RR10S and RR10R

[Gdawgs]

I've looked under and worked on my RR10R chassis. Cleaning the tag bridge assembly, greasing, adjusting etc. What is the difference between the RR10S and RR10R besides the radiator placement?

[96 Wideglide]

Well, thats the main difference. Some filters get moved around due to the greater access through the hood.

[Gdawgs]

Filters locations etc. are the only things I can see that are different. I thought there may be something structural but I couldn't find any difference.

Thanks

[Randyman1]

It was my understanding the "S" meant steel, as in all steel cage construction. The "R" chassis was aluminum cage. JMO

[Gdawgs]

Originally Posted by Randyman1

It was my understanding the "S" meant steel, as in all steel cage construction. The "R" chassis was aluminum cage. JMO

No..steel cage front and rear are the same. S and R refer to the location of the radiator...side and rear.

[Steve Ownby]

Originally Posted by Randyman1

It was my understanding the "S" meant steel, as in all steel cage construction. The "R" chassis was aluminum cage. JMO

RR8S & RR10S is Raised rail, 8 air bag or 10 air bag, side radiator
RR8R & RR10R is Raised rail, 8 air bag or 10 air bag, rear radiator
S Series is the welded and steel framed semi monocoque. This is what your Navigator is built on.

[Gdawgs]

Think I found my answer...

Foretravel began building motorhomes on a semi-monocoque "chassis" in the late 1980's. Our 1993 coach is a "Unihome"-- its name in part from Unibody (aka monocoque).

In a semi-monocoque coach, the structure for all but the heavy rear axle and drive train and the front axle are monocoque/unibody. This center monocoque structure joins frame rails to hold the heavy components front and rear.

If you look in the under a coach and in the basement, you will find NO frame rails (long beams as traditional frame rail chassis have), as the grid IS the structure.

This construction is lighter and stronger (and as you likely suspect, more expensive) than body on frame and offers more resistance to twist/body flex. Most cars as well as OTR busses use this type of construction.

Semi-monocoque implies some welded structure of the chassis forming part of the sidewalls. With the advent of slides(monocoque and semi-monocoque chassis makers were the last to add slides for a reason), the full length horizontal steel rail with diagonal steel members running the full length of the coach and extended a few feet above the sub-floor, were interrupted. This meant that the extra strength and rigidity provided was lost. To make up for this, builders had to go to larger twin stringers, located much the same as raised rail chassis I-beams. By the time quad slide coaches were available, the size of these stringers became very close to the size of rail chassis main rails.

Therefore, the original concept of semi-monocoque chassis was lost with any weight or center of gravity advantage as well, even though it is still a strong, rigid construction methodology--just different from the original concept.

I can see why this would not work well with a full wall slide.

[96 Wideglide]

Your talking 3 different chassis now.

The RR10R, the RR10S, and now the S series semi-monocoque chassis.

[Randyman1]

Originally Posted by Steve Ownby

RR8S & RR10S is Raised rail, 8 air bag or 10 air bag, side radiator
RR8R & RR10R is Raised rail, 8 air bag or 10 air bag, rear radiator
S Series is the welded and steel framed semi monocoque. This is what your Navigator is built on.

Thanks for the clarification Steve!

[Gdawgs]

Originally Posted by Gdawgs

Think I found my answer...

Foretravel began building motorhomes on a semi-monocoque "chassis" in the late 1980's. Our 1993 coach is a "Unihome"-- its name in part from Unibody (aka monocoque).

In a semi-monocoque coach, the structure for all but the heavy rear axle and drive train and the front axle are monocoque/unibody. This center monocoque structure joins frame rails to hold the heavy components front and rear.

If you look in the under a coach and in the basement, you will find NO frame rails (long beams as traditional frame rail chassis have), as the grid IS the structure.

This construction is lighter and stronger (and as you likely suspect, more expensive) than body on frame and offers more resistance to twist/body flex. Most cars as well as OTR busses use this type of construction.

Semi-monocoque implies some welded structure of the chassis forming part of the sidewalls. With the advent of slides(monocoque and semi-monocoque chassis makers were the last to add slides for a reason), the full length horizontal steel rail with diagonal steel members running the full length of the coach and extended a few feet above the sub-floor, were interrupted. This meant that the extra strength and rigidity provided was lost. To make up for this, builders had to go to larger twin stringers, located much the same as raised rail chassis I-beams. By the time quad slide coaches were available, the size of these stringers became very close to the size of rail chassis main rails.

Therefore, the original concept of semi-monocoque chassis was lost with any weight or center of gravity advantage as well, even though it is still a strong, rigid construction methodology--just different from the original concept.

I can see why this would not work well with a full wall slide.

Since Monaco moved away from the S series semi-monocoque chassis because of the quad slide industry movement, I'd think RoadMaster's move to the raised rail forced them to move the rails further apart than industry norms in an attempt to gain back some of the rigidity of the monocoque chassis construction. Any thoughts??

[Steve Ownby]

Originally Posted by Gdawgs

Since Monaco moved away from the S series semi-monocoque chassis because of the quad slide industry movement, I'd think RoadMaster's move to the raised rail forced them to move the rails further apart than industry norms in an attempt to gain back some of the rigidity of the monocoque chassis construction. Any thoughts??

Monaco built many quad slide coaches on the S Series chassis. The original design for the S Series was by Chrysler. Monaco bought the design as well as the Roadmaster chassis division from Chrysler back in the mid 80s. TheS Series has main rails with the wide spacing and when Roadmaster started building the RR chassis, they had to up size these rails but the wide spacing remained. From the early 2000s until Monaco Coach Corp ended production in early '09 the S Series chassis coaches and the various RR chassis were built concurrently. When Navistar bought the assets of MCC, they finished coaches in production and used up lots of chassis inventory they inherited. When they started introducing coaches designed during their ownership, no S Series chassis were built. Their flagship Dynasty was built on the RR10S chassis. That caused much weeping, wailing and gnashing of teeth among Monaco faithful. I was one of them.

My wish is for a S Series chassis be built using the current Freightliner front & rear clips. The decision makers don't think anyone cares about a strong, stiff chassis design.

[RCLImperial]

Originally Posted by Randyman1

It was my understanding the "S" meant steel, as in all steel cage construction. The "R" chassis was aluminum cage. JMO

Until 2005 or so, Holiday Rambler coaches were aluminum superstructure above a Roadmaster steel chassis. The front cab structure was steel for strength. This was a holdover from before HR was bought by Monaco. That was changed sometime after then. My coach, a 40 ft. Imperial on a RR8S chassis doesn't have a tag, but the later 40 footers have one. I assume that the new steel superstructure weight necessitated the tag axle.

Dick L '04 HR Imperial

[Steve Ownby]

Originally Posted by RCLImperial

Until 2005 or so, Holiday Rambler coaches were aluminum superstructure above a Roadmaster steel chassis. The front cab structure was steel for strength. This was a holdover from before HR was bought by Monaco. That was changed sometime after then. My coach, a 40 ft. Imperial on a RR8S chassis doesn't have a tag, but the later 40 footers have one. I assume that the new steel superstructure weight necessitated the tag axle.

Dick L '04 HR Imperial

The steel framed S Series chassis coaches were only the top few in the Monaco line. In 2000 that was the Signature, Executive, Dynasty and Windsor. At some point the HR Navigator was added and still later the Imperial. There were a couple of Beavers at some point. The rest of the coaches were more conventional construction with aluminum framed house structure.

[CampDaven]

And the glorious RR10S may never be seen again.
A great loss for RVdom