how to shave weight on rocks????

[patooyee]

It seems every conversation about making rockwells lighter inevitably tuns into a rockwell hybrid conversation. That should say something right there. I'm obviously a big fan of rockwells but I sadly admit that there is little to nothing that can be done to them to make them equal in weight to a ton.

Since the conversation seems to have shifted though, I decided to get my box of axles down off the shelf and do some comparisons. I'll post pics later but here are my observations comparing a bare d80 housing to a bare 14-bolt housing. I wanted to get the numbers posted now before I forget them but I am still at the shop tethering internet and uploading pics is slow.

- Ground clearance is within .25" of one another. From bottom of dif to bottom of axle tube both measure right at 5". The 80 has bigger axle tubes by about .5" though. The difference in axle tube radius is why I say that a d80 is about .25" worse ground clearance. That makes sense though since the 80 ring gear is .25" radius larger. Both axles are completely stock, unshaved. Both could be shaved to gain more.

- The only scale I have here wouldn't register that small a weight but just judging by hand, they are about the same. The 14-bolt is surprisingly heavy for its size. I don't know if the iron used in the 14-bolt casting is denser or something? I don't even know if that is possible ...

- If you are making a hybrid front passenger drop axle the 80 will give you about 1" more axle tube on the short side. This may or may not be important to the builder but rockwell outers are wider than 60 outers so if you need some axle tube over on that side that 1" becomes even more important with rockwell outers.

- The 80 pinion is slightly longer, but not by much. Definitely not enough to be an important factor in deciding between the two. I would guess they are within 3" of one another.

- You'll see in the pics later but the 80 housing is substantially beefier.

- Other than the lip at the bottom, both the bottom side of the diffs are fairly smooth. The 80 definitely has less of a lip though.

And just for whoever said that a rockwell bull gear is 9" dia., I measured one I had out of the axle. It's about 10.5" OD. I believe the few rockwell gearsets that have broken tend to the at the ring and pinion though. The top gearset ratio in a stock rockwell is about 2.44 : 1. The bottom gearset ratio is about 2.75 : 1. Is the overall gear reduction being shared by 2 gear sets the reason rockwell gears tend to hold up better than tons seem to?

J. J.

 

[patooyee]

I'm not understanding what light preload and polished gears do for weight?

Nothing. They increase gear efficiency and therefore decrease parasitic loss through the axle.

J. J.

 

[xjpaddler]

Even if you did all of that no one could afford it. Im breaking shafts like crazy I may try the rcv shafts im sure there a lifts lighter than the ouversons but I don't know about strengths

what motor and tire size?? also which shafts???

 

[xjpaddler]

looking forward to the picsJ.J. what would you think to be minimum thickness for a housing. Seams that you could go lihter on the topside on the tubes. I know 3/8 seems to be the a standard on linkmounts, but I would think with the proper gussets and doublers you could go lighter there as well.

ive convinced myself to stay with the rocks. its going to take me a long time to build them, but I have a few ideas ive not seen yet, they may work and they may not we will just have to see.

 

[doctordick]

A Rock will be way less likely to break gears because of the double reduction. Lower numerical ratio (higher geared) puts more pinion teeth in contact with the ring gear. A 14bolt will be less likely to break gears than a D80 because of the shorter pinion shaft and the pinion support bearing which the Dana doesn't have. $0.02

 

[TBItoy]

Nothing. They increase gear efficiency and therefore decrease parasitic loss through the axle.

J. J.

exactly, thanks jj

Also, running a lower viscosity gear oil like a 75w90 will save a surprising amount of parasitic loss compared to say a 140 weight oil.

 

[patooyee]

A 14bolt will be less likely to break gears than a D80 because of the shorter pinion shaft and the pinion support bearing which the Dana doesn't have. $0.02

I'm no longer certain about this. Steve Gerstner seems to feel very strongly that a d80 is stronger despite the 14-bolt's extra bearing due to the contact angles of the gears and the support bearing spacing. He has built several 80's to replace broken 14-bolts in his customers' mud trucks. He said he had one who busted seven 14-bolt gearsets in a row and went to an 80 to solve it. I'm not a differential engineer so I have to put faith in what those who claim to be say. He claims that the 80 is the first computer-designed gearset and much stronger as a result. The bearings in a 14-bolt are MUCH closer together than an 80 which makes the 80's load rating much higher and in theory the 14-bolt's shorter pinion shaft will twist less before snapping and the 80's longer shaft will twist more. (Why people break so many more stub and short-side axle shafts than long.) The 80 has a microscopically larger pinion shaft with more splines which makes the minor dia. larger than the 14-bolt's. He also claims that the design of the 14-bolt was directly copied from the Ford 9". This makes sense when you see the two pinions of equal ratios sitting next to one another. The gear portions are very nearly identical in size and shape. He argues that if you want a 9" pinion with a larger ring gear and a design that was done by hand back in the 50's, get a 14-bolt. But if you want something that will hold up, has genuine mass, and was designed recently with computers get an 80.

