Race a GM 14 bolt full floater?

[Stephen]

This has been floating around on another thread and I thought I'd bring it to it's own post here.

Some weight comparisons we found here:

40 spline, trussed, spooled, Sandy Cone full floater 9" with wilwood calipers and an iron dropout: 250 lbs
Detroited 14FF with disc brakes and 8 lug hubs: 385 lbs. I'm guessing that by losing the diff (replacing with a spool) and trussing the housing that you would end up near 400 lbs. This is also assuming you use a heavy steel bracket brake system, there's a LOT of weight to lose by converting to lighter brakes.

14FF:
Has some options for different lug patterns, either by modifying the factory hubs or running aftermarket alum. hubs.
Shafts are 1 9/16" 30 spline without much room to fit a larger shaft through the spindle
Wheel bearings are decent size and have a big separation
Diff has a great R&P setup with a 3rd pinion bearing and a big ring gear with good ratio availability in the range that we need for racing.
Comes with a heavy duty housing to start with.
Cheap to start with.

Problems with 14FF:
30 spline axles are equivalent or a bit stronger than a 35 spline which is pretty beefy but not like a 40 spline.
Weight
Wheelbearing nut system could probably use some help since both spindles are RH. I think this could be solved with running a solid bearing spacer and a double nut or some kind of lock system.
Cast center section is a pain to weld to compared to a sheet steel housing.
Pinion would have to be shimmed solid since they come with a crush sleeve.

Sounds like a pretty good rear end for a limited class or pre-runner on a budget to me, other opinions?

Also, I'm pretty sure I saw an ad years ago with a white lightning truck that I was sure was running a 14FF, what did class 8's run way back? Has it always been a 9" or nothing?

There is a spool available from Randy's, a better choice might be to bug Cone to get one that might be a better part, at least a lighter part. For a street driver, the Detroit is cheap, easy to install and very strong.

[Ramsey_ElWardani]

Sandy Cone does make a spool for the 14 Bolt Full-Floater 10.5inch but it is really pricy. The Suburban Prerunner below has a 14BFF in it all trussed up with plate; don’t know what ever happened to it though. I’m using a modified 14BFF in my project.

http://www.race-dezert.com/forum/attachment.php?attachmentid=834

[johnnyweb]

one other draw back to the 14 bolt is the ground clearance is about 2" lower the a 9". i use one in my blazer 4wheeler and it is constantly dragging on everything. i have not broke it yet thow! the pinion is also very low to the ground. just a couple of things to think about.

[ChuckH]

Making a custom housing would cut the weight down ( stock is about a 1/2 inch thick) and running 39 inch BFGs should give you enough clearance for racing.

Herbset has had good luck with their 14s

[Ramsey_ElWardani]

The pinion on a 14BFF is actually higher than a Ford 9 inch which has a very low pinion. The ground clearance can easily be addressed by “shaving” the bottom of the center section and would be no lower than any rearend using a 10.5” in diameter ring gear which is 1.5” in diameter greater that a 9”, thus the lower ground clearance.

[Stephen]

Light weight, cheap, strong; in this case we get cheap and strong.

Oh yeah, lets go back to that thing about the herbsts and "their 14's" Are they actually using a 14FF r&p in a custom dropout? Does anyone actually know for sure? That takes the "cheap" right out of the equation but adds lots to the "light" and some to the "strong".

[FABRICATOR]

Bolt = number of bolts in ring gear
inch = unit of measure for distance
14 bolt = 10.5" ring gear
Herbst = 14" ring gear

[ZTFab]

Herbst = 14" ring gear

Holy crap...that's not a ring gear that's another wheel....

[movindirt]

Holy crap...that's not a ring gear that's another wheel....


I was thinking the same thing....

[Stephen]

Anyone have weight info on a D60 rear? I know they're somewhat commonly raced.

