1978 Mustang II 4 Stud Axle to 5 Stud Axle Swap

78musttwo · 08-30-2007

New to the Forum & did a search on this but would like to clarify this swap; get the proper "conversion" parts, do it right One Time! I'm planning on running Drum Brakes for now & just want the Simplest (KISS) solution! I'd like to swap the four bolt axles in the diff to a Five Bolt axle and drum. Is/are there any potential problems I should watch out for? If anyone has done the swap, I'd like to hear from you! I've read on the forum that 1983-88 Ranger Driver side or any year Aerostar Passenger side axles (with 9" Drums) work. Correct? Is there any Passenger Car axles that will work? Thanks in advance for the assistance!

**74stang2togo** · 08-31-2007

I've heard this, (from a source I trust), even passed it on, but I've never tried it... Other guys have simply had their rear axles re-drilled by a machine shop and bought Ranger drums.

78musttwo · 09-07-2007

I do/did NOT want to redrill any axles. Looking for an "Inexpensive" fix if such a thing exists! Hope to hear from some who have done this swap. THX!

Stretchmobile · 09-09-2007

Redrilling your axles is the most inexpensive way. I had my axles and drums redrilled for less than $100. You already have them, no need to buy more axles or drums. Plus you know they will fit! I have redrilled many axles and drums to put on different wheels and have never had a problem. Especially when you go from 4 lugs to 5. If 4 lugs held the wheels on for this long, then a fifth lug is going to add that much more clamping force. There is plenty of meat to redrill one hole is clost to the access hole, but what the heck that's just the extra lug anyway.

78musttwo · 09-13-2007

One CAN'T just "drill another hole" in the axle to make a Five Bolt Wheel from a Four Bolt Wheel!!!!!! Stop and think about it.

I was hoping to get some constructive input; however, I'll give it the old college try and I may report back as to how successful I have been! Thanks, EH!

Stretchmobile · 09-15-2007

People have been redrilling axles since cars were invented. I have a year of daily driving on my redrilled axles. Obviously you haven't thought about it. Since the five lug is 4.5" circle and the MII is 4.25 circle you have a couple of choices. Plug one hole (weld or interference fit steel plug) or offset one hole slightly. The next two holes down are close to the previous existing holes and the last two are spaced farther apart. The real reason this is harder on MII axles is the access hole to remove the bolts holding the retaining bearing on. It is a larger hole. However if you play with the circles you can get a satisfactory spacing to allow the axle to be redrilled. You have to drill all five new holes, not just one more hole! I have had axles redrilled to go from Ford to Chevy, 4 lug VW to 5 lug Porsche, early Ford 5 lug to 5 on 100 and 4 lug VW to 5 lug Chevy. Not just talked about it but done it! However, if you don't believe me go ahead and do it your way. Just don't ask for advice then denounce it when someone gives it to you. You wanted the most inexpensive way to get five lugs and I gave it to you in detail. I am not blowing smoke up your ***, I have been there and done it for the last 30 years.

eric_cartman45 · 11-26-2007

hello i was reading your post and i have also converted my mustang 2 4 lug to 5 lug, i'm a engine machinest and builder, and i know a few guys arround here and i talked to them and i had both my axles welded and redrilled and it only cost me 30 bucks an axle. 20 bucks if you weld them yourself.

aslo you can find a ford 9inch to bolt up right from a 70 linclon versale with disc brakes or from a ford granada, or merucry monarch, those with drum brakes. i've heard those cars had 9inchs and they bolted up perfect..... correct me if i'm wrong...