Thermal grease will do no good for a rectifier

I just got done redoing ALL of my electrical charging system. Stator, rectifier and wiring. All new.

Now, before someone comes chiming in about that thermal grease and ground wires :beatdeadhorse: let me explain why I said what I did:

I put in a new Ricks stator. I wired it up straight w/o plugs in the middle to a 2009 Yamaha R1 MOSFET-type rectifier. Used Eastern Beaver plug kit to connect that to the battery direct (30amp fuse in-line) and ground to the battery and frame and engine. All grounds were cleaned (the frame is anodized, so that HAS TO BE scraped off in order to get a good ground). Die-electric grease was used throught. Voltage gauge is hooked up to the battery. It all works and works right.

The previous owner had used that thermal grease on the backside of the last rectifier he put in. Now, my observations of the rectifier this weekend was to ride a few hours, then got off the bike and took the seat off and felt how hot to the touch the rectifier was. It was pretty hot...couldn't keep my fingers on it for long. But here's the thing: If thermal grease is to be used as a heat sink to get the heat out of the rectifier, then where is it going to go? I ask becasue my WHOLE SUBFRAME was the same hot to the touch as the rectifier! Everything metal on that side was HOT, and I really don't think that it's from the rectifier, as the wiring was NOT hot. Repeat: The wiring was fine...not hot at all.

So, in my non-scientific observation of my personal bike, the thermal grease isn't going to do much in an enviroment that is NOT condusive to getting rid of heat. Maybe even take some of the heat from the subframe and put it in the rectifier itself!

No, I am not going to wire up a computer fan, as blowing hot air in a hot enviroment w/o an intake and exhaust of that said hot air is fruitless. That's why computers use an intake of fresh air and an exhaust of hot air with the aid of a computer fan. Otherwise, it seems to me it'll do no good.

If the subframe area around that rear exhaust is getting as hot as the frame on that right side is, making the rectifier get hot in the process, then what good will thermal grease do? None, IMHO.

Anyhow, I have a spare rectifier on the bike just in case and the new charging system worked perfect for the 400 miles I rode, so it's all set to go on a long trip next week to Utah.

The heat that the VFR puts out is a problem and everything metal soaks up that heat. Same as my buddies 6th gen on the frame...very hot.

Really, I think spacing the rectifier away from contacting the subframe would do more for heat dissipation than the grease would ever do, as you would have two smaller contact points to draw heat from and a little air between the backside of the rectifier and the subframe.

Heat will always transfer from the hotest spot to the colder spot. The frame on my 95 gets hotter then the r/r ever should. The 1st time I had to replace mine it had thermal paste on it. I was like wtf why would they even try to use this hot frame right near the exhuast as heatsink for the r/r. Now if you put a ton of thermal paste it could act to slow the transfer of heat instead of helping it, but then your r/r would have to be mounted loose to keep the gap or it would just squeeze it all out.

the thermal grease acts as a conductor to transfer the heat of the RR to the metal frame, which is the heat sink. even if the the frame is hot, the RR is hotter and the heat flows from it to the frame. so, it isn't the grease that sinks the heat, it just makes the conduction of heat more efficient.

I know all about how a heatsink works. and the frame is hotter then the r/r it is not taking any heat away from the r/r it is transfering into the r/r. Maybe during the winter or cool days the frame might be a good heatsink not in the summer. Take your r/r off the frame run the bike around and then sit in traffic. Take a temp measurement of the frame and the r/r see which is hotter.

BTW, If you add too much thermal paste it becomes a insulator not good for transfering heat.

[image: View Post]rchecks, on 10 September 2010 - 12:06 AM, said:

Take a temp measurement of the frame and the r/r see which is hotter.
I think your observations of "relative heat" are incorrect, but why don't you do that experiment and report back to us? An infrared thermo will do the trick, or unbolt the RR and let it hang by its wires and see how long it lasts.

I think you'll find that if you take the RR off the frame, it will get very hot. You won't feel it on the cooling fins, but if you touch that smooth mounting surface where the thermal grease should be....it's damn hot! Much hotter than the frame would be from overall transfered engine/exhaust heat.

