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Hello
I have 54 f600, atleast that's what's on paper. It is an old airforce truck. I was thinking of putting a 2 speed rearend or putting a newer one in as well as upgrading the brakes as I'd like to be able to tow with it every so often. Anyones thoughts would be much appreciated.
thank you
Welcome to the forum. First, why can’t the truck pull a trailer with its stock axle? Are you concerned perhaps about slow road speed with the stock low gearing and want to be able to drive the highways? Or are you wanting to pull a heavy trailer which could be helped by use of a two speed since it would add a lower ratio to get the load rolling. There are solutions to both.
Next subject to learn about is your truck’s wheels. They have outer rims known as the Firestone RH-5°, today simply called “widow makers”. Rather than me going into the speech, please do a Google search of those terms to learn of their risks. There are solutions here too. Stu
Looks very solid, appears to be an Ex Army and has been upgraded to FT power, 330 HD or 361 is a good guess. Finding a highway ratio in the 5 lug will be difficult, they were pretty much all 6.20. A 2 speed high is around 5.83. If you think outside the box, many vintage motorhomes , both Ford and Dodge came the 5 lug axles with highway friendly ratios for traveling the countryside. Do your axle ratio, tire diameter , rpm calculations before purchasing anything.. Camper usually have the safer lock ring wheels or solid wheels. Here is an example of something that might work, a rv salavage yard type candidate.https://camper-forsale.com/needs-res...vco-motorhome/
Agree that one of those Travco motor homes would be a good donor for both its 19.5” tubeless wheels and Dana 70HD rear axle. The D70HD should have a 4.56/1 ratio if that is the solution you are looking for. I have one of these axles available if it’s of interest, but no longer have the 19.5s that were on it. Stu
Sorry I didn't say why I wanted to change everything. Towing is def not an issue But I'd like to take it on the highway. I hit 40-45 mph and I try not to make it go over that. This would be my first big project by the way. I've done small things like brakes and I did an oil pan seal i believe a long time ago. As far as the wheels I did see something about using m35 truck wheels. But I figured I'd start with the rear end and kind of go from there.
The transmission is 5 speed with 1 being a granny all the way to the right. So 2345 and then 1 and reverse. Looks like a Clark 2653 maybe from the limited research I just did.
Okay, that makes sense. But regrettably the use of military surplus wheels and tires is not gonna be an option for you. Your truck, although it’s an F-600, has the earlier 5 lug x 8” bolt pattern while the military trucks used the 6 lug x 8.75” pattern. Your better option is to familiarize yourself with old salvage yards within reasonable driving distance to find the safer locking side ring wheels that can still be serviced. Dodge and IHC trucks are your best donors.
The other option would be to find 22.5” wheels that were the tubeless replacements for the 20” tube types. Rare in the extreme but can be found. I sold a set last fall to the fire department of a St. Louis county community for their parade truck. Reproduction 22.5” x 6.75” wheels are also available from companies like Wheels Now up in the Milwaukee area.
As for the rear axle, any big truck will have a lower gear ratio (higher number) than a modern truck. Swapping in a more modern axle would also entail some engineering work on your part to meld the dual hydraulic system of the axle to the single master braking system of the truck. The D70HD axle I mentioned would also require minor mounting adaptations. If this is your first venture into big truck ownership that might be challenge. Sorry I don’t have better ideas. Stu
Edit - one option, but an expensive one, is a Gear Vendors overdrive unit. Might be something to research. Stu
Thank you for the advice. I do have a buddy who seems to know just about everything and would know exactly what you all are talking about haha. I appreciate it
The easiest mods are usually the best, but unfortunately in is not 1980, when you can easily find a good used Clark 280 V0 or a NP 542 FO , or heck, probably buy one brand new, Both were 5 speed overdrives that were options behind your FT engine, with .8 overdrives, and your 6.20-6.80 axle ratio, they would be ideal. I believe the P 500 bread van, similar weight range as your F600, came with a 5.29 axle, IF, and only IF, it had the diesel engine option. It would be great if gear vendors had an overdrive unit for your 5 speed, but chances are it probably require a machine shop to fabricate an adapter plate and dealing with how to reconnect the parking brake drum.
I don't know how true this is i haven't had time to sit down yet but I was told by the dude I bought the truck off of said I could look into a bus rear end...?
Yeah, those four 22.5s have been on eBay for a while. At $250 each they are fairly priced, but there are only four. I have a fifth I could add to the mix but don’t know of #6 right now. The eBay wheels, and my extra, are the 5.25” wide version (Budd 69930s). Those eBay 19.5s are obscenely overpriced imho, but it’s a full set. They’ve been on there a while too so maybe either seller is taking offers. And like you said, the 8R19.5” tires would be about 4” shorter than 9R22.5s which would defeat the goal of adding road speed unless the axle was swapped too. It’d be cheaper to just do 22.5s and call it done. Stu
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F600, at least that's what's on paper.