dot 5.1 vs dot 4

29-06-2004, 12:17 PM

I just bought some dot 5.1 to top up my clutch and brakes levels.
I though i got it wrong at first, because the bike markings specify something like 3-5. i looked through the archives and an old post seemed to confirmed that dot 5 was not compatible with dot 4, and screwed your seals.
So i got back to the shop today to exchange. They told me that they dont do dot 4 anymore, and that dot 5.1 is the replacement. They promised it will be compatible with dot 4 and wont damage my seals.
so, i am a trusting guy... (famous last words)
any comments ?

07-07-2004, 12:40 PM

I got some dot 4 fluid without any problem just a couple of weeks ago.......
maybe it was old stock.

I'd get a second opinion from a Duke dealer/mechanic, just to be on the safe side.

spacemonkey · 07-07-2004, 03:06 PM

DOT 5 is the silicone stuff. I never heard of it damaging seals etc, but it can't me mixed with normal glycol fluids at all. The whole system needs to be emptied then well flushed with the new if you're gonna change. Advantages are that it isn't hydroscopic and has a much higher boiling point ergo it doesn't need changing anywhere near as often as 'normal' fluids. And it won't damage paintwork either. perfect..

11-07-2004, 02:03 PM

You MUST not use the silicon fluid, It WILL DESTROY YOUR SEALS,have a look here www.tawvehicle.com/technotes.htm there was also a guy on Yahoo MV site who put the stuff in all 6 of his bikes believing it was the thing to do--as did I--he went f*****g crazy with me untill I re-bled and flushed the stuff out, It cost him nearly $1000 to replace seals and cylinders etc--
**************IF YOU HAVE IT IN FLUSH IT NOW****************

11-07-2004, 05:58 PM

If i may just say, it is the 5.1 i have, not the 5. I think they are very different.

11-07-2004, 08:23 PM

Just done a quick google and came up with this

http://www.motorspot.com/dot51.html

The Motul one there (dot 5.1) is non silicon base.

11-07-2004, 08:41 PM

5.1 is OK, It`s the 5.0-and it`s normally purple to distinguish it from "normal" fluid-destroys seals in brembo stuff, the lad I spoke to on Yahoo said all his brakes/master cylinders (6 bikes worth)the lot were solid due to the seals swelling, I even rang the dot 5 importer and he said it was OK to use it, then I read that "taw" web site I mentioned and drained and flushed the lot, I`d done both my MV and S4R, imagine the expense replacing that lot-not to mention it would have taken about 6 years to get any spares for the MV

spacemonkey · 12-07-2004, 08:14 PM

Interesting.... but I thought that silicone and rubber were safe together, so what gives? Do Brembo use some special monkey rubber or something?

12-07-2004, 08:21 PM

it's special italian rubber to go next the special italian wiring that goes with the special italian engine paint

12-07-2004, 09:07 PM

I cant understand why anyones changing fluid on a bike thats less than a year old anyhow!??!!

Steve Willmott · 12-07-2004, 09:57 PM

Guys don't worry about using silicon fluid

I have had it in my monster for 5 years and had it in my jap bike for a couple of years before that and all the rubbers are perfect, infact I just gave a m8 who has a 900ss the top seals from my master cylinders (I got some fancy radial m/cyls) because his were swollen so bad he couldn't get them back in & that is with dot4 fluid.
Steve

13-07-2004, 08:32 AM

B. All brembo braking products use natural-rubber base seals, and therefore are INCOMPATIBLE with DOT-5 SILICONE-based brake fluids. DOT- 5 SILICONE-based fluids react with natural-rubber seals to swell them WHICH CAN CAUSE SEVERE PISTON RETRACTION PROBLEMS. There is no cure for problems caused by DOT- 5 use other than complete seals replacement - USE ONLY DOT-3/4 NON-SILICONE TYPE FLUIDS such as CASTROLTM 'LMA' in your brembo components.(Yes, we know the cap on the rectangular master cylinders says "DOT 3 - 5 Fluids"-BUT PLEASE NOTE: Silicone DOT- 5 fluids are NOT generally in use in Europe, but Glycol-based â€œDOT-5.1â€ fluids ARE. Hence, the â€œDOT-5â€ cap designation). For best braking performance, we recommend changing brake fluid twice a year. If the machine is to be stored in a damp environment (over the winter, say), we recommend installing fresh fluid before and after the storage period. At minimum service levels, glycol brake fluids MUST be completely changed at intervals not to exceed a period of 18 months.

This is from "brembo".......The people who make your brakes-thats my last word on the subject

29-06-2004, 12:17 PM	#1
stef Guest Posts: n/a	dot 5.1 vs dot 4 I just bought some dot 5.1 to top up my clutch and brakes levels. I though i got it wrong at first, because the bike markings specify something like 3-5. i looked through the archives and an old post seemed to confirmed that dot 5 was not compatible with dot 4, and screwed your seals. So i got back to the shop today to exchange. They told me that they dont do dot 4 anymore, and that dot 5.1 is the replacement. They promised it will be compatible with dot 4 and wont damage my seals. so, i am a trusting guy... (famous last words) any comments ?