The RR's total heat is "small" thermally, but much higher than ambient frame heat. You can bet that frame is absorbing the high heat of the RR. Think of the RR's heat in terms of a cigarette lighter: You wouldn't stick your finger in that flame for very long, but that lighter would never warm the frame of a bike (except in a very small area, maybe). And the guts of the RR wouldn't like that lighter flame for very long, either.

The very first mod I made to my VFR was to mount a little computer fan to my RR. Five years later......all is good in my charging system.
http://i127.photobucket.com/albums/p127/TracyValsi/RRFanInstall-1.jpg

Anyway, I suggest that VFRD members don't rush out to their bikes and clean that thermal grease off the back of their RRs! :goofy:

[image: View Post]btl68, on 09 September 2010 - 11:28 PM, said:

Everything metal on that side was HOT, and I really don't think that it's from the rectifier,

No, I am not going to wire up a computer fan, as blowing hot air in a hot enviroment w/o an intake and exhaust of that said hot air is fruitless.

I came to the same conclusions and opted to relocate the RR to a cooler place. It now sits above the rear wheel on top of a passive cooler. Here is a HOWTO that describes what I did, it is in Dutch but I think the pics speak for themselves.

[image: View Post]rchecks, on 10 September 2010 - 12:06 AM, said:

Take a temp measurement of the frame and the r/r see which is hotter.

That's what I did and although the frame gets hot (120+) the RR heats up even more, I measured temps up to 165F.
The relocated RR now gets to a little over 100F.

I didnot use thermal grease between the r/r and the frame but the r/r and the heatsink........ :biggrin:


http://i113.photobucket.com/albums/n206/Dutchy_748/HPIM1890.jpg
(pre VFRness upgrade)

[image: View Post]V4 Rosso, on 10 September 2010 - 04:40 AM, said:

I came to the same conclusions and opted to relocate the RR to a cooler place. It now sits above the rear wheel on top of a passive cooler. Here is a HOWTO that describes what I did, it is in Dutch but I think the pics speak for themselves.


You have to be a member there to see the post... any chance you might translate it and post it here as well?

Ah, I didn't know that. I thought most of that forum was open to everyone.
I'll put an english translation up here somewhere.

[image: View Post]V4 Rosso, on 10 September 2010 - 04:40 AM, said:

[image: View Post]btl68, on 09 September 2010 - 11:28 PM, said:

Everything metal on that side was HOT, and I really don't think that it's from the rectifier,

No, I am not going to wire up a computer fan, as blowing hot air in a hot enviroment w/o an intake and exhaust of that said hot air is fruitless.

I came to the same conclusions and opted to relocate the RR to a cooler place. It now sits above the rear wheel on top of a passive cooler. Here is a HOWTO that describes what I did, it is in Dutch but I think the pics speak for themselves.

[image: View Post]rchecks, on 10 September 2010 - 12:06 AM, said:

Take a temp measurement of the frame and the r/r see which is hotter.

That's what I did and although the frame gets hot (120+) the RR heats up even more, I measured temps up to 165F.
The relocated RR now gets to a little over 100F.


Funny, I've checked mine several times and my frame, after a ride, has always been a lot hotter than the R/R. I'm guessing if I went down the the interstate for 10 miles or more pulled off, and quick measured, the frame might be the cooler of the two. Before I get to the house to measure, I have to troll along at 30 mph for a couple miles, so I'm guessing that is heating the frame pretty good.

Here's my question. If the frame is getting hotter than the R/R, then doesn't that mean that the frame is getting heated from some heat source? So what's heating up the subframe? Probably isn't the exhaust since it's out on the side (3/4th gen). Some might be from the engine, but not THAT much. So what's heating up the subframe in that spot if it isn't the R/R?

[image: View Post]YoshiHNS, on 10 September 2010 - 10:30 AM, said:

So what's heating up the subframe in that spot if it isn't the R/R?

