".............does anyone out there know if there are differences in
modulators for the 455? I recall reading something on the =
GMCnet way in the past that Caspro uses a different spring
in theirs."
When I purchased my coach I thought I would have to overhaul
the transmission. It felt like it was slipping really bad.
Turned out it had a faulty modulator and would not downshift.
What felt like slipping was the torque convertor working it's tail
off because the transmission was always in high gear.
The transmission shop I went to has a reputation for fixing
transmissions ............ not overhauling.
They found that at sometime in the past a cheap modulator
had been installed. They claimed that these were known to
be a problem and that they also lacked the altitude
compensator that a good modulator has. Apparently without
the additional diaphram that provides the compensation
the modulator can only work properly at sea level.
Once the modulator was replaced the transmission functioned
just fine.
One of the clues to the cheap modulator is the size of the case.
The non-altitude compensating modulator has a smaller case.
Just to complicate things more there are cheap modulators out
there that are the same size as the good ones. I am told that if
you know what you are doing you can tell the cheap modulator
in the large case by its lighter weight.
The modulator they used on mine was locally available. I
don't know if the modulator they used was unique to the TH425
or if it was the same as that used on the TH400.
As to carrying a spare, I believe that carrying a spare modulator
may be a bit excessive since they advised that a good quality,
altitude compensating modulator should last a long time.
HTH
Regards
Gary Zingle
1973 GMC 26 foot
modulators for the 455? I recall reading something on the =
GMCnet way in the past that Caspro uses a different spring
in theirs."
When I purchased my coach I thought I would have to overhaul
the transmission. It felt like it was slipping really bad.
Turned out it had a faulty modulator and would not downshift.
What felt like slipping was the torque convertor working it's tail
off because the transmission was always in high gear.
The transmission shop I went to has a reputation for fixing
transmissions ............ not overhauling.
They found that at sometime in the past a cheap modulator
had been installed. They claimed that these were known to
be a problem and that they also lacked the altitude
compensator that a good modulator has. Apparently without
the additional diaphram that provides the compensation
the modulator can only work properly at sea level.
Once the modulator was replaced the transmission functioned
just fine.
One of the clues to the cheap modulator is the size of the case.
The non-altitude compensating modulator has a smaller case.
Just to complicate things more there are cheap modulators out
there that are the same size as the good ones. I am told that if
you know what you are doing you can tell the cheap modulator
in the large case by its lighter weight.
The modulator they used on mine was locally available. I
don't know if the modulator they used was unique to the TH425
or if it was the same as that used on the TH400.
As to carrying a spare, I believe that carrying a spare modulator
may be a bit excessive since they advised that a good quality,
altitude compensating modulator should last a long time.
HTH
Regards
Gary Zingle
1973 GMC 26 foot
