Tuesday, August 22, 2017

This is why we take short trips first....

Managed to get three weekend trips to various parts of NY this Summer, the last was Herkimer Diamond Mines KOA just north of Herkimer. I recommend it for families and 'empty nesters'. The campground was FULL that weekend. We were assigned slot #1 right next to the office and store. Only complaint would be the weather. First night it came down in buckets! The only leak was the side door where the drip edge has crumbled and let water in behind the door. No biggie.

Almost the oldest RV in the park until this one showed up!!

An Astro Van Allegro from 1986! Great couple that is traveling in this one. They have a Harley as a toad!

After spending the weekend at Herkimer we followed the Canada River down to Herkimer and got on the NYS Thruway headed home. At exit 39 the transmission dropped down to first and we crawled off that exit (I do NOT want to pay an RV tow off the Thruway!!) and got ourselves to Camping World in Liverpool (NY). The folks there were really nice and let us park the LH2 in their lot so we could set up service on her.

The problem?? Well the RV has a TurboHydromatic (TH400) three-speed transmission and there are a couple of things that happen to these over time. One is the vacuum modulator can go, stopping it from shifting. Simple part to replace if you have it. I'm keeping spares in the RV. The other possible (and more likely) issue is with the little plastic gear on the end of the governor that controls shifting. This part is purposely made weak to prevent damage to the tranny should any abuse take place. The part gets used up and saves other more valuable bits inside.

A lesson on the TH 400 GM Transmission:

A shot of a very clean and new TH400 (I am so jealous!) the white thingy with the red nipple is the modulator (or as Marvin the Martian would say, the PU36 Space Mod-u-la-tor!) Near the back is the governor cover plate on the same side.

This is a picture showing what happens to that gear over time. Once it looks like this it's toast and you wont get out of first gear. The kit costs about $8 online.

A kit you can buy off Amazon for about $7 to fix what is likely the main suspect in your no-shift issue.

This is what your governor looks like if its in working order. These can be had for about $70.

A red stripe vacuum modulator that controls shifting. Sometimes these go or the vacuum line gets brittle. Cheap at about $16 so it's worth just getting if you're not sure.
Of course this is all wonderful if this is the problem and I really hope it is because this fix takes about 15-20 minutes to perform if you are comfortable with working on your RV. I'm heading off to Camping World to see if I can perform the fix and get the heck out of there since it's also the first day of the New York State Fair right down the road....

More later once we get there and see what's up! Oh, the joy of owning a vintage RV!

UPDATE! Got to Camping World and did the gear swap. The old gear was completely worn down! The RV is safe at home now and awaiting a new transmission filter and oil change.

Thanks for reading!!


  1. D.R thanks for the informative post. I too do my own work and lived upstate N.Y. before going in the Navy in 1960's. Older rigs require these skills as many of the techs seem baffled by the plumbing and certainly don't like dealing with the inevitable chassis rust.

    If your up for a really long haul the Pacific NW is paradise in September. The kids are back in school and you can cruise without reservations for the plentiful and beautiful state campgrounds. Both Washington and Oregon have well maintained parks at very reasonable rates.

    My rig is a 75 GMC with the 455 Olds engine and THM 425 transmission and it too is beginning to need cosmetic work as well as a having a growing list of little things to be done. It's still all original, shag and all, but I like it that way.

    Mark your calendar for the first weekend in October. That's when the next Kinetic Sculpture race is held in Port Townsend WA on the Olympic Peninsula. A funky fun race through downtown, the harbor, sand pits and mud bogs by human powered vehicles. Make it a 2018 goal! Hope to see you there, Tom Fender

  2. Hi Tom,
    Thanks for the comment and info. The events you mention sound like great fun and I hope some of the readers here and on GoodOldRv's do the same. With my job and kids in school it would be a challenge to get to the PNW but next summer may be the season to do so. Always have a safe trip and great memories!