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Dana 25 disc brake swap with dana 30 parts

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Millennium falcon View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Millennium falcon Quote  Post ReplyReply Direct Link To This Post Topic: Dana 25 disc brake swap with dana 30 parts
    Posted: 24 July 2022 at 12:21pm
Here is a documentation of my disc brake conversion for a dana 25. This swap uses parts from a jeep dana 30. Below I will include pictures part numbers and years of the parts I used. While you could order all the parts separately I recommend buying a whole axle. I found a guy selling them for $75 each. I bought 2 of them. There are many different options for disc swaps.. This is just the one I happen to like. It uses cheap "jeep" parts and has 11.750" diameter vented discs and really large piston calipers what work great with the stock single reservoir master cylinder. My other jeep with this conversion can lock up the wheels on pavement without too much difficulty. Calipers and rotors for this swap are around $30 each 

Step 1) locate a dana 30 front axle. You want a 77-79 cj5/7/8 axle that has the thicker 1.125 thick rotors. the 7/8 rotor axles will not work for this swap. The thick rotor axles use a 6 bolt caliper mount that works with the dana 25 knuckles.  A quick measure of the rotor thickness will help you out at the junk yard. 
*****YOU WANT 1-1/8" ROTOR ALXES.


Step 2)

Strip them down.. This is pretty basic start at the hub and work your way in until you remove the 6 bolts that hold the caliper mount on. Save all the parts and hardware you remove. 
The parts needed from the dana 30 are....

rotors
calipers
caliper mount
spindles
hoses
hub
bearings
seal
wheel studs. 

Here are the parts i removed. 
I sand blasted my caliper mounts, and rotors. As long as they aren't warped or completely wore out you can reuse them. 


Here's everything cleaned up and ready to go! 


Step 3) 

remove all the drum brake stuff from your dana 25
Strip it all the way down to the knuckle. Its a good time to check and replace your kingpin bearings and re pack your pudding!


This is where you should end up. 


Step 4) 

This is the only "custom" part needed for this conversion. You must use the dana 30 spindle and they have a larger bearing to support the axle whereas the dana 25 uses a smaller bushing. Drive out the bearing and press in the bushing. The picture below shows the bearing after its removed and the custom bushing I pressed back in. 


Here are the dana 30 spindles. (left) on the right you can see the smaller dana 25 spindle with the small bushing. 


Parting the new bushings....


Ready to roll! 


Here are the dimensions so you can make your own. It may be something McMaster Carr carries.. I didn't look since i was able to make them. 


Pop quiz... where did that note paper come from? haha! 

Step 5)

Install the spindle and then the caliper bracket in this orientation. The clocking is important for everything to clear properly. You will need a total of twelve 3/8-24 bolts 1-1/4 long with lock washers for this install. I would use grade 5 or 8. 




Step 6) 

clean up your dana 30 hubs and install new bearings & seal. (part numbers will be at the end)


Step 7) 

press your studs back in. The rotor goes behind the hub. Dana 30 studs are not swaged and can 100% be reused if you want to. I re-use mine as long as they are not damaged. If you dont replace your rotor you will be able to skip this step. 

Step 8) 

install the hub on the spindle just as you would the dana 25. You can  use the big nuts and washers from the dana 30 or 25. they are the same. You will also be able to reuse what ever hubs or drive flanges, gasket and hardware you were using on your dana 25. You cannot use the hubs from the dana 30. 







(Part II) Coming in the next post. 




Edited by Millennium falcon - 24 July 2022 at 5:45pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Millennium falcon Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2022 at 12:50pm
Step 9) 

Pat yourself on the back, look at your awesome disc brakes and have a beer... you're doing great!




Step 10)

throw these things out... you wont need them anymore.