Uhhh......the R/R? :laughing6-hehe:



I tell ya...the guy who originally came up with the idea of putting a little computer fan back there is a friggin' genius (VFRD or not). There used to be a how-to for that here, but it's so easy to describe:
1. Drill a few holes in the fins so you can ziptie the four corners of the fan to the R/R.
2. Find a switched source of power for the fan. It can be as simple as splicing into the taillight wire, cuz the fan draws so little current.
3. Find a convenient grounding location (there are plenty in the subframe area!).
3. Done. :fing02:

I have been asked this question more times than I can remember...there are a few things to keep in mind:

90-97 VFR locates the R/R on the right side, where they also have complaints (90-93 anyway) of hot legs....so there is heat directed at that spot from the motor or exhaust? The CBR that uses the same R/R benefits from adding an aluminum plate to help sink the heat.
98-01 VFR locates the R/R on the left side...overheating here is not usually an issue unless the R/R is bad, and then it overheats anyway.
02-09 VFR locates the R/R under the front fairing, and I have NEVER heard of the R/R being too hot to touch. Additionally, it doesn't even mount flush to the frame like the 90-97 models do, so it wouldn't heat sink well.

Thermal paste is meant to fill in tiny imperfections in the mating surfaces of processors and heat sinks...it insulates better than it conducts, but it conducts better than air pockets, thus the reason it is used. Thermal paste should be applied in a very thin coat when used.

The 90-97 R/R is a seriously underpowered unit, and generates a lot of heat usually. Running a fan will help to cool it, as long as the air is cooler than the R/R. A fan however should NOT be required (but won't in most cases hurt anything).

If I had a 90-97 VFR, my first consideration would be relocating the R/R, and using a better one...newer VFR unit that is Mosfet, or R1 unit (connectors for these are a pain, and I like a clean install). I would mount mine in the front, since that has been a good location for the 6th gens.

[image: View Post]Tightwad, on 10 September 2010 - 11:41 AM, said:

If I had a 90-97 VFR, my first consideration would be relocating the R/R, and using a better one...newer VFR unit that is Mosfet, or R1 unit (connectors for these are a pain, and I like a clean install). I would mount mine in the front, since that has been a good location for the 6th gens.
Eastern Beaver has the exact plugs needed for the newest MOSFET installs from the latest model R1's. ZX10's and ZX14's and even the CBR1000's. I bought a kit from him and it got here in a week from Japan. Perfect, clean installation.

http://www.easternbe...connectors.html





As for the installation of the whole mess, I read this thread on triumphrat.net...explains the charging system perfectly and what you can do to make it better...

http://www.triumphra...or-upgrade.html

This page will also tell you what years R1 (2007-up) and others will be MOSFET-type R/R's...older than 2007 are still shunt-types and get hotter.

[image: View Post]YoshiHNS, on 10 September 2010 - 10:30 AM, said:

Here's my question. If the frame is getting hotter than the R/R, then doesn't that mean that the frame is getting heated from some heat source? So what's heating up the subframe? Probably isn't the exhaust since it's out on the side (3/4th gen). Some might be from the engine, but not THAT much. So what's heating up the subframe in that spot if it isn't the R/R?
IMHO, look at the massive heat shielding on the right hand side of the frame/subframe area on a 3rd gen. Even those cast-in vents on the rear of the frame itself (3rd gen only) are COVERED on the right hand side with a heat shield due to the pipes being so close to the framing there. Plus, the cylinder head just about touches the rear part of the frame there on both sides...I just think they stuffed 6 pounds of crap into a 5 pound bag with this bike and the heat is poorly managed.

[image: View Post]btl68, on 10 September 2010 - 01:41 PM, said:

just think they stuffed 6 pounds of crap into a 5 pound bag with this bike and the heat is poorly managed.


You have 20 years hindsight here........ we are afterall talking about a bike design 20+ years old.... :biggrin:

[image: View Post]Dutchy, on 10 September 2010 - 04:43 PM, said:

[image: View Post]btl68, on 10 September 2010 - 01:41 PM, said:

just think they stuffed 6 pounds of crap into a 5 pound bag with this bike and the heat is poorly managed.


You have 20 years hindsight here........ we are afterall talking about a bike design 20+ years old.... :biggrin:

I know... :biggrin:

Only Hondas I have ever owned before were from the 70's. I have been a Kawasaki guy for decades. Only had this VFR for a year and I really haven't played too much with it until recently.

