View Full Version : Can 4 lug axles be drilled for 5 lug?

02-15-2013, 05:51 PM
Ok, this may be a really dumb question, but you just don't know til you ask. Is it possible to drill 4 lug axles to make them a 5 lug pattern? If so, is it a bad idea?

02-15-2013, 06:10 PM
Yes, and to answer your second part: no. Several here have done it.

02-15-2013, 10:12 PM
The spacing on the 5 lug requires the hub to be welded if memory serves me. As the 4 lug winds up having one of the 5 lug holes half covered. people have dun it i do not axles are fairly cheap and why do it and most likely it will cost more than new axles any way. You cant hand drill them at home and have them spaced correctly. To answer you question i would say NO!!

And YES it is a BAD IDEA!!! :flame::hick::mullet:


02-15-2013, 10:44 PM
Lol, I didn't say it was cheaper than just getting 5 lug axles. However, I DID say it can be done, and it HAS.

Let's use my Sport for example. I could've had my stock axles welded in, then the 5 lug pattern drilled. Bought 2 1988 Grand marquis/Crown Vic rear drums, and with my existing 10" drum brake hardware, effectively had 5 lug drums, for the cost of welding/drilling, and sourcing the new drums.

For ease, I just used SN95 Stang axles (either 7.5 OR 8.8, the axles themselves are identical) knocked the ABS rings off, and used, yep, you guessed it, the older Panther car drums. 5 lug, drum brake. Done.
Yeah, some of you snobs will look down on my keeping drums, but I don't want to have to change lines, master/booster, and deal with the prop. valve.

But don't my word for whether it can/can't be done; search this very sub-forum and see the threads yourself. :flip:

02-15-2013, 10:55 PM
Here. (http://www.foxtbirdcougarforums.com/showthread.php?34791-easiest-cheapest-way-to-5-lug-the-rear&highlight=drilling+axles)

02-15-2013, 11:26 PM
The reason I brought this up is that I have found a set of used moser 31 spline axles for $120, but they are 4 lug, and I have been looking for a set for my project. I just want them to be 5 lug. I'm not gonna try to get them if it is not practical. You folks area great resource!

02-15-2013, 11:34 PM
The reason I brought this up is that I have found a set of used moser 31 spline axles for $120, but they are 4 lug, and I have been looking for a set for my project. I just want them to be 5 lug. I'm not gonna try to get them if it is not practical. You folks area great resource!

You'll also need to change your differential, as our cars were all 28 spline...again, nothing that can't be overcame with a little $ or junkyarding. Explorers and later rangers had 31 spline diffs, most with trac loc and 3.55 gears...but then with a 31 spline rear, NO stock Mustang axle will work in YOUR car, only aftermarket axles. Ranger left sides will be too short, although 5 lug and (later years) 31 spline...

Confused yet? lol

The average joe probably shouldn't attempt it. But someone who has a drill press, and good welding skill could pull it off cheaply...and safely.

I wouldn't attempt, but someone who had the proper tools to get everything centered, properly welded, and drilled in 5, could.

Then again, Stang axles are cheap, but if you are hell bent on keeping drums as I was, you'd have to source the 10" drum backing plates, or else spend some $ on the disc brake stuff, master cylinder, brake booster, etc.

So, does it boil down to bottom dollar, or what style of brakes you plan to use afterward. If you're going to do this to say, a TC, keep in mind you'll also need to drill your rotor, as NO current Stang 5 lug rear rotor will work with TC's caliper setup, as the TC had vented, Stangs had solid. Cobras did have vented, as did Mark 7, but again, they also had different calipers, and the Cobra stuff will require a 17" wheel, and most likely and 18 incher after '96 or 97.

So if you've got access to a full-on automotive shop and the know-how to do it safely, then do it. It's been done, and will be again.

If you want to 5 lug on the cheap to a TC rear, find backing plates from an '86 up 10 inch drum car (they'll be smooth, a lot like the Ranger's 10", but a different hat depth, not much, but enough to be an issue) the '88 year Panther car drums...and...slap them on.

