Ford 9" Axle Offset For Wilwood Brakes

[duffymahoney]

I have a stock 1977 rear end. I cut the ends off and added the big bearing ends and 31 spline axles years ago. Wilwood makes their rear kit for either 2.00 or 2.36 offset, I have an oddball axle offsets of 2.125", what I can't figure out is how this offset is set? Is it from the axle design? How far the bearings are pressed on? Spline depth? From what I can see, the axles are semi floating?

I ended up buying the 2.36 kit, thinking I could simply space out the bracket, but that won't work, the drum parking brake ends up hitting the back side of the arp wheel studs. I can get bearing spacers, that push out the axles, but I don't have enough spline left to space it out the .235 I need. I have roughly 1" of spline engagement now, so spacing out a 1/4" isn't an option.

Any thoughts?

To make things worse, I narrowed my rear end years ago to clear 285/70-17s, but now I don't have that setup, I run .25" spacers, which gives me the look and clearance I like. Moving the axles out that amount and spacers will give me roughly .5" out from my cut off of 1" per side. Which might be even better.

I can't seem to find any axles that state 2.36 offset or anything like that. Is the offset from axles, bearings, or even the welded on ends?

 

[jamesroney]

I have a stock 1977 rear end. I cut the ends off and added the big bearing ends and 31 spline axles years ago. Wilwood makes their rear kit for either 2.00 or 2.36 offset, I have an oddball axle offsets of 2.125", what I can't figure out is how this offset is set? Is it from the axle design? How far the bearings are pressed on? Spline depth? From what I can see, the axles are semi floating?

I ended up buying the 2.36 kit, thinking I could simply space out the bracket, but that won't work, the drum parking brake ends up hitting the back side of the arp wheel studs. I can get bearing spacers, that push out the axles, but I don't have enough spline left to space it out the .235 I need. I have roughly 1" of spline engagement now, so spacing out a 1/4" isn't an option.

Any thoughts?

To make things worse, I narrowed my rear end years ago to clear 285/70-17s, but now I don't have that setup, I run .25" spacers, which gives me the look and clearance I like. Moving the axles out that amount and spacers will give me roughly .5" out from my cut off of 1" per side. Which might be even better.

I can't seem to find any axles that state 2.36 offset or anything like that. Is the offset from axles, bearings, or even the welded on ends?

The axle offset is determined by the machined shoulder on the axle itself. As you have figured out, there are three brake offsets for the Bronco. The normal 11 inch one is 1-7/8, and the other normal one is 2-3/8. All of the decimal conversion crap just confuses the issue. The third brake offset is the 2-1/2, which is the one you need for the Wilwoods. 2-1/2 is a strange number, but it is basically the 2-3/8 plus 1/8 more for the added thickness of the caliper / parking brake shoe mounting bracket plate.

If you run less than 2-1/2 axle offset, then the heads of the lug studs hit the parking brake shoes. This is worse if you run thick flange axles, or heavy duty studs. (so don't...) For whatever reason, Wilwood refuses to make a tech note regarding this problem. The vast majority of Wilwood 9 inch kits are for passenger cars, and they are 5x4.5 lug pattern, and no problem at all. But yeah...their application notes are worse than useless.

You can pick up "free" axle offset by putting a spacer or collar between the bearing and the shaft. Usually 1/8 inch won't hurt spline engagement. But you do have to watch out. If you are running SET-20 tapered rollers, then you don't need to worry about seal engagement.

Wild Horses 4x4 figured all of this out years ago when working with Currie on the Explorer conversion. So they know it backwards and forwards. They practically invented the Explorer 2.5 brake offset with ring spacer solution. It is elegant, and simple, and almost impossible to install.

I have a set of Wilwoods in the garage that will go in my next project. But I will either have to custom countersink flathead bolts and thread the 2.36 axles, or I will have to buy 2.5 offset axles and run standard press in studs. (Which explains why it's still in the garage...)

Turns out that if you CALL Wilwood, they actually know how to make it all work, and sell a special caliper mount spacer to get you to the 2-1/2 axle offset. My buddy ordered a set of spacers last week, and then ordered the brake kit from Wild H.