[image: View Post]btl68, on 10 September 2010 - 01:41 PM, said:

[image: View Post]YoshiHNS, on 10 September 2010 - 10:30 AM, said:

Here's my question. If the frame is getting hotter than the R/R, then doesn't that mean that the frame is getting heated from some heat source? So what's heating up the subframe? Probably isn't the exhaust since it's out on the side (3/4th gen). Some might be from the engine, but not THAT much. So what's heating up the subframe in that spot if it isn't the R/R?
IMHO, look at the massive heat shielding on the right hand side of the frame/subframe area on a 3rd gen. Even those cast-in vents on the rear of the frame itself (3rd gen only) are COVERED on the right hand side with a heat shield due to the pipes being so close to the framing there. Plus, the cylinder head just about touches the rear part of the frame there on both sides...I just think they stuffed 6 pounds of crap into a 5 pound bag with this bike and the heat is poorly managed.


Guess the point I was trying to make was that the R/R was dissipating heat to the subframe, which is better than not dissipating it anywhere. There's going to be a temperature difference between the heatsink, and the actual R/R unit. Not sure how much airflow goes on between the subframe and the plastic, but I can't imagine it's very much, so I'm not sure if lifting it from the frame is going to do it any favors, or keep the subframe any cooler since you say on the 3rd gen you have all those other things heating the subframe up.

[image: View Post]Trace, on 10 September 2010 - 11:17 AM, said:

[image: View Post]YoshiHNS, on 10 September 2010 - 10:30 AM, said:

So what's heating up the subframe in that spot if it isn't the R/R?

Uhhh......the R/R? :laughing6-hehe:



I tell ya...the guy who originally came up with the idea of putting a little computer fan back there is a friggin' genius (VFRD or not). There used to be a how-to for that here, but it's so easy to describe:
1. Drill a few holes in the fins so you can ziptie the four corners of the fan to the R/R.
2. Find a switched source of power for the fan. It can be as simple as splicing into the taillight wire, cuz the fan draws so little current.
3. Find a convenient grounding location (there are plenty in the subframe area!).
3. Done. :fing02:




Trace, is your fan blowing against the R/R or blowing away from it? In an enclosed area like the tail I doubt it makes any difference but was just curious.

On a related topic, I was walking to my car at work and came across some old computer equipment discarded on the sidewalk as you see on most city streets these days. One thing that caught my eye was computer ICU chip cooler with copper heat tubes going from a ICU chip mounting plate to a "radiator" box with a computer fan on it. I always wondered if this cooling system will work for our RRs if I mount it on the coolling plate....with some thermal silicone grease on it......
The heat tube cooler still works as it got pretty cold when I plugged the system into a 12V source.
Anyone try this yet?

Beck
95 VFR

the cylinder head just about touches the rear part of the frame there on both sides. this is the same with the 6th gen altho its only on the right side.and atleast on that side of the bike a 20min ride will get the frame too hot to tuch.so i would say honda didnt learn diddly in the 20 years between the 3rd gen and the 6th gen.

[image: View Post]dutchinterceptor, on 10 September 2010 - 05:41 PM, said:

Trace, is your fan blowing against the R/R or blowing away from it?
Well....that is a very personal question, don't you think? :blush:

But since I just got off the thing a few minutes ago...after visiting sevreral purveyors of boozy beverages...and because it's hot as hell here in Ponte Vedra Beach, Flor-a-dee, I will tell you!

It blows into the fins, which also means it doesn't suck.

These little 12V computer fans are free for the taking in every rubished computer in the world. And they'll run forever and a day, moving lots of air against your RR's cooling fins. It's win-win from every aspect!! :fing02:

[image: View Post]Beck, on 10 September 2010 - 06:17 PM, said:

On a related topic, I was walking to my car at work and came across some old computer equipment discarded on the sidewalk as you see on most city streets these days. One thing that caught my eye was computer ICU chip cooler with copper heat tubes going from a ICU chip mounting plate to a "radiator" box with a computer fan on it. I always wondered if this cooling system will work for our RRs if I mount it on the coolling plate....with some thermal silicone grease on it......
The heat tube cooler still works as it got pretty cold when I plugged the system into a 12V source.
Anyone try this yet?

