| Author | Message | ||
| Robert Drake (Draker)
Registered Member Username: Draker Post Number: 1 Registered: 8-2006 Posted From: 216.46.130.231 Rating: N/A |
I have a 1959 GMC 4104 Highway Coach with a 4 speed standard and I want to change it to a Automatic.I need to know what trannys and what years will work.It has a 671 Detroit with a V style standard tranny. | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 984 Registered: 5-2001 Posted From: 65.74.70.16 Rating: N/A |
An automatic, if there are no changes to the engine, is likely to hurt both performance and fuel economy of your coach. These are typically very difficult and expensive conversions. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| Tim Hoskinson (Tdh37514151)
Registered Member Username: Tdh37514151 Post Number: 180 Registered: 9-2004 Posted From: 4.253.121.238 Rating: N/A |
Robert it would be very difficult to install a automatic trans with out changing out the engine to a v style. Also because the V angle of the auto trans is different the rear axle should be changed as well. Your bus being a 96 inch width will be difficult to fit a in line 671 to a auto trans. The city buses that did use the in line engine with an auto trans were 102 inch with. The 96 inch wide buses used the V block engine to reduce overall lenth of the engine and trans. The 4104 can and has been converted to a V style engine with auto trans but it dose take a good bit of work and expense. Best of luck. Tim | ||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 15 Registered: 7-2006 Posted From: 208.181.100.47 Rating: N/A |
i have seen one 4104 that had the 4 speed replaced with the auto, this was done by a very knowledgable ship mechanic of over 85 years old and it requires a lot of know how. not only do you have to change out the tranny but you must get the drive shaft lined up to the tranny and the rear end pumkin or you will have vibrations all over the place. also you will need engine mods.as to water pump oil and coolant lines. next will be a larger radiator with more cores. this means that the engine must be removed and the whole bulk head should be rebuilt. and shifting the auto will require a different set up. yes it has been done and some of the change overs are a mess so be carefull how and who does it that they know what they are doing or you have a coach that will end up in a scrap yard long before it should. the fellow that did the one i seen passed away over a year ago so cannot ask him what is also required and i have some of these trannies but gave up on the idea of a switck. | ||
| David Evans (Dmd)
Registered Member Username: Dmd Post Number: 72 Registered: 10-2004 Posted From: 71.125.9.62 Rating: N/A |
Robert, sit yourself down with a pad and pencil and use the search feature in the archives. There is alot of info on these as well as the famed auto vs stick wars of days past. I have seen several 04's with an auto and it seems that an upgrade to an 4106 rear differential is required for proper gearing. I'm sure someone with a modified 04 will chime in soon. Good luck. | ||
| Craig Craddock (Gs4)
Registered Member Username: Gs4 Post Number: 40 Registered: 12-2004 Posted From: 69.19.14.31 Rating: |
Robert I have done two. Both we have since repowered. Most of the above info is correct. I would buy a bus with the desided engine and transmission. You will be way ahead. If I can answer any specific questions my address is Craigc at hughes dot net Craig C | ||
| frank-id Unregistered guest Posted From: 67.136.154.191 Rating: |
Changing a GMC to an auto trans was one of the best bus improvement I have madeto my GMC 4107. If the engine trans is a Vee drive, no major problems. I installed a 6V92Ta and auto from a city bus made by Flex. This is a very doable project. The engine and trans are removed on a dolly. The driveline chase needs to be modified slightly. The joy of driving is terrific. That old gear grinding is no more. Only folks who have not done any major work on a GMC posted. Frank | ||
| Charles Seaton Unregistered guest Posted From: 170.28.136.41 Rating: N/A |
Sorry Tim, GM TDH buses (transits with autos) came in both 96 and 102 inch widths. Bob, I've never been one to spend someone else's money, but if I were changing a 4104 over to automatic, I'd change the engine also and go 6V92 and V730. Having said that, I've owned a TDM5108 (Old look suburban) with the same driveline set-up as the 4104 and are very easy shifting buses and even fun to drive. | ||
