doubleclutchinweasel Posted March 9, 2014 Share Posted March 9, 2014 I know this has come up before, but I'm still unclear about it. So, 'xplain it to me! And, as always, pictures help.Need a tach cable. May need a tach too, but that's another discussion.The build sheet calls for, I believe, a 54MT314AP88 cable. The one on it now is longer than the 88" implied by that number, and the engine end has been spliced for some reason. Maybe to adapt the end? Maybe something to do with the drive pin?Numbers available now are 54MT314DP88/94/108, etc..., suggesting revisions have been made.This number series shows up as a "speedometer" cable in several places.Are the tachometer cables standard speedometer cables? And, if they are, how does one deal with the odd-ball drive gizmo on the engine end (see pics)? I don't believe a standard square speedometer cable can stick into this thing and still thread on...too long, I would think. Or, is it? That gizmo sticks up quite a ways from the drive gear. Do you stick the cable into it and stake it? Or, would the end, shown below, interfere with the sheath?Please help! Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/ Share on other sites More sharing options...
r686st Posted March 9, 2014 Share Posted March 9, 2014 In my 1991 RD690s the tack and speedo cables are the same. They both thread onto the adapters going into the engine. I admit I was curious if they would work on mine but after putting them on they did. Quote Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/#findComment-236605 Share on other sites More sharing options...
j hancock Posted March 9, 2014 Share Posted March 9, 2014 Same cable. Different lengths available. Came with a little bag of tips. It has been a day or two since I did one but that is my recollection. Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/#findComment-236606 Share on other sites More sharing options...
r686st Posted March 9, 2014 Share Posted March 9, 2014 Yea, the original tips are metal but now you get plastic when buying from Mack. You can reuse the old tip if it's still in good shape. Quote Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/#findComment-236608 Share on other sites More sharing options...
doubleclutchinweasel Posted March 9, 2014 Author Share Posted March 9, 2014 Okay! So the cable comes with different tips, and you pick the one you need? That makes a little more sense.And, yes, the drive tip is in pretty good shape.By the way, is there any significance to the 54MT314 series compared to the 54MT313 series cables? I noticed the 313 is used on the speedometer. Is the 314 series the interchangeable tip type? No biggie, just curious! Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/#findComment-236612 Share on other sites More sharing options...
j hancock Posted March 9, 2014 Share Posted March 9, 2014 I used 314 for both applications. Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/#findComment-236613 Share on other sites More sharing options...
doubleclutchinweasel Posted March 9, 2014 Author Share Posted March 9, 2014 I used 314 for both applications.Sounds like those may be more "universal" than the 313s.By the way, does anybody have a functional "old" tach? I think it may be a 17MT379. It's the old one with the "counterweight" on the bottom end of the needle. Mine has a broken needle! Found some on eBay. Never know 'bout those guys! Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/#findComment-236623 Share on other sites More sharing options...
doubleclutchinweasel Posted March 10, 2014 Author Share Posted March 10, 2014 Well, I measured the current tach cable sheath. I know it's not "virgin", since the end has been spliced. It's about 97-98" long. So, either the build sheet doesn't actually say 88, or I misunderstood it!Anyway, I don't see how the cable could possibly reach if it was 88" long. So, maybe I need a 97-100" cable. I think there is a 54MT314DP100 listed. 100" long, I believe. Now, if I can just find a suitable tach, maybe I can tell how fast the old-timer is spinning! Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/#findComment-236774 Share on other sites More sharing options...
j hancock Posted March 11, 2014 Share Posted March 11, 2014 I have had good luck buying both B speedos and tachs off ebay.I used a 94" cable on my B75 with L cab. Just came out the firewall across the cross rods and dropped right down. Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/#findComment-236794 Share on other sites More sharing options...
doubleclutchinweasel Posted March 11, 2014 Author Share Posted March 11, 2014 I have had good luck buying both B speedos and tachs off ebay.I used a 94" cable on my B75 with L cab. Just came out the firewall across the cross rods and dropped right down.That's the route I plotted, too. Needs every bit of 97-98". Must be the taller hood of the R model! Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/#findComment-236811 Share on other sites More sharing options...
j hancock Posted March 11, 2014 Share Posted March 11, 2014 That's the route I plotted, too. Needs every bit of 97-98". Must be the taller hood of the R model!Sorry, had a brain fart. Thought your were working on a B. Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/34983-more-tach-questions/#findComment-236824 Share on other sites More sharing options...
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