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PTO hydraulics on a GMC Top Kick

Discussion in 'Construction Equipment Attachments' started by Willie B, Apr 21, 2018.

  1. Willie B

    Willie B Senior Member

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    I've had no time to pursue the rivet challenge. I've bought a washing tip for the acetylene torch, and a new plasma cutter. The Hypertherm 45XP has a few months ago introduced a flush cut kit. I've only experimented a bit with it.

    No, I will use frame bolts. The rivet holes are a bit loose with 1/2" bolts, but the spring experts say they only use 1/2" bolts for replacement in my size truck, and have never had a problem.

    Winter is coming, and I hope to find a bit of time to work on it.
     
  2. 56wrench

    56wrench Senior Member

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    I would personally drill the holes out to 5/8" or use a metric size(if there is one) that fits the hole with no movement. it is much easier to do it right the first time than try to keep crossmembers tight after they come loose and wallow out the holes. we used to replace the hanger rivets on Hendrickson walking beam suspensions after they broke. bolts would fit too loose so we drilled them out or used a bridge reamer to get a snug bolt hole. whatever size is used ( grade 8) use the thick, hardened flatwashers under the bolt head and the nut(grade 8 stover locknut). red Loctite, torqued and you're good to go.
     
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  3. Willie B

    Willie B Senior Member

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    I like the way you think. I won't be able to use them in every hole. Some won't have clearance to use 5/8" washer head bolts unless I grind away some of the diameter of the head.
     
  4. Willie B

    Willie B Senior Member

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    It has been a while. The fire truck has sat untouched except to move it to prevent rigor mortise. I was not finding time in warmer weather, it doesn't fit well in the garage. I found a truck mechanic.

    The frame is shortened, axle moved, new brakes & springs, New PTO, hydraulic pump. Everything sandblasted & painted. Massive fire body & pump gone. New driveshaft. Exhaust in progress! Getting very close to receiving the dump body.

    I'd like AC. Might get Mrs B to accompany me on an occasional adventure if I had AC. I just can't figure belts to drive a compressor. I'm pondering an electric unit like those used on some farm tractors & railroad maintenance equipment.
     
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  5. Willie B

    Willie B Senior Member

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    I stopped on my way home from work yesterday Temp must have been 90. Took it for an illegal ride. Couldn't keep the rear tires on the ground. Might have worked better with less air in them. Turbo doesn't offer a great deal of boost, but it was very noticeable. Still can't wrap my brain around the 427 gas engine in my old truck being horsepower rated similar to the 10.6 litre turbo diesel. The Allison transmission wouldn't have been my choice, but it efficiently sends power to the wheels. New springs, new brakelines&tanks Fire truck 2.jpg

    Waiting on a new hydraulic valve, (I hope Monday) Then the 14' flat dump goes on.
     
  6. Birken Vogt

    Birken Vogt Charter Member

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    I've driven similar fire trucks with the 3208 and the 427, and I would take the 3208 any day. I don't think the turbo added much of any HP to the engine. Older ones were available with almost the same HP ratings non-turbo. I think it was added to clean up some of the filth. 3208s were a dirty engine.
     
    repowerguy likes this.
  7. 56wrench

    56wrench Senior Member

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    i have had several 3208's over the years and the highest power in a non-turbo that i had was a 3208 at 210. the turbo engines were 225 and then 240 and 250 that i saw. depends on the arrangement number. the turbo engines definitely had a lot more power at a lower rpm than a natural topped out at. the natural 210 was rated at 2900rpm and the turbo 240 was something like 2600. the 3208 turbo at 250 would run circles around a 3116 at 250. i was told by cat that there was no comparison because of the tighter emission controls on the 3116. one of the places i worked at had them as plow trucks with slide-in box sanders.
     
  8. Birken Vogt

    Birken Vogt Charter Member

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    I do remember the non-turbo could be as high as 225, and I think maybe even higher. I may also be confusing that with an 1160, don't remember. These were all highway motors. I did kind of forget about the high RPM, you are right about that. Some of these things were worth forgetting.

    The later model 3208 turbo motors had a lot of low end grunt for sure. The non-turbo made you want to drive it like the old Detroit Diesel adage.
     
  9. Willie B

    Willie B Senior Member

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    Research says these engines were lots of different horsepower ratings. It isn't here, or I'd look. It is printed on the engine the horsepower. I remember it as 250. In any event it's more robust than my 427 in the old truck. The 427 tall block was rated all over the place also. I think they rarely were rated at anything beyond 4000 RPM explaining in part why a modern 7 litre is rated at 6000 RPM Yeah that's more horsepower, but running at 6000 makes for a short life.
     
