems to work fine.
Honestly I bought it because the auto parts stores really don't carry a wide variety and it seemed closest to what Avid requires (dot 4 or 5.1).
Who told you that? US Hope brakes are filled with MOTUL DOT 5.1, Hope specifies that if you are going to use DOT4 that you flush the system and not just top off with DOT4.
Who told you that? US Hope brakes are filled with MOTUL DOT 5.1, Hope specifies that if you are going to use DOT4 that you flush the system and not just top off with DOT4.
I went ahead and used the Valvoline SynPower Brake Fluid. Absolutely no issues on a 20 mile ride. Don't believe there will be any in the future either. This was for a Hayes HFX-9 system.
Who told you that? US Hope brakes are filled with MOTUL DOT 5.1, Hope specifies that if you are going to use DOT4 that you flush the system and not just top off with DOT4.
Mr. Hope employee who answered the phone at Hope US in Cherry Valley told me.
He said they assemble the brakes in the US and fill them with Valvoline SynPower 3/4.
That's what I bled them with when I put on SS lines this weekend. Works fine.
Really don't know why it would be necessary to completely flush the system when going from one grade of brake fluid to the next-you can add different motor oil weights together, why not brake fluid? If you mixed 5.1 with 3/4 in equal proportions, it'd be 4.3!
I went ahead and used the Valvoline SynPower Brake Fluid. Absolutely no issues on a 20 mile ride. Don't believe there will be any in the future either. This was for a Hayes HFX-9 system.
Mr. Hope employee who answered the phone at Hope US in Cherry Valley told me.
He said they assemble the brakes in the US and fill them with Valvoline SynPower 3/4.
That's what I bled them with when I put on SS lines this weekend. Works fine.
Really don't know why it would be necessary to completely flush the system when going from one grade of brake fluid to the next-you can add different motor oil weights together, why not brake fluid? If you mixed 5.1 with 3/4 in equal proportions, it'd be 4.3!
Well he must have been mistaken, Brake fluid numbers are specification revisions not a measured property (like viscosity) So no, if you mix two brake fluids you do not get the average (ie 4.3) DOT 5 isn't even glycol base like 3,4 and 5.1 (it's silicone based)
I am not a chemist nor a brake designer, however HOPE recommends NOT mixing DOT4 into the system. If you are going to use DOT4 they (not me!) recommend that you flush all of the 5.1 out with 4 first.
I think it is only the UK assembled brakes that come with the DOT 5.1 fluid, it is a lot easier to find this spec in Europe. The US ones are filled with Synpower DOT 4. DOT 3,4 and 5.1 are all compatible with each other, DOT 5 is not.
Asahi had some ATE brake fluid that is DOT 4 rated but has a very high boiling point. If you are boiling your brakes regularly then it may be advisable to go with a higher quality fluid.
Then what does the Hope bleed kit come with? Why would they send 5.1 with the bleed kit and you would not be able to bleed with it until you flush all of the original fluid out?
I think it is only the UK assembled brakes that come with the DOT 5.1 fluid, it is a lot easier to find this spec in Europe. The US ones are filled with Synpower DOT 4. DOT 3,4 and 5.1 are all compatible with each other, DOT 5 is not.
Asahi had some ATE brake fluid that is DOT 4 rated but has a very high boiling point. If you are boiling your brakes regularly then it may be advisable to go with a higher quality fluid.
Most high end motorcycle parts shop and automotive speed shops carry DOT 5.1. (it is use extensively in the US for racing or high performance/extreme conditions applications, MOTUL is the most common brand) Again, I don't know the reason why Hope says not to add in DOT4, but they do. (and they designed and manufactured the brake and specified the fluid) Here is the quote from the service guide:
This Hope disc brake contains DOT 5.1 hydraulic brake fluid which is available from cycle retailers and motor accessory stores. If you cannot obtain DOT 5.1 then DOT 4 is acceptable but you must flush out all the old DOT 5.1 first.
I am not dissing Hope US, but it is a sales office (all Hope is designed and manufactured in the UK). Filling the brakes with DOT4 is fine, but I would take the word of those who designed the brake and flush out the existing fluid. Has anyone been told that it is ok to mix 4.0 and 5.1 fluids by someone at hope US?