Beck
95 VFR



that would be a "heatpipe"style cpu cooler


http://en.wikipedia....omputer_cooling

if you can get it mounted, it is free, go for it! and post pics :biggrin:

Let 'er breathe! 7 wire Gixxer r/r along with its OEM bracket mounted to the lower triple.

http://www.vfrdiscussion.com/forum/uploads/1284150097/gallery_611_2920_217626.jpg
KG9K6452.jpg

[image: View Post]FotoMoto, on 11 September 2010 - 10:13 AM, said:

Let 'er breathe! 7 wire Gixxer r/r along with its OEM bracket mounted to the lower triple.

http://www.vfrdiscussion.com/forum/uploads/1284150097/gallery_611_2920_217626.jpg
KG9K6452.jpg

Is that a MOSFET-type or shunt-type rectifier?

How hot does it get after a 1/2 hour ride?

Interesting location...fins are oriented in a totally illogical way to work efficiently though.

I re-wired the entire charging system and moved the r/r years ago on my '96 750. The r/r now lives up the front of the bike, below the LHS of the instrument cluster (opposite whre the fuse box is). I re-wired everything from the stator out including stator --> r/r and r/r --> battery. The r/r is a 5-wire unit from the early series Yam R1. All this rig-up is now 5 years old and nothing has gone wrong (touch wood), and the r/r never gets hot enough that I can't touch it, even in mid-summer temperatures in Sydney in traffic (high 90sF). On the odd occasion I take the front fairings off, I check and clean all connections and spray with contact cleaner - routine maintenance in other words.

Previously I'd gone through two r/r untis when they were situated in the OEM position behind the right rear panels (blew the r/r thankfully, not the rest of the circuit and the battery). IMHO CPU fans may help delay the unit's demise, but in the end all they're doing is moving hot air about. An extra benefit of moving the whole shebang (on the 750s at least) is that the stator --> r/r wires no longer go through the V of the engine where the heat from the motor contributes to breakdown of the wires.

I'd link to the three-part write-up I did on this on OZVFR, but that site's been through so many iterations and collapses and now all the galleries and embedded links have gone (for good, it seems), plus you need to be registered there. :angry: When I get a roun tuit I'll repost the whole thing here, but the photos I uploaded HERE should give you an idea of how it worked out.

[image: View Post]Parker, on 11 September 2010 - 05:09 PM, said:

snip* All this rig-up is now 5 years old and nothing has gone wrong (touch wood), *snipHow many miles (or kilometers) in that 5 year span?

[image: View Post]btl68, on 11 September 2010 - 05:49 PM, said:

]How many miles (or kilometers) in that 5 year span?


Probly about 50 000km.

I have a Gen 3 and explained here
http://www.vfrdiscus...__1#entry716234
how I moved my R/R to the front between the forks, just below the oil radiator.

For your information, the R/R now runs "cold" at open road speeds. Obviously the air flow is sufficient to keep it to the current air temperature. If I travel around town in traffic, with stopping and starting, it gets very slightly warm. You can notice that it is warmer than the forks for instance, but only just.

[image: View Post]mobikie, on 11 September 2010 - 11:54 PM, said:

I have a Gen 3 and explained here
http://www.vfrdiscus...__1#entry716234
how I moved my R/R to the front between the forks, just below the oil radiator

Yeah, I had the same idea, when I first did mine, that I got from someone on the old VFR mailing list who'd slotted his there. The problem I had was insufficient clearance to the front mudguard (fender) on full compression of the forks.

Great thread.... :fing02:

[image: View Post]SEBSPEED, on 10 September 2010 - 06:13 AM, said:

You have to be a member there to see the post... any chance you might translate it and post it here as well?

Here it is.

