The Stovebolt Site Forums The Parking Lot Tons 'o Fun 5.14 Rear Ends: How fast can you run them?

How fast can the 5.14 geared rear ends run safely (outside of brakes, steering, etc)? I've read that some drag racers run 5.14's but not sure how much difference there is between those and our antiquated 5.14's.

Would 60 mph on 5.14's out of a 1954 dually be too much for the rear end or drive shaft to handle? The 235 in it runs strong but the effective RPM range is so small. The SM430 with granny 1st has so much difference between the gear ratios that I have to rev the heck out of it before shifting, then the next gear lugs terribly. I've been wondering if a 6 speed or 5 speed OD manual transmission behind the 235 would be just good enough to get to 55 or 60 or so?

Thanks

Interesting question.

Ignoring brakes and steering and the condition of the suspension and tires and all those kind of things, I think you're getting into discussion of bearing durability and drive shaft speed. I've seen some online calculators that deal with drive shaft speed but never one that deals with bearing durability.

But you are ignoring a lot of very important factors there.

My own bet is that you'll be pushing the 235 harder than it will go before you'll exceed the abilities of the Eaton HO72. The Eaton has been used in racing applications, but that was mostly years ago, and today they aren't too common there.

You might want to start by looking for the 4.57 or 4.11 gears available for the Eaton before spending money on a 6-speed. Some of the cheaper overdrive 5-speeds or 4-speed might be a more practical choice. But the most common 5-speed swap isn't stout enough to support the loads your 1-ton was designed to carry, so swapping something like that in might be asking for trouble.

The racer crowd can accept failures and service intervals that don't make sense for those of us who need our vehicles to work every day. While what they do can be interesting and instructive its not often the best approach to copy.

In good condition that rear isn't the first part I'd worry about. I'd start with the tires and brakes and steering. But we're ignoring those for the moment...

Steve is on the right track. You'll blow the engine long before you get to the breaking point of the driveshaft and rearend. Besides the gear swap, another option might be to look into a Ranger Overdrive. It's basically an auxilliary transmission that bolts between the bellhousing and the main trans. They're available in Overdrive and Underdrive versions, both of which will give you 8 forward gears to choose from. It does moove the transmission back about 7".

I've thought about changing gears but the dually 5.14's don't have any 3rd member swaps as far as I've read on this forum. I would have to put a P30 rear end or something under it. Having a higher gear ratio would be great but the wide gearing in the granny 4-speed would be even worse than now.

I am in the process of obtaining 6 of the 19.5" P30 wheels and will put some decent radial on them. Probably pursue the disk brake custom conversion on the front at some point and add a brake booster. Steering seems to be pretty tight, but will have to wait to see how it acts after getting radials and some more speed on them.

I've thought about that gear box ahead of the transmission at one point. Not totally sure how it works but if there would be 2 shifters and have to switch each one on every shift, then that would be a lot of work. I can look into them more though.

I've gone around and around trying to decide whether to leave it stock or to just go ahead and make it a comfortable, safer, faster driver. I'd be happy with 60 mph.

The HO52 and 72 rearends use the same 3rd memeber, other than gearing, regardless of single or dual wheel. The 5.13s were pretty much exclusive to the 1 ton, though it was offered in the 3/4 ton in some years. There also was a 3/4 ton 4.56 duallie rearend. Either way, the 3rd member is a direct swap.
You mention athe wide gearing, are you using first gear to take off? If so, try using 2nd instead. First gear on that trans is a very deep 7.05:1, and is really meant more for taking off with a heavy load.
Here's a video of a truck with a Ranger overdrive coupled with an SM465. The shifting part of the vid istowards the second half. Niow, that's using it as a gear splitter. You wouldn't necessarily have to drive it that way. You could just sput it in overdrive and leave it there.
At least it's not like this one!

I too think the rear axle it's self is not a weak link, it's the math and the gear ratio that will hold you back.

Here's a gear calculator for you to play with
http://www.onlineconversion.com/bigger_tires.htm

In my experience the 55 model 235 in my 1 ton ran well at 2,500 rpm or thereabouts, anything over that just wasted fuel, it would run faster but didn't seem as happy.

