Disc Brake Conversion

[FordTruckGuy96]

I am looking at swapping my 5 ton axles over to disc brakes. After doing a lot of research on this forum and on the internet in general I was able to figure out which rotors/pads/calipers I needed for the swap. On an old thread I saw someone say that instead of using F550 calipers that it would be better to use 4 piston Meritor calipers off of a F750. I finally got all the parts together and when mocking them up it looks like the caliper is going to potentially rub against the studs. The rotor that I got is 6.07” tall. I am hoping that someone can let me know if I got the correct parts or if I need to get a different part number since I am using the 4 piston F750 calipers instead of the 2 piston F550 calipers. I attached pictures of the F750 caliper and pads set on the rotor.

 

[th3v3rn]

I am looking at swapping my 5 ton axles over to disc brakes. After doing a lot of research on this forum and on the internet in general I was able to figure out which rotors/pads/calipers I needed for the swap. On an old thread I saw someone say that instead of using F550 calipers that it would be better to use 4 piston Meritor calipers off of a F750. I finally got all the parts together and when mocking them up it looks like the caliper is going to potentially rub against the studs. The rotor that I got is 6.07” tall. I am hoping that someone can let me know if I got the correct parts or if I need to get a different part number since I am using the 4 piston F750 calipers instead of the 2 piston F550 calipers. I attached pictures of the F750 caliper and pads set on the rotor.

Did you ever get further in this or figure out what you need to do to get it to work?

 

[FordTruckGuy96]

So I haven't worked on it further yet, but I do plan on working on this over winter. But what I need to do is cheat the calipers over slightly and I should have enough clearance for the studs

 

[charlesmann]

@FordTruckGuy96

Are you mounting the R&C where drum and shoes were or attaching to the 3rd member at pinion input? Iv seen disk brake conversion kits for both 2.5 and 5 ton and they were mounted at the pinion input and they were dual caliper setups.

 

[FordTruckGuy96]

I was planning on following the build thread found here: https://www.tgwforums.com/post?id=5154598&trail=20

I believe he is mounting them to the pinion input.
Also looking at Gearhart Engineerings kits, I am using a different rotor than he is, as well as swapping the dual piston calipers for 4 piston calipers.

 

[charlesmann]

I was planning on following the build thread found here: https://www.tgwforums.com/post?id=5154598&trail=20

I believe he is mounting them to the pinion input.
Also looking at Gearhart Engineerings kits, I am using a different rotor than he is, as well as swapping the dual piston calipers for 4 piston calipers.

He mounted to the outside of the axles, replacing where the drums and shoes would have went.

Pinion mounted would be where the drive shafts connect to the axles. and i stand corrected, the kit offered are single caliper, but using 2 kits per axle, @ $1160 per axle, it would still give offer a similar braking capacity of having brakes on each end of an axle.

 

[FordTruckGuy96]

He mounted to the outside of the axles, replacing where the drums and shoes would have went.

Pinion mounted would be where the drive shafts connect to the axles. and i stand corrected, the kit offered are single caliper, but using 2 kits per axle, @ $1160 per axle, it would still give offer a similar braking capacity of having brakes on each end of an axle.

Sorry, I wasn't thinking when you asked the question before. I am looking at replacing the drums and shoes with a caliper and rotor. I had looked into pinion brakes before, but the disadvantage is that they are really meant for offroad use only and I plan on driving mainly on paved roads. But even though I don't have everything yet (I still need hoses/line/mounting brackets) my cost is only $550 per axle.

 

[Superthermal]

Watching with great interest.
When first considering discs I was thinking I wouldn't want to flip the rear hubs, but seeing how having them flipped hides the rotors inside the wheel far from potential "road" damage, I am sold on flipping them.
An additional benefit of flipping the hub is with the HEMTT rims I am running this would give me the same track width front and rear. With the HEMTT rims as they are the rears are tucked in just a bit compared to the front.(I am assuming here the front and rear axles are actually the same width which could be an incorrect assumption.)
This flipping the rear hub would also make the HEMTT wheel clamping bolts accessible with the tire mounted. Just o check tightness periodically for maintenance.
Concerns about rotor strength and GVWR. The LTL9000 GVWR is from 35-60,000 from what I can find, which is a good thing because the rotor specs for the front axle on the LTL9000 and the front Ford F550 appear to be the same which is very odd seeing they have such a large GVWR difference. It is important to note that all heavy hauling M800 and M900 series have drum brakes for a reason on the back. Personally I don't think I am going to be hauling much over a 5tons so a total weight of 35k or so running these discs with some heavy calipers on all 6 wheels seems decent to me.