  10. Willie B

    Willie B Senior Member

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    OK, the truck has been a few runs on road. Tires were OK, but rears were chewed some from tire chains. The old truck has new tires all around, and they are heavier load rating than the fire truck.
    I wanted to switch tires.
    The tire dealer is at least second generation, a good guy with enough employees that riding herd on them is more than a full time job. He said breaking down these tires is a big deal, he alone is qualified to do it. Not an option to do them during business hours. He'd try to do one a night.
    To me that seemed a very big thing, long wait. I decided to break down the fire truck tires. That proved a bigger job than I had imagined.
    The concept is simple: Free the rubber tire from the bead of the wheel, it falls away a bit from the narrow ring of the wheel. Work the narrow ring free from the snap ring, the snap ring comes easily.
    In practice this does NOT work! A big pucker of rust formed on the inside of each wheel it is impossible to force a 14 ply tire bead past.
    You Tube videos show a tire hammer being struck one handed with a soft surface dead blow hammer to free it from the wheel flange. I didn't have either, but noticed it is shaped exactly like a backhoe tooth. I used a 12" wide backhoe bucket with only one tooth. If it weren't for the big swell of rust it'd work. No amount of lube or force was going to push it over that ridge. I dismounted two tires successfully, then ruined one.
    I finally gave up, and ordered 4 wheels & tires 22.5" They arrived Wednesday, but didn't fit the truck. Still waiting for the new ones.
     
    Last edited: Aug 8, 2020
  11. Willie B

    Willie B Senior Member

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    Next chore:
    Servicing the transmission.
    I can't find much on the Allison MT643. What I find is about newer models. Some say older models were to use 15W-40 engine oil, less old used Dexron III, and all can now use synthetic auto transmission oil. They go on to caution that a thorough wash down is essential as synthetic & petroleum oils shouldn't be mixed.
    Newer models have filters inside the transmission, this has a spin on filter outside. I've seen some mention of an internal filter, and a suction screen.
    Does anybody know?
     
  12. colson04

    colson04 Senior Member

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    Call Weller Reman, or another Allison Authorized Remanufacturer. I have an MT653 in my dump truck and was advised by them to use full synthetic transmission fluid only. Also, I only have an external, spin on filter, no internal filters.
     
  13. Birken Vogt

    Birken Vogt Charter Member

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    The old Allison MTs have a filter in the pan much like a car transmission. Most are paper and need to be changed but not very often. Some have a steel screen instead and a filter installed remotely on a cooler hose or something.

    They can run engine oil or transmission fluid but not to be mixed. Just look at what is in there now, and drain and fill. No reason to go to a lot of work to fully flush if nothing is wrong with it. I would not spend for synthetic as the transmission will probably never see the kind of miles to make it worthwhile.

    They mostly used engine oil in the ones that had a retarder braking system on the transmission. They usually had ATF.
     
  14. Willie B

    Willie B Senior Member

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    I don't know about a retarder. It locks up to effectively use the engine for downhill holdback. Is this a retarder?
    Is it enough to drain & clean out the pan, then replace with Dexron III?
     
  15. Birken Vogt

    Birken Vogt Charter Member

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    A retarder is a normally empty cavity that has some moving blades and some stationary blades attached to the drive shaft or input shaft depending on model.

    When you want to slow the truck down the transmission fills it with oil which picks up a lot of heat.

    They were often controlled by a third pedal on units of that era. They are a big chunk on the transmission that would not otherwise be there. There would be an "R" in the model number for retarder.

    Drain and remove the pan, change the filter, refill. Good enough.
     
  16. Willie B

    Willie B Senior Member

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    Thanks for that info. Now I track down the external & internal filter & gasket Dexron I'm sure I can buy.
     
  17. Willie B

    Willie B Senior Member

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    I got nothing to say.
     
  18. Willie B

    Willie B Senior Member

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    Other threads I've cluttered with my story. I scheduled an inspection last week. I failed on SO MANY counts! All four air cans failed. Something undetectable in right wiper. U bolts on rear springs not long enough, water in headlights, I have new tires & wheels rear, but right front scalloped. I can't see or feel it! My triangles & two fire extinguishers weren't bolted. Air leak when parking brake is applied.



    Oh well! I got frustrated this morning, Texted Rico, a truck mechanic who does NOT want publicity. I said I fear I'll die of old age before I get a sticker on the windshield. He took over. He says he has an appointment for 7:00 AM tomorrow. He will take it, answer to any challenges. He is confident it will now pass.

    I'll tell you the outcome tomorrow.
     
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  19. crane operator

    crane operator Senior Member

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    Great to hear. Good Luck!
     
  20. Willie B

    Willie B Senior Member

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    I just picked it up. It PASSED!!
     
    Theweldor likes this.