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TR4/4A Where to mount MSD box on TR4/4A

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Darrell_Walker

Darrell_Walker

Jedi Knight
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For those of you with a TR4 or 4A and an MSD (or similar) box, where did you decide to mount it? I'd like to put it on the distributor side of the engine, but can't find a good place to mount. It fits nicely over the passenger foot well (where the master cylinders would be on a RHD car), but that means a long run for the connections to the distributor/coil (but a short run for the power connections).
 
Darrell,
I have a TR3 and I put my MSD6 in the glove compartment and there is still plenty of room for other items. Short run to the power and longer run to the dizzy but the wires follow the main branch into the engine bay.
Makes things look a bit more stock.
 
Hmm, had not considered inside the passenger compartment, I'll have to look around there a bit. I don't think it would fit in the glove box, either the TR4 has a smaller box, or my MSD is bigger. No worries about keeping my engine compartment looking stock, that bridge was burnt long ago!
 
Well, I have not yet found any better place than the firewall area on the passenger side. According to the instructions: "The trigger wires should be routed separate from the other wires...". I believe the mean the white wire (for a points system). I'd like to run all of the wires together (the two to the coil as well as the trigger wire), has anyone else done that and had any problems?
 
My coil/trigger run together basically but not exactly wound as single unit/ just give some space (i.e. opposite side of the same grommet/wire bunch)
 
I have a TR6 and mounted mine on the Drives side wheel arch but made an angle bracket so it was mounted somewhat horizontal. Also read the instructions about a diode you need to install inline on one of the wires so you dont get power feeding back to the coil and the car runs on, I had that problem and the diode solved it

Hondo
 
hondo402000 said:
I have a TR6 and mounted mine on the Drives side wheel arch but made an angle bracket so it was mounted somewhat horizontal.
Click to expand...

Thanks, Hondo. Do you have any pictures handy?

I've also considered removing the windshield washer bottle, then I could mount it vertically on the side of the engine compartment. Even though the pump sort of works, I never use it, but for some reason I'm reluctant to take it out.

-Darrell
 
Dunno if this would work on a TR4; but on a TR3 there is quite a bit of wasted space behind the dash and to the left of the steering column (on a LHS car). I've got several boxes mounted there and I believe there would be plenty of room for a MSD. And the kick panel is double-walled, so you can put (short) sheet metal screws into it without anything showing.
 
Thanks for the idea, Randall. I believe the layout is a bit different, but it looks like I could mount it to the left of the pedals, pretty much "under" the wiper motor. That would leave the unit upside down, which they say not to do because of drainage, but that hopefully won't be an issue under there!
 
hondo402000 said:
Also read the instructions about a diode you need to install inline on one of the wires so you dont get power feeding back to the coil and the car runs on, I had that problem and the diode solved it
Click to expand...

I've read those instructions, but it isn't clear what I should do. I have installed an alternator (3-wire, internally regulated). Where would the diode go? They also talk about a resistor inline with the small red wire, but the picture is showing a ballast resistor.
 
MSD presents two different solutions; one uses a diode and the other uses a ballast resistor. The ballast resistor approach is simpler and requires no modifications to the car's wiring; but my preference would be for using the diode (which is what I did). That resistor is going to get hot and waste energy. Not much, of course, but why waste even .0001% of what could go to the wheels ? /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

The diode goes in series with the wire from the alternator to the warning light on the dash. Ideally it should be supported at both ends, but I just taped it to one of the other alternator wires for support (after soldering the connections and putting heat shrink tubing over the connections and diode).
 
Darrell_Walker said:
That would leave the unit upside down, which they say not to do because of drainage, but that hopefully won't be an issue under there!
Click to expand...
Well, I have to say I'd take their advice, especially if I lived near Vancouver. It's possible for dew to form inside the box (as it's not hermetically sealed). If you can't find a vertical surface, then just use some long bolts and clamp the top of the MSD against the bottom of the panel.
 
TR3driver said:
Darrell_Walker said:
That would leave the unit upside down, which they say not to do because of drainage, but that hopefully won't be an issue under there!
Click to expand...
Well, I have to say I'd take their advice, especially if I lived near Vancouver. It's possible for dew to form inside the box (as it's not hermetically sealed). If you can't find a vertical surface, then just use some long bolts and clamp the top of the MSD against the bottom of the panel.
Click to expand...

There doesn't appear to be any drain holes in the bottom, but you might be right that it isn't sealed either. I found this bracket that I could use:

https://store.summitracing.com/partdetail.asp?autofilter=1&part=SME%2D2804&N=700+115&autoview=sku

Should be easy enough to fab my own version.

-Darrell
 
TR3driver said:
The diode goes in series with the wire from the alternator to the warning light on the dash. Ideally it should be supported at both ends, but I just taped it to one of the other alternator wires for support (after soldering the connections and putting heat shrink tubing over the connections and diode).
Click to expand...

Man, I don't want to cut up my pretty new alternator wiring! It should work any where in the path between lamp and the alternator, right? Then I could hide it under the dash.

-Darrell
 
Darrell_Walker said:
Man, I don't want to cut up my pretty new alternator wiring! It should work any where in the path between lamp and the alternator, right? Then I could hide it under the dash.
Click to expand...
Sure, no problem. Just be sure to support the wire so it can't vibrate and strain the diode.
 
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