cross member build

Cummins Conversion & Builds

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cross member build

Postby jethro » Tue Dec 02, 2014 11:03 pm

Today I stopped at the steel place and got a 5 foot section of 4 inch square tube (3/16 wall) to make a new transmission cross member out of. I am planning on cutting it up with the chop saw at slight angles and welding the joints back together to make the up and down jogs where the exhaust pipe goes over and the upward hump in the middle.
Do yall think that tube material will be heavy enough for the zf-6 's weight ? (F-350 ford)

I have 2 ways to hook it to frame.
1. Like the factory did- both sides of the member go in from the drivers side. This means one side sits inside the frame and the other side sits outside the frame. not completely clear why THEY did it that way........ unless it was somehow easier to fit.... (?)

2. I can just have flat plates on the outside of the frame which hang down 4 inches below the frame- and those downward hanging stubs get welded to the ends of the square tubing. Have to get the length JUST RIGHT for a tight fit- but I should be able to do that. This means that the box tubing is effectively riding on the bottom edge of the frame in terms of ground clearance....... If I did it the first way- the tube would be INSIDE the frame and not really hang down that additional 4 inches..... would that be a good reason to do it the first way ? ( I am thinking - YES- now........ )

Thoughts...... ?
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Re: cross member build

Postby ellis93 » Wed Dec 03, 2014 6:43 am

IMHO your over killing it with that tubing. All you need is a piece of 4" flat bar and a piece of 1". The square tube will be brick schit house tough but my god at the room taken up. That trans is not really that heavy.....don't believe me,look at what ford threw under it! :lol:
Is this what your dealing with?
Image

Image
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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Re: cross member build

Postby jethro » Wed Dec 03, 2014 7:11 pm

That looks like the same basic type of piece - except there is another short piece on one end......

If you know me you would know Im an overkilling kind of guy- (overkill is under-rated)

I believe the trans is 400 pounds- and there will be some more weight as this mount becomes the third contact point
for the whole engine/transmission combination. The engine and clutch-flywheel is probably 1200-1300 lbs. easily 1/4 of that
could bear on the rear mount. so there is 700 lbs...... then you consider the G-loading of going off a curb holding 700 lbs...

I don't mind strong if I can get it up under there neatly...... but most of all I want the freedom to put it where ever it needs to go (front to back) . I don't think I will know where that is till I get the engine in and the transmission joined to it...... to see how far back the whole rig needs to go.....

Tim
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Re: cross member build

Postby ellis93 » Wed Dec 03, 2014 7:25 pm

Well it's definitely your decision to make,I like to over kill on things too.....but ease of removal in the future/looks are two of my factors as well.
My point in showing that was that oem piece holds fine with zero issues,with the same weight.....nearly :lol:
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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Re: cross member build

Postby jethro » Wed Dec 03, 2014 11:55 pm

Yes..... the ford stamping- even though it doesn't weight that much- due to the compound curves and the work hardening and stresses of being a deep draw stamping - that sucker is STRONG ! I don't have any of those advantages on my side so I will have to make up for it in other ways. They had a small I beam that would have worked but I think it would have been susceptible to wiggle front to back. The 4 inch tube is not as heavy as it sounds. I think I can fit it inside the frame too.
It is pretty easy for me to build stuff like that- so it will take a little time - but it wont be hard. This whole truck project seems
to be evolving into making the truck the way I wished ford had made it in the first place !
I am even cleaning and painting the frame rails and all the suspension parts. Ford just lets all that rust. If you are paying 60K$ for a king ranch F-350- they should paint the chassis with amerflint polyurethane and make the body stainless steel.
Ford had a GOOD product in the 60's and early 70's- they didn't change it much for about 15 years. They just about got most of the bugs out of it during that time. Then in 86 when the first fuel injection hit- well - it might as well have been a Russian Zill. :bom:

If I could get dropbox to work here I could post pics !

t

Tim
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