[Ramsey_ElWardani]

I was talking to Sandy Cone today about another matter and asked him about this subject. He does make a mini-spool that goes in the stock carrier (open differential only) and he did make a 46 spline full spool and has some left over, as well as some 14 Bolt center sections (i.e. the tubes removed) that they use to put 4130 tubes in. They used Cone snouts and hubs to accommodate the 46 spline axles. He built them for Walker Evans and Dale White, to name a few.



14 Bolt refers to the number of bolts on the cover, not ring gear.

[14802]

mini-spool in a 14 bolt???? how long will it last..... wait are these special made cone units??

[ntsqd]

The 14bff open carrier is stout enough and large enough that the Detroit offered for them fits in the stock carrier. I would think that if a mini-spool has any chance of living in the Desert that the first choice would be a 14bff axle.

[FABRICATOR]

14 Bolt refers to the number of bolts on the cover, not ring gear.

With most differentials, the number of bolts on the cover is the same as the number in the ring gear.

[Stephen]

So it sounds like the 14ff used to be a base for some pretty cool stuff. I bet they would take a lot of abuse with 46 spline shafts in them. Kind of makes me wonder about the weight and how big a deal it is. Even with light brakes and hubs, with a 46 spline shaft (maybe tubular?) and the cast center, you're not going to get a complete rearend much under 400#. But if that's what it takes to live, that's just what it takes.

For the price range I'm talking about though, as soon as you cut the spindles off, you're out of budget and should probably start looking at building a 9". So that brings us to the weak point of the axle being the 30 spline shafts and how much will they take. That's in a new post now.

[pappawheely]

I used a 78 k5 blazer as a chase truck for years. The stock housings would flex and the axle tubes would get loose and it would destroy the bearings. I put in a 14 bolt ff from junkyard, welded the axle tubes in and never had a bit of trouble. I was hauling several hundred pounds of tools, tires, etc. but I was not traveling at race speeds (at least that's my story and I'm sticking to it). I also installed disc brakes so I could ditch the 50 lb.s each brake drums. the truck had the sm420 trans so the rear did see some abuse. The only problem I saw was axle flange bolts coming loose but safety wire solved that. You do need to grind down the lip on the bottom of the housing, it catches on everything. I noticed a lot of bottoming on 33's but 36 inch tires gave plenty of clearance.

[Ramsey_ElWardani]

We raced for years on 35 spline semi-floating Currie alloy axles and broke many of them. We figured they were good for 500 miles, but pushed them further, often until they broke. They always broke just outboard of the wheel bearings and when they did it was instantaneous. Because they broke outboard of the wheel bearing and looked like the sheered off as opposed to twisting off, I believe it was mostly the load bearing factor of a semi-floater that was the problem. Four other Class 8 trucks that I have been associated with ran Dana 60 housings from Summers Brothers. Summers Bros. starts with a new bare Dana 60 Center Section and presses in .250 or .375 wall 4130 axle tubes. The housing then gets trussed and Cone snouts welded in and Cone hubs, 40 spline gun barrel drilled axles and Mark Williams spool added to it. With CNC Calipers and rotors to complete the package, you’re looking a $5,000 to $6,000 in the thing. A comparable 9” housing made from 4130 and the same tubes, hubs, axles, etc. and a quality third member will cost about the same. The main advantage of the 60 over the 9” is the higher pinion of the 60. The truck that broke all the 35 spline semi-floater axles, now sits on a Tube Works 9” and even with the best possible sponsorship level pricing from Tube Works, Hughes Differential Systems, Rob Moore Axles, and Complete Fabrication, there is $5,500 invested in it. The reality is that there are no cheap race quality rear axle options out there. The 14Bolt axles that Sandy Cone built started with just the cast center section (just like the Summers Bros. Dana 60’s above) and 4130 axle tubes were pressed in and all the other steps done to the 60’s. The 14Bolt pinion is also higher than a 9” and is stronger than either. The pinion has three bearings on it like the 9” but they are bigger and the 10.5” ring gear is huge. What Stephen is looking for, I assume, is to take advantage of the strength and full-floater characteristics of a stock 14Bolt. I think it is worth trying, and I am in fact doing so for my Blazer project. You can get a stock 10.5” ring gear 14BFF for as little as $75.00 at Ecology or Pick Your Parts. The stock axle tubes are 3.5” in diameter and 375 wall and stronger than hell. There are after market Aluminum hubs available for them from Grady’s in 5 on 5.5” bolt pattern or the stock hubs can be used. I chose to use the stock hubs and turn them down to almost nothing and then press on aluminum adapters that are hub-centric. The only questionable parts are the stock axles. They are very strong and alloy versions are available, but only time will tell if they will hold up. For under $1,000 you can have a Full-floater rear axle that should be every bit as strong as any 35 spline Full-floater 9” that costs 3 to 4 times as much. If the stock axles don’t hold up, it would be possible to use 300 M non-flanged axles and customized drive plates to replace the flanged axles. This is what Jeremy Spirkoff did on his Stock Full Sized Championship truck that ran a stock Dana 61 Full-floater with stock hubs, drum brakes and 40 spline axles. Steve, go for it!

