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noiva · 12-02-2005, 01:19 PM

(I suspect this topic has been covered in another thread, and if so, please just direct me to it.) Has anyone had any experience with places like Gear Vendors who sell "Overdrive" gears for 3-speed trannies? I have a 1989 370LE, new to me, and the Gillig axle ratio is right at 5:1, which means the 460 with the C6 Ford tranmission is screaming at anything above 60 mph. The coach has less than 17,000 original miles, so it's no where near needing work that could justify doing this to repair and maintain the present system. I can live with it, but there are times when you need to be able to run faster than that on the interstates just to stop from holding people up. Is adding an "overdrive" worth the money? About how much would that cost? Has anyone done that who could give me advice? Thanks in advance for any help with this.

Noiva

GlenCoombe · 12-02-2005, 02:12 PM

Novia, I'm not sure about the price for the Gear Vendors setup but one thing for sure I do know is that a lower turning engine is better in a lot of respects. I'm blessed with a 3.73 in the AS I've got. You will likely spend in the area of $2500 to $3200 if memory serves. That's a lot of cash if you don't do much mileage. If you intend to do a lot of traveling you may well justify the expense. Less fuel, less wear, quieter....
Another less costly way is to change the rear end ratio. I know that the 460's have lots of power and other than burning exhaust valves are pretty stout. You are much longer so I'm not sure the ramifications of this on your chassis.
I'd still love to have just one more gear, or 500 rpms of releif at highway speeds. I don't like to get up over 3000 rpms so limit my speed to about 65-70. Would love to do that at 2400-2500 rpms.
BTW I broke 10mpg last night on a fill up!! 10.1 in fact.

noiva · 12-02-2005, 10:07 PM

Glen,
I was pretty sure the cost would be prohibitive. The axle gear is another issue. Since Gillig made the chassis I've been led to believe the gear is theirs, but I think I'll try to find out. As much as I love this unit, the mixture of Airstream, Gillig, Ford, and Chevrolet all in one vehicle makes for some strange issues. It all seems to work well enough, and the interior/exterior are as beautiful as I've seen, but these mechanical issues can be a killer. There are some things that aren't covered under the Airstream manual nor the Gillig manual. There's even a note to call for assistance if you can't figure out who is responsible for a given item. Of course, that was for 1989. No one wants to take the responsibility now. I could live with this for many years, but I agree the real answer would be a true overdrive 4th gear. Anyway, I'll try to see if there's any realistic chance of changing the axle gears, but I'm not very optimistic. I guess I'll adopt the motto that "Slower is better." Thanks for responding.

Noiva

noiva · 12-02-2005, 10:09 PM

By the way, congratulations on the mileage. I get about 8, and I'm told that's pretty good for this rig.

Noiva

wahoonc · 12-04-2005, 08:41 AM

novia,
Have you looked at the Gear Vendors website? I am most likely going to get one for my Ford PSD monster truck. I have a relative that installed one on his older gas MoHo and loves it. I like the idea of being able to split gears on the diesel. I would give them a call and see what they have to say. From best guess I would say it is going to run you close to $4k or a bit under. They do list pricing on their website. What Chevy parts do you have on your Gillig Chassis? That C-6 tranny is a beast, I have had them go over 100k under heavy use with nothing more than a heavy duty clutch kit and program kit installed.

Aaron

noiva · 12-04-2005, 09:51 AM

Aaron,

Thanks for the tips, and the assurance of the C-6 tranny. I just studied the Gear Vendors site, and it certainly looks like they have what I would need. Now I just have to figure out the money angle. I'm giving this MH a year of use to be absolutely sure I want to stay with it. In the meantime I'm hanging on to my 30' Avion(sorry) trailer and 2500 Suburban. Ultimately, something's going to go, and if it's the trailer that's when I could conceivably do the gear thing. Thanks so much for the help. If you think of anything else, please let me know.

Noiva

GlenCoombe · 12-04-2005, 10:04 AM

Novia, my mind went numb when you said angle drive. It never ocurred to me that the Gilligs had angle as I thought that only came into play with rear engine setups like the old highway buses.(edit, oops I misread it and thought you had said angle instead of axle.) never mind

Your mileage is pretty good for the length/weight of the coach. Has it had any modifications done to exhaust or ignition? I believe the carb/headers/exhaust redo on my rig have helped me obtain the great fuel economy I have.
I love my vacum guage. It lets me know when I'm being too agressive on the throttle. I've been looking at digital flow meters from Navman as another monitor of fuel consumption.
I'm still on my way to a new Mallory ignition setup but just the electronic box and distributor, not the manual timing deal. But now with a new coil in my old distributor I'm going to wait till spring likely.
The next big job is likely a repaint of the topside of the bus. I'm very seriously looking at chrome paint for the topside. I have no desire to maintain a polish job but would like it to be bright.
The bottom line is that this is a business expense for me and as I'm running up the miles it all seems to work out.