BTW anyone trying to figure what spec fluid is in their Hope brakes can use this as a guide; Any brake bought (US or worldwide) that came in the familiar black box (with green writing) would be a UK assembled brake and would contain DOT5.1. Brakes filled in the US come packaged in generic white boxes.
I've been running Hopes for years and the us office told me for the us market they are using Valvoline synthetic because the Dot 5 is hard to find is some areas of the US.
I have and know at least 10 to 15 bikes using this fluid with Hopes with no problem so anyone with Hopes will be fine.
I've been running Hopes for years and the us office told me for the us market they are using Valvoline synthetic because the Dot 5 is hard to find is some areas of the US.
I have and know at least 10 to 15 bikes using this fluid with Hopes with no problem so anyone with Hopes will be fine.
Did anyone here, at any time, say DOT4 would not work in Hope brakes?
BTW I'm (almost) sure you meant to write DOT5.1 in your post, DOT5 is fairly easy to get but a completely different animal from DOT3, 4, or 5.1 (it is silicone based rather than glycol based) and should not be used.
Again understand that most of the Hope brakes sold in the US were filled with DOT5.1 (in the black and green box) only brakes delivered in generic white boxes are filled with DOT4.
So far all of the Hope brakes I have bought/installed/seen while in the US, about 15 brakes, have come in the 'generic white boxes'. Do they sell any UK assembled brakes?
So far all of the Hope brakes I have bought/installed/seen while in the US, about 15 brakes, have come in the 'generic white boxes'. Do they sell any UK assembled brakes?
Yes, from what I understand most of the Mono brakes that have been sold in the US are UK assembled. It is interesting, I have never seen the generic white box. All the Hopes I have seen to date have been the standard black and green box. And some of those have to be recent revisions as they have the new "through the pin" retaining clips rather then the older clip on type. (a hole through the pin rather than a groove)
I use Motul RBF 600 in my Hayes brakes. It makes the brakes work noticably better than standard DOT 4 fluid. It is full synthetic, so the Valvoline may be as good, but I can vouch for the RBF 600 being wickedly more powerful and fade-resistant than DOT 4. It's what the LBS puts in all the tough-guys' brakes. Available at moto shops.
I use Motul RBF 600 in my Hayes brakes. It makes the brakes work noticably better than standard DOT 4 fluid. It is full synthetic, so the Valvoline may be as good, but I can vouch for the RBF 600 being wickedly more powerful and fade-resistant than DOT 4. It's what the LBS puts in all the tough-guys' brakes. Available at moto shops.
Wow, that's pretty spendy for brake fluid! But, it is indeed excellent fluid. I use this in my car which sees track duty, but it is pricey and not much different from the ATE Super Blue (neat blue color) or TYP2000 (identical, except for amber color). I happened to have recently bled the brakes on my car, so I had a small amount of Motul left and used it to bleed my Hope Minis. While it works just fine, I cannot tell the difference between DOT 4 and therefore personally cannot justify purchasing it if I didn't already have it. I think it is overkill (or maybe I just don't ride hard enough?). I think Valvoline syn for ~$5 works just fine. YMMV.
Note on ATE Super Blue and ATE TYP2000: These are identical fluids other than color (blue and amber). This is done to help facilitate a brake fluid change; you'll know when the old fluid is flushed when the color changes. Not a bad idea for bikes, too. Again, this isn't the cheapest stuff, (~$12/liter), but half the cost of Motul (~$12/500mL).
Anyway...just one man's opinion.
BTW, Watermoc, I completely agree with the Motul being more fade-resistant; it has excellent boiling characteristics. But, I'm curious as to the 'wickedly more powerful' claim. How do you mean?
BTW, Watermoc, I completely agree with the Motul being more fade-resistant; it has excellent boiling characteristics. But, I'm curious as to the 'wickedly more powerful' claim. How do you mean?
I second this question/point as well. Why would 5.1 be anymore powerful? Unless you are routinely hitting the dry boiling point of your brakes, using DOT 4, none of this should come into play. I personally have not measured disc pad/rotor/MC temps after long DH runs, but I don't think they are reaching 400F. Maybe, but i really don't know for sure. Yes they get hot, but 400+? DOT 5.1 is for folks that are worried about hitting 550F+ routinely.
Maybe if you weighed 300lbs and did the big runs at Whistler...
What we need is someone with a laser pyrometer living next to a hig DH...
