Chassis differences

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Chassis differences

Postby Richie O » Sun Jun 07, 2009 8:38 pm

I stole this from another site. It was posted by MYSTERYMAN on TDR. I tought this might be useful.


1st gen frame repairs and swaps

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The frames from 72 threw 93 are basically the same at a glance but quite different if you look closely..

The 8" (some were 7.5") frame was used on all the cab/chassis models. It was also used on all the 1 ton pickups and select 3/4 ton trucks..

Most of the 3/4 ton and all of the half ton's used the smaller 6" center frame.

The 1st gen diesels 89,90,91.0 250, 3/4 ton used used the 6" frame but it was a bit heavier than the earlier gas version. You could order the 8" frame
if desired but most were called single wheel 350's rather than 250's

89,90,91.0 350, 1 tons used the taller 7.5 " to 8" frame. The 8" was a bit heavier than the earlier gas version..

In 91.5 the 8" frame was updated and is heavier than all the rest that came before it... This is hard to see with the naked eye. But quite obvious on the blueprints. It was updated and the 6" frame was discontinued due to breakage problems... in conclusion.....
All 91.5, 92 and 93's 250's and 350 diesels used the SAME frame ...

The exceptions.....2wd verses 4wd....The frames are the same except for the front cross member's and spring hangers....

Converting a 2wd frame to a 4wd frame is rather easy assuming that you have the 4wd engine cross member and 4 spring hangers...


Converting a 4wd frame to a 2wd frame is a whole lot of work !!!!! You have
to change the front cross member and the engine cross member.. Weld in the motor mounts. Mount the upper control arm brackets.... None of the holes will be pre drilled for you. You will have to drill them all yourself.. The tolerance for these holes is .125 (1/8") on center .. If you miss the mark you may never get it to take a front end alignment or track properly...
I would not recommend doing a 4wd to 2wd frame conversion to a novice
or back yard mechanic..

One last note..... If you need to replace an 89,90 or 91.0 6" 250 diesel frame. And if you can not locate a diesel frame.. You can use an early 7.5" 300 gas frame.. All the holes will line up for the most part...

Be sure to measure the wheelbase of the doner frame you buy...
Trucks that were sold as "cab/chassis" have longer frames than Pickup trucks.

And dually rear axles out of "cab/chassis" trucks are NARROWER than the dually rears out of pickup trucks..

Dually rears out of "cab/chassis" CAN be used in most cases in single wheel pickup trucks.. You may need to change the gears to get highway speeds with the diesel.. 3.55 to 1 ratio is the best choice for all around use when using stock size tires.

I hope this answers all the frame questions
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Re: Chassis differences

Postby BobS » Tue Jun 09, 2009 3:51 am

Richie O wrote:I stole this from another site. It was posted by MYSTERYMAN on TDR. I tought this might be useful.


1st gen frame repairs and swaps

--------------------------------------------------------------------------------

The frames from 72 threw 93 are basically the same at a glance but quite different if you look closely..

The 1st gen diesels 89,90,91.0 250, 3/4 ton used used the 6" frame but it was a bit heavier than the earlier gas version. You could order the 8" frame
if desired but most were called single wheel 350's rather than 250's

In 91.5 the 8" frame was updated and is heavier than all the rest that came before it... This is hard to see with the naked eye. But quite obvious on the blueprints. It was updated and the 6" frame was discontinued due to breakage problems... in conclusion.....
All 91.5, 92 and 93's 250's and 350 diesels used the SAME frame ...



I hope this answers all the frame questions


For an accuracy clarification there are quite a few of us that have 91.5 intercooled trucks WITH the 6 inch frame. This was discussed a few months ago on DTR. 91.5's used the left over parts from the previous on hand stock so they are a mix of 90 through 92 components.
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Postby CE_TX » Wed Jun 10, 2009 9:07 am

Converting a 2wd frame to a 4wd frame is rather easy assuming that you have the 4wd engine cross member and 4 spring hangers...


What are the differences between the 2wd and 4wd engine crossmembers? Is it material, size, position or what??
1985 Dodge W350 Crew Cab with 1992 Cummins drivetrain---undergoing frame off restoration.
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Postby txs » Sat Jun 27, 2009 7:03 am

the 4x4 crossmember is much shorter front to back to clear the center section of the front axle and it doesn't have the a arm hangers. There ARE some 10" cab and chassis frames out there, I know a couple guys that have one. the shortest cab and chasis frame I've seen is 6-8" longer than the standard cab box bed frames.
93 w250 6 speed 4" exhaust, caution, work truck, she's no beauty. building 1 ton dually 4x4, dana 80, 48rh, 205 Scratch the one ton, bought frt. dually 4x4 98 12 valve with the tiny rear doors. rides so much better than the 93.
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Postby CE_TX » Tue Jun 30, 2009 4:20 pm

Thanks for the info!
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Postby Mad Max » Wed Aug 19, 2009 10:11 am

...so we're at the bone yard yesterday...and we compared my '93 diesel frame to that of a '90 150 and '92 250 gasser frame. I could not tell them apart - same height, width, girth, and thickness.

