Geoff Weeks

If you weren't 1/2 a world away, I'd send you a case. I think at this point a better unit would be as cheap as replacing that one no core.

Electronics were a huge step forward. Very few mechanicals can make it over 1m miles, and that is with several cable changes. Some of my electronics have over 2 million miles. No ratio adaptor or tailshaft gear to wear. esp good for long runs with and aux trans. Most can handle an Eaton 2 spd axle internally with no changes. pick-up is non contact so non wearing. Mechanicals needed adaptors to make the drive 1000 rpm@ 60 mph. so any driveline change need a speedo drive change also. Only the 1st Motorola's were fixed, everything after that were re-settable. My Marmon had/has mechanical speedo and tach, I changed out the speedo when it died at almost 1million miles. Easy change and never a problem. It was nice when I fitted 2 spd rears, no gear box and cable change needed, just a wire to tell it when it is low. Since my '83 already had the wiring and plugs for the Motorola, I installed that, but because of the ratio and tires being different I used the Dakota Digital box, rather than a tone ring in the hub. My antiques will keep the OEM gauges, but anything I was running commercially, I would want electronic.

I also found I have ISSPRO's speedo calibration chart, but don't know if it is the same as Prestolite.

Worse case, I've got a NIB one of these that I used when I put the '84's speedo in the '83 and used a 16 tooth gear on the transmission. It will allow for re-cal to just about anything. https://www.summitracing.com/parts/DAK-SGI-5?srsltid=AfmBOorVpbEa8dgVMpyBjapdwrI3Uur-C6qqCadyeRYodCjpqVlt4EZr

It will be when mine arrives at his address!

For what it is worth: My 1983 had a mechanical speedo, but the plugs were in the wiring harness for the Motorola electronic. My 1984 had the Motorola, with the tone ring in the hub and were not recalibratable , you had to order the head for the hub revs/mile. My 1989 had the Prestolite trekstar and was settable by dip switches. By the time of electronic engines, most speedo's were part of the whole CanBus and not stand alone. So looking at mid to late 90's That leaves a ~10 year period where stand alone speedo (and tach) were used. At some point I think Mack switched to Amteck (or something like that) Speedo. So Mack may have used the Prestolite for less time than IHC. I can find little info on the Trekstar on on the .net.

I think that one is too new, you need to go back to the 80's early 90's for the Treckstar. Speedo is on the way to Stutz.

Freightliner! What is the difference between a Freightliner and a traveling Evangelist? You can shut the door on the Evangelist!

If you are going to open it up, get a set of brushes, and a paper clip. You have to remove the regulator and brushes to get at the bearings, when you re-assemble before installing the regulator on top of the brushes, poke a paper clip though the small hole to hold the brushes in place while installing the regulator, then pull the clip out before tightening down the regulator.

Looks to be 4x8, neither front hub looks like it is a driver.

If you can, go back with something brushless! I don't know how many of those L/N JB series I have kicking around. I always replace with something without brushes.

You didn't say what engine you are working on, but; My experience: Heating several times, trying to break free, working back and forth once it did, still ended up with a cracked casting. From then on, Drill them out progressively until just under the thread size and collapse them in. Labor intensive but safest.

PM sent to Stutz

I got a bunch of stuff, mostly IHC, that when one failed, and I could track down a source, I would buy more than one, often they were being sold off as a "lot". I have things like horn button brush, that most don't have or replace, until you needed, to, then can't find them. I'd love them to go to somebody who could use them, but the hassle of selling on Faceplant or Ebay, only for somebody to want to return them, on my dime when they mis diagnosed, or just didn't want it, isn't worth the hassle. That speedo is going for anywhere around $100 and up on ebay, I can't remember what I paid for it, and I can't give it away? Kinda mind boggling!

I got to say, this is aggravating. 7 months ago he asked about a speedo, at that time I said he could have it for free, just pay the shipping. Nothing for 7 months, than asks if I still had it. I replied again I still had it, Then he wants to know if i have the female connector, and how much. I go dig out the harness and find it isn't the right connector, but list places he can get it I again offer it for free, he pays the postage. and add in how it is currently set. Then again, I get radio silence? People ask why I don't sell my store of parts? Hell, I can't even give them away! It is getting not worth the trouble. I found a box, found some pages on the internet that would help with the wiring. And yes, I've checked, he has been on the site since my last post. I am generally free with my time, but when someone asks me a bunch of questions, and then nothing?

