The Stovebolt Site Forums The Parking Lot Big Bolts P30 Axles?

Hi all, I have a quick question. I'm now the new owner of a 48 1.5 ton. I'm planning on putting a 6BT cummins in it and using it as a hauling truck. I have an opportunity to possibly get the axles and rims (with radial 19.5" rubber) from a P30 Frito-Lay truck. I was thinking this would be great, as I would end up with much easier to find tires, disc brakes in front, and still have the 10-bolt style bolt pattern. Will this work ok? I plan to leave the front suspension as a leaf system, but the rear suspension will be a custom self-leveling air ride system (like semi-tractors have)....

I was at first worried about weight capacity as the P30 is only a 1 ton chassis, but then I found that the gross weight of my 1.5 ton is only 12,500 so I should be ok with the P30 axles I would think...

Looking for feedback. Thanks!

-Matt

Hi Matt, and welcome!!

If the P30 has a Dana 70HD or Dana 80 rear the GVW as a P30 was approximately 14,000 lb.

Your plan sounds reasonable and achievable to me.. It should, as the axle swap you describe is what I have done with my truck. I even have plans for a full air ride rear suspension, similar to a Hendrickson model HAS-120 or the Kelderman kit offered for a F550

Check out the picture link at the bottom of my signature, the axle swap folder in particular.

The short answers:
The rear is a simple swap, only need to move the rear spring pads out approximately 1" each and at the same time adjust the angle to suit the drive-line, this assuming you use leaf springs. If air ride to start with, then the P30 rear axle width works well with the 36" wide rear frame, the rest is up to you.
Front axle will need springs with 2" more lift, and the big thing is it needs to be narrowed approximately 10". Chances are you can use the original steering gear box if you please.

One thing to consider is the 19.5 wheels, even with 8R19.5 tires at about 33" tall I think they look small and out of proportion on a 1.5 or 2 ton truck. There is a 22.5 option, but somewhat difficult to find the wheels. Check out this tech tip: http://www.stovebolt.com/techtips/wheels/

Sounds like fun, and a lot of work,
Grigg

Yes, I'd much prefer the 22.5" wheels...... but that is out-of-budget right now..... I figure on running the 19.5's until EVERYTHING else is taken care of, then I can upgrade rims.... Rickson will make me brand new custom rims for $325/wheel....... Yikes!

On narrowing the P30 front Axle, what is involved in doing that? Cut/weld or??????? Seems like there wouldn't be any real easy way of doing that..

Exactly, cut out the middle, discard it, and weld the two halves back together. The first one I did took several days of measuring, layout, and prep, then a few hours of actually welding, and another day or two on finishing. That process can be seen here, although not very detailed or complete http://rides.webshots.com/album/484062061lhMQfr The next one I did took about a day total. That one can be seen here in more detail http://rides.webshots.com/album/558384968mIheUE

Also involved is figuring out the steering, be it stock or newer PS. The front springs need to be changed, have new ones made. The spring pads and u-bolt holes need attention, there are two ways to approach that, and both are covered in the picture links above. Don't forget a newer master cylinder and hopefully a booster to work with the new disc brakes. You'll see that one change leads to another, and another and another...

If you are not very comfortable with your welding skills have a professional do it. Actually both axles above I had a friend do the welding, I just set everything up, chipped slag, and wire brushed for him. Now that my welding ability has improved I will do the next one myself.

Again, this is not a swap for everyone, but if done right it is a big improvement and almost necessary if hauling much of a load at today’s speeds on the highway.

Grigg

I'm thinking the Frito-lay trucks with the 4BT had 8 hole wheels with coil spring front ends. They used the GM 14 bolt rear axle.

I guess I'll have to find out on that with the wheel issue there...

Glad to hear that the front axle can just be cut and welded..

I definitely am going to put a hydroboost master cylinder on the truck... I might be able to get it from the P30......

Gotta get ahold of that guy....

Grigg, those Dana rears come with stock disk brakes????? Awesome!

Now, that front axle is cast right? Definitely will want to find a welder that's competent on cast iron in that case....

So, my game plan is get a P30 10 bolt front and rear axle with rotors and calipers, I'll get the hydroboost master cylinder and powersteering box off of the van. Rear suspension will be air. For the front, what would keep me from using the P30 front springs? Seems like they should be about right weight-wise.


Still learning.......

I don't know what engine combos came with what suspensions and axles, but there are several choices of axles.

I have seen all of the following on P30 chassis, or on chassis very similar to (I did not read all the tags):
A, 5 lug front 10 lug rear I-beam front, Dana 70HD, Dana 80, or Rockwell rear.
B, 5 lug front independent suspension, 10 lug rear, similar rear choices as above.
C, 8 lug front and rear with I-beam, very few of these, and probably Dana 70, 70HD, or a 14 bolt rear.
D, 8 lug front and rear with independent front suspension (most common 8 lug P30 chassis) and probably the same rear axle choices as above.

The one of interest for an AD 1.5 or 2 ton is the first choice, choice A, an I-beam front with 5 lugs and a Dana rear. The Rockwell is not such a good choice as fast gears are either not available ever, or hard to get/expensive, quickly spot a Rockwell by the square axle "tubes".

Grigg

Right, they should have disc all the way around with the 5 lug/10 lug, I have not seen them any other way (other than our antique trucks)

Front axle is forged steel, probably forged cast steel, and definitely not cast iron. Proper pre and post heating is the only real secret to welding them, that and having a welder that throughly understands the process and the consequences of a poor job.

Good idea to get the hydroboost and entire brake system too.

Front suspension, I think you will find that the front springs are very long in comparison to the stock ones, and they they also look rather flat and not curved so much. To use them you would likely need to make custom spring hangers. I feel that having custom somewhat original springs made is a better solution, less work, you get new not used springs, and they will be a much cleaner solution. Downsides could be a somewhat harsher ride because of the short length, I don't mind, or even notice for that matter.

Steering gear box is not very desirable. They typically mount to the left of the left frame rail, in front of the wheel and partly attached to the bumper or it's support. I have looked pretty close at the one I have on the shelf, and I see no easy way to use it in an AD truck.

Grigg
Gear Calculator:
http://www.onlineconversion.com/bigger_tires.htm

Thanks Grigg. I'm hoping to get ahold of the guy I know in NC who has this... When I can, I'll ask him first off if it's 10 bolt or not... If so, sounds like it'll probably be a go...

I reaaaaalllllllyyyyyy hope this pans out.

Yah, I new the P30 steering gear mounted toward the far front of the truck.... Didn't think it'd be a big deterrent... Though I don't know all the details of the fender arrangements, etc..

Oh, you have mail!

Thanks again grigg for the call last night. hope I didn't keep you up too late..

Sheds alot of light on the subject for me....

Sure, no problem, glad to help. And not to late, I still made it to work a few minutes early this morning.

Grigg

LOL!! That's all that matters!!

Oh, here's some pics of the truck in case anybody wonders what it looks like: http://www.new.facebook.com/album.php?aid=56913&l=86f91&id=733618614