: '73-'90 Chevy 1 ton dually, Help needed please



jim in n.y.
12-27-2009, 08:10 PM
I would like to someday build a '73-'90 Chevy 1 ton dually with a 4-53 Silver in it. I want a 2wd truck that I'm thinking of swapping the IFS for a dropped I beam, 8 lug axle out of a mid '90's Chevy bread van. This would be for oil pan clearance and be able to close the hood over a factory Silver valve cover.
My questions are these:
Can anyone out there with a '73-'90 Chevy dually 2wd , measure the track width ( center to center )on the front wheels ? Also, the distance from wheel mounting surface to mounting surface? And finally the width of the front springs and their center to center distances. These last two dimensions would of course be from a 4wd truck. The chevy Duallies should be the same ,as far as I can tell , from '73-'90.
Grigg has been helping me with the dimensions from an 8 lug axle from a bread van. All I need to do is compare these dimensions to the 1 ton dually to see how much work it would be to swap everything over.
Thanks in advance, Jim.

2tons of fun
12-27-2009, 10:41 PM
ill get it for you tommorrow.

Grigg
12-28-2009, 12:07 PM
Just checked again, looks like the 8 lug I-beam front is closer to 82" from Wheel Mounting Surface to WMS. This is still not an exact measurement.

Spring centers are 32" apart and came with 2.5" wide springs.

Grigg

Octamog
12-28-2009, 03:19 PM
There's a ton of info available on most of GM truck models in the upfitters guide online.

It may not have everything you need, but a great place to start and a great reference.

http://www.gmupfitter.com/body_builder_manuals.html

jim in n.y.
12-28-2009, 05:10 PM
Thanks guys,
2 Tons... I look forward to your help.
The axle I'm looking at is an 8 lug off a '96 Chevy bread van. The seller says that the wheel mounting surfaces are 74'' apart, the springs are 2-1/2'' wide and 32'' apart center pin to center pin. He also says it will NOT fit a 3500 HD. Don't know why . Maybe 10 lug? I'll have to ask. He runs a Chevy only dismantling yard and seems to know his stuff. Maybe because it might still share some dimensions from the earlier '73-'90 chassis ? I do know there was a difference in spring mounting.... or the frame , between the '90 models and the '91& up. Can't remember exactly what. King Nothing might be able to help here.So, if I can gather info on these three different types of chassis I can report back with what I find.
Thanks again , Jim

KingNothing50
12-28-2009, 06:24 PM
Thanks guys,
2 Tons... I look forward to your help.
The axle I'm looking at is an 8 lug off a '96 Chevy bread van. The seller says that the wheel mounting surfaces are 74'' apart, the springs are 2-1/2'' wide and 32'' apart center pin to center pin. He also says it will NOT fit a 3500 HD. Don't know why . Maybe 10 lug? I'll have to ask. He runs a Chevy only dismantling yard and seems to know his stuff. Maybe because it might still share some dimensions from the earlier '73-'90 chassis ? I do know there was a difference in spring mounting.... or the frame , between the '90 models and the '91& up. Can't remember exactly what. King Nothing might be able to help here.So, if I can gather info on these three different types of chassis I can report back with what I find.
Thanks again , Jim




Yep. 3500HD runs a 19.5inch 10 lug wheel.


Not really sure what your asking there in that last part, but to my knowledge the frames should be the same 73-91. 92 They switched to the IFS on the 1 ton 4x4 trucks.

khaoskustoms
12-28-2009, 06:28 PM
what about finding a chev 3500hd cab and chassis with the i-beam axle in it??

Grigg
12-28-2009, 07:01 PM
I had mentioned that too, but considering that there are no 3500HD crew cab pickups Jim thinks a front axle swap may be a simpler idea?
If it is as simple as installing spring hangers and the I-beam axle I think it may be the better choice. Also to figure out is steering linkage, and I expect that 3500HD linkage and bell-cranks can be used with probably 4x4 steering box, possibly 3500HD steering box.

I used a 3500HD axle under my 48, but narrowed it about 10.25".
I just checked some P-30 axles I have and just rough figuring I would need to narrow one of them (either the 8 lug or 5/10 lug version) about 5.75" or there abouts.
Which makes me think that the 3500HD axle beam is wider than the P-30 axle beam?? I don't have my original 3500HD measurements to check and find out for sure.... who has a 3500HD axle to measure?