The Dual piston caliper for the LTL9000 has 2.88 diameter pistons. (These cannot be mounted with a plate style mount welded to the axle and are for reference here only)

https://www.napaonline.com/en/p/ADC3163XD?impressionRank=1

The F750 Dual piston caliper has 73mm (2.87") diameter pistons (Physical appearance varies per year but all seem to have 73mm pistons, some have only 2 mounting bolts others have 4 but all can be plate style mounted)

https://www.partsgeek.com/d2d9ypj-ford-f750-brake-caliper.html

The only reference for the F750 4piston diameter says 70mm(2.75"). This is the one I would want to run as it has 6 total mounting bolt holes to take the sheer load where theF750 dual piston has at most 4 that I have seen. (BUT DOES IT FIT!!! that is what FordTruckGuy96 is going to find out for us soon when trying to put some studs into the rotor. (See post 1 in this thread).

LH / RH Disc Brake Caliper w/ Phenolic Piston for Ford F650 F750 2009-2013 2015 | eBay

Ford F750 2015 All Engine Left with 70 mm Piston, Rear Mount Caliper. Ford F750 2015 All Engine Right with 70 mm Piston, Forward Mount Caliper. Ford F750 2009-2013 All Engine Left with 70 mm Piston, Rear Mount Caliper.

www.ebay.com

The F550 Dual Piston caliper has 64mm (2.51") diameter pistons or 66mm pistons on some others depending on year. 2 or 4 sheer bolts.

Nugeon Brake Caliper Dual Piston Floating NUG 9918059A | Buy Online - NAPA Auto Parts

Buy Nugeon Brake Caliper Dual Piston Floating - NUG 9918059A online from NAPA Auto Parts Stores. Get deals on automotive parts, truck parts and more.

www.napaonline.com

At 1000psi that gives the Dual Piston 2.88(2.87) 6514LbF of force per piston. (about 9% more force than the 4 piston)
At 1000psi the 4 piston 70mm gets 5965 Per opposing pair ,since each pair of 5965lbf pistons only are pressing against each other. More evenly and modulated as the front piston pair clamps first giving a better "peddle feel"... or so they say but it does not double the force).

Obviously the Deuce with the 5 ton disc brake axles starts and stops fine, has only 2 sheer bolts per caliper and seems to be working fine, but a fully loaded 5 ton may not. I think the recommendation to use the 4 piston caliper has merit... BUT DOES IT FIT! We shall see.

Napa Rotor for LTL9000:

NAPA Premium Brake Rotor NB 4886839 | Buy Online - NAPA Auto Parts

Buy NAPA Premium Brake Rotor - NB 4886839 online from NAPA Auto Parts Stores. Get deals on automotive parts, truck parts and more.

www.napaonline.com

The rotor that "seems" to match the one FordTruckGuy96 has for the F550 LN7000, C8000 and a bunch of other medium commercial models:

Centric 120.79016 Disc Brake Rotor + Cross Reference | FinditParts

Centric 120.79016 Centric Premium Brake Rotor ✓ Order now for same-day shipping on eligible purchases from FinditParts.com, America's online marketplace for heavy duty parts.

www.finditparts.com

The photos are not mine but from the Bobbed Deuce on 5 ton link in the other comments above.

 

[Superthermal]

In looking more into the mounting of the disc brake 4 piston caliper. This is a snip from a video on youtube showing a brake change on an F650 with the 4 piston caliper. The plate will need to look similar. That 4 piston caliper is MONSTROUSLY large. The plate is threaded for each of the six mounting bolts.

 

[FordTruckGuy96]

In looking more into the mounting of the disc brake 4 piston caliper. This is a snip from a video on youtube showing a brake change on an F650 with the 4 piston caliper. The plate will need to look similar. That 4 piston caliper is MONSTROUSLY large. The plate is threaded for each of the six mounting bolts.

In looking more into the mounting of the disc brake 4 piston caliper. This is a snip from a video on youtube showing a brake change on an F650 with the 4 piston caliper. The plate will need to look similar. That 4 piston caliper is MONSTROUSLY large. The plate is threaded for each of the six mounting bolts.

I just got the axles pulled into the garage to start working on them. That is some interesting information that you found, and when I am able to mount them I will definitely be posting if the 4 piston caliper fits or not

 

[Superthermal]

Once you get some more info, it would be nice to know which rotors you sourced, stud bolts used etc... parts lists are always a great help. Good luck and Merry Christmas.