Chrysler starter spin down time

[Al Bundy]

Thanks TylerW for sharing the videos too.

 

[TylerW]

Well, I thought I would contribute to this thread again since, in the intervening years I have bought and rebuilt many of these starters and used several for parts. I feel that I can condense a lot of the information that has already been posted in order to answer the original question in a way that is easy to understand.

To begin with, any gear reduction-type Mopar starter fits any engine that was originally equipped with one. They do not fit engines that used a direct-drive starter. Most of the time that would be engines with a HD clutch, no matter WHAT engine it is. I'm certain it has to do with flywheel diameter, not starting capacity. In other words, you could have an automatic slant six use the same starter as an automatic 426 Hemi, which they did in fact. But, you can't cross between an automatic slant six and a 4-speed Hemi with HD clutch, nor can you put an automatic Hemi starter on a rare slant six with HD clutch.

Speaking of, there have been various people that sell(or try to) restored Hemi starters, or 440 six-pack starters, or whatever. They are still around but I've called them out several times for misleading information. Read carefully: There ARE NO Hemi starters. There ARE NO six-pack starters. There ARE NO 383 Commando starters. When your '68 426 was built, they "grabbed" the starter out of the same rack that held all the other 2095150 slant six, 273, 318, 340, 383, 440, 426 starters. I have several '66 through '69 starters that might have been on your Hemi originally, but who knows? So, if you are captivated by the idea of paying $700 for a "original Hemi starter" that ain't one, be my guest. Personally, i would find a matching numbers core in good shape for about $50, spend about $50 on the original Mopar brushes and solenoid parts that are still available, paint it black from end to end with a nice paint job and use the excess money for a ring for your wife so she loves you even more.

Now to get to the spin down time question-

Dan listed the part numbers and when the speed and noise increased, but we can clarify. Very simply, keeping the large-frame starters out of the equation, you have two groups of Mopar starters...the earlier 3-series/shunt wound units, and the later 4-series units.

Shunt-wound: 3-series(field coils) and one coil that is wired as a shunt. Not being an electrical engineer and assuming you aren't either, when the 4th "shunt" is present, it acts as a speed limiter of sorts. It will not allow the starter to keep increasing speed once the load is removed.

Shunt-wound starters are all of the 2095150 units, all of the 2875560 units and all of the early-73 starters, part number 3656650. I'm not sure that is the early starter actually. Note that this is AS-BUILT. Lots of these starters have been through a rebuilder at least once and you would have to carefully unbolt the field housing and slide it up to investigate whether the shunt wire is present.

The good about shunt-wound starters- They turn slower, so they are quieter. They do not overrun even if you hold the key too long. They are the quietest original Mopar starter you will find.
The bad about shunt-wound starters- They are frustrating to use these days because they turn slower and make starting a very cold or hot, heat soaked engine a prolonged affair. They also are not rebuilt anymore because of the unavailability of new sealed-in solenoids and shunt coils. Your best bet is to rebuild an original core.

This is about the time you see all these goofballs on Youtube complaining that "it ain't spinning over fast enough, we need a new starter". There goes the originally starter in the trash.

Non shunt-wound starters- 4-series. These are every starter after the early-73 units. They are louder and ALL of them have the long overrun and spin-down. I have tested original, as-built by Mopar 1974 starters that I own and they all overrun loudly. It is the nature of the beast. However, they will whirl an engine over far more quickly than the early starters. I dispute the design parameters statement. I've never seen one of these starters fail from overspeed. They CAN fail from being overheated, and the solenoid contacts will fail first.

So, that's the long and the short of it. If you are ok with the quieter, non-overrunning but slow turning unit, rebuild it as-is. If you want to speed it up but use your original date-coded housings, swap out the 3-series/shunt coil set with the later 4-series and nobody will ever know the difference but you. Not even the judge with his flashlight and clipboard.

My personal go-to starter is a rare 1965 2098500 starter that was used on 170 slant sixes through 1969. It is a 4-series with no shunt and came that way originally. It sounds just like the later 4-series units. Supposedly the later coils are larger, but they sound the same to my ear. I've only seen one other of these. I switch mine from car to car and replace it with the original shunt starter when ready to sell.

One other anecdote: I've bought at least four original, unrebuilt Mopar starters out of the junkyard, and they have ALL worked. 1965 2098500, 1970 2875560, 1971 2875560 and a 1972 2875560.

Hope this is informative!

 

[slantsixdan]

the earlier 3-series/shunt wound units, and the later 4-series units.

Almost, but the fly in that ointment is your go-to starter:

My personal go-to starter is a rare 1965 2098500 starter that was used on 170 slant sixes through 1969. It is a 4-series with no shunt and came that way originally. It sounds just like the later 4-series units. Supposedly the later coils are larger, but they sound the same to my ear.

2098500 was introduced for use on all '63 engines, and it was also used on '64-'69 170 Slant-6s. Its coils are the same relatively small size as the 3 series coils in the 2095150/2875560/3656650, but there are four of them.

