Transmission rpm question

[brutherb]

I own a 1987 32 ft triple e regency with a 6.2. I love it as it literally sips fuel but at 100 km/hr it’s reving at 3000 rpm. Seems to me an overdrive tranny would be a good swap. I believe these rigs have a 3 speed t400 thinking a 700r4 would be a good swap. Any thoughts. I would like to be able to do 120 on the highways

[convert2diesel]

I own a 1987 32 ft triple e regency with a 6.2. I love it as it literally sips fuel but at 100 km/hr it’s reving at 3000 rpm. Seems to me an overdrive tranny would be a good swap. I believe these rigs have a 3 speed t400 thinking a 700r4 would be a good swap. Any thoughts. I would like to be able to do 120 on the highways

Not to sound glib, but have you ever driven a 30 year old motorhome on the highway at 75 MPH? Hope all your suspension parts and tires are new and you are on absolutely smooth pavement with no crosswinds. That much weight and sail area, mounted on a van chassis, hurtling down the highway at 120K is a scary thought. Even at 100K things could get dicey.

On the question of tranny, with the weight of that motorhome, you could easily turn, even a built 700R4 into a pile of broken parts. They were never designed to take that kind of abuse. You will never find a 700R4 in anything over a 1/2 ton pickup. The only reasonable 4 speed would be a mechanical 4L80 but they are hard to find or even an add-on overdrive unit would be a possibility.

What's your hurry? If your in your motorhome you are on vacation so sit back and enjoy and stay in the right lane.

Bill

[Robyn]

Indeed...
A 700R4 is a very light tranny and will not even begin to handle the task at hand of hauling that house around

[Robyn]

There are add on OD units that will help, butttttttttttttttt $$$$$$$$$$$$$$$$

The TH400 was used in these rigs because they are nearly bullet proof.

[DmaxMaverick]

I absolutely agree with the above advice, 100%.

That said, the 6.2L is perfectly happy screaming down the big slab against the governor, and as you said, it will sip fuel doing it. The key to longevity is merely scheduled maintenance. Keep all the fluids fresh, the cooling system clean and monitored, and keep wear items up to date.

The drawback is, they are noisy. Running at lower RPM's at higher speeds will leave you with too little power, and the economy will take a serious nosedive, with your big, heavy rig, in all but the downhill side of a grade. This is one rare case when it's OK to address only the symptoms (noise). Do your best to minimize the noise by refreshing engine compartment insulation (or adding some), and make sure your fan clutch isn't stuck in "warp speed" mode.

[convert2diesel]

Had the same tranny and gearing in my 89 GMC. The noise at highway speeds was annoying as there was virtually no insulation around the firewall (was spec'd as a military truck but ended up on the new car lot). Just cranked up the old AM radio louder to drown out the noise. That combination lasted over 700,000 Km with only normal maintenance and one pump and injector replacement. Was still running well when rust took out the rest of the truck.

Still using the pump and injectors in my 88 for snowplow duty. Starts (when the starter hasn't sheared off its mounting bolts) and runs well.

Seems that 3,000 RPM didn't have any adverse effect on the longevity of the engine.

Bill