| Author |
Message |
Dave Hartshorne (Yeeolde48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 04, 2005 - 8:38 pm: | |
Hi All, Sorry for the long question, but I just got offered an HT750 for my Scenicruiser from a good friend. Trans was fully rebuilt, then after a couple hundred miles in his bus it lost drive. After cool down it worked fine, with firm shifts, then same thing again after another 100 miles. This time it would not go back into drive, and the bus was towed. I am getting the complete trans at core price, so no real risk, as I could trade in the core if it is completely shot, but I have to think that is unlikely. Does anyone have experience with the 750 to suggest if this is a known failure scenario. One suggestion was a bad pump, but my experience has been a pump failure is sudden and terminal. Another was the shifter set incorrectly, but don't know enough about these transmissions to know if that would cause the trans to overheat, or quit. Fluid is clean and not burned. I plan to do the normal checks for debris etc. but hope most of the core can be saved, if so this could be a very low cost swap. Any known problems I should look for based on all you experience.
I had planned to look for a new trans this year anyway, as the 4 speed is a challange with the big trailer, so this was very good timing, and probably still a good deal even if I have to get it rebuilt again.
I have read some of the postings recently that these transmissions are bullit proof. When one fails does it normally mean they are prone to further problems, or does a rebuild normally set things right.
Finally, has anyone experience rebuilding the HT750, and how difficult are they. I do my own car and race transmissions (T400, Powerglides, etc) are the alisons a lot different or require very speciallized tools that would stop me trying myself?
Cheers,
Dave
PD4501-304 |
TWO DOGS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 04, 2005 - 9:24 pm: | |
I....would love to have your bus with the standard 4-speed.......I think you are going to create a nightmare... |
TWO DOGS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 04, 2005 - 9:34 pm: | |
It's such a beautiful bus...."IF" you want to improve it...leave the 4-speed and bolt a 425 cat to it...same money spent & it won't be scared of no hill |
dave 4106
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 12:15 am: | |
put a 425 in front of that spicer....say bye bye 4 speed |
Mci102
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 2:43 am: | |
The HT750 is almost a perfect transmission for your Scenic. I would also agree that one properly setup and running is bullet proof...,amazingly so. Where I would try to convince you otherwise is attempting to rebuild it yourself. I would also suggest stop guessing why it overheated and malfuctioned and find out exacty what happened because in the case of a 750 the parts can cost thousands of dollars. I can remember back in the 1980's when small charter companies would spend 6 or 7 grand having there 740's rebuild. In that same time period I rebuild mine parts and labor for around 2 grand because it was done in time and the expensive parts didn't need replacing. I strongly suggest you have this transmission examined/rebuilt by somone who really knows them. |
TWO DOGS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 7:27 am: | |
the spicer will work fine as long as ya' don't do any burnouts...silly people...(AND)....like the other guy said ...7000 just to fix 'em...yuk |
BrianMCI
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 8:38 am: | |
I had my 4 speed crash box replaced with an HT-748 Allison. I couldn't be happier...
The funny thing is the guys with manuals usually are the only ones that hate automatics... The guys with automatics love them, and more than a few with manuals wish they had them.
Id have that tranny looked at by an Allison guy before I did anything, then if it's a fairly minor repair, swap that baby in!
Brian |
Jon W.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 9:14 am: | |
"The funny thing is the guys with manuals usually are the only ones that hate automatics... The guys with automatics love them, and more than a few with manuals wish they had them. "
I am sure that is true, except I for one would love to have a manual in my Prevost. The world transmission does a nice job, but there is very little that is as satisfying as matching gears and having total control over the shifting.
Unfortunately manual transmissions are going the way of four track tape players. |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 9:18 am: | |
For those new to the issue of swapping a manual for a automatic, there's cooling issues in addition to changing the flywheel for a flex plate, adding a torque converter and different linkages and wiring.
The DD 2 Strokes had a much larger heat exchanger and radiator package to handle the extra cooling loads imposed by the auto tranny. The double heat exchangers can be tough to come by on occasion.
