Is it worth it to change from an enclosed driveline to open? Can I change out the front of the rearend with that of a 55-59 TF? TIA
It's definetly worth changing over to an open drive line. You can change the third member to a 55-59 with no problem, but you will also have to change the spring perches because the originals are hinged. You will also have to drill a new locater hole in the new spring perches so the rearend doesn't sit too far forward. The better way to go would be to find a newer model rearend. For a later model Trans. you might want to consider a Saginaw 3 Spd. They will bolt right in and adapt to the column shifter with little work. Here's a link that might help with a rearend choice. http://www.chevytrucks.org/tech/ifs&rearend.htm
No ! It is not benificial ! . Your Torque Tube rear end is 62 years old and still going . Why mess with sucess just because you don't understand it ? . My '49 working shop truck retains it's original Torque Tube and I tow , tour and haul scrap with it as well as 65 MPH freeway driving and canyon carving , climbing mountains , desert dirt roads and on and on.... If you go to a V-8 , then it'll prolly be wise to change .
I agree with Nate that the best way to keep a hard on is don't f#%k with it but if you want the advantages of a fully syncronized Trans., a better selection of gears for different cruising speeds and a selection of parts that are easier to find, then yes it's definaetly worth it. I did this swap years ago on another 54 Chevy truck with a stock 235. It cruised a lot better, was a smoother ride, shifted better and was a lot easier on the engine. I had no regrets and the person I set it up for was very happy. It's never too late to move forward.
Its a good question. I have heard several people say the close drive line is a great drive line, my question is there an easy way to install an overdrive system with out changing the drive line? My impression is to do this you have to change the transmission than change the drive line. It doesn't seem cost effective to go this way. I have the original 4 on the floor with a 235 and with the Patricks 3.55 gearing but don't know how she will do on the highway yet. I am not looking to go fast but want to keep up with traffic and I will be on the highway occasionally. I'm just curious? Dave
Freeway Speeds My '49 3100 is so equipped and it'll drive all day long @ 65 MPH , no engine strain . You must use the correct diameter tires of course, 15" or 16" you're looking for about 32" IIRC .
Thanks Nate. I'm comfortable with 65, I'll let you know once I get it on the road. I'm set up with 15 inch wheels right now, but just bought some old original 16 inch wheels. Next purchase it tires for the wheels. I could only find 4 of the original 16 inch wheels, any ideas where I might fine a 5th one for a spare? I like the original style better. What is a "32"IIRC." Dave
One WHAT ? I know you're not talking about a Truckstell overdrive ! The last time I found one , the bastard made me a deal then shopped it aound 'till he got a better offer....r
What is a "32"IIRC." Dave It is the outer diameter of the LT tire , when you're properly setting up a 6 Banger powered vehicle , the diameter of the drive tires is really important .
Hi Nate. So, you have the 49 3100 with original equipment and will drive it 65 with no problem? Or did you change out anything? I have a 4 speed and the enclosed drive-shaft with original 53 gears. TIA
My Shop Truck it's a 1949 base model 3100 pickup with SM420 floor shift four speed , compound low transmission , it has a 1957 235 that runs O.K. and the Torque Tube , I was told by the previous owner it has a set of Patricks' 3.55 gears in there . as the entire rear end is quiet and doesn't leak , I don't fool with it apart from the usual 10,000 mile drain & re-fill service . it has Dayton 16" LT radial tires , the correct specific size so they work and look like original tires , I posted this size many times over the years and some one will post it up again if you wish . Yes , I drive it everywhere @ 65 MPH , no strain , no worries , no problems going up The Grapevine either .
Thanks. I have the same setup as you and was thinking of adding the Patricks rear-end gears. This sounds good. Thank you for your advice
Sounds Good It all depends on what you want to do ~ I don't mind my '49 taking it's time to wind up to freeways speeds and I also don't mind taking 800 mile road trips ona whim without ever worrying about breaking down or what not . Stock is always going to be the most reliable but you have to be willing to take things a bit easy . Your stock 216 equipped truck will easily go 75 + MPH but doing so will kill the engine sooner than later . The outer diameter of the rear (drive) tires is really important ~ some who don't understand this will say otherwise but 50 + years of working in , with and on old Chevys has taught me better .
' SM420 ' Transmission It is an extremely tough light duty tranmission designed by Muncie . It has four forward gears , first is a straight cut , compound low for moving at a walking pace only . Muncie called it the model " M420 " and GM called it the SM420 , it was also used by Dodges and in Gamma Goats until the eng of thier production so N.O.S. ones occasionally pop up in Military Surplus... I stupidly passed on a brandy new Gamma Goat SM420 for $375.00 just two years ago whoops . FWIW , this tranny is still highly sought after by serious Jeepers for extreme rock crawling use , it's nearly un-burstable .
Okey Dokey. I guess you had best know that I have a 58-62 235 that is being rebuilt now. And am using 15 inch wheels since the original ones were trash - 15 inch are easily found and a lot more economical to purchase. So. Yes, you are correct in the outer diameter of the tires being important. This truck will run on 15 inch. What kind of change or difference will this make to what we are talking about? I am planning on running the 235 with the sm420. I do not plan to change from the torque tube but would like to consider putting in the Patrick's gears. Thanks again for all your help.
rpm = (mph x final gear ratio x 336*) / tire diameter At 75mph, my truck , with a 3.08 and 350t-1:1 final drive, and 235/75-15 tires(29 inches tall) would be.... 75x3.08x336/29=2676RPM for an overdrive, like a 700r4 which has a .70 Od, mult. final drive(3.08)xOD(.70) to get 2.156. Plug this in as your gear, 75x2.156x336/29=1873RPM@75MPH Add the lockup converter for an addition 3-400 RPM drop, 1473RPM You can play with this to see about where you should be with which tire/gear combo. So, with the factory 4.11, and a 30" tire, 75x4.11x336/30=3452RPM or at 65-2992RPM Or, with the 3.55= 75x3.55x336/30=2982RPM 65x3.55x336/30=2584RPM Have fun, Russ
Pay attetion here ! Didja see what Russ did ? he used science & mathmatics to show that you can indeed run 15" tires and stock running gear (even a 216) and go 65 MPH *if* you're careful about buying your tires by the external diameter . I agree 100 % but being a Country mechanic , I'da just said buy some skinny & TALL LT radial tires and you'll be fine . I hope you follow the tire diameter advice as you'll be quite happy driving on the Freeway . Don't waste time using first gear tho'