It works. I've got this setup on my Sport with a TC rear. You will also need 10 small flat washers, (I have the thickness wrote down here somewhere, I'll edit this when I find the measurements) to space the drum slightly off the backing plate.
This is it. (http://www.foxtbirdcougarforums.com/showthread.php?33996-10-quot-drums-on-a-TC-8.8-with-5-lug-axles.-Update-and-success!&highlight=10+inch+rear+brakes)

02-15-2013, 11:41 PM
It is on an 87 TC and I have planned on drilling the rotors just to be able to keep the current disc brake setup. BTW, the motor is not a TC, but a 351W that is making about 550 hp. That's why I want the 31 spline. This is a strictly drag car project, but I am a victim of the current economy so I am trying to do this as inexpensively as possible. ThunderbirdSport302, I looked at your link showing what had been done. It was pretty interesting.

02-15-2013, 11:53 PM
I already have a 31 spline spool for it. One good thing about being poor, is it gives me plenty of time to look for good deals on parts! :)

02-16-2013, 12:04 AM
Well, I would say with the Moser axles, probably just be better at that point to locate some '94-'98 Stang calipers and all the related stuff (rotors too) and mount them. There's a kit on Summit and Jegs from Ford Racing that allows you to mount the newer rear brakes on older cars. If you've got fab skills though, you could just make your own. Keep in mind though the rotors will be a solid, non vented type, if that's a consideration. Since your car is already rear disc, that's how i'd keep it. Cobra rear brakes would be an expensive option, but since you'd need new wheels anyway (unless you already have them) you could get some 18" wheels..just a thought, to keep ya going. lol

02-16-2013, 12:10 AM
Yeah, I want to keep the TC vented rotors because of the weight difference. Less rotating weight. I have a set of Weld Drag Lites for the rear with slicks. The axles are really my last piece for the rear. If I get those, get a roll cage, a shifter, and have my C4 rebuilt I have just about everything I need to put the car together.

02-16-2013, 12:16 AM
In that case, I could see why you want to drill and weld...any automotive machine shops nearby?

For that matter, you could knock out the studs, place a 5 lug rotor on the hub, take a punch, and carefully mark your new stud centers, then have someone weld in the old lug stud holes, and drill the new ones out.

No rocket science in it, in my opinion. ;)

Just one quick question...are those axles for an SN95, or a Fox Stang (fox stang axles will be too short..SN95 are just right)

02-16-2013, 08:10 AM
I am going to say this with Conviction. And i do not care what others think or have dun

DO NOT RE DRILL A 4 LUG AXLE FOR A 5 BOLT PATTERN> IT IS DANGEROUS AND FOOLISH. Axles are so dam cheap i think as low as 60 Bucks. Do not do it it is DUMB. Just me.

I agree, holes are too close together to be considered safe. Get the ranger axles and quite being cheap.

02-16-2013, 08:59 AM
You would be pushing the stock axles pretty hard on a 500hp drag car even if they weren't hacked. Another thing to consider is that if the bolt circle isn't absolutely perfect its going to shake and vibrate at speed.

02-16-2013, 11:15 AM
I agree, holes are too close together to be considered safe. Get the ranger axles and quite being cheap.

That might be a good idea...if he was working on a Fox mustang.

02-17-2013, 11:28 PM
That might be a good idea...if he was working on a Fox mustang.

OK, 95 Mustang Axles, Strange, Moser and many other companies can offer off the shelf axles for whatever you are working on for $200 or less. Your life and cash ride directly on those axles. I do not care what you are working on. I know for a fact the holes are too close to be considered safe, I drilled a set of drums and decided to EFF that. Axles.....you are a braver man than I.

02-17-2013, 11:31 PM
Aftermarket axles is the way to

02-18-2013, 12:11 AM
OK, 95 Mustang Axles, Strange, Moser and many other companies can offer off the shelf axles for whatever you are working on for $200 or less. Your life and cash ride directly on those axles. I do not care what you are working on. I know for a fact the holes are too close to be considered safe, I drilled a set of drums and decided to EFF that. Axles.....you are a braver man than I.

I've got SN95 axles in mine with a drum conversion, no discs for me. I didn't drill anything, just staed that it has been done by others. The OP wants to keep his TC rotors, but have 5 lug..provided he gets absolute center of the rotors, as well as machine the hub area out, he'd be ok, I think. At least if a rotor flies apart at high speed, you will still be able to maintain control.

