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Big Dog
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Posts posted by mattb73lt

  1. 3 minutes ago, Hobert62 said:

    I didn't use the mack rear I used the Rockwell from the freightliner air ride cutoff.   It gave me a much better gear ratio.  My last mack crossmember is at the rear of the doubled frames.  It is about 2' of just freightliner frame  before the first freightliner crossmember.  

    I've got a 4.62 rear and a double overdrive Triplex going in this one. Nearly the same as I set up in my other B, but with 24.5" rubber going on this one. Cruises nice at 65, with more top end. The Triplex gives good flexibility around town and highway.

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  2. 4 hours ago, Hobert62 said:

    Freighttrain & myself did something similar.   I can't say for him but I didn't use any type of shims.   Everything pulled together    like it belonged.   I bolted it through 3 of the mack crossmembers then added the fuel tank mounts and some other brackets through the splice as well.        I think my overlap is about 4'

    A couple of years ago I posted a question of the frame stretch, I think Freightrain responded with some pics of his stretch. That and a few other responses confirmed that it was pretty sound to go forward that way. Most of my measurements are close and just need to be tightened up a little. Right now I'm thinking that there's 1/4" difference from inner to outer spacing, that could be made up with two 1/8" shims down the overlap. I still need to finish cleaning both sets of rails and then finalize everything.

    My plan is to use the two Mack cross members where the original axle is, then staggered bolts in between. There'll be two more cross members  where the donor axle is. The Mack axle will fit the springs that are in the donor frame. It has a Eaton twospeed under it now that'll be removed. The plus is the body is already mounted and will just need to be remounted. Looks like there'll be about 7' added to the wheelbase.

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  3. 5 hours ago, j hancock said:


    Thanks all!  Nice day at the show.  The dash plaque was just plain old luck.  My name was drawn out of a hat at our chapter's fall potluck meal and meeting.

    Matt, I will send the WOW back to you because the B-73 is looking excellent in your restoration thread!

    Thanks, I waited a long time to get to it. The thread keeps me motivated to get something done each week so even it's something minor.

    Your Tandem B is really nice though, I'll have to track you down at one of the shows to see it up close.

  4. 9 hours ago, eddeere said:

    All of this has got me confused. The speedometer on my B 61 never worked. When I pulled the engine and trans the cable had an adapter on the end that had a square drive on it about .111". The trans needed on that one that was .125 ". I got one from Bobs Speedometer. Have not driven the truck yet so not sure of the fix. Hope I do not have to go thru all of the above.

    I've parted a few trucks that had the small square offset boxes that are ratio adapters for errors on the speedometer when you change something like the rear end ratio, Freightrain posted a picture of one. I've had several problems over the years with the speedometer and the drive off the tail shaft. The pencil gears and spiral drive I posted mostly came from donors I've had. Those reside in the tail shaft housing Freightrain also posted and did a really nice electronic conversion to.

    The issue is determining where your problem lies and how you want to fix it. There are many solutions (GPS, electronic) that can cure these issues.

  5. That should help get us in the ballpark of the issue. Those gears I posted reside within the housing that Freightrain posted and the pencil gear is about 4" long. His modification is nice as there are no moving parts for the "drive" and will probably outlast all of us. The thin collar is against the bushing the cable connects to. On my B-42 there is a small plastic adapter that  connects the replacement cable to the pencil gear. On the pencil gear there will be a small series if numbers for that gear. The mesh is important as you will wear out the gears quickly if there's a significant mismatch.

    As for the chart, I made one for mine for every gear using all the ratios/final drive/tire diameter (RPM=Gear#=MPH). Helped a lot as my speedo was inop when I first had it on the road.

  6. 1 hour ago, Red Horse said:

    Thx Matt.  I did not get to it today but I'm going to pull the 2"adapter, engage the cable, then spin the cable  (from the adapter end) while I have an observer in the driver's seat to see if cable is turning.  If it does, I guess case is made that problem is in the tailshaft-correct?

    It may be. If the cable, speedometer head and connections all check, then I would suspect the pencil gear or spiral drive. The pencil gear is really easy to pull and check.

  7. If the cable checks Ok, sometimes there's an adapter to interface with the "pencil" gear drive. Check that and make sure that everything locks and drives together. If all that is good, I would suspect the pencil gear and the spiral drive on the tail shaft of the transmission. The pencil gear is pretty easy to get at. Back off the bushing where the speedometer cable attaches, the small shaft should lift out with a little effort. I've had those eaten up by the spiral drive. If it's the spiral drive, that's going to be a little tougher to get at if it's bad.

    I have several pencil gears and spiral drives I've collected up to fix issues I've had. If that pencil shaft is bad, the gear can be pressed off and put on a good shaft to keep the speedometer accurate or at least working. Let me know if you need one and I'll get it to you. I'll take some pics of them tonight.

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