WHAT'S THE MOST COST EFFECTIVE WAY TO LOWER ENGINE RPM

frankfreda Posted 2014-12-07 11:15 PM (#2449) Subject: WHAT'S THE MOST COST EFFECTIVE WAY TO LOWER ENGINE RPM Location: 345 Ridgecrest Dr. Santa Barbara Ca. 93108 (68.6.125.116) LOWERING ENGINE RPM WHILE CRUISING. Whats the best and most cost effective way to lower engine RPM while cruising ? I guess the word is OVERDRIVE ? Allison sounds like an expensive word to me. Any ideas of what has or could be done ? Thanks Frank Freda (frankfreda@cox.net) B. Sitton Posted 2014-12-08 8:53 AM (#2453 - in reply to #2449) Subject: Re: WHAT'S THE MOST COST EFFECTIVE WAY TO LOWER ENGINE RPM Location: Ignacio Colorado (174.125.141.216) A couple of coaches have been fit with the Chrysler 518 overdrive. It requires an adapter kit to bolt to the 440 and other work to bolt it up to the differential. Have to use a 4 wheel drive unit. I know there is a few ways to do it as I have talked to the other 2 coach owners that run them. Even if you can do it all yourself it is going to be pricey. Heads up that all 518's are not created equal. I built the ones for our project by finding a unit (47RH) from a 94 or later V-10 or cummins and installing the heavier duty internal parts into a case from a gas 5.2 or 5.9. 518/46RH. Then I used a rebuild kit for the 98 year model 47RE. This gets the most clutches in the overdrive clutch pack. No park brake on the transmission but one is in the works and is sounding like it will work for any engine combination. Bill frankfreda Posted 2014-12-08 9:58 PM (#2456 - in reply to #2449) Subject: Re: WHAT'S THE MOST COST EFFECTIVE WAY TO LOWER ENGINE RPM Location: 345 Ridgecrest Dr. Santa Barbara Ca. 93108 (68.6.125.116) Hello Bill, thanks for the information. It appears to me a park paw is very important. It looks like you may come up with a way to work this in. What is your RPM in direct drive and overdrive. Also did you do the math and figure out what the increase is. I don't see any discussion about a lock up torque converter? My expertise is very limited when it comes to assembling automatic transmissions. I wonder if what you have laid out here is common knowledge with specialty transmission shops ? Please forward me your phone number. Thanks Frank Freda B. Sitton Posted 2014-12-09 9:33 PM (#2461 - in reply to #2449) Subject: Re: WHAT'S THE MOST COST EFFECTIVE WAY TO LOWER ENGINE RPM Location: Ignacio Colorado (174.125.141.216) Frank, I have not put the overdrive into the FMC at this point. I have brought together what I (reads TEAM) thought was the best and easiest way to put an overdrive into the FMC. I was the transmission guy in the team and much of the credit will go to another for fabricating many pieces required to make the 4 wheel drive version of the Chrysler 46RH overdrive work in the very limited space of the 2900R coach. This transmission does have the park pawl and a park position. The transit I have with the Allison, as well as the other 440/Allison and 8.2 Detroit/Allison units do not have a park pawl and a positive park. They use a drum style park brake similar to the one on the stock Chrysler 727. The overdrive is 0.69:1. If you currently run 3,200 rpm cruising then with the overdrive it should be down to 2,200 rpm. The overdrive can be built with or without a lockup converter. With a lockup you could shave off another 200 or so rpm. My plan will include engine work to get the most torque in the lower rpm range without having to build a stroker engine. The goal is to get the best fuel economy, drivetrain longevity, with the least modifications to the coach. Use the best parts Chrysler made for the job at hand. This is not going to be a drivetrain package ever put together before. As I said in an earlier post, there are at least 2 FMC's already running the Chrysler overdrive transmission. The engine that is planned for this setup has never been done. We think it will prove a very dependable combination. When I have one running I will give real driver seat data. Bill