A question I get alot is about the wheels and spacers. I run 1" spacers to clear my 7.50-16's so its a non issue for me. 3 of my original 16x4.5 wheels fit fine without spacers but 1 of them needed at least a 1/4" spacer to clear the rivets. If you run 15" wheels from a scout or an amc cj5/7 they will not require spacers. but if you want to run 16x4.5 willys wheels I would plan to just slap some 1" spacers on just to be safe. ive run them on both my jeeps with no issues I get them on amazon for around $90 for all 4. I can share a link if anyone is interested. 

heres my blue jeep with this conversion and 1" spacers. clears everything with lots of room. 

1" aren't really that noticeable. but I totally understand that some people are anti-spacer. 


Here they are with larger 1.5" spacers I used to clear the big SxS tires you may have seen on my jeep some times. 

Step 11)

Flex hoses. Stock CJ5 hoses work perfectly. (Part numbers at the end) they even lock into the factory tabs without any problems. The banjo bolt looks like it will hit the kingpin cap but it doesnt. You can use the same hose for both sides.


 I used the little clip from the stubby drum brake hose to retain the new longer hoses.





Step 12) remove the residual valve. this is located inside your Master cylinder all the way at the front clipped into the main spring. This is an important step because it keeps too much pressure on the system for disc brakes to function properly. You can poke holes in it but I like to just remove the whole thing. If you dont your disc brakes will drag really bad.....  




Step 13) bleed the system... Im sure you can handle that on your own. 


Step 14) 

Put it all back together. 





I think that is basically all... please ask questions. I hope this helps someone out. I will be doing a rear conversion this week if anyone else is interested I will gladly share. Thank for reading!


Part numbers.




napa  bearing                      pbr35
napa  bearing                      pbr50
Wheel seal Napa                 23035
Brake pads napa                 pf-7013m
Flex hoses  rock auto          150.67015
Rotors rock auto                 3550R
Caliper advanced auto        184095 & 184096


Cheers!!!! have fun be safe! 




Edited by Millennium falcon - 24 July 2022 at 8:29pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob W Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2022 at 7:28pm
Originally posted by Millennium falcon Millennium falcon wrote:

Pop quiz... where did that note paper come from?

Cool upgrade writeup.

The Willys Reunion of course!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DeepVeer Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2022 at 8:00pm
Hi brother,

I read the whole post about this conversion.  I doing disc brake conversion all around to my cj2a.  According to your post, do I really need proportion valve and residual valve?  I know you didn't use it but I'm running dual master cylinder.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Millennium falcon Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2022 at 8:21pm
Thanks Bob! Yep I have lots of Bertram merch. Haha! 



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Millennium falcon Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2022 at 8:24pm
Originally posted by DeepVeer DeepVeer wrote:

Hi brother,

I read the whole post about this conversion.  I doing disc brake conversion all around to my cj2a.  According to your post, do I really need proportion valve and residual valve?  I know you didn't use it but I'm running dual master cylinder.

The proportioning valve is optional one of my Jeeps has an adjustable one that I have biased towards the front but I haven’t found it to be very noticeable. It stopped very controllably without it as well. So that’s up to you. 

The residual valve is already in your master cylinder and must be removed. That is the case with stock MC’s not sure about the dual reservoir mc’s. 



Edited by Millennium falcon - 25 July 2022 at 12:35am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Barry S Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2022 at 8:59pm
Very nice write up - I'm sure it's going to help a lot of folks.  I too like the confidence of disk brakes on all 4 corners. 

Great Job!

-Barry
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Millennium falcon Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2022 at 9:38pm
Originally posted by Barry S Barry S wrote:

Very nice write up - I'm sure it's going to help a lot of folks.  I too like the confidence of disk brakes on all 4 corners. 

Great Job!

-Barry

Thanks Barry! Yeah once you drive one with 4 wheel disc it’s hard to go back. I also like how easy they are to service and clean…. And they never need adjusted. 👍 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LuzonRed47 Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2022 at 10:48pm
Seth, 'how-to' instructionals are your calling card. You do 'em really well and the D30 disc-to-D25 axle one is really useful.