So what transmission (overdrive) ratio, axle ratio, tire size, and engine RPM do you need to go the speed you want? And then will the engine actually pull that?

I feel that my 1 ton would be great with 4.10 gears, 33.5" tires, the original 4 speed, and the newer 235, but any faster gears and the engine lacks power.
Most recently I ran 4.56, which is great for a working truck on short trips, 50-55 mph but empty trips over an hour and the one step faster gears would be welcome.

Grigg

From reading Grigg's posts and others, I was under the assumption that there wasn't any swaps for the 5.14's in the 1-ton duallies.

I'm using 2nd to start off with. 1st is too low.
Thank you.

I wasn't concerned about the axle itself, rather if the entire 3rd member would explode turning that fast, or more importantly, would I throw a drive shaft spinning that fast.

What I envision is to do your P30 swap without changing the front end (was hoping to just change 3rd member but still doubting availabiltiy of 4:10's for that). I'd try the disk brake conversion like in the other post and get it up to speed to see how it handles before changing the whole front end. If the 4BT mostly drops right in, as you inferred, then I'd probably do that to get the torque I need for the SM420. I am not opposed to change the transmission, however I do like the PTO hookup that drives my hydraulics for the dump bed. Maybe with the 4.10 gears, 33" tires, and the 4BT I could get to 60 (calculator). Running 2500 RPM I could get close to 60, and hopefully the 4BT would have enough torque to pull through the wide spaced 2-3-4 gears of the SM420.

Does that sound about right?

Thank you

Well, I still feel the axle is up to the job however fast you end up turning it, and think about it, it's only the pinion that turns faster, the carrier turns slow, in fact extra slow because of the large reduction.
Let me restate that, I think the rear axle will hold up fine, but you'll have a difficult time getting the speed you desire out of those slow gears with whatever transmission and engine you want up front. The gears are just to low to do what you're asking, and that's the problem, not durability.

Switching to a a 4BT does not help your current gearing plan, it would be wound pretty tight at 2500, but you could do it no problem.
More realistically 1800-2000 rpm is what you want for the 4BT, should see reasonable mileage there.
The smaller RPM range of the diesel would make the 4 speed less desirable, the jump from 3rd to 4th would seem even worse.
And to overcome the slower operating speed an OD transmission will be helpful.

If you want the 4BT think about buying a whole P30 with the 8 lug I-beam front axle (to narrow and swap) and a 14 bolt GM rear.
The rear probably comes with 4.10, and faster ratios are easily available.
You may not want a cab and chassis rear axle (probably comes in the P30), check that the dual wheels still fit and don't hit the springs. If that won't work a pickup truck dual wheel axle is a little wider and will fit.

First pick your engine, then plan the use for the truck, and calculate gear ratios and speeds from there.
Check out www.4btswaps.com and you may find this one interesting http://www.4btswaps.com/forum/showthread.php?t=3731 although I still think axle swaps are a better idea than a frame swap in most cases.

Grigg

Back in their day, we ran 3/4 tons and 1 tons 60 MPH all day long. In fact the speed limit was raised to 70 in Texas in 1962 and we stayed right with traffic. As long as the radiator stays cool, you aren't going to hurt anything. We preferred the 4.56 gears with 7.50x70 tires which is a bolt in in a 1 ton. People who weren't driving in the 50's just aren't used to the noise a steel fan, solid lifters and no cab insulation makes. I got my commercial drivers license over 50 years ago. My biggest problem was blowing speakers out of radios by trying to hear the radio over the other noise. Actually problems can be discovered easier in noticing new vibrations. I have actually put on some ear protection to block out the noise and try and isolate the vibration.

On my 64 1 ton with a 292 I changed the rearend to a 78 P-30 out of a 78 410-411 ratio, correct width, bigger rear brakes, and also switched the trans to a SM465, everything was a bolt in. Could run 60-65 with no problem, the other switch was to change the master cylinder to a dual type, gave me a safer brake system. Drove it that way for 6 yrs every day carring 9,000 lbs.

I quit chasing parts and had a rear end built for my 1941 1 ton pickup.

I am using a stock SB350,700R4 transmission, coupled to a rearend with 3.73 gears.

