Official Project Franken Axle thread - 56k warning

[K5dreamer]

Ok, quick background for those who arent up to speed. I currently have a D70HD rear axle out of a 1985 K30. I want disk brakes, but need a parking brake that is reliable, and cheap. While walking around the junkyard i found the rear axle from a 1998 Chevrolet G-Van, and the rear axle from a 2000 GMC Sierra 2500 2x4.

First things first, product endorsement. While doing disassebly on the GMC axle, i broke the center pin retaining bolt in the diff. At the suggestion of 4X4HIGH here on the forums, i ordered the "Differential Pinion Shaft Lock Bolt Extractor Kit" from Fabbri Associates. I cannot recomend this tool enough. From the time that i started drilling, to the time i had the end of the broken bolt removed was literally about 60 seconds. a job I had no other known way of doing. Pics of kit and aftermath.....

as you can see from the third pic, if youre doing this on your own rear end, i would lay a rag or something down to catch the debris. this was a junkyard axle, and a gov bomb, so i couldnt care less.

 

[K5dreamer]

STEP 1: Locate donor axles (in my case i needed SRW hubs, and Disk Brakes)

SRW 14bff with drums from a 1998 Chevrolet G-van

and a 14bsf from a 2000 GMC Sierra 2500 2x4

It should be noted that there are some very big differences between the axle tubes on these two axles. Oddly enough, its the SF axle that has the most meat at the ends where the brakes mount. Im not sure if thats a drum vs. disk thing, or a SF vs. FF thing, note the pics below. and the wimpy little mounting flange on the FF, and the beefy flange on the SF.

FF

SF

The flange on the D70HD is beefier than the 14bff, but still no where as big as the SF flange.

 

[K5dreamer]

STEP 2: Get at them parts.

The FF axle was quite strait forward. Youll need a socket set to remove the axle shafts from the hubs, a small pry-tool/pick/screwdriver/pocket-knife to remove the snap ring from the lock nut, a magnet to pull out the metal key, and then either the proper six point socket, or a hammer and screwdriver to remove said lock nut from the spindle of the axle, so you can slide the hub off the spindle. the drum and shoes and such were already gone from the one i found, so that made things much easier. I bolted the axle shafts back onto the hubs to make them easier to move around. the hubs and axle shafts set me back $53. you can see them in the foreground of this pic....

The GMC axle was a bit more involved. the calipers came off easy, the rotors had some snap ring retainers on the wheel bolts that you cut off with some dykes, then the rotor slides off. Heres where it gets fun. The backing plate, which is also the parking brake assembly, and caliper mounting bracket, wont come off unless you pull the axle shafts out. To do that, you have to open the pumpkin up, remove the center pin from the differential, pop out the c-clips, and pull the axles. With the gov locker carrier, i want to clarify that you do not have to pull the metal "block" to get the axles out. it can be seen in this pic....

I spent a good 10 minutes trying to get it out, until a c-clip happend to fall out. this block (looks like the letter "I" above) stays put. removing the center pin is enough to push the axles in and gain access to the c-clips, either with a magnet, or just letting the c-clips fall out due to gravity. just make sure the window youre looking at is facing down, otherwise the c-clips wont fall out. with the axles out, undo the four 24mm nuts on the backside of the mouting flange, and remove the complete backing-plate/parking-brake/caliper mount assembly as a unit. I took one apart needlessly thinking it would help me get the bracket off. The complete assembly looks like one on the left in this picture, the one on the right has the parking brake shoes and hardware removed.

At the end of the day, your tailgate should look like this....

I got the brake lines, and both backing plate assemblies for $30.

I got the calipers, and rotors for another $53... and they are big mofo's, dual piston monsters.

 

[K5dreamer]

STEP 4: Go look at your monster Dana axles and remind yourself that this will all be worth it when your truck is uber bad ass

how yall like my 1973 Ford Bronco doghouse cover for em???

the orange is primer to keep em from rusting too bad.

 

[K5dreamer]

STEP 5: bust out the graph paper, ruler, pen, and colored markers and start doing sketches of each axle setup to plan out the attack..... and see if this hairbrained idea will even work....

14bsf with disk brakes......

14bff with drums (drum not drawn, didnt have one for measurments)

D70HD (very very rough, i didnt do any dissasembly, so the question mark signifies that i have no idea of whats actually inside the drum. but the distance from the mounting flange to the end of the hub is pretty accurate. and the most critical factor here.

and here is my mock up of where the disk brakes and SRW hub would line up on the D70HD, using the existing DRW hub as a reference. note that as long as im even remotely accurate here, ive got plenty of space to build some sort of adaptor between the mounting flange, and the backing plate assembly to mount the disk brake setup. Unless of course there is some curveball inside the D70HD drum that would prevent this from working.

WHEW!!!! all that and i worked a half day today..... not to shabby eh? good lord i need a beer.