I think both are strong enough for what we do and 14-bolts are cheap. But I am willing to experiment with 80's personally as I do believe they are AT LEAST as strong as 14-bolts if not stronger and they don't have many more associated drawbacks.

I have a d80 5.38 gearset sitting here. I wish I had a 5.13 or 5.38 14-bolt to compare it to ...

Finally, Chevy seems to agree with Steve because in all their higher load rated 1-tons they replaced the 14-bolt with an 80 when they easily could have just continued putting 14-bolts in them.

J. J.

 

[B Gillespie]

Good info J.J.

 

[doctordick]

Good info J.J.

Mos def as the :afro:say I would love to set the two side by side and tear them down. I don't know if GM still owns a big chunk of AAM, but the fact that GM switched is telling.

 

[fordcontraption01]

what motor and tire size?? also which shafts???

. It's a 302 ford with 47 ltbs stock shafts broke 9 stubshafts 3 longsides and 4 shortsides never had a ujoint break even when the needle bearings gave out

 

[patooyee]

I tried to line these up by pinion centerline to demonstrate the extra inch or so of axle tube you get on a front pass drop hybrid axle with the 80. It also shows the extra housing beef overall. The other advantage of the 80 is that it has a built-in speed sensor boss which is useful for EFI engines. Even if you don't have an EFI engine, you can run the signal off that sensor directly to an aftermarket digital speedo to get your speed as you are hauling past all your buddies.

14-bolt lip.

80 lip.

This pic is deceiving because there is a shock bracket that you can't see on the other side of the 80 housing that is holding the 80 up off the ground 2 - 3 inches. The 14-bolt is sitting flat on the dif cover flange. If the 80 was sitting flat like the 14-bolt the pinion would be 2 - 3" lower.

Left to right: d70hd 4.56, 14-bolt 3.73, d80 5.38. I didn't really want to post this because the differences are so drastic as a result of the different ratios. I would really like to see a 14-bolt 5.38 next to my d80 5.38 but these are all the gears I have for these axles. But it is worth noting the wider / longer teeth on the 80 ring gear as it spreads the load out over a greater surface area than the 70 or the 14-bolt.

Just for shits and giggles, d80 applications up through 1999:

