Re-Gearing FFPW for road use

[kkeaa53]

I have now driven my 1952 Power Wagon on the open road and immediately I can see the need to re-gear the diff to the 4.88 ring and pinion.

I am searching through the posts but cannot currently find any references on this topic but there must be some somewhere as it's a bit of an elephant when you are revving the nuts off the engine to get up to 25mph.

I can see that I can get a 4.89:1 ring and pinion from stateside if I can find one and would need to find a professional transmission man to set it up.

Are there any other options, complete rear axle change to a newer Dana unit and take the hit on 4x4, or have you guys found a different solution to this road operation for these trucks.


John

.. and a pic for your enjoyment

[CSCameron]

Lots of threads on this topic. Yes, the PW is slow. Realistically, it has a top speed of 45 to 50 mph (with 5.83 gears and 230 motor). Many will tell you it was never designed for our modern highway speeds. To tell the truth, even if I could go 70 mph in it, I never would. Not without MAJOR upgrades to the entire truck.

4.89 gears are the only option if you wish to retain the original axles. They will net you about +8 mph. Using someone that has actual experience doing this swap would be advised, as special tools are required to do it correctly. VPW sells the gears and can do the swap for you, also Bob Stahl - Veteran Vehicles / John Bizal - Midwest Military can do it too. I'm sure there are others. I'm also sure I'll get some push back on not doing it yourself. It may be something you could do but, I don't know your technical skill or setup.

You can also gain about 2 mph by installing taller tires (11.00x16s).

All other options require swapping in different axles which will require some degree of fabrication. Then you'll run into transfer case/transmission/PTO and engine swaps/problems/options. It's quite the can of worms when you open it however, everything is possible with enough time and money LOL. With some research, you'll see many that have done it and in very different ways.

Another option is to swap the body onto a modern chassis such as a Dodge 2500? This presents its own set of problems but is doable.

I've had my 55 on the road for a couple of months now and with my 5.83 gears and 230 motor, 50 mph is about all there is. I installed a tach and have a gps speedometer on my phone so I could get some accurate numbers. I've had it up to 48 mph at 2800 rpm. Very loud. I've read that these motors were designed to run 3200 rpm all day long however, I don't know if that is true and I'm not comfortable with it. I think I'll keep my un-rebuilt motor below 3000 rpm.

In the beginning, I decided to keep the original axles and installed 4 wheel disc brakes, an expensive option. I'm committed to the original axles now. 4.89's are on my list. I also have ARB lockers ready to install. Either way you go isn't cheap.

I'm sure you'll get lots of responses from folks that swapped axles. Good luck whichever way you decide to go! Let us know and be sure to post a build thread.

Clark

BTW, nice looking truck!

[Tom Petroff]

Make sure your transfer case is in High range.
If your only getting 25mph it must be in low?

Tom

[kkeaa53]

Thanks Clark that's what I needed, up front detail, just what I am looking for.

I am in the UK so would need to find a UK based diff rebuilder but the principle stands I do not have those skills and realise I cannot do this personally.

There is a set of the correct 'ring and pinion' on FleaBay currently for $650 delivered to the UK (per diff) and VPW are currently no stock so this is not going to be cheap I can see that. The front and rear diff uses the same part number so at least I cannot get them mixed up.

Tom I tested the transfer box before re-installation so I know it moved from Hi to Lo on the bench and I have it in Hi, perhaps the engine noise at 2000 rpm is un-nerving the engine rebuild wallet memory. I will however double check it goes half as slow in Lo box.

With the rear axle being offset I will struggle to find an easy substitute I suspected but there was always the possibility that a bus or Carryall would have a suitable mechanical option I could look for.

I will also look over the Channel in the Netherlands as those guys also run these machines the Military spec are not a lot of use but they may have the bits to do the same mod for themselves.

So I need to 'bit the bullet' and spend the money and find a shop to rebuild the diff correctly.

All I need is the bits.

I will keep you informed. Can you point me towards a thread that details the diff rebuild for personal education and support detail for the end builder to look at.


John

ps

I would like to say I don't want to go fast in this truck, I got a Lotus for that, I would just like a lower rev on the engine for a reasonable running speed.

[CSCameron]

Hey John,

You can swap a late (1944-1945) 3/4 ton axle with 9-5/8" centered diff. It will give you equal length axle shafts, but if you are interested in running a rear PTO, this will eliminate that possibility. You can swap the 4.89's into it. Beware there are different 3/4 ton axles so get the correct one.