For those of us contemplating this upgrade, any chance you would offer your jumbo custom bushings for sale? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bobevans Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2022 at 10:50pm
Thanks Seth, awesome write up.  And even us old guys can access this info now!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Millennium falcon Quote  Post ReplyReply Direct Link To This Post Posted: 25 July 2022 at 12:39am
Originally posted by LuzonRed47 LuzonRed47 wrote:

Seth, 'how-to' instructionals are your calling card. You do 'em really well and the D30 disc-to-D25 axle one is really useful.

For those of us contemplating this upgrade, any chance you would offer your jumbo custom bushings for sale? 


Thank you! I’m glad you enjoyed it. I haven’t thought much about reproducing the bushings but it may be something I offer in the future. I’ll post updates on here if I do. Thanks! 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Millennium falcon Quote  Post ReplyReply Direct Link To This Post Posted: 25 July 2022 at 12:40am
Originally posted by bobevans bobevans wrote:

Thanks Seth, awesome write up.  And even us old guys can access this info now!
Thanks Bob! Im glad you have access to it… 😉 you seem like a pretty tech savvy self proclaimed “old guy” lol…
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Post Options Post Options   Thanks (0) Thanks(0)   Quote drm101 Quote  Post ReplyReply Direct Link To This Post Posted: 25 July 2022 at 7:38am
Thanks Seth! Very nice. I'm thinking of doing this with the Dana 27 axle in this CJ5 I am working on. I'm guessing that bushing might need to be thinner for the 27, but I won't know until I get it apart. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Millennium falcon Quote  Post ReplyReply Direct Link To This Post Posted: 25 July 2022 at 8:00am
Originally posted by drm101 drm101 wrote:

Thanks Seth! Very nice. I'm thinking of doing this with the Dana 27 axle in this CJ5 I am working on. I'm guessing that bushing might need to be thinner for the 27, but I won't know until I get it apart. 

Cool! You’ll have to double check but I’m fairly certain the axle diameter of the 27 is the same. Perhaps someone else will chime in to confirm or deny this. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rick G Quote  Post ReplyReply Direct Link To This Post Posted: 29 July 2022 at 10:00am
There are lots of disc brake conversions out there and this is one of the easiest "bolt-on" applications. Thumbs Up

Edited by Rick G - 29 July 2022 at 10:31am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Millennium falcon Quote  Post ReplyReply Direct Link To This Post Posted: 29 July 2022 at 10:16am
The problem I encountered with the dana 25 hub and spindle is that they do not property fit the caliper bracket so there is no way to correctly center things it will rely on the the bolts themselves which is a too sloppy for my tastes. That’s why I went this route. I should have taken more pictures of what happens if you attempt to use the d25 spindles. It’s a “no bueno” in my opinion 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rick G Quote  Post ReplyReply Direct Link To This Post Posted: 29 July 2022 at 10:50am
Originally posted by Millennium falcon Millennium falcon wrote:

The problem I encountered with the dana 25 hub and spindle is that they do not property fit the caliper bracket so there is no way to correctly center things it will rely on the the bolts themselves which is a too sloppy for my tastes. That’s why I went this route. I should have taken more pictures of what happens if you attempt to use the d25 spindles. It’s a “no bueno” in my opinion 

I forgot the D25 hubs are slightly different from the D30 hubs (uses thinner bearing sets).  I edited my previous post.  I thought the D25 spindle and the D30 spindle have the same dimensions outboard of the flange face, which means you could use the D30 hub with the D25 spindle with set 45 bearings and hub seal 8430-S?  

This wouldn't address the issue of centering the bracket, however.  That bracket requires the larger shoulder of the larger hub seal and set 47 bearing spindle found only on the D30 with discs.


Edited by Rick G - 29 July 2022 at 10:55am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 29 July 2022 at 11:45am
Nice write up Seth !
Yes the factory D27 bronze bushing is the same as the later D25’s.
In fact the late D25 spindles and bushings are identical to D27’s.
That said D27 uses a slightly different hub and wider wheel bearings than a D25.
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