Community Forums

jaydar · 08-18-2015, 06:54 PM

I have an old vintage RV, 1988 Fleetwood Jamboree. My RV runs great on flat surfaces, but the moment I hit any kind of incline, you can feel it right away, My RV does not have overdrive, so going up hills is like a major burden, my speed drops and feels like my engine is working extremely hard. I been told that the Gear Vendor would solve the problem, also been told that the Gear Vendor Overdrive is a bit expensive. My question, is it worth spending the money and having the unit installed in my 1988, or should I just upgrade to a newer RV?

MotorPro · 08-18-2015, 07:32 PM

They are not a little expensive.....they are very expensive. As far as climbing hills being in overdrive will make it much worse.

stuhly · 08-18-2015, 07:40 PM

Gear Vender also makes an under drive. Also very expensive.

Mr_D · 08-18-2015, 07:41 PM

We put one in our '88 Type B Okanagan MH. It had the TT towing package, a 460 and only weighed 8,800#'s. Just got tired of the high RPM at 70 mph. Still never got 10 mpg though but the noise reduction was nice.
The driveshaft was an aluminum one and they fabricated a new steel one. It had different harmonics and also added some vibration.
Would I do it again? Well, maybe and maybe not.

twinboat · 08-18-2015, 07:46 PM

You would actually need an underdrive to get more power to the wheels but the transmission does that when it downshifts.

I have an overdrive transmission and it drops down to drive, almost, at the sight of a hill. If it's a steep hill, I am in second gear with my foot to the floor, at 45 MPH.

mbridinger · 08-18-2015, 07:53 PM

I go up many steep grades (6%) all the time. I watch the RPM's and not the speed. I do not let my motor go above 4000 RPM and I try to keep it around 3200. It seems to be the "sweet spot" for my set up. Also keeps the temps in range. All that being said, I sometimes putt up the hills at 35. It does not bother me at all. I have a 454 TBI with a toad. To answer your question about the gear vendor....No.

RBeau1954 · 08-18-2015, 07:58 PM

I have the same unit you do except mine is a 1989. It has the C6 3 speed transmission. I know exactly what you are going through, I go through the same thing when traveling. A gear vendors overdrive does not do anything for the hills, it will only give you an overdrive for flat stretches and lower your rpm's for cruising. I have done an rpm calculation on the C6 tranny with the 4.10 rear end. At 55 mph you can safely drop your shifter down to 2nd gear and keep the rpm's up to keep a good speed. Other then that, stay off the hills....

matthewc · 08-18-2015, 08:08 PM

I have done quite a bit of research on Gear Vendor Gear Splitter/Overdrive and my understanding of how it functions for the Dodge 727 at least is it effectively takes the 3 speed 727 and turns it into a 4 speed auto by giving the OD but it also splits gears effectively making it a 5 speed by splitting gears giving you a 1st, 1.5, 2nd, 2.5, 3rd, and OD. Benefits for ascending and descending big hills is the gear splitting, fuel mileage improvements are supposed to be in the 20% range due to the OD.

Yes, they are costly but the benefit of the unit may be worth it if your planning to keep your rig for a long time. If your plan is to upgrade, sell or trade in in the next couple of years it probably wont be worth it.

All of this of course is just IMHO.

Matt

Wdebarmore · 08-18-2015, 08:22 PM

I have a gear vendors overdrive on mine. The rear end has very steep gearing which helps with the hills, but without the overdrive I doubt I could go over 55 on flat ground. It does work flawlessly and I consistently get 10-11MPG.

Martintebbut · 08-21-2015, 04:13 PM

I live in Australia and have fitted a Gear Vendors Overdrive to my 32' 1988 Tiffin Allegro. It has a 3 speed turbo 375. I am very happy in so far as it gives me better petrol economy and with our high fuel prices this is significant. My engine revs at cruising speed on the freeway have dropped about 600 to 700 revs in top gear and you can hear the 454 Chevy say thank you and of course this makes it quieter when cruising.

It does give you an advantage going up inclines as you can easily drop down a cog.

I drive it manually so I am in charge all the time.

I personally recommend fitting the unit but it is expensive and needs to be done very carefully as clearances are critical. If you change your mind after it can be a problem as you have to have your tailshaft shortened.

I also found out the hard way that you do not use the overdrive for engine braking going down hills, and you do not back up over gutters or steep inclines if you can avoid it as there is some sort of small clutch that only works in reverse and it will break the overdrive.

BA-in-Mich · 08-23-2015, 12:06 PM

If it is anything like my 454 was, I know what you are going through. After I had my distributor recurved and the Qjet rebuilt, it was amazing the power I had to go up hills. I already had Thorley headers on the engine, but that in it's self didn't do much.

bsinmich · 08-23-2015, 04:45 PM

If I recall correctly your '88 is a 4 barrel 460 and the '89 is MPFI. That is a huge difference. The fellow with a diesel probably has the 4 speed Allison and that is why he can't get to 55. These are not similar to your question. Assume you would et 1.5 mpg more. Figure the number of miles you drive per year times the number of years you anticipate keeping your RV. Compare that to the cost of the Gear Vendors unit. I had a brand new '89 Jamboree so can remember that. Are you sure the excess noise wasn't fro the fan clutch cutting in? That was very noisy also.

RamblinOn · 08-26-2015, 08:58 AM

I've been looking into one for my 1989 HR 454 turbo 400 set up. Mainly looking for the OD to lower the rpm on the interstate as 60 mph is my personal limit due to the 3000 rpm I see at those speeds. It would be nice to ease up on the ole girl. Mine too suffers in the mountains, and I see a significant increase in water and tranny temp on the grades. The Gear Venders is the way to go in my opinion, although they are not cost effective. Unless your full timing in your old coach, and put a lot of miles on it per year, you'll never see the fuel savings add up to the cost of the install.
We're at a cross roads deciding if we are going to sell and upgrade to a newer unit with the Allison, or keep our older coach. If we keep it, the over/under will be top of the order for install.

Tim

Itldo · 08-27-2015, 08:00 AM

I am thinking what I need is an underdrive unit. I pull a 4500 pound trailer behind our 16,000 lb small class A. I am thinking that it would provide less wear and tear on unit/engine and give better hill climbing. We are fulltimers...return on investment by resale is not in my equation. Better overall performance and less wear and tear on unit is my primary concern.