noiva · 12-04-2005, 11:09 AM

Glen,
Boy, you had me worried I had written ANGLE instead of AXLE. Anyway, I have a vacuum Gage on the dash, and I use it faithfully. I towed in the pre-electronics days, and I learned to use a vacuum Gage as the key measure of strain on the engine. Mileage is definitely better when I keep it above 10, and around 12 is even better, but harder to get. I have no modifications to the stock setup, but there are several things I have discovered. Headers won't go in the engine compartment. I tried to switch to them when the stock ones started leaking, but the clearance and heat problems made after-market ones impossible. The exhaust is stock except the new one from several years ago has no crossover pipe. Not a fatal error, but I intend to get it put on. The carb is original also. Since I use the vehicle for travel (camping) only, changing these kinds of things probably isn't cost effective until they need replacement. The engine/drive train are fine, run well, and are in excellent condition. The low mileage means I probably have some years before replacement things will be cost efficient. I am going to investigate an overdrive as discussed above once I determine to sell the Avion trailer. The low rear axle gearing is great in town and climbing mountains, but I desperately need a higher gear for cruising at highway speeds. I have to make myself run about 60 mph or the engine starts to go over 3000 rpms - where it is obviously not supposed to be. The manual says you can run at up to 4500 rpms at steady speeds, but that's just not correct. No big block should rev that fast.

Roof - I don't know what I'm going to do with mine. The whole unit was redone outside at Jackson Center in 2002, and the plasticoat on the roof is already falling off in sheets. Sides don't appear affected. What do you think? I'm thinking of just waxing the roof areas more than the rest of the body, and leaving the plasticoat alone. It looks good, but up close you can tell it's peeling.

Please let me know if you have any ideas or suggestions. I have enjoyed reading about your adventures with the funeral coach. Thanks for the help.

Noiva

GlenCoombe · 12-07-2005, 06:19 PM

Novia, it sounds like you've likely got 456 rears. Most moho's of our vintage had these. My old Champion came with 410's and did better but the 373's in the funeral coach give me a solid 69mph at 3000 rpms.
It might be more economical to look into dropping the ring and pinion for a lower number.
One could only hope that your G frame has a Dana rear end. Have you researched that part of it yet?

noiva · 12-07-2005, 07:53 PM

Glen,

The info on the rear axle ratio is in my Gillig manual. I have not gotten around to locating whether it belongs to Gillig or Ford - since it's a Ford engine and tranny maybe the whole driveline is Ford. The Gillig manual lists 2 ratios for this coach, but gives no help in how you determine which you have. Bad news is that one is like 5.33 and the other is almost that. Lowest gears I've ever dealt with. My Suburban has a 4.10, but of course it doesn't weigh over 17,000 lbs. It does, however, have an overdrive, of course, and that makes all the difference. I'll do some more research and see if I can determine for certain who made the differential. That may(?)help, I'll keep you posted. By the way I get exactly 3000 rpms at 60 mph. Anything over that and things get dicy. To may revs, too hot, too much strain on all the rotating stuff.

Thanks for taking the time to write. Always helpful.

Noiva

TheGanzman · 12-08-2005, 07:41 AM

Quote:

Originally Posted by GlenCoombe

Novia, it sounds like you've likely got 456 rears. Most moho's of our vintage had these. My old Champion came with 410's and did better but the 373's in the funeral coach give me a solid 69mph at 3000 rpms.
It might be more economical to look into dropping the ring and pinion for a lower number.
One could only hope that your G frame has a Dana rear end. Have you researched that part of it yet?

Glen - any idea if 3.73's are available (and where?) for my '77 Argosy 20'? I'd LOVE to drop down from the 4.10 slugs that are in there now! That thing pulls like a mountain goat right now, and I'll never tow anything but about 100 pounds of bicycles, so the 3.73's might allow me to keep a TH400 in there. . .

87MH · 12-08-2005, 08:25 AM

Quote:

Originally Posted by noiva

...The info on the rear axle ratio is in my Gillig manual. I have not gotten around to locating whether it belongs to Gillig or Ford - ...

If you're lucky, it may by attached to the differential...
Crawl under the MoHo, there should be a tag secured by one of the differential cover bolts that looks like this (Picture 1).

The tag can be intrepreted as

41 teeth on the main ring, 9 on the pinion.

41/9 = 4.555556 (4.56)

The second pic is of the one ton Dana 10 bolt dually (4.56) axle under the '87 345 Motor Home.

GlenCoombe · 12-08-2005, 09:51 AM

Ganzman, Dana parts are NAPA or Chevy or Summit Racing. Finding someone to do the swap is the key. It's not just slip one out and slip in the new. They often require shimming to mesh just right. Unless you've done it before and have the right equipment it is best left to the pro wrench.

