MR2 Alternator Upgrade?

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BaileySims
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Re: MR2 Alternator Upgrade?

Post by BaileySims »

For those of you who upgraded the alternator, how exactly are you modding the upper bracket to get the belt to tension up on it?
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Re: MR2 Alternator Upgrade?

Post by Abletobecain »

Bump. Fresh pics of that GM set up would be great! Damn Photobucket concealed all the images.
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Abletobecain
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Re: MR2 Alternator Upgrade?

Post by Abletobecain »

I'm also curious if there's anything else you need to do when upgrading the alternator...like to the wiring or whatever?
1977 BMW R100S 1WD ("Brunhilda"/Summer Fun)
1983 DLX Tercel Wagon 4WD ("Charlie"/Daily Driver)
1987 SR5 Tercel Wagon 4WD ("Sprocket"/Off-road-Camping)
1985 SR5 Tercel Wagon 4WD ("Lucky"/Project)
1983 SR5 Tercel Wagon 4WD ("Cadaver"/Parts Car)
1985 Ford F250 6.9IDI ("Franklin"/Hauler)
1987 SR5 Tercel Wagon 4WD ("Ravensburger"/in a million pieces)
2006 BMW 530XI Wagon ("Inga"/Roadtripper)
1969 Mercury Montego MX Convertible ("Big Ed"/My Dad's Old Car)
1983 SR5 Tercel Wagon 4WD ("Al"/for sale soon)
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Re: MR2 Alternator Upgrade?

Post by The Professor »

Abletobecain wrote: Mon Jan 06, 2020 3:31 pm I'm also curious if there's anything else you need to do when upgrading the alternator...like to the wiring or whatever?
It wouldn't hurt to run new cables, considering they're underbuilt and 30+ years old...
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Re: MR2 Alternator Upgrade?

Post by MrWrench »

Reviving this thread. I am heading out on a 3,000 mile road trip soon and would like to upgrade my alternator beforehand. I have a reman 60 amp that runs at 14.4 volts almost always. But when I have the radiator fan on, the blower motor, radio, recently installed electronic fuel pump and the headlights on, the voltage drops below 12.4ish and the fuel pump will kick and die.
I'll likely have up to 3 phones charging and possibly a flashlight via the cigarette outlet too during the trip so having a 100 amp MR2 alternator would be amazing!
Has anybody made an MR2 alternator fit?

I'm wondering if I replaced the wiring with a thicker gauge wire if it would help?
Thanks in advance!
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Re: MR2 Alternator Upgrade?

Post by NWMO »

Good afternoon Luke,

I have replacement EU headlamps to install and some have struggled getting them wired w/o difficulties. I know with the undersized stock wires, voltage drop can become an issue. The common workaround is to use the existing "headlight" wire to "switch" a solenoid that has a larger wire providing battery voltage direct from the battery or ALT. This would help some, but you may also need a larger alternator and associated wiring due to additional electrical loads.

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Re: MR2 Alternator Upgrade?

Post by SinusoidalTendencies »

Ok ya turc'lings.... Mr2 hundo amp alt
Taking the dive, and I'm taking pics
This is on an 87 T4 A/T

Hopefully I don't incapacitate my wip as this is not entirely plug in play if you don't have access to fabrication tools/shop
(aka welding, drilling, cutting stuff)

First impressions
NITRO_55C_01222023_122115.jpg
Bracket needs to come towards the front of the car just a wee to be in front of the tensioning bolt tab
NITRO_55C_01222023_122132.jpg
If you cock it in front of the tab and put the front bolt in the bracket to check alignment you'll see it sits just above the tension bolt hole where the hammer and heat to bend the back mounting tab in seems appropriate
NITRO_55C_01222023_122203.jpg
Possibly of no concern as it's hard to tell by eye, but the belt seems to slightly angle frontwards going to the alt.

One more rib available on the mr2 pulley frontwards so possible that shaving the inner backside tab on the lower bracket could allow for moving the alt back a wee with some washers in front solving the horizontal alignment issue.

Hmmm......to be continued
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Last edited by SinusoidalTendencies on Sun Jan 22, 2023 8:54 pm, edited 1 time in total.
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SinusoidalTendencies
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Re: MR2 Alternator Upgrade?

Post by SinusoidalTendencies »

And .....it's in

NITRO_55C_01222023_150106.jpg
Who needs a vice anyways... Tab bent easy enough with just a hammer...at the first bend, just a wee inwards

Cutting the hole out took forever with a hand file
NITRO_55C_01222023_162031.jpg
Two of those thick head bolt washers was perfect spacing for the front bolt and even though it was still slightly cockeyed bolted in fine with enough belt tension.

Last step was to ream out the positive connection hole as the new post is slightly bigger.
NITRO_55C_01222023_163439.jpg
I usually like to be more precise but I'm satisfied with this so far.
Be aware that your just about slotting out that back bracket tab for room forward. Cutting some of it off and welding to the hoist hook would be an option if you've a welder instead of hand tools

Cheers
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SinusoidalTendencies
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Re: MR2 Alternator Upgrade?

Post by SinusoidalTendencies »

I should report that my battery and temp dash lights are now on constant my first day driving around.
NITRO_55C_01232023_083433.jpg
If I recall from a previous topic this is a sign of an alt going out.

Can anyone confirm? Do they come on from too high a voltage perhaps?
Solutions?

My running voltage with everything on is steady around 14.7v now. Fsm states 15v as the max high end for the terc
NITRO_55C_01232023_112853.jpg
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Re: MR2 Alternator Upgrade?

Post by dlb »

It's usually the battery and brake lights that illuminate when the alternator has failed. Is your car an automatic? I think I've only seen a temp light like that for the auto trans temperature.
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Re: MR2 Alternator Upgrade?

Post by SinusoidalTendencies »

Yep. A/T
The temp and battery (charge) lights both come on on starting and stay on.
Seems odd for the trans to be hot before even the engine so thinking due to the new more powerful alt....but why
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SinusoidalTendencies
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Re: MR2 Alternator Upgrade?

Post by SinusoidalTendencies »

My brake light is on too actually

Was just oblivious to it earlier
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Re: MR2 Alternator Upgrade?

Post by Paul »

I would check the voltage at the battery while its idling. I recently tried adapting a different Denso alternator, and discovered the battery getting hammered with 19 volts. The charge and brake lights were lit. A proper alternator should be at or about 14.5 volts.
Edit :sorry, just saw the meter pic showing good.voltage.
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Re: MR2 Alternator Upgrade?

Post by SinusoidalTendencies »

I've added terminals inside for an inverter and running extra do dadds. My voltmeter spends most of it's time monitoring the tercs battery.
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Re: MR2 Alternator Upgrade?

Post by Paul »

Is your voltage steady with everything off - just idling? I just checked my stock alternator: at idle 14.45v with everything off, 13.1v with the lights and blower fan on high. Something in the regulator puts voltage on the L terminal to light the charge lamp if there is a problem... odd that the brake light comes on too with the manuals.
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