Why not gasser rear enging?

SIV had serious brake problems and notoriously caught fire. All but 2 of the original ~100 that were built were recalled. There was some intent of the design to be reminiscent of the GMC, hence the tandem rear axles.

IIRC, they differed from most tag axle coaches in that the forward of the two was the tag and the rear one was the drive.

With as many UFO gas pushers that were built, I am still surprised at how many people never heard there is such a thing. People ask me if I am sure mine is gas. I tell them it better be, because that is what I buy at the pump. I have been asked what a UFO coach is. I reply that it is a diesel pusher that burns gas.

-Gramps- wrote:
I reply that it is a diesel pusher that burns gas.

Gramps, that sounds like a DP wannabe. Are you leaning toward the dark side?

gbopp wrote:
UFO Chasssis

UFO Chassis Posts

I thought the UFO's were the future and still think it would have been if not for the economy, Workhorse's upset, and the demise of the GM 8.1 engine. Probably not going to happen now, unless Ford gives it a go, but why should they invest that kind of money when sales are already through the roof to the coach manufactures?

My guess is its mostly related to cost and volume. Ford for example builds its V10 drive train for a large variety of trucks in addition to RVs. The more you build, the lower your unit cost. Also, the V10 having been around so long and used in so many vehicles, it has become refined and highly reliable. For me the engine noise is only loud at high rpms in lower gears while excelerating or climbing very steep grades which is a small percentage of my total drive time. For me this was the most cost effective option given that I no longer spend months on road trips and am not a full timer. I think the DPs are a great product but I just couldn't justify the much higher cost. Ford would have to redesign the entire rear axle/drive train in order to do a rear gasser. Probably not worth the cost. Fords truck sales volume probably holds down the cost of their V10 RV chassis and is probably the reason they dominate the gasser market now.

In todays market it would seem that the likely suppliers of a rear engine gas chassis would be Freightliner and Spartan.

Either could rather easily offer a gas engine chassis simply by installing said powerplant in their existing diesel chassis. The problem remains one of cost vs demand. For many years there were heavy duty trucks powered by gas engines that included air compressors for brakes, air ride, etc. so maintaining that feature would not be an issue. But simply repowering their diesel chassis would not reduce costs by any really significant amount.

If there was an option for this type of chassis I believe there would be owners or potential owners who would opt for the gas for the possibility of lower costs of operation. Of course that would have to be proven over time.

The remaining problem I see is the current lack of any proven engine of an appropriate size being readily available in today's marketplace.

Despite the cost factor, I can see a lot of benefit to potential owners who don't really travel a lot of miles annually or over the life of their coaches. The elimination of a long driveshaft allows for some savings as well as opening up added storage space. Losing the long exhaust system could only reduce heat input to the coach and cost marginally, but appears to be a benefit.

I may be in the minority, but I believe that there could be a market for a rear engine gas chassis coach in the 34-38 ft. range which would also have air brakes and air ride suspension. Unfortunately the lack of an available chassis and the price point of such a unit throws that idea into the dream category.

Actually, Bill, I don't think there would be any major redesign to put the Ford V-10 and its existing drive train in a pusher, just the simple addition of a 1:1 pair of gears to reverse the output shaft rotation. Alternatively, the V-10 could be mated to a pusher transmission such as the Allison.

Special Interest Vehicles did theirs using a ZF transmission, as I remember.

As an FMC owner, I feel I ought to reply to a couple of points. First is that FMC had some issues with heating in new coaches because of having received some bad radiators (tubes plugged with solder) from the radiator manufacturer. That was cured with corrected radiators.

Over time, ANY rear engine unit (gas or diesel) with a REAR radiator will have a heating issue UNLESS the owner keeps the radiator clean. Given the lack of ram air with the rear radiator, radiator clenliness is critical. All FMC owners that I know that have had a heating issue have historically cured it simply by cleaning the radiator. When a radiator is in the rear, more stuff is drawn into the radiator and reduces air flow which caurses the heating issues. Do a search on diesel engine heating and you will see what I am talking about.

A few people have replaced their old heavy radiators with modern, lightweight aluminum radiators with good results.

In general, the key is airflow design followed up by proper maintenance for any rear engined unit. It is NOT a gas vs diesel issue.

I absolutely love my rear engined coach which is small and historically gas powered. The sound is in the rear at all times and there is no engine hump up front. The FMC was built on its custom chassis as a low profile unit for traveling vs camping. With the rear engine design, the main floor of the coach is only 18 inches above the ground which makes for very easy entry/exit from both the passenger side and driver side doors. A front engine and rear drive would have prevented the low profile design. That ease of entry gets more important each year my knees get older!

With its custom chassis, four wheel independent suspention (trailing arm, torsion bar in the rear), and rear engine design the coach was not cost competitive with the standard frame/engine designs that had wide usage. Combine the cost of the coach, the 1974 gas crisis, and that FMC got the contract to build Bradley Fighting Vehicles, the motor home plant was gutted and converted to building Bradley's. That was an easy decision!

As some people know, in my case, after putting 60,000 miles on my coach with the original powertrain, I am in the process of replacing the 440 with an engine and transmission that was not available until fairly recently. I purchased a lightly rolled 2006 GMC pickup and am moving the 6.6LTD Duramax LBZ diesel and 6 speed Allison sideways into my coach. I don't have a justification for doing this as my coach has made multiple trips over the Rockies just fine with the 440 other than I just wanted to do it!

The demise of the UFO chassis was a very similar story 30+ years following the demise of FMC manufacturing.

The majority of FMC's are still on the road which is a tribute to the coach's original design. Storage - limited, slideouts - none, but a great traveling coach to this day.