By using the longer 700R4 transmission I eliminated 1 drive shaft and the support bearing.

Stock 7.50 X 17 tires.

I expect 70mph at 2,000 RPM. The only caution I was given was not to exceed 80mph because I might throw the long drive shaft. I can live with that restriction.

The complete new rear end cost me $1,800.00 and saved a lot of looking and agravation.

If your driveshaft is at risk of destruction with your setup you need a different driveshaft designed to handle your application.
I would not want the driveshaft to be a weak link or possible failure anywhere close to normal working range.
Here are some links to good driveshaft info
http://www.stovebolt.com/techtips/driveline/setup/index.html

After skimming through that you may determine you have a good shaft for the job, and if not I'd call a professional driveshaft shop and have one built pronto.

Grigg

I drive my 1 Ton every day, 35 miles, often with a ton in it. I find that if I have any load, over say 300 lbs in the box, I use low to get her rolling. If I am on any kind of a hill, I use low gear, often, on steep hills from a dead stop, I'm just rolling by the time I get into second gear. Otherwise there is just too much clutch slipping to suit me. I do find, as others that when unloaded, I could really use another gear. I don't run over 50 mph, as the roads here are just too curvy and hilly to go faster. I do tend to run the engine up pretty fast, so when shifting, it falls back into the power-band. One of the great advantages of the 5.14, is that I can chugg along at 25 mph in forth. Then I can hear the radio finally!

So while were on this topic, what is the aprox rpm that is safe for a splash system 216? I have a ton with 5.14gears and 7.50x17 singles. seems about 45 mph is really twisting.

My guess is 2,500 rpm tops if you want it to last.
But that's judging from my '55 235 and from other 235's that run a little faster with no problems. I haven't driven far in a 216 truck to have a good answer for you.

Grigg

It seems to me, that my truck is turning around 2200 or so, at 50 mph. I have 7.50x17 tires, which are pretty tall. I also seem to remember that the standard oil "troughs" are good for about 3000 rpm, after which the puddle doesn't have time to reform. Our friends at Chev have thought of this though, that's what the sprayer things are for. I know people use to race the so called splash oilers up to 6000 rpm. I think though, that might be a little excessive. If your engine is in good shape, I don't see why you couldn't run at 55 mph all day long. But, I think your mileage might suffer. My truck does really well (milage-wise) at about 30 mph.
There is a rpm calculator at Randy's Ring and Pinion website, that you can use to calculate your various rpms at different speeds, and with different tire sizes.

Even if you have a full pressure 235, they really aren't designed, IMHO, to run at high rpms, without consequences. My old Pontiac is full pressure, and it doesn't really like to go much faster than 50 mph.

I think to go really fast all day you might want to change the gears out. But, the thing to remember is, you can only stop as fast as your tires will hold. If your drums will lock up all four, you really can't do better than that. Oops! I'm wandering again.

I meant to say Captain Tractor, Nice truck!

Some of the old timers here, guys who drove these trucks when they were almost new, claim they used to turn them fast enough to run 50 and 60 and sometimes more.

While mileage would sure suffer and an already worn motor would be at greater risk, I suspect a fresh 216 will run much faster than many of us would be comfortable listening to.

And I do think its listening that is the issue. Those of us who grew up with pressure oil and quiet hydraulic lifters and lots of insulation aren't accustomed to the noise these old motors make.

I'm not suggesting you run a tired 216 at 4500 RPM, but if your motor is solid it may well be good for far faster speeds than you think. That 'really twisting' judgment is based on noise right? Put a tach on it and see what it is really doing.

I had a pro build my rear end and supply the drive shaft.

To go with an unlimited speed drive shaft I would have spent $700.

The unit I settled on was $275.

Since the suspension is stock I can not ever expect a need/reason to go over 70mph.

Is there such a thing? My guess is one approaching "unlimited" would be very short and very small diameter,(pocket size), if not smaller...
But for a useful driveshaft for a vehicle how can one be "unlimited" by speed?
The longer the length the slower you must run it before it starts to whip.
the smaller the diameter the same as above.
Wall thickness also affects speed limit, thin ones are rated slower.
If diameter is to big eventually there is a limit when it tries to come apart from the centripetal force (not likely in a vehicle application)

Just curious?