When Honda finally changed the design of the RC36 OEM reg/recs from the potted ones to the finned ones (this was long after production ceased), they included an alloy plate that goes between the frame and the reg/rec. The reason was likely because they decided to no longer rely on the subframe to sink heat away from the reg/rec; instead, the reg/rec was now supposed to be insulated from the subframe and the fins were designed to dissipate the heat into the air. If anyone has a better explanation, I'd like to hear it! :blush:

Ciao,

[image: View Post]JZH, on 19 September 2010 - 01:19 AM, said:

When Honda finally changed the design of the RC36 OEM reg/recs from the potted ones to the finned ones (this was long after production ceased), they included an alloy plate that goes between the frame and the reg/rec. The reason was likely because they decided to no longer rely on the subframe to sink heat away from the reg/rec; instead, the reg/rec was now supposed to be insulated from the subframe and the fins were designed to dissipate the heat into the air. If anyone has a better explanation, I'd like to hear it! :blush:

Ciao,


the fin design is indeed made to bleed heat to the air.. and has been around since the late 1950's
the plate.. made of aluminum..draws the heat faster from the r/r and spreads it to the subframe faster than just the r/r on the subframe.
the back of the vfr R/R used to be silicone.. then they started dying..and after a while honda got a clue.. and switched to the ones that had a better base plate of aluminum with a BIG surface area to spread the heat faster

[image: View Post]gll429, on 20 September 2010 - 01:01 AM, said:

[image: View Post]JZH, on 19 September 2010 - 01:19 AM, said:

When Honda finally changed the design of the RC36 OEM reg/recs from the potted ones to the finned ones (this was long after production ceased), they included an alloy plate that goes between the frame and the reg/rec. The reason was likely because they decided to no longer rely on the subframe to sink heat away from the reg/rec; instead, the reg/rec was now supposed to be insulated from the subframe and the fins were designed to dissipate the heat into the air. If anyone has a better explanation, I'd like to hear it! :blush:

Ciao,


the fin design is indeed made to bleed heat to the air.. and has been around since the late 1950's
the plate.. made of aluminum..draws the heat faster from the r/r and spreads it to the subframe faster than just the r/r on the subframe.
the back of the vfr R/R used to be silicone.. then they started dying..and after a while honda got a clue.. and switched to the ones that had a better base plate of aluminum with a BIG surface area to spread the heat faster

That aluminum plate theory sounds nice, but the newest MOSFET-type Yamaha R1 rectifier has the aluminum plate on the back, but it's mounted to plastic on a stock Yamaha R1.

Explain the heat transer to plastics and how that'd work...










Anyhow, on my 4k trip this past week, I checked the new rectifier after sitting shut down for 5-10 minutes and it was COLD, but the sub-frame and main frame on the exhaust side (right) was still HOT, so I am still standing by the sub-frame receiving it's heat from the rear header pipes that are right next to the sub-frame area. There are heat shields there for a reason...

[image: View Post]gll429, on 20 September 2010 - 01:01 AM, said:

[image: View Post]JZH, on 19 September 2010 - 01:19 AM, said:

When Honda finally changed the design of the RC36 OEM reg/recs from the potted ones to the finned ones (this was long after production ceased), they included an alloy plate that goes between the frame and the reg/rec. The reason was likely because they decided to no longer rely on the subframe to sink heat away from the reg/rec; instead, the reg/rec was now supposed to be insulated from the subframe and the fins were designed to dissipate the heat into the air. If anyone has a better explanation, I'd like to hear it! :blush:

Ciao,


the fin design is indeed made to bleed heat to the air.. and has been around since the late 1950's
the plate.. made of aluminum..draws the heat faster from the r/r and spreads it to the subframe faster than just the r/r on the subframe.
the back of the vfr R/R used to be silicone.. then they started dying..and after a while honda got a clue.. and switched to the ones that had a better base plate of aluminum with a BIG surface area to spread the heat faster

Hmm. Nice try. You're suggesting that an aluminium plate sandwiched between metal objects acts as some kind of "heat accelerator"? Well...

FYI, the old-style OEM reg/recs were solid metal on the back, and potting material on the front (which made them rather unsuitable for fitting PC fans to--not that it stopped anyone...)

