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#846 Cummins Swap.
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LCAC_Man
Posted 2018-12-13 1:02 PM (#6116 - in reply to #6035)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001001001002525
Location: Oceanside, CA
How about an update...surely you've wired brushed a few bolts in the past 20days!
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andy1canada
Posted 2018-12-13 7:45 PM (#6117 - in reply to #6035)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001002525
Location: Victoria, BC. Canada
Hey,

Too busy. I know it sucks but that's the way it is. Construction is stupid busy up here these days.

Been doing quite a bit of framing lately and - besides killing me at my age - it gets me home late and tired.

Tied up all last weekend, too, up in Tofino visiting family. Great time; went easy on the booze for a change :-)

Should get to some stuff this weekend. Got my crane scale and am going to take the rear bumper apart after I weigh it to see what each piece actually weighs (the stainless vs the monster steel plate behemoth backing it up). I'm hopeful there'll be an opportunity to shave 50 lbs or more off the entire structure. Some of the class-3 (5000/lb) hitches I've been looking at are in the 40 lb range without the ball/mount.

50 lbs may not seem like much but when you consider where it's coming off of, its' huge. Now that I have a reasonably accurate scale that can weigh up to 660 lbs, I hope to make a useful record of areas where significant weight can be shaved off these coaches posterior.

Mark my words: the extra 400 lbs the 12-valve brings to the table - is going to disappear at a modest expense!

Terry
#846

Edited by andy1canada 2018-12-13 7:46 PM
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andy1canada
Posted 2018-12-15 9:48 PM (#6120 - in reply to #6035)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001002525
Location: Victoria, BC. Canada
Hey,

Finally got around to weighing the bumper assembly on #846: the SS bumper with the 1/4" plate backing assembly and tow-ball mount weighs in at - 154 lbs. Wow!

Mine is the heavy reinforced type for towing. I'll post a pic of it tomorrow along with the individual weights of the stainless part & plate steel part once I separate them. I've estimated the SS bumper portion (@ approx 9 sq/ft) to weigh about 80 lbs or less (3/16" SS plate = 8.5 lbs per sq/ft). We'll see.

My vote is that this is serious overkill on rear structure weight. I will look to halving-it while maintaining a 3500 - 5000/lb towing standard; however, if I allow a generous 40 to 50 lb allowance for a decent Class III hitch assembly to replace the 1/4" plate Goliath, it's looking less likely that I will realize a substantial/useful reduction for the time & money spent.

Hopefully my new crane-scale will tell me the stock (dry) FMC radiator & support assembly will weigh in at 500 lbs or so and shed new light on Terry's whack-O weight-reduction program fiasco! ;-0

Terry
#846
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LCAC_Man
Posted 2018-12-16 7:04 AM (#6121 - in reply to #6120)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001001001002525
Location: Oceanside, CA
The stock radiator/mounting is heavy, but I picked it up and loaded it in my Grand Cherokee to take to the shop for reconditioning on my own...I eat my Wheaties but I'd have left my spine in the driveway if it were more than 200lbs..
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BigRabbitMan
Posted 2018-12-16 8:47 AM (#6122 - in reply to #6035)
Subject: Re: #846 Cummins Swap.



Expert

1000100100
Location: Cottage Grove, OR
I initially installed an aluminum Ford radiator for a 550 powerstroke. I then replaced that with the stock radiator. Also upgraded the fan at that point. Couldn’t tell any difference in handling.
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byegorge
Posted 2018-12-17 1:53 AM (#6124 - in reply to #6035)
Subject: Re: #846 Cummins Swap.


Veteran

1002525
Location: Olympia, Washington
Stephen:

What up-grades if any have you done to 1046's rear suspension?
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BigRabbitMan
Posted 2018-12-17 10:46 AM (#6125 - in reply to #6035)
Subject: Re: #846 Cummins Swap.



Expert

1000100100
Location: Cottage Grove, OR
None to this point.
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LCAC_Man
Posted 2018-12-17 10:51 AM (#6126 - in reply to #6125)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001001001002525
Location: Oceanside, CA
Did you ever mount those steel weight plates you got from me?
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BigRabbitMan
Posted 2018-12-17 12:42 PM (#6127 - in reply to #6126)
Subject: Re: #846 Cummins Swap.



Expert

1000100100
Location: Cottage Grove, OR
LCAC_Man - 2018-12-17 8:51 AM Did you ever mount those steel weight plates you got from me?


Yes, they are behind the front bumper. At this point I have traveled 48,000 miles with my coach since I completed the engine/transmission change. Most of it has been in the 60-65 mph range, but last summer I have cruised at 75 mph in states where allowed and did cruise across ID on I-84 at the legal speed of 80 mph as was wanting to get to a certain place that day.