Other than the obvious wheel and bolt pattern differences between the 8 lug p30 and the 3500HD with 5/10 lugs, some more axle differences are (note also thrown in this comparison is the 5/10 lug P-30 axle) :

location of steering dampener, P30 axles have a forged tab on the axle to bolt to, 3500HD use a bolt on bracket
Spring widths, are 2.5" for P30 and 3" for 3500HD, so u-bolt holes in the axle beam have different spacing.
Steering linkage, P-30 has front to back drag-link and the tie-rod is behind axle and below springs. 3500HD has Y type linkage in front of axle and above springs.
Sway bar mounts are completely different, P-30 sway bar is mounted to truck frame, 3500HD has it on the axle
Caliper brackets, 5/10 lug version uses bigger diameter rotors than the 8 lug version.


As far as I know you can swap the 8 lug for the 5 lug hubs (would also need to swap caliper brackets).

Grigg

jim in n.y.
12-28-2009, 07:51 PM
Thanks again guys,
Andy, I was having a brain fade. I new you had told me there was a difference in the '92 & up 1 ton 4x4's . I forgot about the IFS . I was thinking about what you went through changing the IFS 4x4 back to a straight front axle and having to mount the leaf spring hangers on the frame rails.
So, do I have this right? It sounds like I would have less work if I were to use a P30 , 8 lug axle in a 2wd ,'73-'90 1 ton dually ? I think I just need to compare the critical dimensions( spring width, track width, spring center and steering linkage ) of the P30 axle to a 4x4 and see. Probably also need to use a smaller rotor and caliper bracket off a 3500 HD unless I go with the larger (19.5'' ? ) wheels and tires
Update.... I am certain that the leaf spring width on a '73-'90 1 ton 4x4 is 2-1/2'' with a 32'' center to center distance. So,based on that and the fact it's 8 lug instead of 5/10, that is starting to tip the scales toward a P30 axle for now.
Jim.

jim in n.y.
12-28-2009, 07:56 PM
Ooops... I reread Grigg's post about the 3500 HD having larger rotors and corresponding caliper brackets. So, this is one more reason to think the P30 axle might be the way to go for me.
Jim.

KingNothing50
12-29-2009, 10:18 AM
I dont know much about them, but Ford used a solid I beam axle in some of there F-350's or F-450's. Im thinking late 80's early 90's. Surely the track width would be the same or close. I would guess that the spring pads on the Ford would be 36.5 and the chevy should be 32.5.


Just thought id throw that out there.

Grigg
12-29-2009, 11:58 AM
I don't know much about them, but Ford used a solid I beam axle in some of there F-350's or F-450's. I'm thinking late 80's early 90's...
They have 10 lug on 7.25" circle with a 5.46" center bore. Only wheels I know of for them are 16" (Accuride part # 29581).
However GM 19.5" 10 lug wheels could be bored to fit the larger 5.46" hub.

Personally I'd stick with the GM stuff.
Dan Resh with the Silver 4-53T in his Dodge used the ford I-beam axle, not knowing about the GM one at the time. I believe he said that had he known about the GM axle he probably would have used it.

Grigg

2tons of fun
12-29-2009, 02:45 PM
track center line is 63"
wms to wms is 73"

KingNothing50
12-29-2009, 04:34 PM
They have 10 lug on 7.25" circle with a 5.46" center bore. Only wheels I know of for them are 16" (Accuride part # 29581).
However GM 19.5" 10 lug wheels could be bored to fit the larger 5.46" hub.

Personally I'd stick with the GM stuff.
Dan Resh with the Silver 4-53T in his Dodge used the ford I-beam axle, not knowing about the GM one at the time. I believe he said that had he known about the GM axle he probably would have used it.

Grigg



Just did some looking around on the web. Found some mid 90's F-450s with I beam axle and they have a 16inch rim, but a 10 bolt pattern. I never looked at them that close before..... I always just assumed standard 8 lug pattern. I should have known not to assume anything when it comes to Fords.

jim in n.y.
12-29-2009, 05:22 PM
Thanks, Grigg, 2 Tons , King and everyone else.
Based on the measurements I am going to buy the P30 axle . It appears that it is very close to a drop in fit as far as the critical dimensions are concerned. Here's how it breaks down :
Spring width :
'96 P30 = 2.5''
'73-'90 1 ton 4x4= 3"
I'll use 1/2 ton springs( 2-1/2 " wide) with a 4'' lift ( to accomodate the 4'' drop in the I beam axle) and extra leaves for the weight.
Spring center width:
'96 P30= 32"
'73-'90 1 ton 4x4 = 32''
WMS to WMS:
'96 P30 = 74'' ( as near as the seller can measure)
'73-'90 1 ton dually= 73'' ( as per 2 Tons )
The only thing I have to sort out is the steering linkage. I can't forsee this beeing a serious obstacle , Though.
Thanks again , everyone, for your help.

jim in n.y.
12-29-2009, 07:29 PM
I just got off the phone with Grigg and he reminded me that I need to account for the fact that on a tube type axle (Dana 60) the springs are mounted on top of the tube ( 3-1/2'' dia.) Grigg really is on the ball !! Plus the thickness of the perch ( 1/2 '' maybe?). So, I need to add this to the 4'' drop in the I beam axle when I order springs. This should make it about a 6-1/4'' lift for the new springs. I will be sure to measure before I order any springs !!!
Jim.

