2009 Monaco Cayman broken trailing arm replacement.

 First things first.

This is not intended to be a step by step instruction manual on making changes to the suspension of any Motor Home (MH). It is just my reflections on the work we did with the help of some great friends in order to get our specific MH rolling again after a failure in the suspension.

All the parts and equipment mentioned are very heavy duty and you can easily crush fingers, toes and other body parts if tools and jacks are not strong enough. The trailing arms alone weigh close to 180lbs a piece, beware, be safe, don't get hands under parts supported by jacks, use stout wooden blocks to support pieces being installed or removed.

SAFETY FIRST! Wear appropriate clothing, wear safety glasses, use hearing protection.

First the background. 

Our 2009 Monaco Cayman 

We bought our Monaco partly on impulse. It was a low mileage very nice looking diesel engine unit and that blinded us to an extent.

We had always heard that Monaco was a quality brand and well built. Ours was a 2009 model built just as the company went out of business after the recession around 2008.

We weren’t novices to RV’s but we didn’t have a lifetime of experience just 5 years on the road.

I joined the Monaco Owners section of IRV2 online and they seemed happy with their units. I saw occasional posts about broken rear trailing arms but they seemed to be before our year which had upgraded pieces as a result of a recall. Ours had no recalls outstanding when we bought it.

When we bought it it had 19K miles and over the next 2 years we increased that to 38K. That's when we hit trouble. Driving thru some EXTREMELY rough roads in Pennsylvania trying to avoid hurricane Henri we noticed the rig was rolling side to side like a rowing boat in a cross sea. It hadn’t done that before, I suspected a front shock absorber that wasn’t damping the swaying. In addition when I applied the brakes it would gently pull to the left. We spent the night at Lums Pond SP in Delaware.

When I crawled underneath there were no typical signs of a shock absorber failure which normally is oil leaking out of the body of the shock. I posted on FB about our problem and started calling all around repair shops in Maryland which was our next planned stop. Nobody wanted to help. No RV stores or truck repair shops would take it on. I extended my search to Virginia and North Carolina where we planned to stop after Maryland.

An old friend from our days riding Goldwing motorcycles replied to my post on FB, Dave Pumphrey and his wife Gloria who are super people. They ran the disco at our daughters wedding hence Dave’s nickname DJDave!

Dave has a motor home too, he is a trained mechanic so he has all the tools. He also has a huge yard and workshop with full hookups yet! He invited us to come over and see what the problem was.

First he organized a party for all our old Goldwing motorcyle friends!

A great bunch of friends to party with.

After that we got underneath and discovered that one arm of the rear suspension had broken clean in two,

End and side views of the broken trailing arm

Now this isn’t a skinny piece of metal, its 3 inches square tubing with ¼” thick sides.

A hefty piece of metal

My working life has been on shipbuilding. One of the first things we would be taught was that ships flex and square corners create stress points that lead to structural failures. The famous WW2 Liberty ships started breaking in half because of square hatch corners.

If you look at the broken trailing arm you can see a hard square corner,

On top you can see the rectangular plate with sharp corners where the break started

Doing some research revealed that the company had replaced the original trailing arm after the recall with strengthened pieces. During the recession/recall time the company went bankrupt. All recalls were unenforceable.

As things turned out the strengthened pieces also failed. Ours was one of those.

Now with the company gone how were we to fix this major failure??

A company in Oregon had recognized the need for replacements. Source Engineering had redesigned the whole piece and to my structural engineering trained eye had done a REALLY nice job. They had added side plates, eliminated the square edges completely and used a process called shot peening which impacts the surface and reduces the likely-hood of cracking.

Old piece top, new bottom

When I called Source they had a backlog of at least 4 weeks but identified one of their dealers in Michigan who had 5 sets in stock.

Veurinks RV Center 800-822-5292 were very helpful and dispatched a set express shipping by YRC (Yellow Truck Lines) to the YRC depot in Baltimore.

Well it turned out that express, rush, and guaranteed are all different services. We were told on Thursday that they would arrive Monday. Monday came and I called the YRC depot only to be told not to call them, they would call me when it was ready to pick up. 

Not being one to take no for an answer I kept calling anyone and everyone and finally found that the pieces had arrived at the depot on Sunday but they had a delay of up to 8 days to unload  the trailers after they arrived. Express didn't mean anything except you paid more for the name. Rush wasn’t a rush and only Guaranteed would have resulted in fast unloading or a refund if it wasn’t.

Finally they unloaded it on Tuesday and Dave and Gloria lent us their pickup truck to fetch it.

Dave called in Butch and George who are also old Goldwing friends on Tuesday afternoon and we started the project.