As I have discussed with Terry, only consider an engine change if you are going to drive it significant miles. I have done so and I believe Terry will as well.
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andy1canada
Posted 2018-12-19 7:10 PM (#6128 - in reply to #6035)
Subject: RE: #846 Cummins Swap.


Elite Veteran

5001002525
Location: Victoria, BC. Canada
Few more pics up as I played with the bumper a bit today. Home nursing a sore ankle for the last couple of days so... why not mess around with a 154-lb bumper?

http://www.fmcowners.com/mbbs22/photos/photo-thumbnails.asp?albumid...

Got the assembly apart finally. Was hoping the iron section would better 100 lbs of the 154 lb total weight of the structure; but it didn't.

The iron part came in at 93 lbs. according to my cool little crane-scale.

https://www.amazon.ca/Klau-Industrial-Digital-Hanging-Factory/dp/B01...

After some deliberation I've decided that I'll nix the 5000 lb towing capacity in favor of the 3500 lb setup. It'll suffice for all I'd be needing to tow - including a toad.

If I can replace that iron section with a 3500/lb towing hitch that comes in at close to 50 lbs less than the current weight, I'll probably bite and do it. I've seen production 3500 lb hitch kits in the 40 lb range without the ball & mount.

Losing 50 lbs or so - at the rearmost extreme of the coach - is significant I think.

Courting the 'butt-sag' remedy...

Terry
#846

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andy1canada
Posted 2018-12-19 7:43 PM (#6129 - in reply to #6035)
Subject: RE: #846 Cummins Swap.


Elite Veteran

5001002525
Location: Victoria, BC. Canada
Just saw this as an example of what can be welded up to handle 3500 lbs.

https://www.curtmfg.com/part/13536

This little sucker only weighs in at 25 lbs without the ball & mount.

Me thinks knocking off 50 lbs from #846's extreme arse-end is looking more doable.

Terry
#846

Edited by andy1canada 2018-12-19 7:45 PM
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LCAC_Man
Posted 2018-12-20 7:40 AM (#6130 - in reply to #6129)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001001001002525
Location: Oceanside, CA
Quite a bit of fabrication required to adapt it to the frame end connections and then how the bumper will be attached will be another bit of work. You'll have a bunch of hours in it..
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andy1canada
Posted 2018-12-20 8:22 AM (#6131 - in reply to #6035)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001002525
Location: Victoria, BC. Canada
I'm asking what structural component the SS section brings to the equation?

It appears FMC dismissed that contribution, then way overbuilt the iron frame section. I'd bet that plate steel section would suffice to tow 15 - 20/K with a 1000 lb hitch weight; indeed, a job the FMC was never designed, or, intended to do.

I will look to use whatever structural integrity the SS section brings to the table to perhaps lessen the amount of iron needed to fashion a much lighter, DOT certifiable, 3500 lb towing set up with a 2" receiver.

I'm fortunate that I have a good career welder guy to advise me on this that has built countless trailers.

Also considering pulling a 'Chip Foose' and sucking that rear bumper inward a couple of inches or so closer to the coach. Some of you may have noticed that there's actually already a matching molded profile indented in the fiberglass at each rear corner of the coach that nearly matches the bumper footprint. Seems a natural cosmetic improvement to me.

The ladder would also have to moved forward to keep it plumb.

Terry
#846

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hemi354az
Posted 2018-12-20 10:08 AM (#6132 - in reply to #6131)
Subject: Re: #846 Cummins Swap.


Extreme Veteran

500
Location: Scottsdale, Aridzona
Are you still going to put a Cummins Diesel and Allison Tranny in it ?
Lou #120
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BigRabbitMan
Posted 2018-12-20 10:10 AM (#6133 - in reply to #6035)
Subject: Re: #846 Cummins Swap.



Expert

1000100100
Location: Cottage Grove, OR
I don’t think the SS bumper brings as much stiffening as you think. The end of mine bent rather easily! You are thinking that all of that steel is for a hitch. As Len mentioned earlier, it is my feeling that it is also there to stiffen up and tie together the ends of the frame members. By anchoring the ends of the frame members, that helps stop frame flex due to torque loads. And you will be increasing the torque loads.

I would put the dollars you will be investing into the hitch into putting air bags on the coach while the engine is out. Much more benefit for the dollars and hours.
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andy1canada
Posted 2018-12-20 11:12 AM (#6134 - in reply to #6132)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001002525
Location: Victoria, BC. Canada
96' 12-valve/47RE (stubby version).

Terry
#846
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LCAC_Man
Posted 2018-12-20 11:12 AM (#6135 - in reply to #6133)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001001001002525
Location: Oceanside, CA
You might be able to get away with the much lighter duty structure in the bumper/hitch area if you make up for it in the engine crossmember structure...but...that means all new structure there..
I'm with Stephen, that bumper is decorative and requires as much to hold it up as it provides in strength...it's a net-zero in my book..
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andy1canada
Posted 2018-12-20 11:20 AM (#6136 - in reply to #6035)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001002525
Location: Victoria, BC. Canada
I was referring to the area between the frame rails its attached to; not what's unsupported outboard - flying in the breeze.

