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B81SX Quad Transmission


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Hopped in my B81SX with a quad the other day. Temp was about 20 deg. F. Main box shifted fine, but back box (4 speed) would not shift, at least easily, for about 5 miles.

Would it be safe to put synthetic in this transmission? If so, what weight? Any brand recommendations?  Would I need to flush out the old fluid before switching to synthetic?


As you can see, am in the process of installing a Holmes 750 on the unit. Will be hooking up a PTO to the transmission, so now is the time to change the fluid, if possible.
Also in the process of installing fenders on the wrecker bed, as below.
Thanks for your help.
Day Radebaugh
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Hi Day,

Nice truck - B-model wreckers are always good looking rigs.

Would you like to have your truck listed on the B-Model Registry - a place to try to document all the B-models still showing signs of life?

If so, you can send me your VIN via PM, or you can go to the registry website and fill in the data form, and I'll get you listed.  If you're not comfortable listing your personal info, that's fine, but it would at least allow us to know that your truck is still out there....

Here's a link to the site if you'd like to check it out:  http://www.mackb-modelregistry.com




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I'll certainly post some pix when I get her painted this spring.  Roughly what's left is:

--install some of those rubber fender flares on the fender cutouts we did

--paint it

--hook up another air tank

--hook up pto

--for you wrecker dudes, I have to move the control handles which were originally on the side of the truck.  I ran out of fender space, and will install the control handles on the surface of the wrecker bed.  The geometry of these control handles should work the same, just shifted in position 90 deg.  This control rod mechanism is a nightmare anyway, and explains why hydraulics caught on so fast.

Should have it on the road by the beginning of the spring season.  By the way, this B81 is running a 237.

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3 hours ago, dayradebaugh said:

Just test drove Terry's suggestions above and it worked fine, good enough to get me out on the road where I could really warm it up.  Appreciate the suggestion.  

I would grease it also.    terry:D

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