02-18-2013, 01:13 AM
Where did you source the rotors? I think that's the only piece the OP needs to complete his puzzle.....

As for me, I stayed drums with a little ingenuity and NO mods :)

If you've already got a disc rear car, then hell yes, it's easier to stay discs, same with drums. There's no way to swap discs into an '88 Sport without either modding something, OR replacing those few somethings with the necessary parts from a TC. Park brake cables being one, the brake line being another.

But yes, with a little work, it can be overcame. But it's not 100% plug and play. I've got a TC rear in mine, but elected to stay drum as I didn't want to change master cylinder, do the brake line modification, and pay out the ass for those expensive and often too-short-lived rear brake calipers. I'm not saying my way is better for everyone, but I don't hear myself bitching because I have ancient tech out back. Hell, it works.....that's all I ask of it. Someday when cash isn't such an obstacle, perhaps I'll have a nice Cobra/PBR setup..till then...I'm happy.

02-18-2013, 09:49 AM
Tom, yes I am interested in the rotors that you used. I am thinking you must have used a larger diameter rotor than the stock TC and therefore you had to modifiy the mounting bracket. Is that correct?

02-18-2013, 05:03 PM
I've got redrilled Axles.

I would have preferred proper 5 lug axles, however the complete lack of availability locally meant it would have costed significantly more to go down that route.

in saying that, my bird will likely never be used in a manner that will put huge strain on the axles, and i'd bet the diff itself would let go before the axles failed.
in the event i decide to upgrade Diff, i'll probably get something local modified to fit.

02-18-2013, 07:23 PM
The lugs only hold the tire against the hub. The hub should be a perfect fit and hold the weight of the car, in a perfect world. It wouldn't bother me personally to redrill the axels.

02-19-2013, 08:22 AM
I actually seen a guy who drilled ford bolt pattern on his chevy truck to run ford wheels that he scored for free, one of his rear wheels came of at a stop light and rolled down the road forever before it stopped. Yeah I can how stupid that could be, now imagine some kid who did this on his car and got the bright idea to see how fast he can go, vibration will make things come apart or fail if it occurs at the right frequency or resonance; hence people who can shatter a wine glass with their voice same idea. I see on my chainsaw cylinders once in awhile as well, it makes em fall apart for no apparent reason. If drilling out your axles seem great how come manufacturers didn't have cars with multi bolt patterns on their axles? This is like holding a firework in your hand and lighting it off, yeah you can do it, is it safe or smart, probably not.

02-19-2013, 02:26 PM
Yeah, never heard of anyone running corvette or viper brakes or axles with a ford bolt pattern before. Or even running "universal" rims that are not hubecentric.

Is it the smartest thing to do, no. Does it happen everyday, yes. Hang out at a tire shop for an afternoon and see how many people have been driving around for thousands of miles with a busted off lug. I consider that to be more dangerous then a welded axle with the bolt pattern re drilled.

02-19-2013, 09:56 PM
Tom Renzo...where did you get those rotors?
OP might be interested in that info, rather than everyone's opinions on someone's welding ability.

02-19-2013, 10:43 PM
OK how did you accomplish this???? Curious.

Paid a diff specialist.
Had no intention of doing it myself.

still significantly cheaper then trying to get a set of axles shipped to AU.

02-19-2013, 11:13 PM
Tom, yes I am interested in the rotors that you used. I am thinking you must have used a larger diameter rotor than the stock TC and therefore you had to modifiy the mounting bracket. Is that correct?


02-19-2013, 11:19 PM
If anyone is interested in keeping the 4 lugs and upgrading to 31 spline, this is a great deal on ebay. It is what caused me to start the thread. I'm not gonna go the drilled axle route. Just to risky for my taste.

02-19-2013, 11:38 PM
Brief description do they fit TC or what year mustang ?

Hope who buys them gets what they need

02-19-2013, 11:45 PM
Brief description do they fit TC or what year mustang ?

Hope who buys them gets what they need

They came out of a Turbo Coupe. I verified with a question to the seller. The ad description also states same.

