Bill H.
You have one of these. They claim to "pay for themselves". Now with the high cost of gas should I buy one or not........ they're a couple of grand, that's a lot of moolah for us pensioners.

I believe one would pay for itself in gas mileage over a long period. There is also a payback in reduced engine stress, though, and second OD is so VERY nice up the hills. Third OD is so nice and quiet on level cruise, too. So that is a payback as well.

Here is an example: If your mileage goes from 6 to 7 mpg (a 16% increase), and you drive 5000 miles a year, and gas is $2.20/gal, you will save $261 per year. So it will take ten years to save enough to pay for it (not counting the installation). If you drive 10,000 miles per year, the payback period is around 5 years, and so forth. And, of course, if gas goes up even more, you save even more.

The heavier the coach, the nicer a GV is, and the steeper the mountains, the nicer a GV is. Some manufacturers put GVs on their longer gas coaches. Have you done Thorleys yet?

Edited to correct stupid math error.

[This message has been edited by bill h (edited May 16, 2004).]

Have you done Thorleys yet? [/B][/QUOTE]

Bill,
No we haven't. I was thinking about them and also the Gibson ones that claim to have increased a 454 mpg from 4.57 to 8.03. Then I read Olroy's report on his coach with Thorley's and the results were about the same as mine without, so I put that idea on the back burner. Did I make a major mistake again?

I have put Thorleys on a number of vehicles, and have noted little if any mileage increase. But always much better throttle response and torque. And lower doghouse temps. I suspect that using the increased power makes the hoped-for better mileage go away. I know one fellow who thinks his GV is the best thing he has done to his coach. I believe I published his hillclimb test figures here somewhere.

Here are some test results from Larry Reed. He did pretty much what I did, but did better testing. I should also mention that he has installed a Performer intake manifold, and says his coach now tows as if it did not have a toad. I am surprised he did not do the hill climb test on the performer, as well.
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GM P30 Performance Improvement Notes:

Modifications performed in stages

Vehicle: 1988 32' Bounder on GM P30 Chassis Test Conditions: Hill climb, paved road, 7000' Elevation, 6% grade, .5 miles Test Technique: Start hill @ 50 MPH, full throttle and manually shift for best speed. Metric: Speed at top of hill.


Stage 1:

All stock, new plugs, wires, carb adjustment etc. Stage 1 Cost: $0

Stage 1 Result: 43 MPH 2nd gear, speed still falling


Stage2: Added self fabricated air scoop*, 2.5" dual exhaust w/HP mufflers,cross-over pipe. Stage2 Cost: $350

Stage 2 Result: 48 MPH in 3rd gear, speed still falling.


Stage3: Added Doug Thorley Headers. Stage3 Cost: $600

Stage3 Result: 53 MPH in 3rd gear, speed holding steady. Note: Stage3 allowed acceleration up the hill

Stage4: Added Gear Vendors Gear Splitter.
Stage4 Cost: $2700


Stage4 Result: 58 MPH in 2nd and Over, Speed holding steady


Note: Gear Splitters effectively double the number of forward gears. The benefits are obvious in many ways but are not fully
appreciated until you have tried it.

*I made the air scoop from a 2.5"x14" furnace floor register and 4" round flexible furnace ducting. I removed the silencer/flash suppressor from my air cleaner and connected the 4" duct to the air cleaner snorkle. The scoop hides easily behind the motorhome grill out of sight but in unrestricted air flow. "
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Note from bill h: I found no easy way to route the air intake duct behind the grille, so it goes under the front bumper.

Bill,
Thanks, I remember reading this before, but I'd forgotten it. Our Barth has dual 2-1/2" exhausts.... I thought they were stock. So now I'm wondering if they were more than likely added by a previous owner? What's your guess?
Cheers, John

Yes, one could interpret that Larry had something other than duals with high performance mufflers. I suspect that he already had duals, and added the hp mufflers and an H pipe. My two P30s had dual 2 1/2 exhaust systems from the factory, but I have seen some later P30s that had one single, perhaps 3 inches. Chevrolet and Workhorse seem to be going back and forth on this. But, a pair of high perf mufflers and an H pipe really helps. The mufflers help across the board, and the H pipe helps low and mid range. The H pipe also quiets down a noisy dual system.

If I had to guess, it would be that yours came with 2 1/2 duals and somewhat restrictive mufflers.

Larry's improvements seem to give about 5 mph up the hill for each stage. As much as I like the GV, I would put on an Edelbrock Performer intake before I did the GV, as it would seem to be more cost effective. I have had Thorleys and Performers on several of my tow cars, and was very happy. But, I do believe there is a big payback in engine longevity with a GV.

hello again Bill,
We have a Gear Vendor OD as well. It was disconnected by the previous owner. He explained that it had an electrical short in it somewhere due to an alternator going out. I'd like to reconnect it and try to get it working again. Any idea where the unit could have shorted ?

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Jack and Daiva
1988 Barth Regal

the first thing would I do is check the fluid level.

The GV is really a one wire circuit with a lot of foolishness added in the circuit that controls that one wire. You know, the speed sensor, the box, and the panel. When the solenoid is energized, the unit is either direct drive or overdrive. One or the other. I forgot.

I would suggest running a wire from the cockpit to the solenoid and making sure it works first. If the solenoid is good, and the unit works, you might consider eliminating the other circuitry and operating with a simple switch.

Jack, would you like me to mail or fax you you a copy of the troubleshooting procedure?

Thanks Bill. Actually I believe I have all of the original literature for the GV. To be honest being almost a week away from departure. I'm almost tempted to leave it alone so as not to create any costly(time or money) complications. The unit was disconnected underneath the coach. The switch is still mounted on the transmission shift lever. I could crawl underneath and reconnect everything in a few seconds, I'm just apprehensive about shorting something out. According to my lit:"The Dual Range electrical wiring for the automatic consists of a two- circuit sysetem. The first, the control circuit, includes the shift control module, and grey signal switches, protected by an in-line low amperage fuse. The second, the power circuit, includes the control module and the shift motor protected by a 15 amp automatic re-set circuit breaker."
Yes here it is, I just pulled out the troubleshooting guide

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Jack and Daiva
1988 Barth Regal