Dave and George working hard

I don’t know how to describe a major project like this involving heavy parts, huge bolts and torque wrench settings up to 350 foot pounds. Suffice it to say that four of us worked about 6 hours, tag teaming as we got tired. Eventually we had one of the broken arms off and the new one in and firmly attached.

Darkness stopped us that night and the next day Hurricane Ida swept thru Maryland. Tornadoes touched down causing major damage in Annapolis about 20 miles away.

Having a day off allowed us to think over how we had done the first side. We had struggled for hours trying to get the U bolts out. 

Dave realized it was all wasted time as we cut the U bolt with an air grinder in the end, but we only cut one side. The kit comes with new U bolts anyway so we could have cut both U bolts on both sides of the axle.

U bolts cut thru with a cutting disc on an air grinder

We had tightened up everything before we tried to attach the rear link bar and had to loosen everything off to get it aligned. If we left the final tightening to the end we would be able to waggle things into place.

Rear axle looking forward. Showing to the left the shock, airbag and the trailing arm.
The rear link bar joins the two trailing arms at the rear.

We struggled to get the front of the arm up to the pivot and were nearly to the point of it slipping off the jack a couple of times. I realized we could attach it at the rear using the shock absorber bolt first which left the front of the arm almost horizontal when jacked into place.

The front end of the new training arm with the new nut on the pivot pin

Front of the new arm looking back

We spent much time and effort getting the U bolts torqued up to the required 350ft/lbs. Dave had a big ¾ drive impact wrench but it didn’t get it close to tight enough. On the second side he replaced a coupling on the airline that was leaking air and the wrench tightened the nuts down to almost the right torque first go.

The inside of the new arm looking back showing the u bolts and the airbag.
The rear link bar is below that.

The second side took less than half the time the first side took and with 2 less people.

Our final sequence of events was.

With the coach on heavy duty jack stands at the rear.

Cut both U bolts on both sides of the axle

Remove the nuts holding the airbag to the trailing arm

Remove the bolt attaching the rear link bar at the rear 

Remove the nut from the bottom of the shock 

With a jack to support the rear of the trailing arm remove the bolt holding the shock to the trailing arm.

The trailing arm can now pivot on the front pivot bolt until the rear of the trailing arm touches the ground.

Now move to the front and support it with a jack, be very careful, When you remove the pivot bolt the jack might slip and the arm can crash down and crush your hands. Use stout wooden blocks to give support if the jack does slip. Remove the nut from the pivot pin and then the pivot pin. Mine had 3 washers inside the bracket on the chassis, two of them are needed for the reinstallation. Note that the kit comes with 2 replacement nuts for the pivot bolts.

Remove the old arm and the pieces of U bolt from the top of the axle. Not that there is a “Pin” on the bottom of the axle that fits into a hole in the plate for the U Bolts to locate the axle. The new arm also has a hole for this pin and the new arm needs to be aligned to get the pin properly in the hole so don’t tighten bolts fully until this alignment has been achieved.

With the new arm in approximate alignment under the MH and with blocks under it to allow a jack to get in, jack up the rear of the arm and get the bottom shock bolt thru the lugs on the arm. Put the nut on by hand just to keep the bolt in place.

Slip the U bolts over the top of the axle taking care not to trap the wire on the front side of the axle. Let the bolts hang down then move the jack forward to the back of the plate the U bolts go thru. The arm can then be jacked up so the u bolts can go thru the holes in the plate and the nuts run on by hand. This is just to hold the arm up safely, the nuts will have to be removed again and the lower plate will have to be installed before completion.

Move the jack all the way to the front of the arm and jack the arm up so the pivot bolt can be inserted. Take 2 of the washers that were on the old arm and put 1 each side between the lug on the chassis and the new pivot bearing. This is harder than it looks, we used a piece of flat bar about 3” long to push the washer up and stop it rolling out all the time. 

With the new nut on the pivot pin in place but not tightened up, go back to the U bolt plate. There is a lower plate that has a ramp built in, the highest part of the ramp facing towards the front of the RV. Put the nuts and washers back on and hand tighten.

The u bolts and the bottom plate.
Note that the top and bottom plates are parallel if the ramp is to the front of the vehicle.

Move to the back of the arm again and attach the rear link bar checking as you do so that the pin in the axle is in the hole in the top u bolt plate. There will be no gap between the bottom of the axle and the top of the u bolt plate and the arm will be square to the axle not cocked to one side of the other if its correct.

Now its time to tighten up all the bolts using a BIG impact wrench watching as you go that the pin on the axle stays in the hole in the u bolt plate. It takes a BIG torque wrench to get the u bolt nuts up to 350ft/lbs.

Double check that all the bolts have been tightened and everything is lined up.