[FABRICATOR]

The non-floater 14 bolts (wheels bolt directly to axles) were popular in vans. Junk for off-road.

A semi-floater has axles that are splined on one end and have a bolt flange on the other. They have separate hubs like a ¾ ton, and the wheel bearings do not touch the axles.

A full floater has hubs like a ¾ ton but the axles are splined on both ends.

A high pinion is better for ground clearance but, but size for size, a low pinion will handle higher torque loads.

[ntsqd]

I had the opportunity to dissect a 14bff axle tube (it was bent - no idea how it got that way). I needed a free piece of tube for a project. The wall thickness isn't consistant. It tapers towards the spindle. The one I cut apart started at about 1/2" thick where it is pressed into the center casting and tapered to ~5/16" where the spindle was welded on (or appeared to be).

I do not know what those tubes are made of, but I could find no speed/feed/depth of cut combo that didn't shortly wipe out the edge of a cemented carbide boring bar. Chips looked like a Chro-Mo, but came off like a 300 series stainless.

[CanyonMan]

I just picked up a 3/4 ton chevy pickup that I am building into a prerunner (with time and money). Is there a way to convert a non FF to a full FF??

[ntsqd]

Likely not worth the time. 14bff's are common enough. Keep your eyes open and one will come your way cheep.
Definately do the rear disc swap with one. It's well documented on cK5.com

[Stephen]

Some clarification here:
A semifloater has the wheel and brake bolted right to the flange, they run on a single bearing of some sort right at the flange and are retained by a c-clip in the diff or a bearing plate near the axle flange at the end of the tube.

A full floater is any axle design that has a wheel hub riding on bearings and a axle shaft that transmits only torque. Whether that shaft is a flanged shaft that bolts to the wheel hub or a double splined shaft that engages some kind of drive plate on the outside, it's still a full float, just with a different type of shaft. The feature that makes it a full floater is the spindle and wheelbearings holding the weight and the shaft transmitting torque only.

I heard that CTM is building some driveplates of some sort for a 14FF so you can run double splined shafts.

So, assuming we're using this 14FF for a racing application with the stock spindles on the housing, what kind of tips and tricks do we need to look for? Safety wire on the axle flange bolts is a good example. Anyone messed around with keeping the spindle nuts tight since they're both RH threads? The 14FF should work OK since they use a woodruff key to retain the nut and as long as the key stays in place, you can't back the nut off. I've seen a wrap of safety wire on the woodruff key's retainer clip to hold it in place. Any other ideas for that one?
Grinding some on the lip is a good one too, I think as long as the housing is trussed you can take a good portion of that lip off and it has to be trussed anyway.
Shimming the pinion solid is a must
Maybe safety wire on the pinion carrier bolts
They come with a 1350 yoke but a 1410 is available, I might lean toward the 1410 just because I've deformed the ears of the 1350 yoke in my K5 over time.
Some cover beefup might be in order also, just to make sure you don't back into something and dent it into the ring gear. It would also reinforce the lower lip to keep it from peeling back. I wonder if bearing cap load bolts would be good to have in the cover? I doubt they could hurt.

