| Author | Message | ||
| Austin Scott Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 334 Registered: 9-2006 Posted From: 216.37.73.226  Rating: N/A |
A question was posed to me last night at the gig by my co-owner of the bus..... What would be the best combination of engine / transmission / rear-end for our 4104 if we were to re-power it? I'd like to hear your thoughts on everything from a rebuild of the stock engine, adding turbo, engine replacement transmission and dif replacement. I like my manual transmission but am not opposed to having an automatic. Some background on how we use the bus..... We take it to every gig. We currently are doing 4-5 gigs a week. Most of the gigs are local, but we do get a few gigs that take us on round trips of about 1000-1500 miles. The future of the bus is that we would like it ready for more frequent longer trips. 1000-3000 miles stopping to do several gigs over a couple weeks tour. We want a good reliable combination that has over the road power, speed, and fuel economy. Top speed is currently 60mph-65mph I would like to have at least the capability of 70mph even if I would not use it except for passing. | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1529 Registered: 10-2003 Posted From: 71.58.110.9  Rating: N/A |
Honestly, if it is not in mint condition, just find a coach that already has what you need. You'll spend as much as the cost of another coach would cost. People don't figure in the extra parts and labor costs that result, especially if you have to have someone else do it. Also, don't forget to factor in the down time. A 6V-92 with v730 automatic would be the best setup, as these are plentiful at the present as buses are being dismantled; see NIMCO for example. Top speed will be at approx what you have now, maybe another 5 to 6 mph. Mileage will drop 3 mpg. Nice power now, especially on hills. They make a 3:55 ratio rear for your coach, although it makes starting out and backing more difficult. It'll will gain you 10 mph though. Adding a turbo will wake up this engine, but will not help starting out torque with the tall rear. If you could get the other ratio gears for the transmission, this would work nicely. It makes the first three gears lower and increases the gap between 3rd and 4th. In my Brill, third gear was done at 40mph. With the 3:55, it would probably go to 45mph, and the turbo would mask the gap almost entirely. The good setup would be the old Hydrashift, 4:11's and turbo. 4:55's would be perfect if they could be found. Could back up with idling and good low 1st with about 80mph top speed. THAT would make it the TRUE sportscar of coaches. Good luck finding a Hydrashift though. | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 849 Registered: 10-2006 Posted From: 76.216.70.120 Rating: N/A |
"They make a 3:55 ratio rear for your coach," This is a V drive coach FF | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1530 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
and.... Fred? | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1531 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
In case there was confusion on my previous thread: 4104's came with a choice of three gear ratios in the rear axle. 4 1/8, 3 7/8, and 3 5/9. To us it would be 4:11, 3.90, and 3.55. I have never seen the 3.90 version. The transmission was direct or 1 to 1 in 4th gear. When they came out with the 4106 and subsequent models, they made several changes. The standard and automatics were over driven in top gear. Because of this, they only offered 4:11 and 4:375 ratio rears. Some city buses of 4104 vintage and newer used 4:55 and higher numerically. They also changed the angle of the drive train to rear axle because of moving the angle gear set to front of transmission instead of at rear of transmission for greater durability. Due to this change and length of engines used , which were shorter, but trans was longer, the differential was offset to a different position in the axle housing. When you put a 6V92 and V730 into an 04, this drive shaft angle difference must be dealt with or severe drive line vibration and/ or short u-joint life will result. Some install a rear axle out of a 4106, 4905, etc., which will also add the benefit of the ten inch wide brakes off the 4905. Bulkhead trimming and reinforcement will be necessary. Also,a radiator change will be necessary for the increased cooling requirements. Some have flipped the 4104 axle over or upside down or end for end and reused the differential they have. Since the rear cover on a 4104 rear axle is bolted on, this is not a problem. They then do some jockeying of the position of the engine so everything lines up properly. Some use a 4905 differential in the 4104 housing to get the changed angle. From what I understand, the 4905 chunk will fit into a 4104 housing, but the 4104 chunk will not fit into a 4905 housing. It looks as if the bearing caps on the 4104 differential are a great deal larger and will interfere with the inside of the housing before it goes clear in. In case someone asks why someone would want to do this: How about a 3:55 ratio differential installed into a 4905 with automatic. If you could find a constant velocity joint type u-joint to take care of the problem of the angle difference, you would have a nice top gear for cruising. 3:55 times .875= 3:11. Anyway, changing an 04 over to another engine will still be a lot of work and costly. At the cost of used good buses now, it would be quicker and cheaper to get a newer one or turbo the one you have if it is in good condition. | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 852 Registered: 10-2006 Posted From: 76.216.70.120 Rating: N/A |
The easiest drop in might come from a scrap transit. The engine , tranny and rear end could all be taken with a Ser 50 and the dedec. The wider rear axle could be cured with super singles , to keep the wheels from sticking out. Biggest problem is the extra HP and probably the use of a Jake would require massive reinforcement of the coach rear, and with monocoque construction , that aint easy!Ask Boeing. Would not make sense to install a modern 330hp engine and de rate it to 230hp , although that might keep the coach shell together. You want EZ , find a good running turboed 6-71 and install it. Done, FF | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1532 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