Grigg
12-29-2009, 10:46 PM
Here's some Dana 60 front axle info
http://www.pirate4x4.com/tech/billavista/60_front/
If the Chevy truck you're considering starting with had a Dana 60 then it looks like it will be 69.5" from WMS to WMS. But they don't say if that's with single or dual wheel hubs, I'd expect the dual wheel axle to be 8-10" wider than the single one.

Grigg

2tons of fun
12-30-2009, 01:41 AM
69 is srw

drw is 77". wider than a ifs setup.


depending on how the p30 axle steering is setup you can switch to a 4x4 steering box aswell.


are all p30 axles that narrow?

Grigg
12-30-2009, 06:55 AM
...are all p30 axles that narrow? (74")
No, I've got three here that are all approximately 82" from WMS to WMS.

If the one Jim found is indeed that narrow I'd trade one if it helps.

Grigg

2tons of fun
12-30-2009, 11:52 AM
No, I've got three here that are all approximately 82" from WMS to WMS.

If the one Jim found is indeed that narrow I'd trade one if it helps.

Grigg

it would help if you werent on the other side.

jim in n.y.
12-30-2009, 03:01 PM
2 Tons....
Is that 77'' wms you stated for a Dana 60 on a '73-'90 1 ton dually? If so, was the 73'' wms you gave earlier for a 2wd?

Here's an update on what I have found. As I suspected ( based on Grigg's measurements of his P30 axle) the seller of the P30 axle I was looking at measured wrong. It does NOT have a 73'' wms but instead 82''. Which is what Grigg said he thought it should be. That's a bummer . I should have known as much .... Grigg has pretty much been down this road. The 3500HD axle is supposedly even wider but don't know by how much. The seller has a couple of those and measured one for comparison to the P30 but only stated it was wider ..couldn't remember by how much.
I also stated that the 1 ton 4x4 spring was 2-1/2 '' wide and it's not. It's 3'' wide.
Now I have to decide if I want to buy this and go to the trouble of narrowing it 9'' ( or is it 5'' based on 2 Tons measurement). Grigg... do you think it's possible to move the spring mounting pads out 4-1/2'' ( or 2-1/2'') on each side after I narrow it?
Jim.

2tons of fun
12-30-2009, 10:42 PM
2 Tons....
Is that 77'' wms you stated for a Dana 60 on a '73-'90 1 ton dually? If so, was the 73'' wms you gave earlier for a 2wd?
.

exactly, you originaly asked for the 2wd setup and that was what i told you, 73. griggs posted up about the d60 and i was confirming the measure ments for that.

dont go chopping **** up yet.

the 2wd ifs setup makes the tires tuck way up under the truck, the wms isnt even flush with the outside of the fender. imo it dont look right, the tire really needs to be just a hair inside the fender and the rim sticking out. the p30, w/t. hd axle do exactly what i am talking about and looks muuuuuuuch better. it will not affect you steering rate or scrub radious but it will affect your turnign radious some.

jim in n.y.
12-31-2009, 06:46 PM
Thanks 2 Tons for clearing that up for me.
I think I'm going ahead with my purchase plans. I will be near the seller on some other business so I'll grab it while in the area. When I build up a truck I'll decide then if I want to narrow it. Junkyards around me seem to think everything is gold plated so prices are high.
Later, Jim.

Grigg
12-31-2009, 07:34 PM
Measured a 3500HD axle today, looks like 79.5" from WMS to WMS. (not an exact measurement but within an inch or so.)

So I was wrong by guessing it is wider than the ~82" P-30 axles.

Next we'll need to measure form king pin to king pin to see if that's where the difference is, almost has to be I think.

The 3500HD trucks came with about a 2" fender flare, that may be part of the solution when swapping to one of these axles.

If you want to I'm pretty sure you can afford to move the spring centers out 2.5" per side, and I'm sure you can get more if needed by welding to make bigger spring pads.

One way or another this axle swap will work.

Grigg