[ShaneR]

I have a 1984 (I think) Chevy 1 ton dually. I have been told that the rear end in this truck came in 4 or 5 years of chevys but most people I talk to call it a Corporate 14 bolt. Is this the same rear end? I was thinking about using this rear end in a prerunner project also. The main reason I wanted this unit is because it is 5" or 6" wider than other Chevy 1 ton and 3/4 ton axles I have measured. I have 3 or 4 of the 3/4 ton units also from the same year trucks, and do not see a difference other than the width? Am I correct or do I have an odd rear end in this truck?

[Ramsey_ElWardani]

http://www.pirate4x4.com/tech/billavista/14b_bible/index.html

Some of the best info available on GM 10.5" 14bff is found here.

[FABRICATOR]

Stephen, et alia, you be right on the common trade nomenclature. My head is always in the hard core race stuff. There are at least a couple of big drag race axle makers that only refer to a double splined axle as being full floating. Moser, who calls it your way, had an interesting torque rating chart for their axles.

30 spline - 6,200 ft. lbs. (per axle)
31 spline - 7,000 ft. lbs. (per axle)
33 spline - 8,200 ft. lbs. (per axle)
35 spline - 9,600 ft. lbs. (per axle)
40 spline - 12,000 ft. lbs. (per axle)

[Stephen]

Does double spline = full floater come from buggy stuff? I could see it applied to a plunging shaft in a CV joint.
Is there any advantage to running a double splined shaft beyond the easy availablilty of super alloys? I would think that having a tiny bit more spline slop on the end could help negate any bending stress from the housing or help accomodate a slightly bent housing. It's also key in letting you run lighter full float hubs since you can use a driveplate secured by the wheel lugs that are already there.

So, looking at moser's numbers and knowing nothing about what alloy they're basing them on, we could run a 400 ft lb motor with a 5:1 reduction in the trans (1st gear + torque converter guesstimate) and a 4.56 axle gear and end up with 9120 ft-lb being (usually) split between the two shafts. So that should be barely safe, knowing that putting all the torque on one shaft doesn't happen much. That number could be padded some depending on what alloy the shafts actually are. I bet those numbers are for 1541h which is still decent material but not 4340 or 300M.

A class 8 motor at 600-700 hp should have a max of 550 ft-lb (?) with the same 5:1 in the trans and a guess of 5:1 for the rear gear would end up with 13,750 ft-lb which should snap a single 40 spline axle shaft with no problems. But 40 spline rears seem to hold up OK so at this point the lower power example from above should be pretty safe.

A GM fleetside dually rear axle should be a Dana 70 which is also 35 spline and has a big ring gear, 10.5" maybe? You can make them even wider by putting single rear wheel 14 bolt hubs on them.

[ntsqd]

The advantage I see in double splined shafts is reduced stress risers. That transition from shaft to flange is the same stress riser that semi-flanged axles have. The bending loads are obviously missing, but still.....

Also should be a less spendy part to make since the blank doesn't have to be huge (with the attendent cut grain) or a forging.

[FABRICATOR]

Lots of racing venues have axles that are splined on both ends. Some of them include drag racing, sprint cars, Modifieds, and Trophy Trucks. It is perhaps the ultimate effort toward strength, especially for something that twists a lot. It minimizes stress risers by being symmetrical in shape and temper. The splined drive plate usually bolts right where the axle flange would go. In the dezert with a spool rear, it’s easy to put all the torque on one axle. That’s why many TT’s use huge 2.25” to 2.5” axles. In comparison, Top Fuel (7,000+ HP) use 2.5” to 2.75” axles. Many things can have an appreciable affect on axles including vehicle weight, engine characteristics, drive line inertia, and suspension setup.