605303 FORD 80 REAR 1988 F-350 SUPER DUTY
605400 FORD 80 REAR 1989 F-350 SUPER DUTY
605445 FORD 80 REAR 1990-91 1/2 F-350 SUPER DUTY
605461 FORD 80 REAR 1992-93 1/2 F-450 CHASSIS-DRW-FULLFLOAT
605499 GM 80 REAR 1992 MOTOR HOME/DISC BRAKES - 80
605524 GM 80 REAR 1992 1/2-93 1/2 GMT 455 - 80
605526 GM 80 REAR 1992 1/2-93 1/2 P-TRUCK - 80
605527 GM 80 REAR 1992 1/2-93 1/2 P-TRUCK - 80
605575 GM 80 REAR 1993-93 1/2 GMT 455 - 80
605592 CHRY 80 REAR 1994-95 1/2 D3500
605593 CHRY 80 REAR 1994-95 1/2 D3500
605594 CHRY 80 REAR 1994-95 1/2 D/W3500
605595 CHRY 80 REAR 1994-95 1/2 D2500
605596 CHRY 80 REAR 1994-95 1/2 W2500
605601 GM 80 REAR 1993-96 1/2 MOTOR HOME/DISC BRAKES - 80
605632 FORD 80 REAR 1993-94 1/2 F-450 CHASSIS-DRW-FULL FLOAT
605638 GM 80 REAR 1994-95 1/2 W2500
605638 GM 80 REAR 1994 1/2-95 1/2 P-TRUCK - 80
605643 GM 80 REAR 1993 1/2-95 1/2 P-TRUCK - 80
605644 GM 80 REAR 1993-95 1/2 P-TRUCK - 80
605649 GM 80 REAR 1995-95 1/2 GMT 455 - 80
605691 GM 80 REAR 1995-95 1/2 GMT 455 - 80
605695 GM 80 REAR 1994 1/2-95 1/2 GMT 455 - 80
605712 GM 80 REAR 1994 1/2-95 1/2 P-TRUCK - 80
605717 FORD 80 REAR 1995-95 1/2 F-450 CHASSIS-DRW-FULL FLOAT
605718 CHRY 80 REAR 1995-97 SWEPTLINE VEHICLE
605719 GM 80 REAR 1995-95 1/2 MOTOR HOME/DISC BRAKES - 80
605745 GM 80 REAR 1994 1/2-95 1/2 P-TRUCK - 80
605753 GM 80 REAR 1995 1/2-95 1/2 GMT 455 - 80
605767 GM 80 REAR 1995-95 1/2 P-TRUCK - 80
605783 GM 80 REAR 1995-95 1/2 P-TRUCK - 80
605788 CHRY 80 REAR 1996-96 1/2 D3500
605789 CHRY 80 REAR 1996-96 1/2 D3500
605790 CHRY 80 REAR 1996-96 1/2 D/W3500
605791 CHRY 80 REAR 1996-96 1/2 D2500
605792 CHRY 80 REAR 1996 1/2 D2500
605807 FORD 80 REAR 1997-98 E-350 DRW CHASSIS - FULL FLOAT
605810 GM 80 REAR 1996-96 1/2 P-TRUCK - 80
605811 GM 80 REAR 1996-96 1/2 P-TRUCK - 80
605812 GM 80 REAR 1996-98 P-TRUCK - 80
605813 GM 80 REAR 1996 1/2 P-TRUCK - 80
605814 GM 80 REAR 1996-98 P-TRUCK - 80
605815 GM 80 REAR 1996-98 P-TRUCK - 80
605816 GM 80 REAR 1996-98 P-TRUCK - 80
605817 GM 80 REAR 1996-96 1/2 P-TRUCK - 80
605818 GM 80 REAR 1996-96 1/2 P-TRUCK - 80
605831 FORD 80 REAR 1996-98 F-450 CHASSIS-DRW-FULL FLOAT
605834 FORD 80 REAR 1996 E-350 DRW CHASSIS - FULL FLOAT
605838 GM 80 REAR 1996 1/2-97 P-TRUCK - 80
605839 GM 80 REAR 1996 1/2-97 P-TRUCK - 80
605840 GM 80 REAR 1996 1/2-97 P-TRUCK - 80
605858 GM 80 REAR 1996 1/2 GMT 455 - 80
605867 GM 80 REAR 1996-99 GMT 455 - 80
605868 GM 80 REAR 1996-98 GMT 455 - 80
605869 GM 80 REAR 1996-98 GMT 455 - 80
605896 GM 80 REAR 1996 1/2-97 P-TRUCK - 80
605902 CHRY 80 REAR 1997 D3500
605903 CHRY 80 REAR 1997 D3500
605904 CHRY 80 REAR 1997 D/W3500
605905 CHRY 80 REAR 1997 D2500
605906 CHRY 80 REAR 1997 D2500
605924 FORD 80 REAR 1998 1/2-99 F-350 CHASSIS-DRW-FULL FLOAT
605925 FORD 80 REAR 1998 1/2-99 F-450 CHASSIS-DRW-FULL FLOAT
605926 FORD 80 REAR 1998 1/2-99 F-350 PICK-UP DRW-FULL FLOAT
605942 FORD 80 REAR 1998 1/2-99 F-350 CHASSIS-DRW-FULL FLOAT
605944 FORD 80 REAR 199 1/2 F-450 MOTOR HOME - DRW - FULL FLOAT
605975 CHRY 80 REAR 1997 1/2 D3500
605976 CHRY 80 REAR 1997 1/2 D3500
605977 CHRY 80 REAR 1997 1/2 D/W3500
605982 CHRY 80 REAR 1998-98 1/2 D3500
605983 CHRY 80 REAR 1998-98 1/2 D3500
605984 CHRY 80 REAR 1998-98 1/2 D/W3500
605985 CHRY 80 REAR 1998-98 1/2 D2500
606040 GM 80 REAR 1997-99 P-TRUCK - 80
606041 GM 80 REAR 1997-99 P-TRUCK - 80
606042 GM 80 REAR 1997-99 P-TRUCK - 80
606043 GM 80 REAR 1997-99 P-TRUCK - 80
606056 CHRY 80 REAR 1997 1/2 W2500
606064 CHRY 80 REAR 1998-98 1/2 W2500
606073 GM 80 REAR 1998 1/2-99 GMT 455 - 80
606074 GM 80 REAR 1998 1/2-99 GMT 455 - 80
606076 FORD 80 REAR 1998 1/2 E-350 SUPER DUTY - DRW - FULL FLOAT
606123 GM 80 REAR 1998 1/2-99 GMT 455 - 80
606144 FORD 80 REAR 1999 E-350 SUPER DUTY - DRW - FULL FLOAT
606201 GM 80 REAR 1999 1/2 P-TRUCK - 80
606202 GM 80 REAR 1999 1/2 P-TRUCK - 80
606203 GM 80 REAR 1999 1/2 P-TRUCK - 80
606204 GM 80 REAR 1999 1/2 P-TRUCK - 80 WIDETRACK
606211 GM 80 REAR 1999 1/2 GMT 455 - 80
606212 GM 80 REAR 1999 1/2 GMT 455 - 80 WIDETRACK
606213 GM 80 REAR 1999 1/2 GMT 455 - 80
606214 GM 80 REAR 1999 1/2 GMT 455 - 80