 

[duffymahoney]

I

The axle offset is determined by the machined shoulder on the axle itself. As you have figured out, there are three brake offsets for the Bronco. The normal 11 inch one is 1-7/8, and the other normal one is 2-3/8. All of the decimal conversion crap just confuses the issue. The third brake offset is the 2-1/2, which is the one you need for the Wilwoods. 2-1/2 is a strange number, but it is basically the 2-3/8 plus 1/8 more for the added thickness of the caliper / parking brake shoe mounting bracket plate.

If you run less than 2-1/2 axle offset, then the heads of the lug studs hit the parking brake shoes. This is worse if you run thick flange axles, or heavy duty studs. (so don't...) For whatever reason, Wilwood refuses to make a tech note regarding this problem. The vast majority of Wilwood 9 inch kits are for passenger cars, and they are 5x4.5 lug pattern, and no problem at all. But yeah...their application notes are worse than useless.

You can pick up "free" axle offset by putting a spacer or collar between the bearing and the shaft. Usually 1/8 inch won't hurt spline engagement. But you do have to watch out. If you are running SET-20 tapered rollers, then you don't need to worry about seal engagement.

Wild Horses 4x4 figured all of this out years ago when working with Currie on the Explorer conversion. So they know it backwards and forwards. They practically invented the Explorer 2.5 brake offset with ring spacer solution. It is elegant, and simple, and almost impossible to install.

I have a set of Wilwoods in the garage that will go in my next project. But I will either have to custom countersink flathead bolts and thread the 2.36 axles, or I will have to buy 2.5 offset axles and run standard press in studs. (Which explains why it's still in the garage...)

Turns out that if you CALL Wilwood, they actually know how to make it all work, and sell a special caliper mount spacer to get you to the 2-1/2 axle offset. My buddy ordered a set of spacers last week, and then ordered the brake kit from Wild H.

Any clue on what the kit is called? Thanks for the info!

 

[toddz69]

Turns out that if you CALL Wilwood, they actually know how to make it all work, and sell a special caliper mount spacer to get you to the 2-1/2 axle offset. My buddy ordered a set of spacers last week, and then ordered the brake kit from Wild H.

I'll be curious what this is exactly too - as I'm trying to understand how you could add a caliper mount spacer to give more clearance between the parking brake shoes and the axle studs w/o adding axle offset?

Thanks,
Todd Z.

 

[jamesroney]

I'll be curious what this is exactly too - as I'm trying to understand how you could add a caliper mount spacer to give more clearance between the parking brake shoes and the axle studs w/o adding axle offset?

Thanks,
Todd Z.

You are thinking correctly. You must have the full 2.5 axle offset first. Then the spacers center the caliper on the rotor…and the parking brake shoes run shallower in the rotor hat.

 

[toddz69]

You are thinking correctly. You must have the full 2.5 axle offset first. Then the spacers center the caliper on the rotor…and the parking brake shoes run shallower in the rotor hat.

10-4. That makes perfect sense.

Todd Z.

 

[duffymahoney]

So no where does it state 2.5" offset. Is that a bronco measurement method compared to wilwood?

 

[toddz69]

So no where does it state 2.5" offset. Is that a bronco measurement method compared to wilwood?

I was looking around on the Wilwood site last night, as I often do, and noted that for the standard/early big bearing setup, which I think you have, Wilwood only mentions the 2.0 and 2.36"" brake offsets. I can't access the site here at work for some reason, but I bet if you look at the late model big bearing/Torino housing end section, you'll find the 2.5" brake offset as an option (only EBs with that offset stock were the 74-75 medium-duty housings).

It's my opinion that your only option at this point to get those brakes to work is to get a set of custom shafts from Moser. Currie no longer lists custom length shafts for the standard/early big bearing units on their website - at least I could not find them.

Todd Z.

 

[duffymahoney]

I have Toms Differentials in my town, they used to make custom axles. I will see what they say.

 

[toddz69]

Judging by the size of their catalog, they can probably do something.

Todd Z.

 

[jamesroney]

So no where does it state 2.5" offset. Is that a bronco measurement method compared to wilwood?

I'm a little lost by this question. 2.5 inch brake offset is the Ford standard for Torino flanges, and for the Explorer. Happens to be the standard for Jeep Wrangler as well. There's always confusion about brake offset measurement, because you can't actually make the measurement on the axle. So what happens is the axle makers "define" the axle offset as the distance from the flange to the bearing retainer. But the brake makers "define" the axle offset as the distance from the flange to an imaginary location at the bearing retainer minus the thickness of the brake backplate.