By 'net-zero' do you mean that if that bumper was laying across two saw horses supporting it at the same positions that the frame rails do, that you could place 'zero' weight on it, expecting it to support it? I'd hazard it'd support a few hundred pounds before folding up. Now, a sudden impact of 'X' pounds changes everything. I get that part.

I'm implying that the way the 3/16" stainless bumper is rolled and creased adds great strength to it. That's simple sheet metal physics. No?

Terry
#846
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LCAC_Man
Posted 2018-12-20 11:49 AM (#6137 - in reply to #6136)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001001001002525
Location: Oceanside, CA
The form adds considerable rigidity (compared to flat plate of the same dimensions) which is great for holding it's own form but it shouldn't be mistaken for "strength"...in the end it's just a piece of chrome plated 1/8" thick stainless (plating gives a small amount of extra thickness but it's certainly not 3/16". My point about "net-zero" is the amount of force required to deflect one of the frame rail ends(with nothing attaching them) would be, lets say 400lbs, the force required with just the bumper attaching them would (IMHO) be no more than the weight of the bumper itself added to that 400lbs which means the frame rail is task with holding up the weight of the bumper but only gains that amount in strength...net-zero. The forming of the bumper isn't such as it resist much of any twisting force and it flexes in those planes very easily..
I think you are focused on it just being a hitch structure, I can tell you for sure that the frame rails without it (or with something less) are going to flex even more than they do now. You could reproduce a similar (to the original) in 3/8" aluminum (if your friend has an AC tig machine) and get both the strength and the weight reduction...but that would come at a cost.
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andy1canada
Posted 2018-12-20 12:00 PM (#6138 - in reply to #6035)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001002525
Location: Victoria, BC. Canada
You're right again Len: I just measured the bumper in 4 places (with a vernier) and averaged it to approx .185 thou. So, I'm 2-thou under 3/16".

I guess I'm keeping my eye's open for a good deal on aluminum then... :-0

Terry
#846
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ricogomez
Posted 2018-12-20 12:08 PM (#6139 - in reply to #6035)
Subject: RE: #846 Cummins Swap.


Veteran

100252525
Location: Houston, Texas
When we first crank our Cummins we didn't have the brace
that runs across the bottom and bolts the two engine mounting plates
on the frame, therefore the driver mounting plate side was shaking
like a chicken at KFC, that's how we find out how much the brace was
needed, we had no idea.....(shade tree mechanic)



Rico & carmen
397
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hemi354az
Posted 2018-12-20 12:36 PM (#6140 - in reply to #6139)
Subject: Re: #846 Cummins Swap.


Extreme Veteran

500
Location: Scottsdale, Aridzona
The stiffness of a welded/bolted box frame structure never increases if part of it is removed . . . (palm tree mechanic).
Lou #120
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BigRabbitMan
Posted 2018-12-20 1:32 PM (#6141 - in reply to #6139)
Subject: RE: #846 Cummins Swap.



Expert

1000100100
Location: Cottage Grove, OR
ricogomez - 2018-12-20 10:08 AM ….. therefore the driver mounting plate side was shaking like a chicken at KFC, that's how we find out how much the brace was needed, we had no idea.....(shade tree mechanic) Rico & carmen 397

Rico, I love the description! But it does point out the importance of the connectors (ALL of them) between the two rails that support the engine. There is dead weight and then dynamic forces.

You have a lot of bigger fish to fry than the bumper when it comes to putting the Cummins into the coach. I would forget about the bumper and focus on getting the engine and tranny into the coach. One inch forward or rearward will make more difference than the bumper will. If you still want to fool with the bumper, do it during reassembly after all else is done. It is the LAST piece of the puzzle, not the first piece.
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andy1canada
Posted 2018-12-20 2:25 PM (#6142 - in reply to #6035)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001002525
Location: Victoria, BC. Canada
Ha-ha! Too funny, Rico! Glad you got it done regardless.

Maybe in another five or six years - when I finally get this motor swap done - we can meet at a rally in Boot-Fook, Idaho and have a coupla' Corona's while we talk about all the things we could'a & should'a done.

Till then, I'll keep picking away at it.

Terry
#846



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LCAC_Man
Posted 2018-12-20 6:07 PM (#6143 - in reply to #6035)
Subject: Re: #846 Cummins Swap.


Elite Veteran

5001001001002525
Location: Oceanside, CA
Because I was curious I went out with a caliper and checked my bumper,it was a little thicker than I thought, it is actually 5/32" (.160" thick) may have been some differences in year models/bumper vendors.
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