| Tim Hoskinson (Tdh37514151)
Registered Member Username: Tdh37514151 Post Number: 182 Registered: 9-2004 Posted From: 4.252.65.233 Rating: N/A |
Hi Charles there seems to be some misunderstanding about my user name. The TDH has nothing to do with a bus. These are simply my initials ahead of the model numbers of my favorite buses pd3751 pd4151 As for my statement about the width of the transit buses I am aware that they came in both widths but I don't think you will find the 96 inch models were ever produced with a in line 671 and auto trans. This combination was used in the 102 inch width. By the way Frank your statemnet that the only poster here have no experiance is far from true. | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1006 Registered: 12-2000 Posted From: 71.195.113.23 Rating: N/A |
OK, time to jump in here and clear up a few things: 1 - GMC did build 96" transit buses with automatics in them using the inline 6-71. An example are the TDH5103s built from 1951 thru 1953. But these models did NOT use the V-730s or even the VS model automatics, they used the much earlier V-series. Basically it was a two-speed unit (like a giant Chevy Powerglide) with the angle drive where the tailshaft normally would go. 2 - Most folk who have put an automatic in a 4104 have chosen either an 8V71 or a 6V92 coupled to a V-730. Both will work, but, as has already been mentioned, in doing so you MUST use a rear axle out of a 4106 or later model in order for the drive shaft to align properly. Some have had success flipping the 4104's axle over. . . 3 - The one owner I know personally that has a 4104/V-730 combo in it says it's fine for around town and on the flats, but it climbs 6% grades at 15 - 20 mph. He's seriously considering putting a OEM stick shift back in the thing! Frank id - Hey guy, good to see you're still around! Installing the V-730 in the 4107 is a different ball game than in a 4104, much easier. I agree with your points about it making the coach much easier to drive, however. Robert Drake - To the original question, I'd like to bounce that back to you with a "Why?" If it's because you're having problems shifting the manual, then the question becomes "Have you adjusted the clutch properly, per the shop manual's procedure?" When adjusted properly, the 4104 clutch can be as light as a VW Bug's. If it's because the clutch is worn out, that's a different can of worm$. If it's for medical reasons (left knee, for example), it's understandable. If it's because of the lousy 1st & Reverse gearing in the 4-spd stick, we all know about that and grumble constantly. We tend to forget that the coach never was designed as an RV - it was designed to run down the highway from depot to depot, not trying to wiggle in and out of non-level campsites. Lots of info posted, HTH. . .  | ||
| Tim Hoskinson (Tdh37514151)
Registered Member Username: Tdh37514151 Post Number: 183 Registered: 9-2004 Posted From: 4.253.125.91 Rating: N/A |
Hi RJ I wasn't aware of the auto trans you tell about in your post. I have never seen info. on one. I know from looking at a good many buses for repower doners for the older models that I play with that the V drive angle of the 730-731 would be very difficult to install in a 96 inch wide bus useing the 671 in line due to the bevel gear position change. However I know I certianly don't know it all so you will note that I stated I didn't THINK you would find such an animal. Like alot of old equipment it is very difficult to know all the different things that were built. Thanks for the info. part of the fun of playing with this old stuff is learning along the way. Tim | ||
| Dale Waller (Happycampersrus)
Registered Member Username: Happycampersrus Post Number: 239 Registered: 7-2005 Posted From: 172.147.220.3 Rating: N/A |
The TDH is the letters used in the prefix of the GMC Newlook or "Fishbowl". An example is TDH-5301-XXX. The early transmission that RJ speaks of is the VH series. A VH9 is a 2 speed tranny. Robert, The info on a 4104 is correct. Unless the bus is in perfect condition and you can do the work yourself I wouldn't try to repower with a 6v92/v730 because of of the expen$e and several other problems. Dale (Message edited by Happycampersrus on August 31, 2006) |