So, can anyone confirm or deny that the gasser frames from the '90-'93 are the same identical big thick and meaty frames that the diesels used? We checked several points up and down the frame - could not find anything that indicated one was a half-ton gasser and one was a diesel - they just looked and measured exactly the same. I had an extended cab W150 gasser right next to my '93 D250 diesel - no difference. Anyone?

Thanks,
- Sam
"...there's always a way".

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'85 W350 Crew "Big Mack"
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Postby meby » Wed Aug 19, 2009 12:18 pm

Mad Max wrote:Snip... I had an extended cab W150 gasser right next to my '93 D250 diesel - no difference. Anyone?

Thanks,
- Sam


I think that the cab chassis have thicker frames...the rest of them from what I hear are virtually the same.
-1991 D-250 bone stock
-2000 Ford Windstar TDI Diesel 5 spd
-1997 Civic Hatchback
-Case 530 CK
-Old Huskee Garden Tractor w/Cub Cadet deck, Simplicity Snow-blower, loaded tires & chains - is it weird the tractor is modded more than my truck?
-Speedex Walking Tractor.
-BCS Walking Tractor


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Front Spring Hanger Bolts Info

Postby BobS » Sat Sep 19, 2009 3:18 pm

Just an additional note that I found out about. The 92 & 93 front spring front hanger bolts were increased in size to 5/8" This means that 92 & 93 front springs have larger hole eyelets and do not directly interchange with the earlier springs. The 92 bracket hole size is 5/8" The rear shackle bolt in 89 - 93 is 1/2"
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86 D150 wannabe 4BT http://4btswaps.com/
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Postby Mark Nixon » Thu Oct 08, 2009 9:41 pm

Extended cabs are ALWAYS the taller, thicker frame, 1972 to 1993, without fail.
As are Crew Cabs.
Even the 1/2 tons E/Cs were.

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Postby stock91w350 » Wed Jan 20, 2010 1:47 pm

my 91 was a dumper and now it has a regular longbed on it but there is a huge gap between the cab and bed, wonder why? also did the duallys have the bed cut out under the dually fenders cause mine just looks like someone put on those dually fender over a regular bed and dident cut the extra bed out of the wheel well
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Postby KTA » Wed Jan 20, 2010 6:13 pm

Oh and as for a 2wd to 4wd conversion it is NOT straight forward. I looked at converting my Crew to a 4wd and none of the 4wd cross member holes or shock mount holes are drilled in the frame. That means EVERYTHING has to be located exactly and drilled. There is also no hole at the back for the rear shackle mounts for the back of the front leaf springs, so more holes to cut and drill. I do need to look and see if it has the same height frame as my 92 W350 159" wheelbase Chassis Cab. I suspect it does.
Fleet of Junk: 1989 D350 627rwhp 1300 tq B-1/Hx60 twins, KTA pump/injectors, ported head, BIG fuel supply. 13.75@ 109.5mph 1/4: 1992 W350 Cab-chasis, 1993 W350 ext cab cust.370 inj Hx40/16cm 290rwhp hydroboost brakes,1984 D350 crew-cab another project.
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Postby Mark Nixon » Thu Jan 21, 2010 7:33 pm

Interesting that you mention the rear holes for the front leaf springs....
I have seen, owned 1, trucks that actually have the rear center hole and bolt holes pre-drilled.
ALL of the trucks were standard cab '93 2wd trucks, mine was a gasser, but the others were diesels.

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Documented 2WD automatic to 4WD crew cab frame conversion

Postby BobS » Fri Jan 22, 2010 5:41 am

KTA wrote:Oh and as for a 2wd to 4wd conversion it is NOT straight forward. I looked at converting my Crew to a 4wd and none of the 4wd cross member holes or shock mount holes are drilled in the frame. That means EVERYTHING has to be located exactly and drilled. There is also no hole at the back for the rear shackle mounts for the back of the front leaf springs, so more holes to cut and drill. I do need to look and see if it has the same height frame as my 92 W350 159" wheelbase Chassis Cab. I suspect it does.


Documented '83 Crew cab2WD to 4WD Brackets & Spring Mount Locations:

I just did a 2WD to 4WD crew cab frame conversion. I CHEATED on the measurements. I initially removed all of the cab frame brackets because 3 0f the 4 were broken. No surprise there. I ordered grade 5 washers from www.Mcmaster.com that were slightly larger than the original hole size and welded them to the top side of the brackets.

