Rear Disc Brake Conversion
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Mountain Pass
Joined: Nov 2013
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Rear Disc Brake Conversion
Bear with me as I hope to be posting this question in the right spot. I've got a 1977 F100 302 RWD that has a Dana44 rear end. I think it is a 2.72. I've recently converted to a 5 speed transmission and would like to swap rear ends to something with a numerically higher rear end to take advantage of the 5 speed overdrive. My interstate RPMs in 5th gear are around 1600RPM. I picked up a pick a part rear end from a 1988 F150 4WD with a 3.55 rear end. It is a 8.8 rear end. I've done some measuring and I think the spring perches are in the right spot and the shock mounts are pretty close. So as it is I think it would be an easy swap if I stay with drum brakes. But I've been thinking about rear disc brakes. This isn't something that would have to be done but just something that I want to investigate. I've done a bunch of searches but don't have all the process figured out.
Here's what I know:
Is this a doable swap/conversion?
Here's what I know:
- Remove drums and axles from 88 F150 rear end
- Get an 99-01 Explorer with disc brakes and remove the backing plate, caliper, parking brake, cables and misc components
- Install explorer backing plate and parking brake
- Most likely have to grind down axle flange so explorer rotor will fit over the F150 axle flange
- I need a parking brake and don't want to do the GM caddy parking brake swap.
- The Explorer rotor hub register diameter is 2.81" while the F150 axle hub is 3.44".
- The 99 Expedition (big SUV) has a rotor hub register diameter of 3.44" but the rotor has a total diameter of 13.15". This seems to be too tight to fit the caliper in with my 15" tires.
- I don't think I can take the axles out of the Explorer and use them in the F150 because the Explorer is narrower.
- The Explorer rotor is 5x4.5 while the F150 is 5x5.5. This would be easy enough to re-drill.
Is this a doable swap/conversion?
FTE Chapter Leader
Joined: May 2006
Posts: 12,338
Likes: 1,314
From: Central Mississippi
I've been dabbling with this for a while.
I picked up a complete OBS 3.55 LS axle for about $35 & all the Explorer (99) parts for about $50.
I had the rotors drilled 5 on 5.5 & opened up to the 150's hub diameter for $75.
When I replace the bearings & rebuild the LS, I'll pop it in.
Can't say about your 77 spring perches.
Mock up pics here:
https://www.ford-trucks.com/g/album/4851613
Good luck with your project.
I picked up a complete OBS 3.55 LS axle for about $35 & all the Explorer (99) parts for about $50.
I had the rotors drilled 5 on 5.5 & opened up to the 150's hub diameter for $75.
When I replace the bearings & rebuild the LS, I'll pop it in.
Can't say about your 77 spring perches.
Mock up pics here:
https://www.ford-trucks.com/g/album/4851613
Good luck with your project.
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Mountain Pass
Joined: Nov 2013
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Likes: 10
Thanks for the info. So it looks like I'm on the right track. I was really hoping that I could find an existing rotor with the right hub register diameter. I could've drilled the bolt pattern myself. But oh well.
You had your rotors drilled and the hub widened by a local machine shop?
Where were you able to pick up those parts for so cheap? That looks like a good deal.
You had your rotors drilled and the hub widened by a local machine shop?
Where were you able to pick up those parts for so cheap? That looks like a good deal.
FTE Chapter Leader
Joined: May 2006
Posts: 12,338
Likes: 1,314
From: Central Mississippi
I have a "Pull-A-Part" (TM) yard nearby which uses flat rate (one price for specific type parts) pricing.
Yes, I had them done, although there are many suppliers that you can order "spec" rotors from.
You can also re-drill or order spec shafts that go for more common 5 on 4.5 pattern with a smaller hub opening.
There's a guy here who has done that for just the increase in wheel availability.
Yes, I had them done, although there are many suppliers that you can order "spec" rotors from.
You can also re-drill or order spec shafts that go for more common 5 on 4.5 pattern with a smaller hub opening.
There's a guy here who has done that for just the increase in wheel availability.