Massive reinforcement? Come on Fred, are you on crack? The 4104 is built beefier than the newer models and the torque of that "great" 50 series is not going to phase that unit, especially with an automatic. Hope that the installation doesn't make the owner have to get used to the vibrations from that 4 cylinder.Detroit diesel is phasing out the 60 series and probably also the 50 series; another engine that will be harder to get parts for down the road. Might as well stay with the 2 cycle. At least they have been built almost forever. Otherwise, it can be a nice idea. As far as the wide rear, just get a narrow version of the same axle assembly. Also, the radiator will not be needed to be changed. We're still talking about more time, money,and labor than most 4104's are worth now. Just get a newer model with what you want. | ||
| Tom Christman (Tchristman)
Registered Member Username: Tchristman Post Number: 100 Registered: 1-2006 Posted From: 66.218.33.156 Rating: N/A |
I saw a Series 50 a V730 in a 3751 (?) silversides-was a real squish job-but was in and running. I would stay away from the Series 50. While they look good on paper and do get good fuel mileage and power, they have two balancing shafts driven off the oil pump with small fine cut gears that have a tendency to strip out-and when they do the massive offset vibration will tell you. The better setup would be a Cummins ISC 330hp @ 1000lb/ft through the same reverser gear through a V730-then you'd have a modern engine that is still in production and will continue to be in production for the foreseeable future. Good Luck, TomC | ||
| David Evans (Dmd)
Registered Member Username: Dmd Post Number: 334 Registered: 10-2004 Posted From: 173.68.141.145  Rating: N/A |
Pretty much dead on right that another coach would be the smart thing to do..... but then again we need to step up and embrace the fact that we are bus NUTS! When we discussed the expenses involved with repowering a 1948 coach and making it road worthy to explore the USA,Canada, and up into Alaska, it never made any sense, dollar wise. 6 Years ago we could have bought several buses that were already converted with a drivetrain. Now that list has doubled. But we wanted OUR 35' double axle coach with the old look. A 4104 that has been refitted with a 6V92 and an auto would probably work for us. There are several of them out there that have been NICELY done. The one we saw in Arcadia is what got us started on our repower. Good Luck Austin! | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 857 Registered: 10-2006 Posted From: 76.216.70.120 Rating: N/A |
"The 4104 is built beefier than the newer models and the torque of that "great" 50 series is not going to phase that unit, especially with an automatic." Need I remind you that the torque converter (depending on stall ratio) will double the torque on initial start? So a 50% more powerful engine with double the starting torque may eat up any "built beefier" buffer in a heart beat. Heavily built may have a grand 50% overload ability and have had no problems for 1/2 century, but were talking way beyond 100% torque increases at start, or many times with converter unlocked. And a Jake and retarder will load the coach in REVERSE from what was envisioned at the design board. FF | ||
| Austin Scott Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 335 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
Thanks for ALL of the input. We know that a new(er) bus would be the best choice and maybe even cheaper in the long run. A new bus may be the way we go. We do not have any plans to sell this bus as it does have some family/sentimental connection to the co-owner Eddie Smith. Our intention here was to see all the options and the degree of modifications needed to perform the swap. I don't think we want to modify the bus extremely so our best option at this point may be to stick with a 6-71 with turbo. . | ||
| ned sanders (Uncle_ned)
Registered Member Username: Uncle_ned Post Number: 59 Registered: 5-2005 Posted From: 74.235.131.78 Rating: N/A |
I have two 4104's one with the 6-71 and 4 speed and one with 6v92 and 730 allison. The 671 sets in the yard while the auto goes. If you find the right person the conversion will not cost that much.and you will still have that "drivability" of a 35 ft. over the road coach. And when you pull into a gig people will come up to check out that old bus and ask what engine is in that thing. Will be a great calling card. uncle ned "HUGGY BEAR" 4104 with 6v92 and 730 | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 536 Registered: 3-2007 Posted From: 71.53.155.14  Rating: N/A |
I had seen several 04's with a 6V in them with auto 730 and they were great, so Austin do what Uncle Ed said 'find a person to help you and you will not be dissappointed,I garuntee that!!! Gomer | ||
| Kyle Brandt (Kyle4501)
Registered Member Username: Kyle4501 Post Number: 486 Registered: 9-2004 Posted From: 65.23.106.193  Rating: N/A |
Hey Ned, Care to share the hp rating & fuel mileage of that mosquito fogger of yours?  What size trailer will it pull? How often do you have to have the rear section of the coach put back on as a result of that hp upgrade banging around back there? | ||
| ned sanders (Uncle_ned)
Registered Member Username: Uncle_ned Post Number: 60 Registered: 5-2005 Posted From: 74.235.131.78 Rating: N/A |
kyle HP is enough to run with the big boy's. Will pull a airstream and never know it is back there. Have never had any problems with anything falling off, have gotten several s&s's stuck in the exhaust and had to turn the turbo up and blow them out. Fuel mileage depends on the right foot any where from 4 mpg to around 9. Also it has never been on the back of a "low boy" Look forward to seeing all on the fourth uncle ned PS if you make HP you will make black smoke guess close to 400 | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1534 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
One other thought came to me today; that 50 series in front of a v730 is going to be turning 2000 to 2200 rpm cruising down the road due to the limited available overall gearing selection in our v drive coaches. That engine was designed to cruise at a much lower rpm. I don't think it is going to be too happy wound out like that and not be nearly as economical as it is claimed to be. I'm not saying it can't do it, but those two cycles were designed more for this kind of use. Most uses are in city coaches or otr buses with gearing better suited to make use of it's great torque and horsepower curve. It might work great in front of a vs2-8 for low rpm cruising, although nobody will probably try it. |