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Author Topic: ht 740 oil lines.  (Read 1335 times)
berrybus
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« on: February 26, 2008, 03:44:02 PM »

we bought a ht740 for our mci9. it came out of a 1982 fire truck. near the oil pan theres 1/4 inch oil lines with 2 selinoids going in and out of transmission. all other ht740s we looked at did not have these. does any one have information one this? thanks jim.
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"No man is a bus."
luvrbus
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« Reply #1 on: February 26, 2008, 04:07:04 PM »

those line are to lock up the transmmission it's best to remove and plug for bus use
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Songman
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« Reply #2 on: February 26, 2008, 04:59:05 PM »

those are used when you have a jake, keep them and wire it up to your switch
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makemineatwostroke
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« Reply #3 on: February 26, 2008, 06:04:19 PM »

those are added on the Allision to lock the torque converter up in 1st gear the Jake Brake will stay engage longer with them.the 740 will free wheel when it gets below certain rpms without the lockup.the valve can not be mounted but in one postion and that is where it stays closed without power.If you want another problem I say keep them, but they can cost some big bucks when they malfunction do it your way but I would plug those babies one less problem
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buswarrior
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'75 MC8 8V71 HT740




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« Reply #4 on: February 27, 2008, 07:11:25 AM »

FWIW, mine seems to coast as the speed drops through 20 mph.

OK for the flatland, but not going to be good for some places in helping keep the brakes cooler.

Cabot Trail, Cape Breton, Nova Scotia comes to mind. Slower speeds, but long, twisty and STEEP.

happy coaching!
buswarrior
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artglass
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« Reply #5 on: February 28, 2008, 07:20:57 PM »

   We did the same thing on my mci 8  our was about a 78 fire truck, removed , plugged them and had no reverse , put them back on and works fine seems to coast if your not giving any throttle at all,  if you have the tag on the trans call alliosn in indy they can tell youif it will work to remove them, my tag was gone on it , could't tell me if would work, one note not all ht740 housing are the same my trans i was replacing is slightly narrower housing where the mounts are on the trans , had to modify the mounts by cutting them off the cradle and weld them back on out a liitle bit, think it was off about 1" on each side.Not really that big of a deal if you have a welder , grinder.
   Kevin
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JackConrad
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73' MC-8 8V71/HT740 Southwest Florida


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« Reply #6 on: February 29, 2008, 05:04:49 AM »

    Not all 740s are created equal. Ours is OEM in our MC-8. No solenoids installed on the tranny. I wanted to confirm the converter lock-up test port, so I ran a length of 1/4" DOT tubing to the driver's area and added a pressure gauge. Our converter goes into lock-up at about 12-15 MPH (tranny still in 1st gear). Transmission stays in lock-up until bus slows to about 15 MPH before unlocking.  Jack
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makemineatwostroke
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« Reply #7 on: February 29, 2008, 07:44:31 AM »

Jack your transmission is right where it should be coming out of lockup at 850 to 900 rpm. the main purpose for the lockup solenoids was to lock the torque converter for the PTO to run the pumps on fire trucks and run other off road equipment If the lock is not wired correctly you can stall the engine with them and things can go bad from there on.there is a reason that they are not used on buses 

Artglass if your housing is larger than a HT 740 that is a FS 740 housing (FS meaning fuel saver popular in the 70s)
« Last Edit: February 29, 2008, 09:37:56 PM by makemineatwostroke » Logged
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