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Mountain Pass
Joined: Nov 2013
Posts: 243
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My pick a part wants $30 for a rotor. $18 for a caliper. $185 for rear end (D to D).
$30 for a rotor is outrageous for a used one. I can get a new one for that price.
I was looking at the front rotor to see if it was a possibility. The biggest difference seems to be the thickness. The explorer is about 0.47" thick while the 77 F100 front rotor is 1.19" thick. I doubt the caliper could handle that thickness. I'm going to do some looking at my truck over the weekend.
$30 for a rotor is outrageous for a used one. I can get a new one for that price.
I was looking at the front rotor to see if it was a possibility. The biggest difference seems to be the thickness. The explorer is about 0.47" thick while the 77 F100 front rotor is 1.19" thick. I doubt the caliper could handle that thickness. I'm going to do some looking at my truck over the weekend.
Temporarily Deactivated
Joined: Aug 2003
Posts: 1,859
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Didn't late 90's f150s have rear disks? Is there a direct swap like that? Before they changed to metric lugs?
Just curious, if you could get better gearing and disk brakes, why not. Was limited slip on f150s?
Most trucks run empty and the weight distribution makes rear brakes almost useless anyway, just curious.
Just curious, if you could get better gearing and disk brakes, why not. Was limited slip on f150s?
Most trucks run empty and the weight distribution makes rear brakes almost useless anyway, just curious.
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FTE Chapter Leader
Joined: May 2006
Posts: 12,338
Likes: 1,314
From: Central Mississippi
In all the research I've done, there are no 100% bolt on stock Ford discs (in any combination of stock parts) for a 5 on 5.5. for an 8.8 truck.
I got the info from a guy who had a cup of coffee here years back who did it on his Bronco & loved it.
I figure I'll use it a while & dig into some other model sizes & options as time presents.
I got the info from a guy who had a cup of coffee here years back who did it on his Bronco & loved it.
I figure I'll use it a while & dig into some other model sizes & options as time presents.
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Posting Guru
Joined: May 2010
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From: Central Indiana
Didn't late 90's f150s have rear disks? Is there a direct swap like that? Before they changed to metric lugs?
Just curious, if you could get better gearing and disk brakes, why not. Was limited slip on f150s?
Most trucks run empty and the weight distribution makes rear brakes almost useless anyway, just curious.
Just curious, if you could get better gearing and disk brakes, why not. Was limited slip on f150s?
Most trucks run empty and the weight distribution makes rear brakes almost useless anyway, just curious.
If I were looking to increase my stopping power, the front end would get my attention. I would go to 17" wheels, then get a big rotor and caliper combo from Wilwood. That, or get the rotor from Wilwood and adapt a 3/4 ton front caliper onto my spindles. the back brakes on a 1/2 ton truck when empty are just to keep the truck straight in a panic stop.
Just my $0.02 USD worth. YMMV.
Senior User
Joined: Sep 2011
Posts: 442
Likes: 1
From: Roanoke, VA
Well, you're the first one to get the mis-perceived need for rear discs. Most of the braking (70%+) is on the front brakes. Why futz with a rear disc conversion when bigger multi-piston calipers and larger rotors on the front would be more effective? The only reason newer trucks have disc brakes on the rear axle is due to bean counters run the assembly line. Disc brakes have fewer moving parts (the exception is Explorer-style discs with internal drum parking brakes), they are quicker to assemble on the axle and have a lower initial cost.
If I were looking to increase my stopping power, the front end would get my attention. I would go to 17" wheels, then get a big rotor and caliper combo from Wilwood. That, or get the rotor from Wilwood and adapt a 3/4 ton front caliper onto my spindles. the back brakes on a 1/2 ton truck when empty are just to keep the truck straight in a panic stop.
Just my $0.02 USD worth. YMMV.
If I were looking to increase my stopping power, the front end would get my attention. I would go to 17" wheels, then get a big rotor and caliper combo from Wilwood. That, or get the rotor from Wilwood and adapt a 3/4 ton front caliper onto my spindles. the back brakes on a 1/2 ton truck when empty are just to keep the truck straight in a panic stop.
