Joined: Jun 09, 2011 Posts: 776 Location: Bellmore, NY
Posted: Fri Nov 02, 2012 6:12 pm Post subject: I got a rebuild M38A1 speedometer
off Chuck on the board, and a 15 tooth speedometer drive from Pete Debella. Both are installed, both are working fine, and the speedometer is still reading way off. It reads high, like I have civy gears in my axles, but I have the correct gear in the transfer case, the correct transfer case model, and the correct speedometer. The cable I have is the correct waterproof one Pete Debella sells. At this point, I'm at a loss. Does anyone have any ideas? _________________ 1952 M38A1
Marine core reinforced rear bumper, military transistorized turn signal upgrade, arctic heater, 11" drum brakes, 200L PTO winch, Huffy overdrive, deep water fording kit, RT 68 vehicle mounted radio, Trac Locs front and rear.
www.danhenk.com
Joined: Jun 09, 2011 Posts: 776 Location: Bellmore, NY
Posted: Fri Nov 02, 2012 10:05 pm Post subject:
I'll do that as soon as I get back from Mass in a week Wes. I was thinking, if the speedometer is reading high, the gears must be the lower military gear ratio, right? If they were higher, the speedometer would be reading closer to the actual speed? The engine, transmission, and transfer case are rebuilt like new, so I'm thinking if I had a higher gear ratio as well, the vehicle would be faster than the current top speed of around 50 (60 with the overdrive).
I'm using a GPS to determine the actual speed. _________________ 1952 M38A1
Marine core reinforced rear bumper, military transistorized turn signal upgrade, arctic heater, 11" drum brakes, 200L PTO winch, Huffy overdrive, deep water fording kit, RT 68 vehicle mounted radio, Trac Locs front and rear.
www.danhenk.com
If you are positive the diff gears are 5.38's and the tranny and transfer gearing are not pickup or wagon and you have the correct drive and driven speedo gears and the drive cable is new then the only source for the high error is the gage. Send or take the gage to a speedo shop and have them Cal. Check it. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Jun 09, 2011 Posts: 776 Location: Bellmore, NY
Posted: Fri Nov 02, 2012 10:26 pm Post subject:
What would I look for in the transmission/transfer case? I had Novak rebuild them, and they say they are correct. The drive gear fits the 15 tooth military speedometer drive, not sure if that makes a difference. _________________ 1952 M38A1
Marine core reinforced rear bumper, military transistorized turn signal upgrade, arctic heater, 11" drum brakes, 200L PTO winch, Huffy overdrive, deep water fording kit, RT 68 vehicle mounted radio, Trac Locs front and rear.
www.danhenk.com
It's all about ratios which means you would need to count teeth on each gear in the tranny and transfer. I'd start with the easy part and pull the speedo and send it to the shop for a calibration check. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Jun 09, 2011 Posts: 776 Location: Bellmore, NY
Posted: Sat Nov 03, 2012 12:43 am Post subject:
Ok, one more question. I swapped the speedometer I had in there, with a rebuilt one from Chuck here on the board. Both are reading high. Do you think it could really be two speedometers in a row? And if the speedometer is not the issue, can it still be calibrated to give a more accurate mileage reading? _________________ 1952 M38A1
Marine core reinforced rear bumper, military transistorized turn signal upgrade, arctic heater, 11" drum brakes, 200L PTO winch, Huffy overdrive, deep water fording kit, RT 68 vehicle mounted radio, Trac Locs front and rear.
www.danhenk.com
Joined: Nov 19, 2010 Posts: 107 Location: ITALY - TUSCANY
Posted: Sat Nov 03, 2012 7:59 am Post subject:
Are your tires 700x16 NDCC? If they are smaller or larger, the speedometer accuracy will be off. Just a thought. David _________________ David Manning
1952 M38A1, 1953 M38A1, 1954 M38-A1, 1952 M100
Photos on Page 10 of Members Albums.
Joined: Jun 09, 2011 Posts: 776 Location: Bellmore, NY
Posted: Sat Nov 03, 2012 11:29 am Post subject:
At 35 MPH it reads about 60. At 50, the needle is way off the charts. The tires are correct, I just changed them recently as the ones that came with the vehicle were dry rotted. _________________ 1952 M38A1
Marine core reinforced rear bumper, military transistorized turn signal upgrade, arctic heater, 11" drum brakes, 200L PTO winch, Huffy overdrive, deep water fording kit, RT 68 vehicle mounted radio, Trac Locs front and rear.
www.danhenk.com
Joined: Jun 09, 2011 Posts: 776 Location: Bellmore, NY
Posted: Sun Nov 04, 2012 12:13 am Post subject:
That speedometer service manual is pretty daunting. I'll double check, but I am 95% certain that I have the stock 5:38 gears. With a second speedometer that is a rebuilt military unit and still reads the same, a 15 tooth speedometer driven gear, and a military speedometer cable, I think that leaves the transfer case? What should I check next? Novak rebuilt the Transfer case and transmission for me, what could they have conceivably done to alter the speedometer reading? I know when I had a CJ, with bigger tires the speedometer read wrong, and I needed a new driven gear to accommodate it, is that an option? _________________ 1952 M38A1
Marine core reinforced rear bumper, military transistorized turn signal upgrade, arctic heater, 11" drum brakes, 200L PTO winch, Huffy overdrive, deep water fording kit, RT 68 vehicle mounted radio, Trac Locs front and rear.
www.danhenk.com
Joined: Jun 09, 2011 Posts: 776 Location: Bellmore, NY
Posted: Sun Nov 04, 2012 2:05 am Post subject:
The first one I got off Ebay. So, who knows. The second one I got from Chuck on the forum here. They look similar, but have slight differences, and Chuck tells me the one he sold me is a rebuilt military correct one. The thing is, both read the same, but both are not reading the correct mileage. _________________ 1952 M38A1
Marine core reinforced rear bumper, military transistorized turn signal upgrade, arctic heater, 11" drum brakes, 200L PTO winch, Huffy overdrive, deep water fording kit, RT 68 vehicle mounted radio, Trac Locs front and rear.
www.danhenk.com
Then take both of them to the speedo shop just in case only one is in any condition to be calibrated. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
Forum FAQ
Search
Usergroups
Profile
Log in to check your private messages
Log in