Link to Centered Diff info...
http://uglytruckling.com/centered_rear_axle.html

4.89 Info...
http://www.dodgepowerwagon.com/stahl/gearing.htm
http://www.powerwagonadvertiser.com/...ad.php?t=11915
http://g503.com/forums/viewtopic.php?f=56&t=192930

I'll continue looking for links, there are a few specific to the build. I just can't find them right now.

Be sure to check Norway too, they have a lot of WC's and parts.

Clark

[Matt Wilson]

Hi John,

Nice-looking truck. I have 4.89's and tires that are slightly larger in diameter than stock (stock being 9.00 x 16 and mine being 11.00 x 16). I rebuilt the 230 engine many years ago, and drove it at 58 - 60 mph with engine rpm's in the 2700 - 2800 rpm range. The engine was bored 0.060 oversize and had a performance camshaft from Vintage Power Wagons. I don't know the specs of that camshaft, but it was advertised as helping with highway driving. The truck seemed to do fine with all that. The pistons, rods, crankshaft, flywheel and pressure plate were all balanced to minimize unwanted, wear-inducing vibrations. There wasn't an excess of power, and driving up an incline on the highway would result in a little speed loss, but not that much. All in all, it wasn't bad. I still made sure to stay in the slow lane as much as possible.

I don't know if you will plan to rebuild the engine or not, but if so, then the above are options to consider. There are additional performance parts that can be purchased, which are reported to provide an increased boost in power to help with freeway cruising.

The sources mentioned above can install 4.89's for you, and I know some of those folks have good used take-outs that would lessen the sting compared to new units. Of course, shipping across the pond may be a killer.

Good luck!

Matt

[53Crusher]

Gearing

John-

My truck is similar to Matt's except I still have 9.00x16 tires. Stock 230 completely rebuilt with performance grind on the cam, HEI ignition, dual carbs, split exhaust headers and everything balanced. Transmission rebuilt, Transfer case rebuilt and balanced drivelines. Installed 4.89 gears in both front and rear axle with complete rebuild of all axle components.

To me, it has to be treated as a complete system to see noticeable improvements. I can run 55-60 without too much strain on the truck, but a hill will still slow me down. It's exactly what I wanted my truck to do and I am pleased with the end result!

You should be able to find other threads on this, it's been discussed quite a bit.

Good luck on yours!

[Desoto61]

There are some pics in my build thread. Another option if you want to have someone do them is M-series, but that is also here in the US. Be aware that the ring and pinion bearings are almost as much as the ring and pinion set, mostly due to the front double race which seems to be getting rare.

I did my own because I wanted to learn to do it, but I did send out the front spider assembly to have it rebuilt by Charles Talbert, there's a lot of special equipment setting those up correctly, and it wasn't worth it for one axle. The rear I converted to an ARB locker.

Best source of information on how to rebuild them would be the military M-37 manuals. Should be able to find them either on-line or a few places sell them on disk, they're relatively cheap. The instructions are more detailed than you would find in the Dodge maintenance manuals.

If you really want highway speeds and driving I'd have to say the frame swap is your best bet. It's no where near original looking but the best/safest way to get real highway performance, and probably no more or less work than trying to upgrade the stock parts, which were just never built for that kind of thing.

[kkeaa53]

Tom is very astute, but first the story...

Make sure your transfer case is in High range.
If your only getting 25mph it must be in low?

I have a 1952 FFPW just so we are clear and based on reading various documents I understand that with the two levers pushed forwards to the firewall is 2 wheel drive and high box engauged.

Now based on Tom's pointed comment and a quick road run I find that the RH most lever pulled back towards the seat allows the truck to move faster.....

I have been in low and did not know it.

So my question is? is this conventionally correct one lever forwards and one back for high box 2 wheel drive or have I assemble something wrong?

I further add that I have not fitted the front propshaft so I do not know if it's trying to drive the front wheels so if its possible to get the lever assembly wrong and reverse the operation.... I could have done that.

Before ...



After ...


and the rods....



Looks right to me but.......


John

[Greg Coffin]

It looks to me like the rods have been crossed. You were in 4wd Low. Swap the rods at the transfer case, and rotate the one with the bend in it 180 deg, and I think it will line up well. Let us know how it goes.

[Tom Petroff]

Have to agree with Greg.

The lever installation looks correct, but the rods shouldn't be crossed.

Tom