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Mod | | Forums66 Topics126,781 Posts1,039,297 Members48,100 | Most Online2,175 Jul 21st, 2025 | | | Joined: Apr 2009 Posts: 11 New Guy | New Guy Joined: Apr 2009 Posts: 11 | I just bought a great running '66 C-60 and have a few questions since everything is way bigger than I am normally used to (Suzukis).
1. The first question is about the two speed rearend. What is Hi and Lo, out or in (they aren't labled)? I drive big rigs around the work yard, so I understand how 2-speeds work, just I'm afraid to "experiment" for fear of breaking something. And is there a specific way to shift (it's a 4-speed)? The instruction sticker says somthing like switch to Lo and THEN shift transmission, or shift transmission then switch to HI (or visa versa) which has me a little confused.
2. It has the L6 - 292ci and I was wondering if anyone has put long tube headers from LMC on theirs? Do they clear the mounting brackets? From the pictures in their catalog it looks like they would, but I don't know if the motor mounts are different than a normal C-10 or 20.
3. I am considering replacing the motor with a 6.2L diesel. A. If it is possible to mount the diesel to the current 4-speed tranny, how do you think the different RPMs would affect the driving. B. If I replaced the motor AND tranny with an automatic, would that combination work with the 2-speed rearend?
It currently has a long flatbed on it, but I am hoping to mount a sleeper cab and shorten the flatbed so it's just long enough to haul fourwheelers, snowmachines, etc... Not quite a daily driver, but will still be driven a lot so any issues that you may have come up against that I should consider would be great. Any suggestions, thoughts, or comments would be appreciated. Thanks.
ALSO: Does anyone know if they originally had sleeper cabs as an option? If so do you know where any pictures of some are?
Last edited by NateLaw; 04/27/2009 7:13 PM.
| | | | Joined: Apr 2003 Posts: 940 'Bolter | 'Bolter Joined: Apr 2003 Posts: 940 | Can really only answer no. 1.
Button down is LO. Button up is HI.
To downshift to low, push the button down just before you are ready to use it and use the clutch when shifting. When shifting this way you will get less "grinding" from the rear (when "split shifting" shift the trans first then hit the button down). Upshift anytime you are ready to use it and again use the clutch. Many don't use the clutch, but it is better to and it will shift smoother.
You may also want to do some research using the "Search" feature above. We have some very detailed info on file on shifting 2-Speeds.
Bill
'60-'72 Chev/GMC Fan GMC 9500 Fan Detroit Diesel Fan
| | | | Joined: Apr 2003 Posts: 940 'Bolter | 'Bolter Joined: Apr 2003 Posts: 940 | By the way, in my opinion, the 6-292 is one of the best engines ever made.
Bill
'60-'72 Chev/GMC Fan GMC 9500 Fan Detroit Diesel Fan
| | | | Joined: Apr 2009 Posts: 11 New Guy | New Guy Joined: Apr 2009 Posts: 11 | I absolutely agree with you. I was just doing some basic checkup stuff (checking compression, plugs, etc...) 2cyl with 130, 3cyl with 120, and one with 85  and each spark plug was gapped out. So I all I did was reset the gap, and HOLY COW. It purred like a kitten. My 1-ton 454 takes about 5 turnovers before it starts. I was just playing around with the C-60 and he started consistantly only taking two turn overs. I was considering swapping it out, but if I can learn to shift it right I'll probably have the motor rebuilt and keep it as is. I tried shifting again last night and still could not figure it out. It sounds like the 2-speed is switching (vac) but I think I am still doing it wrong.  1st gear, 2nd gear, 3rd gear, 4th gear (all in Lo), then pull out for Hi, and shift to 3rd, and 4th. Is that how it's supposed to work? I've done some searching but nothing clearcut is coming up. | | | | Joined: Jul 2004 Posts: 2,946 'Bolter | 'Bolter Joined: Jul 2004 Posts: 2,946 | If you're just driving it empty, I'd just leave it in high and not even screw around with it. You've got plenty of power. If you're hauling loads with it, then you can get acquainted with the two speed. If you just want to play around with it, for starters go 1-2-3-4 in low, then when you're in fourth, shift it into high. In fact, if you're not loaded, you should be able to start out in 2nd. | | | | Joined: Mar 2009 Posts: 169 Shop Shark | Shop Shark Joined: Mar 2009 Posts: 169 | which hole is low?if its 3 2 id throw a head gasket in there seen that one before with the sixes.Never seen a sleeper would look really cool.Better check where your e brake is if thinkin of changin runnin gear...truck sounds cool timbuk | | | | Joined: Apr 2009 Posts: 11 New Guy | New Guy Joined: Apr 2009 Posts: 11 | 1 - 130 2 - 85 3 - 120 4 - 125 5 - 120 6 - 130 I'm definitly souping up the six, but still debating wether or not keeping it in the C-60, or putting it in the C-10 (currently with a '73 350ci.) | | | | Joined: Mar 2004 Posts: 75 Wrench Fetcher | Wrench Fetcher Joined: Mar 2004 Posts: 75 | It is yours so do what you want. I have the 292 in my 65 C 50 wrecker and I love it.And it is original too the truck. I would love to find a set of headers or split exhaust so I could put and run dual stacks. | | | | Joined: Apr 2003 Posts: 940 'Bolter | 'Bolter Joined: Apr 2003 Posts: 940 | NateLaw,
My experiences are all with Electric shifts and the Vacuum control might shift a little different, but either way the shifting sequence on your truck should go like this:
1 Lo 1 Hi 2 Lo 2 Hi 3 Lo 3 Hi 4 Lo 4 Hi
To start off getting used to it, start off in 1 Lo, go thru all the gears and lastly shift to 4 Hi (as Rich has mentioned). This will give you 5 speeds. Once you are familair on how it shifts you can then try downshifting the rear (as described above) then proceed onto "split shifting".
Bill
'60-'72 Chev/GMC Fan GMC 9500 Fan Detroit Diesel Fan
| | | | Joined: Apr 2003 Posts: 940 'Bolter | 'Bolter Joined: Apr 2003 Posts: 940 | The low compression could also be a Valve. If you do take off the head have the Valves checked. Also check for Piston Slop on the #2 cylinder while the head is off.
Bill
'60-'72 Chev/GMC Fan GMC 9500 Fan Detroit Diesel Fan
| | | | Joined: Apr 2009 Posts: 11 New Guy | New Guy Joined: Apr 2009 Posts: 11 | Thanks Bill, I'll try that shift pattern tonight. I've ordered an abrasive blaster and RustBullet that should be here in a week or so. I plan to play around with it some more until the stuff arrives and then start tearing into everything (cleaning, rebuilding, etc...). There's a really good machine shop that I have all my work done through and they quoted me just over $1000. Considering my little 1.6L Suzuki motor was $1600 to rebuild, it's not to bad of a deal. If I can I'm going to see if they can bump up the compression a little for a little more grunt. ...I would love to find a set of headers or split exhaust so I could put and run dual stacks. I'm hoping to do the same thing. LMCtruck.com (here) http://www.lmctruck.com/icatalog/cbe/full.aspx?Page=63 has a set of long tube headers listed for a 292, and the picture shows it as a set of two seperate (3 front, 3 rear) headers. I haven't confirmed with them yet, but I'm pretty sure the 292 is the same no matter what truck it is in. Since I'm in Alaska, shipping is a [censored] so I'm saving up and gonna order everything at once to try and save some dough.
Last edited by NateLaw; 04/29/2009 7:22 PM.
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