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Rectifier / Regulator Dilema Advice Sought

2K views 12 replies 4 participants last post by  Plasmablaster 
#1 ·
I know, right? Another one of these... Well, I've read through most of them and think this is not a repeat.

The bracket to my old style R/R broke. I ordered a new one and got this new, aluminum style one (see pic). The plan was to just keep this old R/R and put the new bracket in place (gasp!). I have had this R/R for years and it seems to be working fine. I voltage tested it, and no problems.

This new bracket seems to only fit if you have the R/R facing the engine (see pics). The old bracket that broke at least had the R/R facing towards the rear tire, which is maybe why I have had decent life and no problems out of it? That noted, I'm hesitant to put this R/R back in there facing forward because of the heat exposure. So here are my options:

1. Just put it in there facing forward. If it messes up eventually, replace it. The downside here is that I'm already chasing some electrical problems and don't want another variable or failure point introduced. The upside here is that I already have it and want to go ahead and get this bike back together so that I can make the track day next weekend. (I've attached a pic where I make a mock run of installing it.)

2. Find an old style bracket and put it back on. This seems very unlikely as the only few ones I can find on Ebay come with the R/R and make it kind of expensive for just a stupid bracket. ($70+).

3. Get an MOFSET R/R from Ebay (FH012DA / FH012 / etc.) then order the Triumph bracket (T1300047) and Triumph lead/cable (T2500676). I can find an R/R on Ebay for like $30. The two Triumph parts shipped are ~$30. So 60-65 total. Upside: cheap. Downside: waiting on Triumph parts.

4. Get the full Triumph replacement kit for $199 + shipping. Upside: new parts. Downside: expensive.

What do you think?
 

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#2 ·
Since in the old setup the back was metal, its high thermal conductivity would mean that the heat ending up in the R/R directly from the engine (heat transfer through radiation emission) would be roughly equal to a reversed mount. Heat transfer through radiation is (roughly described) primarily a function of the visible area exposed to the radiation and it is about the same either normally mounted or backwards. "Visible" area means the area defined by the outline - in the mathematics involved it doesn't matter if there are grilles or whatever, as long as the outline defines the same visible area.

If you need more insight into this, the total heat received by the unit is an integral: Imagine you divide the engine into very-very small points: each of those points transfers an amount of thermal energy to the R/R through radiation which is a function of how much thermal radiation it emits in total and the visible area of the R/R to that engine point. To make a total estimate of the heat transfer you would have to add the transfer from all those points and hence the integral. It all depends on geometry so given the very similar *visible* geometries between front and back mounts the total heat transfer would be the same.

That said, the lack of a thermal buffer in the reversed setup would certainly mean less time to reach equilibrium temperature which is the temperature at which heat is received and released at the same rate (which is essentially the highest temperature the R/R reaches) so it might mean longer exposure of the R/R to that temperature.

What would be mostly affected is air circulation which is important for the function of the heat sink "grilles". However, given the widely turbulent air flow at the back, it might as well be about the same, but it might also not be - difficult to judge.

So in all I think that probably the heat sinking capabilities might be compromised but not very much.

You could add a heat shield - A piece of plastic of roughly the same shape as the mounting plate which would be bolted-on the same holes where the mounting plates bolt on the frame but facing the other way around - so its vertical surface would stand between the R/R and the engine. You could easily fabricate such a shield very easily out of 2mm polystyrene sheet.
 
#9 ·
I'd try the following in this sequence:

1. Try to modify the new mounting plate to make a normal mount viable.

2. If the above fails, try to make a new one that allows normal mounting.

3. If the above fails try mounting it backwards and see how it goes. Since the alternative is to change everything you've got nothing to lose really. Just check your voltage output regularly after the change in mounting to see that the R/R doesn't play up.

All the above might have some possibility of succeeding so why move directly to the most expensive solution.

Oh - and forget about the plastic heat shield - I checked melting temperatures of polystyrene and acrylic and their degrading temps are at about 100 degrees centigrade, probably low enough for them to create problems. If you are feeling creative, use this stuff:

http://www.ebay.com/itm/EMBOSSED-HE...ash=item25c5b12cb4:g:w4sAAOSwpLNX9wEx&vxp=mtr

to make a heat shield and mount it between the engine and R/R bu forming an L-shaped piece and have it facing backwards. Just make sure it doesn't touch the R/R anywhere apart from the mounting points.
 
#5 ·
Then I might as well replace the whole kit because I would need to do a whole new special wiring scenario. And, anyway, as far as I understand from reading, once you have the new mofset type RR, it handles heat a lot better so you don't have to relocate it.
 
#6 ·
Are you having trouble matching the RR holes up with the hole in the bracket? If so, just drill new holes in the bracket. I had the same problem last month when I relocated mine to the rear. I just drilled a new hole in the bracket and mounted it up, don't over think it. If I miss understood your post then disregard.
 

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#7 ·
Howdy. Thanks for contributing. That's actually not my problem. The rectifier only fits on that bracket facing One Direction because the way the wires come out the top make it so. So the only way to attach it to the bracket it's so that it is facing forward towards the engine. With the old bracket that broke, it used to face backwards towards the tire. I'm worried about it being installed this way causing issues.

You actually have the new style updated RR, by the way. I have the old one. It mounts differently.
 
#10 ·
I went ahead and istalled everything back in using the aluminum bracket that I had a picture of. It's facing towards the engine, but we'll see. I feel like there's a bad batch of those original r/rs, but maybe I got a good one. It's been rocking and rolling for years.

Got it all buttoned up and the bike starts and runs great.
 
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