Matching a drive shaft to power and speed is a standard race car problem and I've seen formulas for calculating diameter and wall thickness at various lengths and speeds. I know of at least one online calculator aimed at the race car crowd.

Drive Shaft Calculator

While I can imagine some guy calling a drive shaft unlimited I suspect what he meant was a drive shaft with huge margins beyond the probable maximum requirements. Maybe a carbon fiber shaft?

I'd probably make the guy admit his drive shaft was not unlimited or I'd choose to go somewhere else. I don't like hyperbole from vendors.

Those formulas (and how and why to use them) are also in the Spicer driveshaft manuals found in the driveline tech tip.
I've printed the manuals and stuck them in a notebook, handy to have and easier to use than flipping "pages" on the computer..

Grigg

I just read both those documents. Very useful information! Thanks for bring that together for us.

No problem,
Glad you liked them. I found them when I was trying to figure what size driveshaft I needed for my truck. Before I found the manuals all I had to go on was other peoples opinions and guesses and mis-information. From what I've seen very few people can correctly answer a driveline setup/design question.. (not that I can either, but now I know where to go look)
Wish more people would read through those manuals, or at least look at the pictures and hopefully read a sentence or two here and there..

Grigg

Reading manuals isn't something most people want to do. It is one of the things I've been able to enjoy recently!

FWIW,right after I got my '62 and not long before I put the first 350 into it,I drove it to Carson City,cruising at about 70 mph. I guessed at the time that I was screaming the motor,but it felt okay,and with rattles,squeaks,wind noise,gear noise and a marginal exhaust system,I couldn't hear anything. It made it to Carson empty and came home with a full load of furniture and appliances without a problem. My number cruncher shows I put about 700 miles on it running 4,200 rpms. I ran it around town for about a month afterwards with no problems,decided to go to SLC in it to pick up a 350 for it. I was in less of a hurry this time so I kept it around 60 mph. Made it about 50 miles before it dropped a cylinder,and developed a REAL knock. I thought it was a dropped valve,but found later it was a burned piston and metal contamination from that ruined a rod bearing and journal.
So-maybe you can go 75,but not for long and expect it to live. (or 60,for that matter...)
Speed

I am new to this group, and just aquired a 49 gmc 250 single with 9' bed, however I have owned several modern one tons, So was looking to update the drivertrain. After reading online many threads I would say the rearend is good to go, just need to make sure you start with a good one. Brakes as far as service may be a problem, but how often do they really wear out?

So I have started the parts pyle with a 700r4/np208 gets me 30% overdrive and the extra length of the transmsision and transfer case should net me a one piece driveshaft.

Tracked down a 3/4 ton 4:56 pumpkin in a neigbors parts truck, looking to run 235/85 radials should net me a nice high way gear/rpm pulling range according to the online calc.

I have a lonely GM 350 engine sitting in the corner but was thinking of drumming up a GM 292 instead...

Second stage of the drivetain upgrade at a later date will inlcude the front axle swap to some undetermined 4x4 axle, which well net me front dics also. Most of what I have looked at online I will probably do a common GM dana 44/60 and narrow it down to look like a napco conversion, from which I still have not found actually how wide the front is on them though.

Keep the parts common and easy to find and service, as the goal is to have a good depenable driver/work horse.

Neal,

That's the very reason I've rejected the original rear on my 1-ton GMC project. The parts for it are no longer easy to find and some of them are very expensive if you can find them.

Actually I didn't want to live with the available gears either...

So if you do end up switching out the rear, please don't scrap it -- keep it or make it available to someone keeping their truck original.

Thanks,
John

Already sold one to another Stovebolt'r. I still have three of them but two of those are hold trucks up.

Put 7.50X17 tires (33" tall) on the rear end of that 5.14 axle. You'll be turning 3,000 RPM at 60 MPH. The 235 motor can handle that all day long. The 216 motor will need to rest every now and then.

I had the same issue with my 41 1 ton. I ended up with a small block 350, 700R4 transmission and 3.73 gears with 700 x 17 tires.

70 mph at 2000 rpm.