Welding help

[Adam Hicklin]

Hi all.  I'm new to the BAC but have followed the forum since buying a new to me 1998 Marquis in December.  I need some guidance.  I need to do some welding on the rear hydraulic jack mounts.  I know I should disconnect the batteries, the engine ECM and the transmission ECM.  I think I have located both ECM's (engine- passenger side of engine.  Trans- electrical bay mounted to top of bay by the light)  Is there any procedure to follow to unplug them and replug them when I'm done?  Anything else I should know but not smart enough to ask?  Any input would be appreciated.  

1998 Marquis Diamanté
C12
Alison 4060

Adam H.

[William Brosam]

Adam what are you welding on the jack mount? the bottom jack pad?

you should isolate the hydralic motor the current if you can get to it so you dont fry the motor/control board through the hydralic system. this is probably overkill trying to be safe.

[Adam Hicklin]

The rear jack is "boxed" in 1/4 inch steel plate.  The back  plate attaches to an extension that comes off the frame rail.  This back mounting plate has a bend in it so when the jack extends, it catches the body panel.  The plan is to attempt to bend it back, the beef it up with some gussets.  It seems next to impossible to actually cut it out and put on a new backing plate.  Also going to beef up the ther side while we're at it.  They seem a little under-supported.  

I plan on disconnecting as much as I can electrically.  You're right, you can't be over cautious. This Beaver is a great coach, but I'm finding out that when things go wrong, it usually is in a spectacularly expensive fashion!

Thanks for your input.  Any others?

[William Brosam]

Prep work is most important, cover up any areas that will melt with hot falling materials you know the average stuff we forget with welder in hand. wondering what that smell is whats burning...

[Steve Huber Co-Admin]

Adam,
I had a similar problem on mine few years go. The base plate that the left rear jack nested in when extended was cracked. I was able to obtain a replacement from BSC (then Monaco). They should have a few in stock as they had to purchase the OEM inventory to get one for me. I've attached a picture as yours may be different.
Steve

[Adam Hicklin]

Steve, mine is very different.  I'll try to post a pic. tomorrow.  Yours looks quite a bit more substantial.  Yours also looks like some thought went in to it.  Mine looks more fabricated on the spot as an after thought.  Other than the jack itself, nothing appears to be a "part" which can be ordered. In fact, they are significantly different from left side to right side.

[Gerald Farris]

Adam,
The first 25 or so '98 Marquis coaches were built on a Gillig chassis, then production was changed to the Magnum chassis. The first of the '98 Marquis coaches that were built on a Magnum chassis had to have some of the jacks moved (I think only the front jacks) after the coaches were built and sold, because the original jack placement was causing windshield failures. This movement of the jack location and welding was usually done at an RV dealer, were the highest quality welding practices were not maintained. So your jack problems were probably caused by repairs that were made after the coach was built.

Gerald  

[Adam Hicklin]

Thanks Gerald.  This is on a Magnum chassis. These are the rear jacks and appear to be original.  I emailed Ken at BCS to pick his brain and he didn't indicate that it may be an aftermarket situation.  These rear jacks float (slight movement side to side) and extend at an angle.  It seems that they are prone to slipping, especially if they come down on blocks.  Speaking of windshield failure, the windshield was popped out of the gasket in the lower passenger corner.  I had it repaired.  I understand that it is from frame twist.  Is this common?  Under what conditions would this happen?  Best ways to avoid?  Thanks for your help.  

[Gerald Farris]

Adam,
If your front jacks are behind the front wheels, that is the proper location. However, if they are located on the frame rails in front of the front wheels, that is the location that causes the most frame twist and windshield failures. I know of one coach that broke three windshields in less than 6 months before moving the jacks to the location behind the front wheels.

The best way to avoid windshield failures from frame twist is to park on as level a surface as possible so that the jacks do not twist the frame when leveling the coach. Several coach owners have added air leveling to their coach to avoid this problem since air leveling uses the air suspension to level the coach, and therefore twist the frame much less.

Gerald

[Adam Hicklin]

Interesting.  Yes, my front levelers are on the frame rails at the very font of the coach, in front of the front wheels.  This coach is equipped with air leveling also.  That sound like it is the better alternative.  Thanks for your input Gerald.  I appreciate your knowledge and advice.

[Joel Ashley]

Adam

Even with the use of air leveling, you can twist the body.  The front cap can flex enough that the stiff, unflexing windshield can pop loose of its rubber seat.  Worse case scenario is if the glass cracks under the stress... been there, done that... slowly, as the coach was parked next to the house, stored for 3 months.  Your two piece windshield is less susceptible, though, than our one piece.

I releveled the gravel pad as it was low at the left rear, and it turned out the factory incorrectly installed the glass in the first place;  no stress problems since the repair.  But one thing I check, even when on campsites that look level, is the gaps around the closed bay doors after parking;  if they are very unequal or not straight and square, that is a sign of body twist that needs adjusting.

You can't rely on the air not to gradually seep out of the bag system, so when long-term stored try to be sure most air is dumped and that one corner tire isn't much higher or lower than the rest.  It's okay if one entire coach end is higher than the other, as long as one corner isn't out of whack.

Joel

[Adam Hicklin]

Joel, I'll be doing some work on my parking pad over the next couple of weeks.  I can get it perfectly level so, at least, I won't have to worry about it at home.  We'll be taking it out for the first extended trip the first week of April (by extended I mean 4 or 5 days)  So far we have just taken it places to be worked on!  I'll be creating another post asking some general questions, and look forward to your input.

[Joel Ashley]

There is no real negative to a perfectly level pad if that's what you'd prefer.  

But one advantage to my "pad" being a few inches lower at one end is that, even though our roofs are domed, water will run off better with the back of the coach slightly downhill.  Its not so far off as to affect the fridge when we start it up before loading for a trip.  Water has less chance to puddle somewhere around a roof component, and find its way in during long term storage.  It's a tad easier to rinse the roof too when washing it, working from front to back.  So take that into consideration if you have an easily tweaked pad like my gravel one.

If, however, you are creating a concrete pad, you may not want to be quite so far off level, except just enough gradient to keep standing water off the pad itself.

Joel

[Gerald Farris]

Adam,
If your coach has both air and hydraulic leveling (probably HWH), the air leveling is a far superior system when considering frame twist. Also the issue that Joel mentioned about the air leaking down over time is not a concern, because your air leveling system is equipped with a 12V electric air compressor that will turn on when needed to maintain the proper suspension height to keep the coach level. I believe that the air leveling system turns on every 30 minutes to check the level of the coach, and readjusts it if necessary.

On some coaches, the non-sealed compressor was installed in an area where it could be damaged by the elements (water and dirt), so if your compressor is not working, contact me and I will tell you a cost effective and permanent cure.  

Gerald      

[Joel Ashley]

Gerald,

I was going to mention the auxilliary compressor, but in the case of parking the coach for long term storage, a person is likely to have turned off the master battery switches so the compressor couldn't come on.  Additionally, it only works if you let the system level itself automatically;  if one opts to control leveling from the pad manually, the automatic air rejuvenation by the compressor isn't functional.  

That situation (switches off) was contributory to my cracked windshield.  For the reasons in this and prior posts, I now guide my air leveling system use according to the specifics of each individual parking circumstance.  Plus, as you referenced, the compressor can be unreliable.  Rather than complicate my advice to Adam, I opted to leave out any reference to the compressor, but perhaps shouldn't have.

Joel