Motul is kind of spendy... are you kidding? You only need to change fluid every few years (5.1 has a longer service life than 4.0) You think 10 or 15 bucks every few years is spendy? (if you DH I would flush every year, but that still only 15 bucks a year) I shudder to think what I spend on biking in a year but I bet it runs in the low-to-mid three figure range.
There is certainly a difference in feel between fluids, anyone involved in motorsport racing can tell you. DOT 5.1 is lower in viscosity (tighter faster, more direct feel) and has lower compressibility so the brakes will feel stronger (firmer.)
Motul is kind of spendy... are you kidding? You only need to change fluid every few years (5.1 has a longer service life than 4.0) You think 10 or 15 bucks every few years is spendy? (if you DH I would flush every year, but that still only 15 bucks a year) I shudder to think what I spend on biking in a year but I bet it runs in the low-to-mid three figure range.
There is certainly a difference in feel between fluids, anyone involved in motorsport racing can tell you. DOT 5.1 is lower in viscosity (tighter faster, more direct feel) and has lower compressibility so the brakes will feel stronger (firmer.)
OK, my Mono Minis came in green and black boxes and have the "R" clip that goes through the retaining pin. I wrote Hope to find out from them what fluid is in the master cylinder and this is what they answered:
In the U.K. we use Dot 5.1. However in the U.S. they use either Dot4 or
the other type you mentioned Valvoline Synpower. All depends what they
can get hold of. As they are all glycol based fluids you can just top up
your brakes if you wish.
Im sorry but I think being concerned about the difference in spending $5 or $12 every three years is kind of silly.
(Particularly if the extra $7 gets you better performance and a longer service life)
I googled compressibility and DOT 5.1 here are the top hits, I'm sure you can get more info if you want to get creative with google. The empirical result is certain however Motul (and other HP 5.1 fluids) has great reputation for "lever feel" (from GP motorcycle racing, but is just as relevant to MTB discs.)
Very interesting and also somewhat confusing. Hope US has told me (numerous times) that in the US ONLY white box brakes are filled with DOT4.
As far as just topping up DOT 5.1 filled brakes with DOT 4. The service manual specifically addresses it as a no no (you are directed to purge the remaining DOT4 with 5.1) This had to be put in for a reason (it 's not like an omission which sometimes slip by in tech pubs) Someone (assumably the engineer in charge of service specifications) specifically put those flush instructions in the manual.
It isn't much money (a few dollars worth of fluid), and if you have the system open it isn't much trouble (no difference at all if you have the bottom up bleed system) so why would you want to go against what is written in the service manual? If you are unsure about the fluid in the system I would always suggest flushing it when adding new fluid.
The long and short is on DOT fluid is: 5.1 is better fluid. (it is by definition a higher specification) it is lower in viscosity than DOT 4 (better lever feel) lasts longer (better service life) and holds up to abuse better (higher stable operating temperatures) and only costs a couple bucks more. Again unless you simply can't find it locally (and don't want to order it) why would you want to use anything else?
Im sorry but I think being concerned about the difference in spending $5 or $12 every three years is kind of silly.
(Particularly if the extra $7 gets you better performance and a longer service life)
I googled compressibility and DOT 5.1 here are the top hits, I'm sure you can get more info if you want to get creative with google. The empirical result is certain however Motul (and other HP 5.1 fluids) has great reputation for "lever feel" (from GP motorcycle racing, but is just as relevant to MTB discs.)
Hmmm...the only thing I found about a specific viscosity figure was in the last link you posted which states:
Viscosity - Here's a really interesting specification. One where the DOT 3 spec could be perceived as actually being better for the micro passages of an ABS system than the DOT 4 spec. Webster's defines "viscosity" as, "Physics, the resistance of a fluid to flowing freely, caused by friction of its molecules." As you may recall from motor oil, the higher the viscosity number, the slower the flow of the oil. Well the same applies for brake fluid although the actual measurement technique is different. The DOT 3 specification for viscosity at -40°F is 1500 mm2/s and the specification for DOT 4 at -40°F is 1800 mm2/s. Yep, that's right, the DOT 3 fluid flows better at the testing temperature than the DOT 4. It should be noted the specification at 212°F for all DOT specifications is 1.5 mm2/s.
I looked for a bit, but I haven't been able to find this empirical result of which you speak.
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