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john Celletti 03-15-2008 21:17:06 4.89.245.8 29262 Report to Moderator	can someone explain to me is this a mechanical or electrical device or both. newly purchased truck and it doesn't seem to work. i've gotten down there and can't trace the wires though there seem to be wires at the knob iin cab. thanks [Reply]  [Send Email]
HeyPigFarmer 03-18-2008 09:15:41 141.219.59.111 29596 Report to Moderator	Re: 1969 c50 hi/lo switch in reply to DaveS, 03-15-2008 21:17:06   We had a 1972 C50 with the vacuum shift rear axle (6.50/8.85) I wouldn't worry about going from lo 4th to lo 1st. You are going to have to slow way down for it to even go in that gear. Second do you know how to split shift? It doesn't shift like a road ranger, you don't run through 4 pull the switch and then run through 4 again. To tell if you are in hi or low just look at the position of the switch. Up is hi, down is low. Easiest way to tell if it is working is to try to use it, if you don't really know what you are doing it will find neutral eventually and it will free rev. Another way to tell is to put a tachometer in it and get another vehicle to lead you (because of the speedometer shifting that just gets messy to use the one in the dash). Have them go a set speed and look at your tach, then try to shift the rear and go the same speed, RPM change on the engine means your rear is working.   [Reply]  [No Email]
Bob 03-15-2008 23:34:15 69.178.228.68 29263 Report to Moderator	Re: 1969 c50 hi/lo switch in reply to john Celletti, 03-15-2008 21:17:06   What's on the rear axle... a motorised shifter or a "vacuum pod". MOST LIKELY, the rear axle is vacuum shifted (by the "pod"), and the speedometer ratio is changed at the same time by an ELECTRIC ratio changer in the speedo cable, which explains the wires you are seeing. Take a look at what's on the rear axle and post back. That will save explaining how BOTH systems work.   [Reply]  [No Email]
john Celletti 03-17-2008 11:15:12 4.131.78.127 29268 Report to Moderator	Re: 1969 c50 hi/lo switch in reply to Bob, 03-15-2008 23:34:15   thanks bob ... i did follow the wires and they do go to speedo junction (i replaced lower portion of the speedo cable yesterday) the black wire was d/c and had a clip on it looking for a mate... i'm assuming this is a ground? Yes there are vacume lines in and out of the selenoid. bob is there any indicator light to show that i'm in hi or lo as it would seem frightful to shift from lo 4th to lo 1st thinking it was hi 1st . if that makes sense thanks again john   [Reply]  [No Email]
ericlb 03-17-2008 20:32:04 72.173.211.235 29273 Report to Moderator	Re: 1969 c50 hi/lo switch in reply to john Celletti, 03-17-2008 11:15:12   john, the 69 c50 i drove back in the ,80's was a electric shift, as mentioned look on the rear axle and see if it has wires to the 2 speed motor, or vacuume lines, if its electric there is a set of points in there that can freeze up [ easily replaced] the knob on the gear shift can also go bad, but usually its those points, your post about going from lo 4th to high 1st has me confused, these transmissions do not use the repete pattern found in the larger rigs, should be start out in 1st low [ if needed] pull switch up rapidly push and release the clutch and you will be in 1st high, then shift to 2 gear, before releasing the clutch and after the stick in in the gear push the knob down for 2nd low, and on up thru the gears, if you are running empty, it may not be nessessary to split shift at all, just put 'er in high axle and go thru the gears   [Reply]  [No Email]
maccina 03-29-2008 19:03:21 4.131.79.248 29399 Report to Moderator	Re: 1969 c50 hi/lo switch in reply to ericlb, 03-17-2008 20:32:04   ericlb..I've narrowed the problem with split tranny to the push/pull cable I 'm going to continue to work with it working alone and need to have someone in the cab activating the knob while i'm under the cab ...can't wait to use it. does it hurt to drive in lo range at lower speeds. will it damage planetaries???   [Reply]  [No Email]
john Celletti 03-17-2008 21:01:29 4.226.225.198 29274 Report to Moderator	Re: 1969 c50 hi/lo switch in reply to ericlb, 03-17-2008 20:32:04   eric thanks for this CLEAR explanation yes now the shifting makes sense...there is a vacuum on the rear end the wires go to the speedo a light colored wire is connected and a black wire is not any idea where it attaches?   [Reply]  [No Email]
ericlb 03-18-2008 03:18:14 72.173.211.235 29276 Report to Moderator	Re: 1969 c50 hi/lo switch in reply to john Celletti, 03-17-2008 21:01:29   im not sure on the black wire but black is usualy ground in a vehicle,on the vacuum, check the lines to the vacuum pot and see if they have good vacuum, with the switch up and down, if thats good, you may have a leaking diaphrame in the pot itself, these old 2 speeds must have real good vacuum to work, that why they eventually went to eletric shift motors   [Reply]  [No Email]
john Celletti 03-18-2008 17:04:28 4.89.243.60 29286 Report to Moderator	Re: 1969 c50 hi/lo switch in reply to ericlb, 03-18-2008 03:18:14   thanks again eric... I was looking at the length of that black wire...it's under the hood near the speedo running toward the drivers side headlight. I'm sure I can get a look at a working unit to figure it out. chances are you are right on with the diaprhram being worn out because activating the knod does nada. I recently discovered another issue seems that brake fluid is seeping thru/around the master cylinder. I thought a rubber gasket must be missing. but people I've spoken with say the "cardboard" insert was all there was. I did notice a small rubber o ring on the bolt that holds the cover down   [Reply]  [No Email]
Bob 03-17-2008 12:04:37 69.178.228.68 29269 Report to Moderator	Re: 1969 c50 hi/lo switch in reply to john Celletti, 03-17-2008 11:15:12   NO shift indicator light. Does the vacuum stuff work, actually shifting the rear axle?   [Reply]  [No Email]
john Celletti 03-17-2008 12:25:33 4.226.225.96 29270 Report to Moderator	Re: 1969 c50 hi/lo switch in reply to Bob, 03-17-2008 12:04:37   i'm not sure the black wire is not hooked up and when i pull the black knob up nothing seems to happen. can you give me a description ie you are in 4th low go into neutral lift knob and you'll hear /feel vacume engage...sorry bob this is my 1st dump truck and i'm clueless   [Reply]  [No Email]