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swapping from 37 amp to 55 amp, direct swap? |
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jl2556
AMC Apprentice Joined: Feb/16/2015 Location: tn Status: Offline Points: 98 |
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Posted: Jul/11/2017 at 7:10am |
On my 69 amx, the 55 amp is cheaper than the 37 but $15 at orileys. I get the jobber prices there so was wondering if I can upgrade to the 55 amp with no other modifications?
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jl2556
AMC Apprentice Joined: Feb/16/2015 Location: tn Status: Offline Points: 98 |
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Cool....Thanks!!
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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If you have a 37 you have the wrong alternator anyway. For your year they used either 35 or 55 - NOT 37.
The 37 came later, about 72 or so, about the time the 55 went away. So if it has a 37 then it's running the wrong regulator for that alternator unless someone changed it, too. My point is - PLEASE check the tag and make sure it's a 35 amp with a red isolation diode. If not, it's wrong and you may introduce troubles. Good grief, the 55 is cheaper? Those people are NUTS. the 55 was far less common and is more expensive due to the larger rotor and stator. But then that's remanufacturers........ they toss all the parts into large bins, they do NOT sort, they have people sitting at tables pulling them apart, any output, any year, any model, and toss the parts all together in big bins. They are then cleaned, etc. and when the parts are ready, they pull parts out and assemble alternators..........and you may end up with a John Deere frame and sold as "will fit AMC" but the case/frame will not be correct in appearance for AMC. That's how they do them so cheap. They use the parts that interchange technically or physically and build what they have the most call for. How do I know? I've been there - I've toured those plants and watched how they operated. It's the same with carburetors - you'll get a reman 4300 for AMC and they've removed the transmission linkage lever and plugged the PCV hole in the back with epoxy and sell it for AMC. But your question is will it fit without problems - yes, rev is right of course. The larger alternator is deeper by about a half inch but that makes NO difference on the mounting at all. But do please check your original as if it's truly 37 please double-check with us before installing the other. It will FIT but if someone has messed with it, it won't charge the correct voltage. You should have a 35 amp with the red isolation diode plate, single diode in that plate. It should be an A12NAM457 on it now and you want a A12NAM605 The A12NAM604 is the same but clocked differently for the 6 cyl engines - so they may sell you something that's clocked differently making wiring a bit of a chore. You need something clocked at 12:00 meaning with the threaded adjusting boss hole at the top the brushes are also at the top. The 6s were usually clocked at 9. |
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dogbone
AMC Addicted Joined: Mar/13/2008 Location: TN Status: Offline Points: 702 |
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I've noticed this too, the 55 cheaper than the 35. My 64 Classic wagon has the 35 and I was considering upgrading to the 55. Will the 55 direct replace a 35?
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64 Cross Country Wagon 770, 79 VW Scirocco, 70 Porsche 914-6, 82 Subaru Brat, 1991 Autozam
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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Yes if it's for the same years, for example, 64 through 70, yes.