Just my $0.02 USD worth. YMMV.
My rear drums on my truck warp as well. Infact I just put new ones on. My rears are extremely touchy. Always have been. Lock up very quickly. The ABS is non existent on the rear since I had to swap the carrier and the tone ring is gone. But it didn't work before that anyway.
All that so say I'd love rear discs. But it's pretty low on the priority list. Lots of other things to fix before I tackle upgrades.
Temporarily Deactivated
Joined: Aug 2003
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Poor maintenance comes up a lot when drum brakes are the subject.
Most people don't want to learn, don't want to understand. Want to blame something else, want to blame someone else.
Print a picture of your brakes. Do them one side at a time so you can look at the other side for reference.
Engineers and planners thought better brakes would make vehicles safer, make driving safer. They made drivers more careless instead.
Most people don't want to learn, don't want to understand. Want to blame something else, want to blame someone else.
Print a picture of your brakes. Do them one side at a time so you can look at the other side for reference.
Engineers and planners thought better brakes would make vehicles safer, make driving safer. They made drivers more careless instead.
Senior User
Joined: Sep 2011
Posts: 442
Likes: 1
From: Roanoke, VA
Poor maintenance comes up a lot when drum brakes are the subject.
Most people don't want to learn, don't want to understand. Want to blame something else, want to blame someone else.
Print a picture of your brakes. Do them one side at a time so you can look at the other side for reference.
Engineers and planners thought better brakes would make vehicles safer, make driving safer. They made drivers more careless instead.
Most people don't want to learn, don't want to understand. Want to blame something else, want to blame someone else.
Print a picture of your brakes. Do them one side at a time so you can look at the other side for reference.
Engineers and planners thought better brakes would make vehicles safer, make driving safer. They made drivers more careless instead.
Logistics Pro
Joined: Aug 2010
Posts: 3,716
Likes: 583
From: Chillicothe
Make something idiot proof and nature just makes a better idiot.
Laughing Gas
Joined: Oct 2014
Posts: 946
Likes: 186
From: Carnation, Wah
Personally, I dislike working on drums,
so I'm guilty of not keeping them in top shape.
But it's not enough motivation to swap.
I have gotten in trouble using one side as a guide-
but, then, my brain dislikes mirrors, too. The cellphone
pic works a lot better for me...
t
Mountain Pass
Joined: Dec 2004
Posts: 177
Likes: 24
From: Vancouver
Not available
Well, you're the first one to get the mis-perceived need for rear discs. Most of the braking (70%+) is on the front brakes. Why futz with a rear disc conversion when bigger multi-piston calipers and larger rotors on the front would be more effective? The only reason newer trucks have disc brakes on the rear axle is due to bean counters run the assembly line. Disc brakes have fewer moving parts (the exception is Explorer-style discs with internal drum parking brakes), they are quicker to assemble on the axle and have a lower initial cost.
If I were looking to increase my stopping power, the front end would get my attention. I would go to 17" wheels, then get a big rotor and caliper combo from Wilwood. That, or get the rotor from Wilwood and adapt a 3/4 ton front caliper onto my spindles. the back brakes on a 1/2 ton truck when empty are just to keep the truck straight in a panic stop.
Just my $0.02 USD worth. YMMV.
If I were looking to increase my stopping power, the front end would get my attention. I would go to 17" wheels, then get a big rotor and caliper combo from Wilwood. That, or get the rotor from Wilwood and adapt a 3/4 ton front caliper onto my spindles. the back brakes on a 1/2 ton truck when empty are just to keep the truck straight in a panic stop.
Just my $0.02 USD worth. YMMV.
I know this is an old thread, but as an owner of a 1990 f150 4x4 302 lariat, I was curious as to the company thst you mention as I tow a boat.
its not that heavy a boat 2500lbs, but brakes are first and foremost for me so I went to wilwood ( thanks I never heard of them before).
apparently, there is no longer an immediate bolt on upgrade to the front brakes, guess i am 15 years late looking at this thread.
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