The front spring hangers are located by using the original predrilled factory holes located just behind the bumper bracket mounting holes.They share an identical frame mounting pattern with the bumper brackets and in my case the rear cab mount frame bracket mounting holes. This keeps the front axle located in the proper location in the frame. When I started to measure the dimensions from the cab frame to the front spring rear hanger location the measurements differed by almost a quarter inch between the left and right sides. The rear bracket location for the front spring is not apparently as critical as it first appears and is demonstrated by the tolerance that was acceptable on the 1992 donor frame. At this point I decided to use the original 4WD frame sections as a donor for making frame templates. I whacked the 4WD frame BEHIND the cab body mounting brackets and using a torch removed the the flat upper and lower sections leaving only the flat vertical faces of the frame. Then I ground the slag and wire wheeled the surface rust before bolting the new templates to the 2WD frame by using two of the cab bracket mounts and the front bumper bracket bolt holes.
Image

At first you need to get all of the bolts in where they are loose. Then in the transfer areas for the location of the new hole you need to use bolts to draw the template to the 2WD frame. In the shock mounting area there are two larger holes that will accept a 3/4 or 7/8 inch bolt with washers. The trick is to draw the template in close by tightening the center most bolts outward to the end portions of the bumper end and the cab end. There will be gaps because you are clamping outside radiuses to inside radiuses between the frame and template. Template bolted to the 2WD frame to locate engine crossmember mounting holes:
Image

The actual large holes for the brackets are easily drilled using a high quality bi-metal hole saw.
Image

The holes may require a small bit of tweaking using a high quality round file. The original holes are oval shaped but are located by placing the hole saw in the cab end of the oval and drilling through. Mine worked out perfectly with just a bit of deburring required using a round file.
Image

I also used a 7/16 inch transfer punch and a 7/16 inch drill bit to transfer the mounting rivet holes for the rear spring bracket and the engine crossmember. I replaced the all the rivets with grade 8 7/16" bolts and grade 5 hardened washers in conjunction with self locking nuts. There was one hole on each side of the 2WD frame that was touching one of the new holes for the new shock bracket mounting holes that I welded up on each side of the 2WD frame. This hole is the rearmost rivet hole that goes through the 2WD inner and outer mounting brackets on the frame. The other option would be to mount the bracket and add a third hole by drilling through both parts.

On the front spring hanger bracket mounting brackets there was an 1/16 inch gap between the hanger and frame because of the very slight differences between the crew frame and the 92 frame. I simply made shims that that were drilled for the hanger bolts to pass through which keep the shims in place. For me this was the easiest method for locating the new holes.
Image

Transmission crossmember brackets and mounting; 2WD automatic to 5 speed 4WD:

Also if not already noted the 4WD passenger side upper crossmember mounting bracket brace has a relief formed for exhaust pipe clearance that the earlier gasser may not have. Since I went from a 2WD automatic to 4WD 5 speed the transmission crossmember needed relocating. Again I cheated by setting the engine and transmission assembly in the frame and used the mounts to locate. What I found was there was only two of the original holes (1 0n each side) lined up. The other 2WD hole is circled in this picture. This is looking at the passenger side of the frame. F=front of frame. I mounted the crossmember using those holes and then used the crossmember as a template to the new holes using the same method mentioned earlier.
Image

Then you end up with the new circled holes for the 4WD crossmember and upper frame brace:
Image

Then I removed the engine & trans assembly and mounted the upper frame brackets to the center section of the crossmember. Then I staggered two new upper bracket holes by drilling through the frame and upper bracket for one hole and just drilling through the remaining hole that already lined up in the frame with the bracket below. Everything now fits exactly as it was in the 1992 frame. Note the exhaust pipe relief that is visible in the upper support brace for the 4WD transmission crossmember in the final picture.
Image

And as a side note, ALL of my metal cutting tools were made by Morse which held up quite well compared to Wallymart or the Harbor tools.
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91.5 W250 NV4500 Conversion
89 D350 Stock
92 W250 Crew Cab finally in progress
86 D150 wannabe 4BT http://4btswaps.com/
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Re: Chassis differences

Postby Mark Nixon » Sat May 15, 2010 8:45 pm

Subject: 2wd LOWER control arms- 1 ton and 3/4.

The Hollander calls out '90.5 (January 2 and later) and up lower control arms as being different from the earlier years and I could not for the life of me figure out WHY.
Dimensionally in thickness, length, shape, bushing hole sizes, center-to-center on the bushing in relation to the balljoint center, ALL of this is the same and I had given up trying to figure it out.

To-day, it slapped me in the face.

While removing the strut, or radius rod, from a '93 3/4 ton frame (needed the lower control arms) I realized that the bolts were 7/8" nut, 13/16" bolt/ head, with a 9/16" bolt shank.
The earlier version (pre-Janaury 2, 1990) is 3/4"-3/4"-1/2".

So, in short if you have the later (post January 1, 1990) lower control arms, you SHOULD use the strut/radius rod to correspond to it.

Mark.
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Re: Chassis differences

Postby BREEZE1 » Mon Oct 04, 2010 6:52 pm

so the dualy axle on my cab/chassis truck is the same width as the axle that come out of a d250?

I measured the dually axle on my cab / chassis truck and from bolting surface to bolting surface its 67.50" So now I need to find out what the standard width single wheel axle is. I did get a chance to measure the hub on both dually and single rear axle and they are the same at 4.75" (note I measured with a tape not calipers)
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