A 55 will indeed bolt in where a 35 was removed. It is odd, ironic, counter-intuitive indeed that the 55 would be cheaper or less expensive but then perhaps fr the remanufacturers and jobbers it's cheaper to stock one size........... Now for the rest of the story - to be very very blunt - the only reason to do so is cost. There is absolutely NO advantage to moving from a 35 to a 55 unless you add AC, a really heavy-duty maxed out stereo or fuel injection. None, zero, zip. You will gain nothing in your case other than the cost savings. Nothing, not a bit, period. So if it's for some other gain, there won't be any at all. If it's to save money, go for it. We all love to do that. If it's to save the 10 or 15 bucks then go with the cheaper since IF they have made the thing right at the remanufacturing facility and marked it correctly for the right cars, it will be a direct fit. Again, there's perhaps a half inch difference in the "depth" front to back but since the mounting is the same - in other words the 35 and 55 take the SAME PART NUMBER front frame half, that means it bolts on exactly the same. Depending on your luck you may get one clocked correctly, or may get one for a 6 that's clocked differently but the main difference there is ease of accessing the wire connections on the alternator. They are functionally the same, connect the same except for the position of the connections 6 vs 8 cyl, and mount the same. Will it make any difference in your lights, starting, or anything else? Nope. Not unless the unit you have now isn't working correctly. So you'll save enough money for a decent steak supper, but it won't matter to your car at all. There is a myth that bigger is better, more is greater - not true. (I know 'em inside and out - it's what I do) (By the way - anyone looking on wondering about how things compared, AMC to the others, ALL ELSE BEING EQUAL - meaning comparing a 35 to a 35 or a 55 to a 55, the Motorola alternator puts out more at idle speeds than the GM or Ford of their day - until GM moved beyond the 10si that is. Charts showing output at RPM show the Motorola puts out more at lower RPM than others. This means that if you do a lot of driving in town, stop and go driving and so on, you are better off with a Motorola than an early Ford or GM alternator until GM upgraded the 10si and improved performance at lower speeds. ) |
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
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Air conditioning doesn't use a lot of current. The blower motor is the same and the compressor clutch only pulls 2A. I have no clue why the 55A are cheaper than the 37A. Maybe the single isolation diode for the 37A is more expensive than the dual isolation diodes for the 55A. I don't know. AMC used 40A and 42A on and off through the years. They were a good way to make up for the extra 2A of A/C without jumping all the way to a 55A alternator.
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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dogbone
AMC Addicted Joined: Mar/13/2008 Location: TN Status: Offline Points: 702 |
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The reason I was considering it is I've put bags on my wagon and the air pump pulls a good bit of current, and I just reactivated the A/C. When the air pump is on my voltmeter drops down pretty close to 12. The alt light has never come on, but it's more load than the 35 was ever expected to handle.
I guess I was concerned about beefing up the wiring from the alternator when swapping to the higher output.
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64 Cross Country Wagon 770, 79 VW Scirocco, 70 Porsche 914-6, 82 Subaru Brat, 1991 Autozam
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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AMC used 35, 40 and 55 into the early 70s then went to 37, 51 and 62 for the most part.
Remember that rating is at full rpm not idle so likely they made the jump to 55 to cover low speed needs and the fact that more accessories were coming to be. Up until about 68-69, 40 was used with ac, etc. Now also keep in mind the isolation diode for a 40 is the same as 55 as is the rotor so for AMC and Motorola to go 55 vs. 40 was little. And no the 35 amd isolation diode is NOT more expensive for anyone at all. Those outfits buy them bulk from Asia and I know their pricing..... If you have bagged the car and run a compressor then by all means - go up to 55. Don't hesitate. You may wish to revisit the wiring anyway....maybe use a breaker on the fender and a dedicated feed (that's what I might do) |
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dogbone
AMC Addicted Joined: Mar/13/2008 Location: TN Status: Offline Points: 702 |
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The pump is mounted in the rear of the car and I'm using a fused #10 wire directly off the battery straight to the pump. There's another 16 ga. that runs to the fuse panel for the electronics. I occasionally get a notification on the suspension control panel indicating low voltage so the pump shuts down. After a while the alternator seems to catch up.
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64 Cross Country Wagon 770, 79 VW Scirocco, 70 Porsche 914-6, 82 Subaru Brat, 1991 Autozam
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dogbone
AMC Addicted Joined: Mar/13/2008 Location: TN Status: Offline Points: 702 |
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I just looked at Rockauto. They have a Remy 20169 for $33 incl the core plus shipping. Pretty darn cheap and it maybe a cheap one at that! Says it's a 61 amp.
Interesting they don't show it cross referencing to fit the 1965 327 motor.
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64 Cross Country Wagon 770, 79 VW Scirocco, 70 Porsche 914-6, 82 Subaru Brat, 1991 Autozam
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