Community Forums

jaydar · 11-24-2014, 07:31 AM

Hello, requesting opinions and suggestions. My 1988 Fleetwood Jamboree, has a three speed transmission, no power for going up hills, on flat surfaces runs like a champ. In my mind the current three speed transmission is working to hard. This is prior to the introduction to the overdrive tranny. I am always waiting for the trans to kick into OVERDRIVE to relax the engine, but that never happens. My question is, can the current 3 speed transmission be replaced with an overdrive transmission and would this improve hill climbing and gas mileage. Can anyone provide any suggestions?

Smitty77 · 11-24-2014, 08:50 AM

Look for a Gear Vendor. You might find a used one, and then have it looked over by Gear Vendor for a fee. I think this would help, and be much easier then try to retro a newer transmission into the coach.

Best of luck!
Smitty

Daveinet · 11-26-2014, 06:41 AM

Ford or GM? GM conversion to a 4L85e is not too difficult. Trans controller is about 600 bucks and is very straight forward. You have to shorten the driveshaft, move the trans mount 2 inches back. Pretty much everything else is bolt on.
If you have a Ford, then I have no idea.

RBeau1954 · 11-26-2014, 06:59 AM

I have an 89 Fleetwood Tioga with the same 3 speed tranny. Gear Vendors can do an overdrive unit for any tranny at about 4 grand but that won't help with the hills. I did a calculation on the C-6 tranny that is in the Ford units and at about 62 MPH the 460 is right about at its peak torque range and doing a little over 2500 RPM. It sounds like it is making a racket but it isn't even close to redline. My unit has the 4.10 rear end.

ahicks · 11-26-2014, 07:37 AM

Without really getting right into it, I would wonder if the engine would have enough power to pull the overdrive ratio on the level, without changing the rear differential gear as well?

If it did, you might pick up some mileage, but how many mile would you have to drive to get a return on your investment?

Last, I don't think an overdrive tranny is going to be of much help in the bigger hills. Most any transmission is not going to be in top gear when climbing hard, so nothing available to gain there.

If you add the price of the necessary mods to what your coach is worth, would you be able to buy a later model coach with a factory equipped trans of your choice?

Curtis in TX · 12-12-2014, 10:56 AM

Quote:

Originally Posted by ahicks

Without really getting right into it, I would wonder if the engine would have enough power to pull the overdrive ratio on the level, without changing the rear differential gear as well?

If it did, you might pick up some mileage, but how many mile would you have to drive to get a return on your investment?

Last, I don't think an overdrive tranny is going to be of much help in the bigger hills. Most any transmission is not going to be in top gear when climbing hard, so nothing available to gain there.

If you add the price of the necessary mods to what your coach is worth, would you be able to buy a later model coach with a factory equipped trans of your choice?

I'm with Hicks on this one. 13 years ago I re powered my 89 Fleetwood from gas to diesel and put its Allison 542 behind it. Sadly the 542 was not an overdrive transmission nor did it a lock up torque converter transmission. The Allison world 1000 we're not on the used market yet when I did this swap in 2001.

I just finally got my hands on a 5 speed Allison 1000 and that swap is going to cost me around $4000 and I'm doing the work myself. The original engine swap cost me 10,000 dollars. If Had to do it over I would have traded my coach in and got me a diesel to do what I wanted to do. But I like my old girl and she comes in real handy. She's paid for it has been for a long time.

Sometimes the math helps make up one's mind.

I will never get that money out if her if I sell.it. But that's OK I'm not planning on selling anytime soon.

If you have to pay a mechanic to do your upgrades then it really is hard to justify.

SuperSteer · 12-12-2014, 11:06 AM

A Gear Vendor Over/Under Drive gives you the option of 2nd gear overdrive, basically giving you a gear in between 2nd and 3rd, very helpful in hills and your current rear end gearing should be fine for 3rd gear overdrive on flat ground.

oldbeek · 12-27-2014, 02:15 PM

Put a gear vendor in my 93 dodge 3500 with 4.10 gears. I was looking for more mileage. Did not help. Did give me 2nd over split. $3500.00 wasted. Should have gone with newer trans with torque converter lock up mods.

Daveinet · 12-27-2014, 10:49 PM

Oldbeek, I'm not the least bit surprised. If the engine RPM is too low at cruise, the TC slips too much, and you loose efficiency. With my old TH400, I found unless the engine was turning 2500 RPM, the TC was slipping. I could travel 60 mph, or 75 mph and would get the same mileage, because I was wasting so much power from TC slip at the lower RPMs.