02-20-2013, 01:21 AM
That's cool

I buy a lot of parts and hate when people get jacked up or wrong stuff

02-21-2013, 11:02 AM
I want to say that www.brakesrus.com has five lug rotors for the TC rear but their site is down right now. They are solid rotors and I believe a little cheaper than the ones Tom posted.

As usual Tom has all the goodies!


02-21-2013, 02:26 PM
Quick question Tom, will the rear rotors for the Mark VII that you posted fit an 87-88 TC rear end or are you having to modify the way the calipers bolt on to make them work? I pretty sure that is what you are doing but not 100% sure.


02-21-2013, 06:49 PM
The hat depth is different. Unless you make new caliper mounts, they won't work.
That's why I said there is NO stock Ford 5 lug vented rotor that will work with a TC rear without mods.

Guess I'll leave the tech up to the old timers who have seen it all, done it all, because someone like me who has spent hours in junkyards and parts stores measuring and comparing parts doesn't know fuck-all.

By god if i posted a pic of a mod, I'd be sure to tell everyone how and what I did to accomplish it. I guess that's because i can remember a time when everyone here helped one another, and weren't all ego braggarts...

02-21-2013, 09:24 PM
I missed what you said on the first page as you guys were talking differentials so I skipped over it...pays to read all the instructions before assembly!

On another note, there is a guy here in the Houston area who is a friggin' wiz at brake conversion and building the brackets to make them work. It helps that he is an engineer so he understands the geometry and he does all his work in CAD so its money and super clean looking when its all done. He also builds T-5 and builds the AODs with the new auto tranny guts (sorry not an auto guy so I cannot remember which one the guts come out of) and to top it off he is a nice guy and charges way to little for what he does. If anyone would be interested in a kit that would convert a TC rear end over to the Mark VII rotors using SN95 axles and reusing the TC calipers and pads let me know and I can get you his contact info. Anyhow, just thought I would throw it out there. Here is one of the threads on a local Houston Mustang site and you can see some of his work and the CAD renderings:


Hopefully you can see the thread if you are not a member. I talked to him a little while ago and he is interested in working up a model of this and seeing what it would take to do the adapter brackets. The model he already has is for the Fox length axles so he does not think it would take to much effort. I will post this in another thread and link it here if anyone is interested. It may take a few days as he does have a day job and other hobbies.


02-21-2013, 11:15 PM
In my 87 Cougar, I used Moser axles with c-clip eliminators which did not allow me to use disc brakes. So I am using the factory 10 inch backing plates and some 5 lug hardware from a Lincon Town Car. I recommend that you save up the extra 100 dollars and use the SN95 Axles because they are only 259 per pair on Summit Racing. That way you are sure the ends are square and not brittle from excess heat. the come machined for c-clips but can be used with the eliminators. Word of advice if you do the eliminators, make sure you take it to a shop that does custom work so that they can trim the axle to length otherwise the hub stick out a little wider than before making tire fitment a concern and on drums the gap between the backing plate and the drum without trimming was 1/4 inch.

02-22-2013, 12:15 AM
According to the Cool Cats website, another possibility for using the stock calipers on a TC rear with a 5 lug upgrade is to use the 1990 Mazda MPV front rotors with a 1/8 in spacer behind them. Has anyone here done that swap?
"Or, you could do the ol' Mustang conversion trick: use 1990 Mazda MPV (V6, 3.0) front rotors, and 1/8" spacers. Place the spacers between the rotor hat and axle flange to put the rotor back into alignment with the stock Turbo Coupe caliper location."

The same site also claims you can use the rear 10 discs which came on the 91 - 92 Mark VII.
"From 1991-92 the Mark VII had 10" vented rear discs in 5-lug and those would be the ones to get. You could then reuse the other stock Turbo Coupe components"

02-22-2013, 03:00 PM
I have read that the SN95 axle flange is too large for the Mazda MPV rotor to fully seat on the axle flange. A person ends up having to remove in the neighborhood of a 1/4" to be taken off the OD of the axle flange. I have not down this so I do not know this for sure but I would think it would be easy to check out. If anyone has a SN95 axle they could run it down to a parts store and check to see if this is internet mythology or the real deal. If the flange has to be machined then that is an additional cost to the project but it is only a one time deal. If it does not have to be machined then you only need the spacer which can be found here:


