| Author |
Message |
Larry D
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 12, 2005 - 10:45 pm: | |
the GMC 4905 I am looking at has a 3 speed Allison with lock-up torque converter, what is this and any special way to use? |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 12, 2005 - 11:04 pm: | |
It's an Allison V730, and only one of only two slushbox models that'll mesh up to the v-drive GMCs. The other is the Allison VS2-8. You can search here and find a lot of info on each.
If you don't like shifting gears, the V730's a good tranny. They generally cost you more in fuel and top speed over the standard Spicer 4-speed. Many converters spend big buck$ to convert the stick to this tranny, so if you're inclined to have an auto, it'd be another check mark on the plus side of this particular coach you're looking at.
HTH,
Brian Brown
PD4106-1175 (forever a Spicer!)
Our Bus SIte |
Jerry Liebler (Jerry_liebler)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 13, 2005 - 12:16 am: | |
Larry,
Look for some form of support for the right side of the transmission. The V730 weighs some 500+ pounds more than the stock manual putting a tremendous load on the engine flywheel housing. A competent conversion to a V730 will incorporate additional support on the curb side. I'd pass on the bus if it's not there. The only caution in driving with a V730 is you've only got engine braking when its in converter lock up so steep mountain downgrades can be a bit hard on brakes. Also there are some 30 variants of the V730, some shift at 1800 rpm, some at 1900, some at 2100. any but the 2100 will compromise your mountain climbing ability. If you'll send me all the numbers on the transmission's data plate I'll consult the V730 manuals and tell you all the options in that particular unit.
Regards
Jerry PD4107M 1120 (yes that's manual) |
RJL
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 13, 2005 - 1:23 am: | |
Larry -
Besides the good information already given, go back to the BNO Main Page, look for the "Articles of Interest" in the LH column, and read the one about "Shifting". Near the end is some tips on driving an automatic transmission-equipped coach.
Oh, and an additional note regarding engine braking - it's really not the same with a diesel as it is with a gas engine. To obtain the best engine braking on a diesel, especially the Detroit Diesel in this 4905, you need a Jacobs engine brake, more commonly known as a Jake brake. That will take a huge load off the brakes, at least while the torque converter's locked up.
HTH,
RJ
PD4106-2784
Fresno CA |
Geoff (Geoff)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 13, 2005 - 7:56 am: | |
I have a V-730 in my RTS and actual experience is that you WANT the transmission to shift at the upper rpm settings of the governor (except 1st to 2nd) to get the maximum power out of the engine and to shift up or down to the next gear at a good rpm. This is also the way you shift a manual transmission with a Detroit (unless you are cruising). Also, with the V-730 the torque converter locks up shortly after starting out in first gear and stays locked up through 2nd and 3rd until you practically come to a stop. The only time you might go out of lockup is going extremely slow in first gear.
So to answer your question the only special consideration you should take with the V-730 is to use second gear and your brakes on the worst downgrades, or just use the Jakes (if so equiped). Having a tachometer is nice on the hills so you can keep the bus in second gear and slow it down with the brakes when the rpms get up to 2300. Other than that, just sit back and enjoy the drive instead of fumbling through the gears!-- there is a good reason automatics are more popular than stick shifts!
--Geoff
'82 RTS CA/AZ |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 13, 2005 - 8:55 am: | |
Hello Geoff,
When does your V730 torque converter lock-up?
Are there variants of this?
The ones I'm familiar with lock part way through 2nd, or so I thought.
I'm open to an education!
happy coaching!
buswarrior |
Geoff (Geoff)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 13, 2005 - 10:57 am: | |
Opps!
http://www.busnut.com/bbs/messages/233/4930.html?1069556163
--Geoff |
Craig Craddock (Gs4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 13, 2005 - 1:33 pm: | |
I too am using a V730 with a 8V71TA I never use the brakes except for below 15 mph when the torque converter finally kicks out during the final stopping. It never kicks out of lockup on grade descending at any time.
I am always pulling a 6,000 lb plus trailer.
I am thinking about installing a switch so I do not use all 8 Jake slave cylinder,such as only 6 and 4 when needed. I go years without actually adjusting my brakes. I do check them regularily. In 10 years since I replaced my brakes I can not see any wear at all. One of my top best investments for me as 75% of my driving is in major mountains. Geoff's link is right on. |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 13, 2005 - 1:54 pm: | |
Craig, my Jakes were set up to turn all, half or none on and it worked great. Like you in 150,000 miles I never had to replace any linings. Putting my foot on the brake pedal was the last thing I would when slowing or stopping. It is really remarkable how much braking can actually be done without using the brakes themselves.
Richard |