| Author | Message | ||
| Mike Everard (Meverard)
Registered Member Username: Meverard Post Number: 5 Registered: 1-2011 Posted From: 98.210.8.135  Rating: N/A |
I have a PD 4104 with a 6-71 engine. I would like some help finding the right tach for me. I don't have the 50DN gear drive alternator that came stock on that motor. I have a Prestolite/ Leece Neville, 130 amp, 14 volt, model #A0012670LC Regulator, that is belt driven. Any ideas where and what I should buy? Will I be able to monitor at the alternator, or will I have to put a pickup at the flywheel? Any help is greatly appreciated. Mike | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 449 Registered: 3-2006 Posted From: 216.198.139.38  Rating: N/A |
Mike Stewart Warner makes a tach that goes to 3500 for a diesel application. There is a sender that goes onto the tachometer drive takeoff from the blower. I'm not sure if the 4104 has this takeoff but most Detroits do. There is also ones that get their signal from the alternator. Do an online search for a diesel tach and there is lots available. Bill | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 1059 Registered: 8-2006 Posted From: 74.33.43.204 Rating: N/A |
Call these guys in Phoenix they can fix you up and answer all questions www.precisionspeed.com (Message edited by luvrbus on March 05, 2011) | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 1266 Registered: 11-2005 Posted From: 75.121.203.118  Rating: N/A |
Mike, Although I'm a big tach fan for trucks and sports cars, I've had a 4104 for five years and have never seen any need for a tach. It is a lot of expense and work for a limited benefit. You can tell by the sound and feel of the ole DD when you need to shift. | ||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 153 Registered: 7-2006 Posted From: 173.180.126.136 Rating: N/A |
Mike i had an stewart- warrener and yes the drive of the end of the blower and had to change that drive unit 3 times so i changed it too an ISSPRO they are made in Portland OR. and they pick up off the teeth on the fly wheel,have had it in for 15 years in our 4104 and have helped other people install them and they are all very happy with them. you will find a tack a great asset when you cannot hear the motor or feel the vibs of the stick as happens when on rough roads in high noise or people talking, or you have music playing as you drive. | ||
| Pete/RTS Daytona (Pete_rtsdaytona)
Registered Member Username: Pete_rtsdaytona Post Number: 641 Registered: 1-2005 Posted From: 184.88.99.113  Rating: N/A |
If you have a GEAR DRIVEN 50DN 24Volt Alternator ---> The "R" terminal output is a +12 volt (inverted sine wave) pulse . Most 6V92 / 8V92--->(2.94 (53/18) gears & 6 pulses per rev=17.66 pulses/rev) . Most 24 volt - 8v71->(2.75 (55/20) gears & 6 pulses per rev=16.5 pulses/rev) . Most 12 volt - 8V71->(2.29 (55/24) gears & 6 pulses per rev=13.75 pulses/rev) | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 2040 Registered: 10-2003 Posted From: 71.58.71.157  Rating: N/A |
Ours had the tach off the gear teeth on the flywheel as well.Had to move it there when we added Sheppard power steering; lost that location to mount the tach drive. Yes, you can get along without a tach, but is useful to avoid lugging engine and timing shifts. | ||
| Steven Foster (57_gmc)
Registered Member Username: 57_gmc Post Number: 37 Registered: 12-2010 Posted From: 72.156.216.251  Rating: N/A |
Mike for what it is worth I have a 4104 and my tach is off the flywheel and the head that is on top of panel has Freightliner on the face. It works great. If you want any numbers off it will see what I can come up with. Thanks Steve | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 1461 Registered: 10-2006 Posted From: 66.82.9.83  Rating: N/A |
What will the tach do? Most folks drive to the gov , shift and repeat till in 4th. The speedo can work as a tach in 4th if you wish, just create a conversion card. The most important RPM /speed is for down hill, as your engine might not like 2600rpm very much. FF | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 1388 Registered: 12-2000 Posted From: 75.204.31.95  Rating: N/A |
We got our tach from Precision Speed, mentioned above by LUVRBUS. It gets a signal from the R terminal on the alternator and cost less than $100. They were very helpful when we changed from gear drive to belt drive alternator and had to re-program the tach. Jack | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 2039 Registered: 12-2000 Posted From: 174.89.173.81  Rating: N/A |
When you have little overlap between gears, and only a few of them, as we do in a stock coach, a tachometer doesn't give you much value beyond what your speedometer already does. The gear you are driving in when there are 3/4/5 gears is dictated by road speed, not driver choice. You shift up and down at the same road speed, because you have little choice. The top of the preceding gear barely gets you to the bottom of the next, and vice versa going down. The big diesel engine RPM range, only spinning to 2100rpm, does not give us the flexibility that a greater RPM range, in, for instance, a gasoline car, where you can use almost all the gears at a given road speed, just by changing the engine RPM, because you can go all the way to 5000 rpm. Interestingly, try to drive a car without going over 2100 rpm, and you'll find pretty much the same conditions as driving the coach! The other variable is the number of gears. The closer the ratios, the more overlap, and the more times you have to change gears, a tachometer starts gaining in value to give the driver information that is easier to use than the speedometer. Bigger engine rpm range, and/or more gears to choose from, means more choice for the driver, and the need for more information to make good decisions. But, regardless, there's nothing wrong with adding a tachometer, if you want one! happy coaching! buswarrior | ||
| Mike Everard (Meverard)
Registered Member Username: Meverard Post Number: 6 Registered: 1-2011 Posted From: 98.210.8.135 Rating: N/A |
Thanks for all of the information. In reading archived threads, prior to posting this one, I was ready for an aray of replies regarding the need for a tach. I appreciate the fact that everyone drives their coach differently. When I purchased my bus the speedometer was not working. I spoke to a very well respected member of the bus community in my area and he suggested a tach. I know they both do virtually the same thing if you understand the RPM's/Speed in each gear. However, I believe the tach will help in downhill shifting for me. Luvrbus, Mel,and Jack - thanks for the info you provided in helping me locate someone who can help me further. Mike | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1792 Registered: 12-2000 Posted From: 71.195.124.20  Rating: N/A |
Mike - I KNEW somebody would come up with the name of that place in AZ - I just couldn't remember it. Give them a call, they'll fix you up. FWIW & HTH. . .  | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 1269 Registered: 11-2005 Posted From: 173.202.4.226 Rating: N/A |
Mike, A GPS will give you far more accurate speeds than any speedometer. I use mine more than the speedo because it is easier to see. It is also a good backup if your speedo needle starts to dance! |