| Author |
Message |
Mike Jackson (Mike4104tx)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 19, 2005 - 5:33 pm: | |
I didn't know that there was an automatic made for the 4104. I am curious how it performs in the bus? What is the top speed? Can you manually downshift it? Is it reliable? How does it effect the MPG? Is it very hard to install?
Mike |
Don/TX
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 19, 2005 - 6:08 pm: | |
They are rare, I have seen only one. It is not an automatic, but simply a two speed box that gives you the same gearshift pattern and clutch, kinda like a two speed rear axle. |
Rick Brown
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 19, 2005 - 6:36 pm: | |
Is this something that might function in a 4905?
-Rick Brown in Reno, NV |
Mike Jackson (Mike4104tx)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 19, 2005 - 6:38 pm: | |
I didn't know that. I guess the advantage to having it is better low speed power and more high end speed? |
Jim Stacy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 19, 2005 - 8:42 pm: | |
The Hydroshift was an extra planetary gear and second clutch disk all mounted in the bell housing. The planetary gearset allowed a second gear ratio input to the original 4 speed (actually providing 8 speeds forward) still with the manual Spicer non synchro tranny. This was not a very robust design even with the stock 6-71 (about 180 HP) and few stayed in service very long. They were usually converted back to the original 4 speed. Parts would be very scarce.
HTH Jim Stacy |
Tim Hoskinson (Tdh37514151)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 19, 2005 - 8:43 pm: | |
Hydra shift was a dual clutch system that had planetary gears built into the clutch disc its self. One clutch was hydraulically controlled the other was controlled by the clutch pedal. The primary clutch stoped the rotational power from the engine to the input shaft the other allowed the planetary gears to revolve thus slowing the output rotation to the input shaft. This allowed for under drive and direct drive to the transmission |
Ron Frazier (Ron_4104)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 20, 2005 - 2:33 am: | |
Keith Crawford, from Crawford Coach near Mifflintown Pa. has a 4104 with hydra shift. He can take off in 1st gear, even on an incline without using the accelerator and still run 100mph if anyone cares to run a 4104 that fast. He says parts are scarce as hens teeth and takes lots of $$$$$$ if you find them. Also not too hard to tear up parts. Wish someone could have figured out how to put a 10 speed automatic in my 04. Keith put a 8V71 with V730 in mine and I'm happy. Some of you may have heard of Sam Crawford, Keith's dad. Thet tell me he forgot more about buses than most will ever know. He is buried just down the road from the bus shop. His gravestone has a 4104 engraved on it. Ron 4104 |
Mike Jackson (Mike4104tx)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 20, 2005 - 2:48 am: | |
Ron,
Thanks for sharing the info. I was happy with 60-65 MPH in old 4104. I can't imagine going 100 MPH... what do you do when you have a blowout on a front tire going that fast??? One thing that did concern me in my olf 04 was getting trapped on a incline and not being able to take off. It never happen to me, but I saw the potential.
When he put the 8v71 with the V730, did he use the engine and mounts off a 4106?
Mike |
Don/TX
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 20, 2005 - 6:58 am: | |
Ron, the hydrashift would be of no help whatever for top speed increase, and I doubt if the old 6/71 would turn that fast with stock gears. Perhaps he changed the differential ratio? |
busboy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 20, 2005 - 8:25 pm: | |
The Hydra-Shift was a "splitter" giving overdrive to the regular 4 gears. It was marketed by GMC as a way to cut down the engine top RPMs to 1900 to save fuel and make the engine last longer. It would also have helped the bus climb hills faster, though at some loss in fuel economy.
They Hydra-Shift used some parts common with other transmissions -- the planetary set and one of the clutches is apparently interchangeable with one planetary set in an Allison VS2 automatic transmission and I believe (not sure) the main clutch can be made by modifying a wet clutch as used in 4107/4905 transmissions. Somebody told me there was also a hydraulic pump on the engine to run the planetary clutches, and there may have been some changes to the transmission case.
I spoke with a mechanic who said the planetary and one of the planetary clutches tended to fail early and often. As somebody mentioned, that was with a 6-71 and the higher power 8v71 and higher bus weight of a 4905 would make it fail faster. Another problem is the transmission bevel gears are a different angle than used in 4106 and on, so you would need to switch out the rear axle to a 4104 axle and I'm not sure you can get adequate brakes or if the various parts of the back axle can all take the load.