GlenCoombe · 12-08-2005, 04:18 PM

Novia, just got back from the local Wal-Mart and filled up after my drive home last night. I moved quicker than usual trying to stay ahead of a trucker pulling a FEMA trailer and was running the generator. Ran about 3100 rpms at times, speed around 70 mph. When I put the calculator to work it said 8.7 mpg including the generator running. The savings being able to run at more conservative RPM while not getting run over my be worth reducing the rear axle ratio on your chassis. Even if you manage to get down into the 4:10 ratio the savings could more than pay for the work in a couple of years.
One consideration I did not mention in my earlier post was that a drastic change in ratio sometimes demands replacement of axle shafts as the splines may not match the new ring and pinion.
One way or the other reducing the RPM's is key to enjoying the coach more and for longer.

noiva · 12-09-2005, 06:51 AM

Glen and Dennis,

Thanks so much for the information and suggestions. I tried to get back yesterday, but for some reason I was blocked from logging on the site. After some initial panic

, I emailed the site administrator several times, and things seem to be working today. Anyway, I have researched the axle. It's a 5.29 ratio

, and I'm almost certain it's a Gillig. The cover isn't even on the back, but is part of where the drive shaft enters from the front. The Gillig manual doesn't say "specifically" that they make the axle, but they talk about their axle in the machanical components section where they mention the FORD engine and transmission, but not axle. The axle is tagged with the ratio, serial #, and other numbers. I will check at my local big rig place to see if they know whether I can put a higher ring and pinion set in that housing. If that isn't possible or affordable, I guess it's back to an overdrive like Gear Vendors sells? Any other suggestions or ideas? I'm open for anything. By the way Glen, I get 60 mph at exactly 3,000 rpms, but almost 4,000 if I push it to 70 mph - NOT acceptable. You are much better off than that, and I could live with your numbers. In fact, sounds like an almost ideal setup for my rig, especially considering the size and weight.
Again, thanks so much,

Noiva

GlenCoombe · 12-10-2005, 05:52 AM

Novia, keep in mind when you do this mental (so far) exersize that you have a longer and much heavier chassis than I do. I only have a small water tank and combined black/grey water tank. No propane, limited cabinets, etc. The one thing you don't want to do is to lower the rpm range into the lugging zone with these big motors. I think the ideal range would have to be above 2400-2500 rpms at your highway speed of choice.
If your driving is going to include a lot of time in the mountains this may not work as you'd have to get down into second gear for climbing.
You may get to a point in the exersize where the gear vendor route is most economical and most usable. It all depends on what you can manage and who does the work to lower the ratio on the rear axle.
The big Ford is notorious for burning exhaust valves so you want to make sure that you're doing your best to keep the thing cool, including inductive heat transfer from the transmission.
I'm planning a switch to synthetic oil in the tranny and rear end on the next service. Also planning a new external transmission cooler.

noiva · 12-10-2005, 04:09 PM

Glen, It seems to me that if I get into making a mechanical change, it should probably be the Gear Vendors overdrive route for maximum versatility. That way I should be able to lower interstate rpms by about 22%, according to Gear Vendors info, which is just about what I would need to do 70 mph at around 3000 rpms or less. It would also the retain the ability to use 3rd gear climbing, in city driving, and when driving at 55 mph on back roads. My thinking is I could sort of have it all. Lower rpms at higher speeds (which are presently I don't even attempt) and still maintain enough rpms at slower speeds, climbing, and city to keep the 460 from lugging. I can't imagine that a simply change to higher gearing (a 4.4 axle, for example) would give me near that versatility. I could end up being able to cruise at 70, but lose the excellent pulling I now get in town and the mountains. 4 gears have to better than 3, it seems to me, given the size and weight-not to mention the 5.29 axle-and the uncertainty of putting higher gearing in the axle.
Noiva

3Ms75Argosy · 12-10-2005, 04:34 PM

I'd like to know how it all turns out. Here's a gear calculator site to help you find the rpm's / mph.
http://www.randysringandpinion.com/c...rs/default.asp

I'm not sure where you are located, but I did use Randy's to re-gear my v8 Chevy Astro. Although I don't have the van now, I felt they did do a great job for a reasonable price. It was around $500.00 for new ring and pinion and bushings. The dealer wanted $1200!!

Good luck!
Marc

noiva · 12-10-2005, 05:19 PM

Marc, Thanks for the encouragement and information. I checked Randy's site, and it does have lots of great gear info. You got a great deal on your job. I changed axle gears about 20 years ago and paid about $1000 to a dealer for the whole job. I'm located in the southeast corner of Virginia in Chesapeake. I forgot to check where Randy's is located, but I'll do that as soon as I send this. Whenever I decide what to do, and get it done, I'll certainly post the results. I'm really leaning toward the overdrive idea. It's considerably more expensive, but with a rig the size of mine I don't believe 3 gears are ever going to be as good as 4. There's a good reason big rig trucks have so many gears. Thanks again, Noiva

GlenCoombe · 12-10-2005, 05:26 PM

Novia, I believe you're on the right track. If you go with Gear Vendors you'll not only improve the economy and performance but you'll add more value to the rig.... should you ever in your wildest dreams want/need to sell it.

I was on the GV site last night and I believe you'll not just get a fourth gear but in fact more like six. Remember that you'll now have both under and overdrive gears.
Why not send for the video?
For the size of your rig, as you said... It's likely the best alternative.
Likely the best $3700 you'll spend on the rig and in the long run...longer run...longest run., you'll realize a return on the investment.