Onward and Upward
Marc |
TWO DOGS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 10:16 am: | |
IF he's haveing trouble going up hills & thinks a slush-a-matic is going to help...he's thinking wrong...all ya' got to do is put an engine in it that has some BALLS |
TWO DOGS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 11:09 am: | |
everybody wants to argue....but ,nobody READS the question |
Dave Hartshorne (Yeeolde48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 12:17 pm: | |
Hi two dogs, really appreciate the comments. I am finding there is a lot of passion around both manual and auto trans use, both for and against. For the most part, everyone I have spoken to that has converted their bus, tells me it is better, but locally it is limitted to a handfull of people, and those with manual trans tell me they would never change. The postings in response to this string, and others I have looked at on the board show the same polarity between the 2 camps. The real problem I have is take-off on a grade where the engine does not have the guts to pull the bus and trailer, or the driver (me) does not have the skill, so I stall the motor or end up slipping the clutch bad. Believe me I have practiced a lot, and even had an old bus driver give me some lessons, he even suggested a lower gear was needed with the trailer. Based on this, I had decided a lower gear or an automatic would help things, not having the money to swap out the complete power train at this time. I understand it's not going to do anything for me on the hills, other than be a little easier to downshift (all of you truckers, and experienced drivers will disagree with me on that I expect), but I have found as long as I keep the revs up and downshift early enough I can keep her rolling on all but the longest hills.
I had got some information on 9-10 speed manuals, and even priced out parts late last year, but was leaning towards an automatic, if I was going to spend money on a swap, spend the extra for an auto. Since I have had this HT750 fall into my lap, so to speak, this has helped sway the decision, and if it is halfway decent inside the trans then it may not cost me much more than a replacement 9-10 speed manual trans. It is complete, including a shifter. I spoke to the local Alison dealer and they will check it out and test it for about $150 so thats the way I am heading. If it is no good, I can sell it for a core and get my money back, but I have found a couple of places that will build it for time and materials, so depending on what is wrong I can decide to build or keep looking.
Any decision on engine swaps will come in the out years, the DD runs good today, but agree a little more power would be nice, just not in this years budget.
Thanks again for all the posts.
Dave
PD4501-304 |
niles steckbauer (Niles500)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 12:23 pm: | |
Dave -
Based solely on the info in your last post - If I were you I'd let the Allison do my shifting for me - But, If I can read between the lines, I think you've already come to that conclusion - If so - let me just reinforce it by saying - If your a novice driver (like me) and don't truly enjoy jammin, leave it to the ex-truckers - FWIW - Niles |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 12:43 pm: | |
I do not know if it is correct, but an old time Greyhound driver told me the proper way to take off in my 4104 was with the engine ideling, to just let out the clutch. The coach would jump a little bit, but even on a hill it woould take off ok. Of course I did not have a heavy trailer attached.
Richard |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 12:44 pm: | |
Dave,
Good logic for your decision. If this thread goes much longer I'm sure somebody will suggest you should move rather than install an automatic! <lol!!!>
I'd weigh in by suggesting you add a jake brake, in addition to the automatic, if you don't already have one.
Hills is hills and jakes are made for 'em!
Onward and Upward |
dave4106
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 12:55 pm: | |
425 cat is rated @ 1450 ft lbs torque. thats an engine w/balls alright . spicer 4 spd ,can handle maybe 900 ft lbs at the most. when your pulling a 6% grade steady, ( not doing a burnout) and your gearbox starts to make wierd noises or just plain splits in two, give two dogs a call. maybe he'll help with the tow bill |
RJ Long (Rjlong)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 1:12 pm: | |
Richard - What you describe is called a "Dead Throttle Start", and most coaches will indeed get rolling from a stop using it. But there's a trick to it: you don't just "dump the clutch", you "walk it" thru the take up point. Once you're thru the take up point and the clutch is fully engaged, then you add throttle and away you go.
Fastest way to burn up a clutch in a bus is to slip the clutch with a lot of throttle while trying to get started, either forward or reverse. I'm talking about the common 4 or 5 speed OEM coach gearboxes, not those that have 10-speed RoadRangers in them.
All bets are off on clutch life with a 10K trailer, however. This is one area where the automatics really shine - again, compared to the common OEM 4 or 5 speed manual.
Dave - I think having DDA take a look at it for $150 will be money well-spent, and THEN you can make an informed, intelligent decision.
While you've got the powertrain out, and if you don't already have it, install a Jake brake, especially since you'll be pulling that heavy trailer. In this application, consider the Jake an INVESTEMENT in your coach, not an expense.