Ciao,

[image: View Post]JZH, on 21 September 2010 - 12:41 AM, said:

[image: View Post]gll429, on 20 September 2010 - 01:01 AM, said:

[image: View Post]JZH, on 19 September 2010 - 01:19 AM, said:

When Honda finally changed the design of the RC36 OEM reg/recs from the potted ones to the finned ones (this was long after production ceased), they included an alloy plate that goes between the frame and the reg/rec. The reason was likely because they decided to no longer rely on the subframe to sink heat away from the reg/rec; instead, the reg/rec was now supposed to be insulated from the subframe and the fins were designed to dissipate the heat into the air. If anyone has a better explanation, I'd like to hear it! :blush:

Ciao,


the fin design is indeed made to bleed heat to the air.. and has been around since the late 1950's
the plate.. made of aluminum..draws the heat faster from the r/r and spreads it to the subframe faster than just the r/r on the subframe.
the back of the vfr R/R used to be silicone.. then they started dying..and after a while honda got a clue.. and switched to the ones that had a better base plate of aluminum with a BIG surface area to spread the heat faster

Hmm. Nice try. You're suggesting that an aluminium plate sandwiched between metal objects acts as some kind of "heat accelerator"? Well...

FYI, the old-style OEM reg/recs were solid metal on the back, and potting material on the front (which made them rather unsuitable for fitting PC fans to--not that it stopped anyone...)

Ciao,


nice try??
simple fact.. aluminum heats up and cools faster than steel..
every OEM 83 to 90 R/R i have installed on a vfr had silicone on the back and fins up front.. and as for the guys r1 mounting the R/R to plastic.. something tells me the designer will be up for dumbass of the year awards later. may be the same guy that forgot to add a spot for the battery on the shadow 1100.. forcing them to make a T shaped battery .. ditto for the guy who forgot the batter on the suzuki intruders. and the nut that put the katana fuse box be hind a 15 bolts and a side panel.
in any case.. there is a chance i am wrong.. i mean i learned this stuff in the honda class at MMI from the honda reps from japan . :comp13:

[image: View Post]gll429, on 21 September 2010 - 01:45 AM, said:

simple fact.. aluminum heats up and cools faster than steel..

That is because it can not store as much heat as steel (lower density) so it heats up faster but that doesn't mean it draws heat faster from the RR than steel. In fact, it is just the opposite as heat transfer rates drop between to objects when the temp difference drop.

The aluminum plate may be beneficial when the RR does not have a full metal mounting surface like in the (aftermarket) RR as seen on the left in this pic:
http://www.vfroc.nl/forumVFR/uploads/monthly_09_2010/post-3497-1285056427.jpg
Adding a aluminum plate spreads the heat quickly over a larger surface allowing for more heat to be transferred between the frame and RR (in whatever direction).

[image: View Post]gll429, on 21 September 2010 - 01:45 AM, said:

[image: View Post]JZH, on 21 September 2010 - 12:41 AM, said:

[image: View Post]gll429, on 20 September 2010 - 01:01 AM, said:

[image: View Post]JZH, on 19 September 2010 - 01:19 AM, said:

When Honda finally changed the design of the RC36 OEM reg/recs from the potted ones to the finned ones (this was long after production ceased), they included an alloy plate that goes between the frame and the reg/rec. The reason was likely because they decided to no longer rely on the subframe to sink heat away from the reg/rec; instead, the reg/rec was now supposed to be insulated from the subframe and the fins were designed to dissipate the heat into the air. If anyone has a better explanation, I'd like to hear it! :blush:

Ciao,


the fin design is indeed made to bleed heat to the air.. and has been around since the late 1950's
the plate.. made of aluminum..draws the heat faster from the r/r and spreads it to the subframe faster than just the r/r on the subframe.
the back of the vfr R/R used to be silicone.. then they started dying..and after a while honda got a clue.. and switched to the ones that had a better base plate of aluminum with a BIG surface area to spread the heat faster

Hmm. Nice try. You're suggesting that an aluminium plate sandwiched between metal objects acts as some kind of "heat accelerator"? Well...

FYI, the old-style OEM reg/recs were solid metal on the back, and potting material on the front (which made them rather unsuitable for fitting PC fans to--not that it stopped anyone...)