When everyone was running drum backplates, the nominal difference in the measurement systems was just considered 1/8 inch, and the world was happy. Nobody actually cared what the brake offset actually measured. All that mattered was that you could tell the difference between the heavy duty, medium duty, and the 76-77 shafts when you had no idea where your Bronco rear axle came from. When the disc brake backplates with parking shoes were invented...they had a much thicker casting (about 1/4 inch)

Now when you add in the complexity of the SET20 tapered roller, and the external seal...it gets even more difficult to measure. This makes it really hard for the Bronco vendors to get the right parts. You will note from the pics below that the axle offset literature is not consistent.

The Currie Explorer Disc swap kit is called the CE-6012. In the kit, you will find the CE-6012-SPACER which is .235 thick. The normal drum backplate is .115 thick. The Explorer Disc backplate is .285 thick. The Wilwood spacer is thinner. I don't remember how much.

Everybody pretty much knows that you want to buy the 74-75 medium duty axle shafts with the 2.5 inch brake offset and big bearings. Then you add the Currie CE-6012 spacer, and you can bolt in the Explorer Discs. But of course the CE-6012 spacer is obsolete, and no one will tell you that the replacement spacer is the CE-9005-TES and it costs $50. Wilwood makes their own spacer, but their crush distance is totally different, because their backplate is thinner. So you can buy the Wilwood 250-6285 spacer for the Torino ends for $10. But the lip is too short for Explorer castings. Or, you can buy the Wilwood 250-11223 spacer for big bolt, big bearing ends for $11. But again, short lip.

I made the mistake of buying the Wilwood 250-6285 spacer for my Explorer set up. Then I talked to Currie for about 15 minutes trying to get obsolete hardware. Then they tried to sell me a $10 spacer for $50 plus tax and shipping. Then I got mad, and then I machined my own spacers, welded them to the wilwood retainers and finished them at .236 thick, cut off my billet housing ends, welded in Torina ends and ran the Explorer brakes. But DON'T do what I did. Or you'll end up with a giant basket of really expensive rear disc parts in a box in your shed.

So what was your question? cc: @toddz69

 

[duffymahoney]

So I believe this is what happened with my rear end.

I had it rebuilt years ago, I didn't know better and the axles were replaced, I have no memory or paper trail on what was used. Since we have that axle company in my tiny town, maybe they grabbed the wrong offset and since I have the caddy setup, it would have been easy to add or remove spacers and make the caddy brake kit work.

My plan moving forward is new 1977 31 spline axles from wildhorses that should have the correct 2.36" offset and bolt right in. Then the wilwood kit is setup for the same offset and they should also just bolt right up. I will need to cut off 1" from them for my narrowed ford 9". Which will leave me 1.5" of spline engagement and should work great.

 

[toddz69]

So I believe this is what happened with my rear end.

I had it rebuilt years ago, I didn't know better and the axles were replaced, I have no memory or paper trail on what was used. Since we have that axle company in my tiny town, maybe they grabbed the wrong offset and since I have the caddy setup, it would have been easy to add or remove spacers and make the kit work.

My plan moving forward is new 1977 31 spline axles from wildhorses that should have the correct 2.36" offset and bolt right in. Then the wilwood kit is setup for the same offset and they should also just bolt right up. I will need to cut off 1" from them for my narrowed ford 9". Which will leave me 1.5" of spline engagement and should work great.

Sounds like a great plan.

Todd Z.

 

[duffymahoney]

Fingers crossed it works.

 

[Woody1982]

Did you ever get this figured out? I just ran into almost the exact same problem. The 2.36 offset kit rubbed, so I ordered the backing plates for the 2.0 kit. They ended up not allowing the rotor to center in the caliper. I ended up taking the caliper bracket off of the backing plate of the 2.36 kit and putting it onto the 2.0 backing plate caliper mount, and to the perfect fit!

 

[duffymahoney]

Did you ever get this figured out? I just ran into almost the exact same problem. The 2.36 offset kit rubbed, so I ordered the backing plates for the 2.0 kit. They ended up not allowing the rotor to center in the caliper. I ended up taking the caliper bracket off of the backing plate of the 2.36 kit and putting it onto the 2.0 backing plate caliper mount, and to the perfect fit!