HTH,
RJ
PD4106-2784
Fresno CA |
TWO DOGS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 1:37 pm: | |
nothing wrong with the trans...............not enough horses.....falling in lap ????....naaaaa... I get to say:...."I TOLD YA' SO" |
Mike Eades (Mike4905)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 1:38 pm: | |
Dave I have 4905 with a 730. It works fine and Do have to pull a few hills but I get there and back. The only part I am having a problem with is the the shifting and I hope get it fized this season. I pull a very heavy trailer with a hitch weight of 1440 lbs. I put 40k on in 8 months a year. I would like better fuel mileage but oh well. Have the tranny looked at and fixed. Use it and love the ease of driving your baby. Mike 4905 |
RJ Long (Rjlong)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 1:49 pm: | |
Mike - Might want to look at the thread about towing behind a Scenicruiser elsewhere on this board. I, like other GMC owners, are concerned about the heavy tongue load you're putting on your coach.
What's wrong with the V-730's shifting??
RJ
PD4106-2784
Fresno CA |
Jerry Liebler
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 6:55 pm: | |
Mike,
Keep a close eye on those two angle iron uprights on each side of your engine. Especially at the top of them where they join the members that attach to the roof with a 1" bolt. With that 1440 pounds and the 900 or so you've added by swaping to the V730 you may have used up the design safety margin. All that is holding up your engine, transmission and trailer is those two bolts and the 1/4" plates they go through.
It would be prudent to jack up the rear of the cradle, pull the bolts and dye penetrant inspect the plates and bolts and look for oblong holes.
I tow a trailer with about 1000 pounds of hitch load but I have the stock crash box. I've done the inspection twice (5000 mile intervals) and found no problems and intend to inspect as above each 5000 miles.
Regards
Jerry 4107 1120 |
BrianMCI
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 8:18 pm: | |
"The world transmission does a nice job, but there is very little that is as satisfying as matching gears and having total control over the shifting."
Jon, I really enjoy rowing through the gears too... in my car.
I know guys that would give their left one for a world transmission, and probably would swap in a 4 speed spicer for you if they could keep the take-outs...
Brian |
Dave Hartshorne (Yeeolde48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 8:25 pm: | |
Marc, RJ, good idea with the Jake Brake, will check around locally to see if I can find one at a reasonable price. |
Jon W.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 05, 2005 - 8:50 pm: | |
"I know guys that would give their left one for a world transmission, and probably would swap in a 4 speed spicer for you if they could keep the take-outs... "
Brian,
I'm going to hold out for a 10 speed.
Actually the world transmission does a pretty good job, but like the 755 in my other coach it still gets confused coming off an interstate onto a cloverleaf, and if I don't mash the gas pedal the downshift is brutal. Using finesse on the gas pedal causes some hesitation and then BANG it picks its gear.
I suppose I should be manually downshifting it as it slows, but it is called an AUTOMATIC, right? |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 07, 2005 - 11:08 pm: | |
On transmission choices: pick what you will enjoy driving at the end of a long day.
For my younger knees, I'd be happy with a stick, however, due to many years of employment yet to do, I have to get in and out of a major city on the weekend to go to bus rallies. Stop and go traffic is no fun with a clutch and a typical bus transmission, because first gear is too tall for creeping in traffic. I have a 740, more because the coach came with it than I picked it that way.
Jon, that World transmission of yours has a problem. They shift smoothly when working properly. Is it the same gear or speed that bangs, or more than one?
When I drive a World, I do a lot of my own gear selecting, probably because I'm one of those old 740 drivers who always preselected the gears for better driveability and passenger comfort. Old habits die hard?
Even with the improvements of computerization over the old valve bodies, there are too many variables that the tranny computer is not making the same decision that I want. The power to weight ratio of a bus is still not that of a car. Lots easier to make a car tranny feel like it is smarter than the bus.
The World is a great tranny, however I find the driveability can still be a bit better by choosing my own gears. I always leave it in 3 in the city, and either punch it to drive as I turn on the highway ramp, or as the mood strikes, shift 4,5 & 6 myself. Same with slowing down, usually do some downshifting/jake/retarder to save the boss some brake life, and keep the brakes cool for me.
happy coaching!
buswarrior |
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