This 2098500 was introduced to improve cold-engine starting behaviour—the starter keeps helping up to a higher engine RPM under borderline sputtering-start conditions (see attached). It worked fine under those and all other conditions. No idea why they mostly abandoned it and went back to the 3-series + shunt 2095150 on all engines except the little 170 starting in '64; the 4-series starter would have been easier and less expensive to make and assemble.

It might sound the same to your ear as the later 4-series starters, but…it ain't. No-load test speed spec at the drive pinion on the 3-series/1-shunt starters is 1,950 to 2,450 RPM; on the 2098500 4-series starter it's 2,950 RPM, and on the January-'73-up 4-series starters it's 3,950 to 4,300 RPM. And while different Chrysler part numbers for the coils don't tell us anything, different aftermarket part numbers do, and they are.

Shunt-wound starters are all of the 2095150 units, all of the 2875560 units and all of the early-73 starters, part number 3656650. I'm not sure that is the early starter actually.

It is, even though the January-'73-up (later) starter has a lower part number, 3656575. That was the first starter with four large field coils in series, and this configuration was kept for the small-frame gear reduction starters up to the end in 1987.

Note that this is AS-BUILT. Lots of these starters have been through a rebuilder at least once and you would have to carefully unbolt the field housing and slide it up to investigate whether the shunt wire is present.

Most of the remanufacturing plants, when they were dealing with Mopar starters in volume, chucked the shunt and 3-series coil in the trash and put in the large 4-series coil set. That way they could just go Burrrrrr with the impact driver and not have to take time fishing the shunt lead through the brush plate hole and wrapping/soldering it onto the contact.

The bad about shunt-wound starters- They are frustrating to use these days because they turn slower and make starting a very cold or hot, heat soaked engine a prolonged affair.

Eh, I donno that I'd agree. Today's oils make a cold engine vastly easier to start than ever before. Oil pumpability is a whole lot more crucial than cranking speed to ease of cold starting; see this 1969 report on the subject.

I'll give you more of the point on a flooded hot engine; the faster you crank one of those, the sooner the over-rich mixture can be cleared out.

They also are not rebuilt anymore because of the unavailability of new sealed-in solenoids and shunt coils. Your best bet is to rebuild an original core.

The 2875560 and 3656560 3+shunt starters had the later-type 2-bolt/rubber-gasket brush plate and solenoid; only the pre-'70 starters (2095150 and 2098500) have the harder-to-deal-with type where the brush plate is held to the pinion housing by a single screw and you have to apply a bead of sealant.

(Another reason the later starters are louder: the armature is supported by a bushing as it passes through the '69-down pinion housing, but that hole is larger and there's not a damn thing there but air in the '70-up pinion housing. So the armature is supported by two bushings rather than three in the later starters.)

This is about the time you see all these goofballs on Youtube complaining that "it ain't spinning over fast enough, we need a new starter". There goes the originally starter in the trash.

Well, I mean, there's slow and then there's slow. A 3+shunt starter in good condition cranks the engine plenty fast enough, but an old starter with heavy wear on it turns slower—no matter what its configuration might be.

I've never seen one of these starters fail from overspeed.

As originally built, they held up fine. As sloppily "remanufactured", they make a much-louder-than-original racket and fail early/often.

So, that's the long and the short of it. If you are ok with the quieter, non-overrunning but slow turning unit, rebuild it as-is. If you want to speed it up but use your original date-coded housings, swap out the 3-series/shunt coil set with the later 4-series and nobody will ever know the difference but you.

If you want a real nice balance, use the 4-series coil set for the 2098500 starter. Still plenty easy to get hold of NOS: Chrysler 2421474, Ace ST-452, WAI/Weatherill 59-301, etc. (Note for future readers of this thread: no, I don't actually imagine anyone going out and doing this. We're bench-racin' starter motors here.)

All the 4-series starters, including the 2098500, were originally built with precision-balanced armatures not considered necessary with the lower speed of the 3+shunt starters. This was done explicitly to cut down on noise from the higher armature spin speed. Do the math: 2,000 RPM test speed (at the drive pinion) of a 3+shunt starter, times the 3.5:1 gear ratio, = armature spinning at 7,000 RPM. 2,950 RPM on the small-coil 4-series starter = armature at 10,325 RPM. And 4,350 RPM on the large-coil 4-series starter = armature at 15,050 RPM (wanna guess how much attention "remanufacturing" outfits pay to armature balance?).

I've only seen one other of these. I switch mine from car to car and replace it with the original shunt starter when ready to sell.

I took the Nippondenso starter off my '89 D100 and put on a carefully-rebuilt original 2095150. My reaction was the same as this guy's after the second start in this video (first start @ 5:11; second @ 5:51 if the linked time index doesn't work):

 

[slantsixdan]

My brain musta been unplugged when I said this part:

2,000 RPM test speed (at the drive pinion) of a 3+shunt starter, times the 3.5:1 gear ratio, = armature spinning at 7,000 RPM. 2,950 RPM on the small-coil 4-series starter = armature at 10,325 RPM. And 4,350 RPM on the large-coil 4-series starter = armature at 15,050 RPM

Oops, derp, nope. Those free-run speed specs aren't at the drive pinion, they're armature speeds, before/upstream of the reduction gears.