Here is one instance of the compatibility issue I am talking about:



02-24-2013, 10:41 AM
here is a pic off a thread here where it was done in 2009 posted in the drive train section
remove axle (haha- this is where it now makes sense to add a 5 lug axle but.........)
pop out studs
lay new rim on the axle
insert alignment tool to catch the hole that lines up
scribe in the new hole locations
X out the new scribed holes
drill out the holes
install studs
install axle
**all things geometrically considered and thinking it through, i dont really have an issue with drilling the axle.
I personally would also consider that the lug nuts are actually "aligning the wheel centerline with the studs" , the position of the circle tranfered to the axle on the X and Y axis isnt really manageble without good planning. with your alignment tool catching the hole that does line up, you would need to insert something like a manderal bit that completely filled up the rim hole and finally using that tool to by hand transfer the circle shape onto the axle surface. Once done, i cant see this being a big enough issue.
the lug nuts will center you up even further as you tighten them.

if your holes you transfer are achieved with thought and measured calculations, and you dont plan to qtr mile the car, i really cant see the issue.
Everything rotating on a vechicle is not 100% even from the factory so thats why we find misc holes , metal taken away or metal chunks added to rotating parts to "balance" the less than perfect tolerances.

the crank shaft is the same, has blance holes or divits drilled out, drive shaft has unique metal chuncs welded for incorrect non perfect engineering, the rim itself has the same concept with a tire on in that weights are added.

In this conversation, its odd no one has said that even from the factory or sales dealership, things are not dead nuts on because if you tell the sales guy to remove those stupid weights from the tires, he would say you are voiding the warranty of the car. What is being said here is that everything needs fine tuning, so if you add your holes with thought and a measured approach, the remaining should not be a worth while measureable mechanical issue. I would think that if you transfered your circle shape in a calibrated manner, we are only talking about .00XX inches if not less of delta.

02-24-2013, 11:54 AM
If i were to do this, i already have determined the only tool that would be a time saver is a larger scale of what is shown below.
A tappered end alignment rod that is hollow with a spring loaded center punch that you hit to mark a dot on the working surface being modified.

granted the below is for another application, i do not know what larger diameter hollow alignment tools are available but i would find it and use it for this task to shorten the mod time and reduce room for error.

02-24-2013, 01:00 PM
nevermind..see next post.

02-24-2013, 01:27 PM
I just measured 2 axles for hub dia. Axle #1 was the original axle in my TC rear, hub dia was 2.534", axle #2 was from a Ranger, unsure what year, but it's 5 lug, and meant for an eventual swap on one of the Mustangs. Anyway, it's hub dia is 2.540".

So my previous post is incorrect, the 4 lug axle WILL be hubcentric after conversion to 5 lug, using stock Ford wheels. I physically verified this by knocking the lug studs out of the Ranger axle and putting it into a TC wheel. Fits like it was meant to, and there's no noticeable play.

My theory stands: provided one was exceedingly precise in centering the lug stud holes, I feel it will be safe if welded properly. Also, I don't think there is a way to use an existing lug hole (4 lug hole, that is) because of the spread of the 5 lug pattern is is little further out. I will get pics of this in a few minutes.

02-24-2013, 11:18 PM
I don't know..I'm not a machinist.

But I do know guys that make brackets from a piece of steel stock. Those brackets are used to hold molds for blow-molding machines in perfect alignment. The machines have a clamp force of several thousand psi. They cycle thousands and thousands of times, sometimes for 3-4 days without ever stopping.

I reckon for a couple of the guys, (one of which has a phD in mechanical engineering) finding the centers of 5 small holes on an axle shaft is pretty mundane compared to what they do to put food in the fridge.

I'd imagine that once the holes were filled, drilled and the lugs were in there securely, that a balance test be done. I would thing a driveshaft shop could do that.

Hell, for that matter, the lug holes are drilled out when the axle is made, no?