I liken my K-7 to driving my 9670 with about 118K on it. It is foot to the floor, and when you hit a hill it pulls down (from 3000rpm) to around 2000 and just hangs in there. No point downshifting until it pulls below ~2000. It means, while it will do 55-60 MPH on the flat, when your pulling hard you drop down to around 40. Driven in the heat, with the windshield and side windows wide open and driven in the cold (-10) for 400 miles. Not as comfortable as more modern trucks but keep going.

The only thing I would change is the transmission ratios. I find the large leap from 3-4 and the short 4-5 not to make the best of the power the engine can produce. I much prefer even steps, and higher rear with direct top gear. The lack of gearsets for the rear, leave that pretty much a pipe dream to make any changes.

You already own something better, IMHO!

Up until Elon destroyed Maxwell, my preferred solution for 24 volt crank/12 volt run was a 24 volt ESM from Maxwell. Charges on 12 volt, provides 24 volt cranking. Completely "hands off" split charge ( transformer/rectifier) alternators and S/P switches are distant 2nd. Too many can't figure out S/P switches, and there are failure modes that leave the truck "dead". T/R alternators are ok but the battery banks don't age equally. I don't consider 24 volt crank, 12 volt run, 24 volt systems at all, they are 12 volt systems that are paralleled for cranking only. I had a service van fitted out with two 8D's down under the body and a S/P for charging. It could start a 24 volt bus with flat batteries. It could also jumpstart 12 volt vehicles.

Only trailers I saw that were 24 volt were either military or gravel screen plants made in Europe. COW are small, single axle things aren't they, I am surprised they would overload 18 ga wire with only a few lights? Cars of the vintage we are talking only had 16 ga at most, I think most were 18 for the lights. 18g can carry 10 amps at least, how many lights did these things have?

On stuff I did 99.9% of the wiring was more than what was needed for 12 volt. I can't think of a single time we needed to change the wiring size. Before the days of solid state "converters" Vanner battery balancers were the only option, for 12 volt supply. Some stuff could be put in series, but not headlights. The must be able to operate with one light blown. Back in the 80's the Vanner's were big clunky things. Motor coaches were 24 volt almost from the beginning. headlights were the main thing that was needed for DOT, the rest didn't matter what voltage the bulbs were. Tail light, brake light, turn signals all had to be there and work, but the bulb voltage is irrelevant. It only mattered for headlights because the bulb also contained the lens and dispearsment pattern. Rest of the required equipment (wipers, defroster etc) didn't matter either. Only time 24 volt becomes a problem is if it has to tow a trailer that interchanges with 12 volt tractors.

I doubt 24 volt lights, At that time period no sealed beam 24 volt lights met the DOT regs, Military headlights were sealed but didn't meet the other requirements for light pattern. I know, I had to convert 24 volt stuff to DOT regs.

More than likely it is. I had IHC's and when I sold the trucks, the manuals went with them. I retained one parts manual and thought it had the settings, but it doesn't Should be the same for all TrekStar speedo's 16 tooth is the most common input, but there were other variations used. My '84 parts truck had a "tone ring" in one of the rear hubs. So far, I haven't heard from him where to send it, so it sits in a box.

I no longer have the service manual with the calibration settings and wiring. You'll need the calibration settings for your application. IIRC it is set for a 16 tooth transmission "gear" and 501 rev/mile tires on a 3.73 rear gear.

No luck on the plug, the wiring harness I have was for an older truck with an early Motorola speedo. You can order the plug from here or many other places: https://brillman.com/product/4-cavity-packard-56-series-female-terminal-connector/?srsltid=AfmBOoqYbrEyZ8pCtYr_O9nAQ5DW_qNtIp72twqfn7Cw0comsmdrD9vId3o&gQT=2 along with terminals: https://www.zoro.com/grote-terminal-56-series-16-14-ga-pk10-84-2013/i/G9793869/?utm_source=google&utm_medium=surfaces&utm_campaign=shopping feed&utm_content=free google shopping clicks&campaignid=21460994854&productid=G9793869&v=&gad_source=1&gclid=EAIaIQobChMI3vS6kdqniwMVtzUIBR3taznaEAQYAiABEgLa4_D_BwE&gclsrc=aw.ds But I bet NAPA could get it all also. PM me with an address, it is yours for the postage.