 

[K5dreamer]

A little digging online netted me this picture of a stripped D70.... I think MTmike might recognize this shot :

From an eyeball perspective, it does look like all i need are two custom built spacers that bolt to the D70 flange, and provide the bolt holes for the backing plates, this may actually work afterall

 

[pauly383]

You should see the wheel bearings in that semi floater , will dwarf your palm

 

[K5dreamer]

You should see the wheel bearings in that semi floater , will dwarf your palm

actually that was surprising to me. given the overwhelming support for the FF axles, that SF axle had quite a surprising level of beef to it. although i would imagine the load on the FF axle being split between the two bearings allows them to safely handle the same load with smaller bearings. also, to be fair id need to look at a factory FF axle with disk brakes, it may be even more beefy.

 

[K5dreamer]

ALSO, i have the issue of wheel studs. the SRW hubs i have use metric threads, the D60 i have up front is standard. So i need to order new wheel studs that will be long enough to "bolt" the rotor to the back side of the hub, and still have enough threads to mount a wheel. At least 4in long should do.

here is the thread discussing this issue, and a link to a source for the needed wheel studs.

http://coloradok5.com/forums/showthread.php?t=259595

 

[Teck]

Would like to see how this turns out. Would like to do a setup like that on my 14b FF

 

[K5dreamer]

Ill have another update on sunday hopefully. Ill drive the wheel studs out of one of the hubs and try and mount the rotor to the backside of it, and assemble the hub/rotor/caliper/backing-plate-assembly, and put it together.

Ill pull the hub/drum/backing-plate off the D70, and do a test fit of the whole brake assembly on the D70, and maybe get some measurements for what kinda adaptor im gonna need. ive got an idea in my head.... but i need to mock everything up to be sure.

 

[K5dreamer]

UPDATE - ok, so being in car sales SUX!! i havent had a day off in a week and a half, and looks like it will be another week till i get one, so next wednsday ill be tearing into the D70HD to get measurements of the spindle and mounting flange.

Also, for mockup reasons, im going to attempt to use the wheel bolts from the D70 DRW-hub/drum assembly to put together the SRW-hub/rotor assembly, giving me the same thread count i had before (obviously) and allowing me to mock up the brake stuff.

QUESTION - Im trying to decide the best way to design the custom adaptors for this project. My technical drawing skills are pretty good, but i dunno if i trust them enough to send them to someone to build me a set of mounts. So the question is two fold...

First - what do yall think of mocking them up in wood? and then having someone translate the wooden mockups into steel?

Second - anyone here a machinist, or a vendor, that would be willing to take on the project? my woodworking skills are pretty good, but i got no means to work magic on metal.

 

[dfl701]

send them to kert, he could help you out

 

[K5dreamer]

send them to kert, he could help you out

im not fully versed in everyones real name on here.... is kert SweetK30????

 

[84zz4ss]

Kert DIY4X4.

I have spoken to him about some flanges for a 14 bolt to use the dual piston calipers and the e-brake backing plates.

 

[K5dreamer]

Kert DIY4X4.

I have spoken to him about some flanges for a 14 bolt to use the dual piston calipers and the e-brake backing plates.

brilliant, thank you sir.

 

[desertrat67]

also, to be fair id need to look at a factory FF axle with disk brakes, it may be even more beefy.

I looked under a first year HD when it was brand new on the lot to see what the feasability of swapping the disks from it over to our style 14 bolt would be. The mounting flange looked wuite a bit thicker and the mounting bolts/nuts were much larger than what our year specific axle has.

 

[Captainfab]

I know this is a year old thread, but how did this conversion work out for you K5dreamer?

 

[K5dreamer]

oh damn, sorry man, missed your question. i should probably subscribe to my own thread

ANYway, things havent moved forward very much until recently. I didnt realize i got the wrong SRW hubs until i started trying to mock everything up, mine are "slip on" style, where the drum slides onto the hub, used after 1988. they are also internally different from the ones i need. which are the "bolt on" style, where the drum is held onto the back of the hub by the wheel bolts, which were used before 1988. My axle is out of a 1984 K30 dually (dunno if thats redundant... did K30's come as SRW?)

SweetK30 has come through and sourced me some correct SRW hubs, and once i get my hands on those, and the weather co-operates, ill be able to make some significant progress and report back.

 

[sweetk30]

fyi if anyone needs backing plates for the newer disk stuff. go to tthe dealer or gmparts direct. you can get the whole thing brand new loaded. bolt on and go.

and yes i got the srw hubs old style non pop off drums.

the beginning of the body change over in 88 lead to some changes for the 14ff design. thay can come both ways and no specific year cut off. but if you have pop off the front drums its the new style . the new style has around a 1.25" shorter spindle and this = shorter spacing of the wheel bearings in the hubs. ( i found this out the hard way few years ago. )

then if you still need to remove the axle/then the whole hub/drum or rotor to get in there its the old style.

and some van axles up to around 2000 had metric studs and older hubs. non pop off style. the studs yes are 2 diffrent part #'s but the specs are all the same minus the threads. so yes you can swap them over from metric to american.

i ran the newer hubs ( for pop off drums ) and rotors on the back with no machine work needed. some kits say to machine them flat. ( i never had any vibes ) worked good no problems.

and as for studs for the 14ff there is short for srw style and long 4"+ for the drw stuff. if you want longer studs for stuff like ( disk conversion kits / or aluminum wheels ) then swap in the drw studs and have more than the correct length of threads.

hope this info helps all.