Ciao,


nice try??
simple fact.. aluminum heats up and cools faster than steel..
every OEM 83 to 90 R/R i have installed on a vfr had silicone on the back and fins up front.. and as for the guys r1 mounting the R/R to plastic.. something tells me the designer will be up for dumbass of the year awards later. may be the same guy that forgot to add a spot for the battery on the shadow 1100.. forcing them to make a T shaped battery .. ditto for the guy who forgot the batter on the suzuki intruders. and the nut that put the katana fuse box be hind a 15 bolts and a side panel.
in any case.. there is a chance i am wrong.. i mean i learned this stuff in the honda class at MMI from the honda reps from japan . :comp13:

I don't know who's wrong, but I'm afraid I still don't see why an alloy plate sandwiched between two metal surfaces would transfer heat better than those two surfaces sandwiched together (leaving aside the heat-transfer paste for the moment). In any case, if heat coming FROM the frame was a problem with the original design, enhancing the heat transfer between the frame and the reg/rec would make matters worse for the reg/rec, too. The fins were part of the re-design of the reg/rec, so it appears that transfer of the reg/rec's heat to the air was part of the new design. That's why I was suggesting that the new alloy plate would most likely have been added to insulate, rather than conduct. Of course, making the plate out of plastic or something like that would have made it a better insulator... I'm still waiting to hear an explanation for the new design reg/rec that takes all of these factors into account (and makes sense!)

Ciao,

[image: View Post]gll429, on 21 September 2010 - 01:45 AM, said:

in any case.. there is a chance i am wrong.. i mean i learned this stuff in the honda class at MMI from the honda reps from japan . :comp13:
Yeah, you learned from the best...the same dumbasses that made the problem we have right now on these HONDA bikes? :blink:

And as for the Yamaha MOSFET-type rectifier...if it doesn't run near as hot (and more efficiently) than the old shunt-types everyone seems to be using, I would suspect it could live well on plastic.

I posted up the solution to the hotter-running shunt-types... http://www.vfrdiscus...ce-and-for-all/

Still, the underlying problem is that the R/R is located in a HOT enviroment and making the R/R try to sink it's heat to the HOT sub-frame is futile. Either relocate the R/R, or get into the newer MOSFET-type R/R's. Circulating HOT air inside a non-vented HOT enviroment will really do nothing. All of these computer fans live in computers that have a COLD AIR INTAKE and a HOT AIR EXHAUST...none of which the VFR right side panel will allow.



If you had your coolant radiator, with it's fan, living in the same hot enviroment as the R/R, with no cool air coming into it's fins and no hot air escaping from it's backside, do you think your bike would run cool for long?

No, it wouldn't.

Same thing applies here with the R/R.

Don't have to have an MMI degree to understand basic physics.

[image: View Post]btl68, on 21 September 2010 - 01:46 PM, said:

[image: View Post]gll429, on 21 September 2010 - 01:45 AM, said:

in any case.. there is a chance i am wrong.. i mean i learned this stuff in the honda class at MMI from the honda reps from japan . :comp13:
Yeah, you learned from the best...the same dumbasses that made the problem we have right now on these HONDA bikes? :blink:





If you had your coolant radiator, with it's fan, living in the same hot enviroment as the R/R, with no cool air coming into it's fins and no hot air escaping from it's backside, do you think your bike would run cool for long?

No, it wouldn't.

Same thing applies here with the R/R.

Don't have to have an MMI degree to understand basic physics.


NOW THAT WAS FUNNY!!! :laughing6-hehe:


there is cool air under the tail, just not good flow.. ergo the fan.. :happy:
bottom line.. the fan does work. its tried and proven method. :+1:

[image: View Post]gll429, on 21 September 2010 - 10:46 PM, said:

NOW THAT WAS FUNNY!!! :laughing6-hehe:


there is cool air under the tail, just not good flow.. ergo the fan.. :happy:
bottom line.. the fan does work. its tried and proven method. :+1:

Yeah, along with that cool sub-frame... :pinocchio:

[image: View Post]gll429, on 21 September 2010 - 10:46 PM, said:

bottom line.. the fan does work. its tried and proven method. :+1:

Sorry, but no one has ever proven that PC fans actually prolong the life of an OEM reg/rec. Loads of theory (some good, some bad), many anecdotes, but no proof whatsoever... :beatdeadhorse:

Ciao,

:lurk:

Id say the pc fan theory is bs there have been many post made by people who's rerulator/rectifier died even with using a pc fan