J. J.

 

[ridenrace6]

I'm not understanding what light preload and polished gears do for weight?

or the cryod bearings

 

[TBItoy]

or the cryod bearings

Yall are some non-reading motha ****ers. The post said shave weight and require less power to turn...

The cryod bearings would help the micro finish of the bearing rollers, with lighter preload on the bearings, and lower viscosity oil, a lot of parasitic loss can be saved

 

[doctordick]

That's some good stuff, thanks for posting up those pics. That d80 ring gear is a HOG DADDY! (Alabama for big) Question is do you want to break teeth due to pinion deflection or break pinion shafts. Looks like the D80 does the best job of addressing both issues.

 

[patooyee]

Question is do you want to break teeth due to pinion deflection or break pinion shafts. Looks like the D80 does the best job of addressing both issues.

I don't know that for sure, just what Steve says. I'm not trying to sway opinion here. It just seems like, when people start talking about 14-bolts vs. 80's, there is very little 80 tech because there are fewer of them out there to actually dissect and inspect. I'm just trying to fill that void. I couldn't ever find any info about 80's so I said, "Screw it," and bought two just to find out for myself.

And pinion deflection may not be the issue when teeth break anyway. Some good discussion on that has gone on Pirate recently in reference to 60's, 70's, and 9" ring gear bolts loosening. The fact that they do indicates that the carrier / ring gear is what is flexing and an extra pinion bearing does nothing to fix that. That is why Currie is building a HP70 housing right now that has a load bolt to support the carrier at the pinion and not a pinion nose bearing. The fact that it doesn't seem to happen with 14-bolts could be because the 14-bolt carrier is so much thicker than the 9" / Dana carriers. If that was the case, the 80 also has that base covered because the ring gear is WAAAAY thicker than a 14-bolt or 70. I should have snapped a side profile, but that 80 ring gear is a good .5 - 1" thicker than the two gears sitting next to it.

Its actually kind of neat to think about this stuff to me and watch how the manufacturers changed the designs through the years to accommodate what they learn. Its neat to me how small, subtle changes result in large gains. I would give a lot of money to be a part of Spicer's destructive testing department.

J. J.

 

[Elliott]

Yall are some non-reading motha ****ers. The post said shave weight and require less power to turn...

The cryod bearings would help the micro finish of the bearing rollers, with lighter preload on the bearings, and lower viscosity oil, a lot of parasitic loss can be saved

Your about a dumb ass over thinking engineer like most others, the ****ing post says how to shave weight nothing about less power to turn, learn to read before you open ya trap!

 

[TBItoy]

Elliot.^^^^^ READ BELOW.

Theres alot of stuff you can do to the inside of the third memeber to reduce weight and reduce the amount of power needed to turn the double reduction unit.

Considering this is the post I quoted and responded to when I questioned and gave ideas on power savings, I believe you to be incorrect sir

 

[TBItoy]

Edit, Nevermind. I asked about AAM11.5 hybrids, but found where JJ posted on pirate about them...

 

[fl-krawler]

I acheived a 40lb weight reduction on my rockwell housings by having the knuckles machined and drilled, and the housings retubed with 1/4" wall square tube

I also made a switch to super 8 hubs which are 9lbs lighter per hub. That alone is worth 58lbs per axle total. In the next week or so, I will be purchasing a set of 16 spline gun drilled shafts, which should drop another 5-7lbs per shaft. I have caught alot of **** for choosing to go this route, but in the end I feel it will be worth it, and if it doesnt work or prove to be reliable, its easy to go back to a conventional setup. Even with all the cash I have thrown at my axles, I will still be arguably stronger and lighter than a stock rockwell, and have considerably less cash invested compared to alot of the bling hybrid axles out right now.

 

[TURNEROFFROAD]

That is SWEETNESS right there!!!

Please keep us posted on this!!!!!