I ended up getting the wildhorses axles, it all worked great! I may however extend out my 9" by .5" on each side next summer. I would love a little wider stance.

 

[rocketman085]

Hi guys

I bought the heavy duty 9” rear end from Toms together with a pair of 31 spline axles and I am planning to put in an order for wilwood disc brakes as well. When I did the measurement according to wilwood instructions - my axle offset came out at 2.5” - enclosed picture. As already mentioned by several , wilwood only offer sets with 2” and 2.36” axle offset for my rear end. I tried calling wilwood but they said they could not help and asked me to contact a company called TCE performance product as they apparently modify wilwood sets and know their products in and out and might have some sort of offset hat on their shelf, I’m still waiting for a hear from them. I also reached out to Tom’s , but they did not know the details of wilwood rear brakes. I tried wild horses to see if they could sell me new axles which would give me 2.36” offset, but they replied that aftermarket axles, unless custom made, would like not fit with wilwood brakes. They said best bet is to modify the spacers or the brackets, or order custom axles. I will likely try to get someone to help modify the parts to get it to fit, but what I don’t get is why this issue is not solved by simply spacing out the flange end with a plate which brings the offset to 2.36 (as per my enclosed drawing), what am I missing, what sort of trouble will I get my self into ordering the wilwood set believing its as simple as adding 0.14” plate to the flange end and believe that’s it, it never is that simple. It might be best to just order the wilwood set and sort out the issue when I see it my selves, but it would be great hearing from you guys first . Is there a chance I will not find a way to get it installed? I live in Norway, return etc is not as simple, and the sets are rather expensive so I appreciate any input!

 

[toddz69]

Hi guys

I bought the heavy duty 9” rear end from Toms together with a pair of 31 spline axles and I am planning to put in an order for wilwood disc brakes as well. When I did the measurement according to wilwood instructions - my axle offset came out at 2.5” - enclosed picture. As already mentioned by several , wilwood only offer sets with 2” and 2.36” axle offset for my rear end. I tried calling wilwood but they said they could not help and asked me to contact a company called TCE performance product as they apparently modify wilwood sets and know their products in and out and might have some sort of offset hat on their shelf, I’m still waiting for a hear from them. I also reached out to Tom’s , but they did not know the details of wilwood rear brakes. I tried wild horses to see if they could sell me new axles which would give me 2.36” offset, but they replied that aftermarket axles, unless custom made, would like not fit with wilwood brakes. They said best bet is to modify the spacers or the brackets, or order custom axles. I will likely try to get someone to help modify the parts to get it to fit, but what I don’t get is why this issue is not solved by simply spacing out the flange end with a plate which brings the offset to 2.36 (as per my enclosed drawing), what am I missing, what sort of trouble will I get my self into ordering the wilwood set believing its as simple as adding 0.14” plate to the flange end and believe that’s it, it never is that simple. It might be best to just order the wilwood set and sort out the issue when I see it my selves, but it would be great hearing from you guys first . Is there a chance I will not find a way to get it installed? I live in Norway, return etc is not as simple, and the sets are rather expensive so I appreciate any input!

If only @jamesroney could come up with the special piece that he mentions in post #2, then you could make yours work too!

Todd Z.

 

[rocketman085]

If only @jamesroney could come up with the special piece that he mentions in post #2, then you could make yours work too!

Todd Z.

As far as I understand @jamesroney post, I want to have 2.5 axle offset, and that’s what I have. However, I assume I will encounter issues somewhere considering wilwood and WH claim I need to modify parts. Question is where will I encounter the problems with to high offset, and not to low as seem to be the main issue encountered by other users in this thread.

 

[toddz69]

As far as I understand @jamesroney post, I want to have 2.5 axle offset, and that’s what I have. However, I assume I will encounter issues somewhere considering wilwood and WH claim I need to modify parts. Question is where will I encounter the problems with to high offset, and not to low as seem to be the main issue encountered by other users in this thread.

Yes, since the Wilwood calipers are fixed calipers, it's very critical the spacing is correct so the caliper will fit over the rotor. It's fairly easy to adapt a 2.5" offset kit to a smaller offset (spacers between the caliper ears and the mounting bracket) but not so for the opposite scenario that you have.

Todd Z.