07-07-2004, 03:06 PM	#3
spacemonkey I see dead people. Join Date: May 2003 Location: Carving a slice thru the braindead masses..(pun intended) Bike: M900 Posts: 1,464	DOT 5 is the silicone stuff. I never heard of it damaging seals etc, but it can't me mixed with normal glycol fluids at all. The whole system needs to be emptied then well flushed with the new if you're gonna change. Advantages are that it isn't hydroscopic and has a much higher boiling point ergo it doesn't need changing anywhere near as often as 'normal' fluids. And it won't damage paintwork either. perfect.. __________________ http://www.jasperfforde.com/swindon/7wonders.html

11-07-2004, 02:03 PM	#4
mikef4uk Guest Posts: n/a	You MUST not use the silicon fluid, It WILL DESTROY YOUR SEALS,have a look here www.tawvehicle.com/technotes.htm there was also a guy on Yahoo MV site who put the stuff in all 6 of his bikes believing it was the thing to do--as did I--he went f***g crazy with me untill I re-bled and flushed the stuff out, It cost him nearly $1000 to replace seals and cylinders etc-- **********IF YOU HAVE IT IN FLUSH IT NOW************** Last edited by mikef4uk; 11-07-2004 at 02:05 PM..

12-07-2004, 08:14 PM	#8
spacemonkey I see dead people. Join Date: May 2003 Location: Carving a slice thru the braindead masses..(pun intended) Bike: M900 Posts: 1,464	Interesting.... but I thought that silicone and rubber were safe together, so what gives? Do Brembo use some special monkey rubber or something? __________________ http://www.jasperfforde.com/swindon/7wonders.html

12-07-2004, 09:57 PM	#11
Steve Willmott Junior Member Join Date: Sep 2002 Location: Stevenage Bike: M900 Posts: 61	Silicon dot5 fluid Guys don't worry about using silicon fluid I have had it in my monster for 5 years and had it in my jap bike for a couple of years before that and all the rubbers are perfect, infact I just gave a m8 who has a 900ss the top seals from my master cylinders (I got some fancy radial m/cyls) because his were swollen so bad he couldn't get them back in & that is with dot4 fluid. Steve

07-07-2004, 12:40 PM	#2
Tigerlily Guest Posts: n/a	I got some dot 4 fluid without any problem just a couple of weeks ago....... maybe it was old stock. I'd get a second opinion from a Duke dealer/mechanic, just to be on the safe side.

11-07-2004, 05:58 PM	#5
stef Guest Posts: n/a	If i may just say, it is the 5.1 i have, not the 5. I think they are very different.

11-07-2004, 08:23 PM	#6
Rabbit Guest Posts: n/a	Just done a quick google and came up with this http://www.motorspot.com/dot51.html The Motul one there (dot 5.1) is non silicon base.

11-07-2004, 08:41 PM	#7
mikef4uk Guest Posts: n/a	5.1 is OK, It`s the 5.0-and it`s normally purple to distinguish it from "normal" fluid-destroys seals in brembo stuff, the lad I spoke to on Yahoo said all his brakes/master cylinders (6 bikes worth)the lot were solid due to the seals swelling, I even rang the dot 5 importer and he said it was OK to use it, then I read that "taw" web site I mentioned and drained and flushed the lot, I`d done both my MV and S4R, imagine the expense replacing that lot-not to mention it would have taken about 6 years to get any spares for the MV

12-07-2004, 08:21 PM	#9
Nigel C Guest Posts: n/a	it's special italian rubber to go next the special italian wiring that goes with the special italian engine paint

12-07-2004, 09:07 PM	#10
Duncan Guest Posts: n/a	I cant understand why anyones changing fluid on a bike thats less than a year old anyhow!??!!

13-07-2004, 08:32 AM	#12
mikef4uk Guest Posts: n/a	B. All brembo braking products use natural-rubber base seals, and therefore are INCOMPATIBLE with DOT-5 SILICONE-based brake fluids. DOT- 5 SILICONE-based fluids react with natural-rubber seals to swell them WHICH CAN CAUSE SEVERE PISTON RETRACTION PROBLEMS. There is no cure for problems caused by DOT- 5 use other than complete seals replacement - USE ONLY DOT-3/4 NON-SILICONE TYPE FLUIDS such as CASTROLTM 'LMA' in your brembo components.(Yes, we know the cap on the rectangular master cylinders says "DOT 3 - 5 Fluids"-BUT PLEASE NOTE: Silicone DOT- 5 fluids are NOT generally in use in Europe, but Glycol-based â€œDOT-5.1â€ fluids ARE. Hence, the â€œDOT-5â€ cap designation). For best braking performance, we recommend changing brake fluid twice a year. If the machine is to be stored in a damp environment (over the winter, say), we recommend installing fresh fluid before and after the storage period. At minimum service levels, glycol brake fluids MUST be completely changed at intervals not to exceed a period of 18 months. This is from "brembo".......The people who make your brakes-thats my last word on the subject