02-25-2013, 12:22 AM
Ok so you are going to use WHAT as a precise measuring device to drill the holes accurately. A rim..


you know thats not what was said. dun pokin?:D

02-25-2013, 12:33 AM
I don't think there is a way to use an existing lug hole (4 lug hole, that is) because of the spread of the 5 lug pattern is is little further out. I will get pics of this in a few minutes.

check it, you should see that one stud ties in and brings the center hub in play as well , i gotta dig up that 2009 thread showing the diy part of it.
The guy also mentioned that leaving the one stud that does line up in place helps because you can add the lug nut and snug it down so it further aligns things,, lug nut being tappered and all.

arrggg, what am i thinking........ Tom said there is no way on planet earth or in any universe this mod can be done because there is no known technology or people with brains enough to do it.... gezz ,,, ill roll over and die now.:shakeass:

02-25-2013, 08:59 AM
i was just playin around with ya,, i thought you were talking to me on post 52.

02-25-2013, 07:46 PM
All this just to avoid finding a set of SN95 axles out of a Mustang which can be had on several Mustang sites for $50 - $100 for the set. I could see doing it if nothing economical were available but not when there are so many sets of these in salvage yards and and the corners of garages? It can be done and most competent machinist can do it but what they would charge to do it right is not worth it when axles are so cheap. If you are a machinist and have access to the tools then that's a different story.


02-25-2013, 08:21 PM
I think the OP's question was could he find a 5 lug TC rotor, and if there was not such a thing, then was the axle drilling a feasible solution ;)

I wasn;t aware there were viable 5 lug rotors to fit the TC calipers WITHOUT mods, but it appears that with a little bracket fabbing it can be done.

I KNOW the Mark and the TC rotors have differences...I looked into this when I was gathering my parts for the rear 5 lug stuff. Suddenly I couldn't find any JY Mark 7 rears, so I just went with my setup.

I think the OP has some options now...we should leave him to his decision and not derail this thread any longer...whatya say? :)

02-25-2013, 10:26 PM
Not so fast! I have another question. Does anyone know if the 91-92 Mark VII calipers will bolt up to the TC brackets? If that were the case, then possibly the rotors and calipers could be used to make the switch without having to fab anything else. The outside diameter of the Mark VII rotors is 10.53 versus 10.16 on the TC. Any thoughts? Been done or tried?

02-25-2013, 11:15 PM
I think when I did my comparisons, the Mark caliper mounts a little different and is also thicker than the TC caliper. There's no mixing and matching of parts the parts, unless you can weld on new brackets. No matter how you look at it, you can't swap to either a Mustang rotor, or a Mark rotor, without pulling the caliper in towards the diff by a small amount.

What I would do (and what I was going to do if I found a complete rear) was pull a whole rear from a mark, so I'd have axles, brakes, etc and swap them into my 3.55 geared TC rear. Sadly, I never was able to find a Mark anywhere within 175 miles.

I wanted the Mark setup so I could have vented rotors and yet stay small enough to run 16" wheels. Now that I have the Bullitt wheels, I may eventually go to a '94-5 Cobra setup using parts from Ford Racing. But that's just an option.

Now if you wanted drums, that's a feasible route, but you'd still need to find a couple uncommon pieces...myself, I'd stay discs if I were you, and try to locate a Mark rear, or a Stang rear if not. You can always save up later and get the bigger rotors, but the big $ are in the calipers. Ughh.

02-25-2013, 11:30 PM
Are the Mark VII rears the same lengths as the TC? Are the mounting brackets the same?

02-26-2013, 08:58 AM
So Tom, would using the LSC brackets, calipers and rotors make for a direct fit without mods to make the 5 lug swap?

02-26-2013, 11:59 AM
LSC axles are longer...I would think you' still need to change where the caliper mount locates to the rearend housing..?

03-02-2013, 10:10 AM
Looks like I may have found some 5 lug rotors that will work on the TC 5 lug conversion. If you scroll down the page on this link, they are listed as the 10.25 rotors, kit #5455. Per my emails with them the dimensions appear to be correct. They actually have 3 different versions.

overall height 2-21/64 diameter 10-11/64 (type vented rotor)
bolt circle 4-1/2 inch (Ford mustang)

03-02-2013, 10:35 AM
Order them up and let us know if they work. They will take them back if they do not fit right. The one thing you need to ask them is if the hub is correctly machined for the SN95 axles. If it is too large they make an adapter for them. If it is too small they may be able to open them up.