I never understood why older buses had 4-speed transmissions. It seems everybody I hear from about the Hydra-Shift says it was popular with drivers but failed early, often, and without warning. But failures are solvable. However, instead of solving the problems, GM just dropped it.
If anybody has more info on Hydra-Shift, I am doing a little spare-time research project (just my own curiousity) and I would appreciate more info. |
Don/TX
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 20, 2005 - 9:34 pm: | |
Well, we have opposing views, was it an overdrive or an underdrive? The one I saw I was sure it was just an underdrive as Tim said. The owner used it to pull a trailer with a race car and tools and equipment, claimed it gave him lower gears. It was busted, that is how I got called in, but I never got to drive it. He claimed you could split shift it, like fourth over, then fourth under, then third over etc. |
Tim Hoskinson (Tdh37514151)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 20, 2005 - 9:51 pm: | |
Busboy I stated earlier that the Hydrashift was a direct and underdrive. However I find my memory is much better if I get out my book and read it again. You are correct the Hydrashift is a overdrive and direct. According to supplement manual that I received with my 4104 the hydraulic pump was engine mounted. The hydraulics were controlled by means of a electric solenoid valve and a regulating valve. The solenoid valve was of course controled by a push-pull switch located on the shifter in the same way a two speed shift was for a two speed rear axle. If you would like any particular info. from the book let me now and I will see if I can find it. Tim |
Ron Frazier (Ron_4104)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 20, 2005 - 9:54 pm: | |
Mike
I purchased a Grumman shuttle bus with an 8V71 & V730. We also used the air throttle & the stone bennett shifter. Keith Crawford has a lot of junk buses, known as parts buses to us busnuts, and he used a fishbowl cradle to mount engine and tranny. We changed the rear punkin to a 4106 to get the right angle to hook up the driveshaft. Gear ratio is called a 4 and 1/8. I think that translates to a 4:11. Radiator is out of a 4106. Lots of work and $$$$, but I'm happy. I've got arthritis and it was getting hard to drive the 04 for any length of time. Now it's a pleasure to drive. I spent more than the 04 is worth on the market, but who in their right mind would sell a good 04? If you love your bus logical is not always practical or is the other way around? Happy Bussin' |
Tim Hoskinson (Tdh37514151)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 20, 2005 - 9:59 pm: | |
Don I would say the bus you looked at probably had a low geared rear axle and the overdrive put the bus back up to nomal gears for the road. When more pulling power was needed it was shifted back to direct and with low rear gears it had good pulling capabilities. I was told once that most of the buses with this arrangment were used in mountainous areas. Tim |
Mike Jackson (Mike4104tx)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 21, 2005 - 12:31 am: | |
Ron,
Hehe... well we sold our 04. We sold it to buy a house. It was our only option at the time and the deal on the house was to good to pass up. I do miss the bus. We plan to buy another one soon. We are not completely sure which bus we are going to get yet, but we have it narrowed down to four buses. (two 4106's and two 4104's)
I agree with you about the bus. We put the money and time into it for our enjoyment... not for the return on the investment. It would be more practical for me to rent a sticks and staples once a year. hehe whats the fun in that. I like the adventure of the bus...
Mike |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 21, 2005 - 6:17 am: | |
"I never understood why older buses had 4-speed transmissions."
For line haul pax service thats all that ever was needed.
Its only when the convirsions add 12,000 of goodies that 20,000 lb coach runs at 32,000 dragging a 5000lb toad lump .
Then some extra gears would be nice , but its far easier to get rid of say, 10,000 lbs and have the coach perform well again.
FAST FRED |
DG
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, November 22, 2005 - 9:57 pm: | |
The first 04 I drove in 1973 had a hydrashift. It it was being repaired and all those little extra clutch pieces were giving the mechanic a headache. Even after the repair it was always a sticky shifter, often getting stuck in 2nd gear. |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 08, 2005 - 10:34 pm: | |
For what it's worth, a 4.11 ratio has nine pinion teeth. The 4106 has eight teeth on the pinion, making it a 4.125 ratio.
Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska |