89 Mustang 8.8 rear end

I see from the replica registry some of you have a ford 8" rear end. We've got a 89 rear end off our donor car and are preparing to do a 5 lug conversion (new axles - 28 spline) and drum to disc conversion at the same time. The manual calls for a Maverick 1973 - 1976 (preferred), before we go and order all our parts, from my calcs, the 89 8.8 axle we have should fit in and hang properly off the upper and lower control arms. No?

I have a 8.8 in mine with a 4 link set up. The rear end will work, is it the right width and gear ratio you want? The rear end is nothing more than a round tube. If you are using the Mustang control arms then you won't have to do anything. If you are using something different then you will have to cut the mounts off the round tube and weld in the ones for your control arms or leaf springs depending on your set up. I would think that a 89 Mustang rear is a little bit too wide but I am not sure. It might be easier and cheaper for you to source out a Ford Explorer rear that already has the rear discs or if you want I am in the Detroit area and will sell you my 95 Mustang rear that already has rear discs and 5 lug axles for $150 and it bolts up to the same control arms as the one you have and that would be a lot cheaper than changing yours.

Hi Bwdz,

Thanks for the memo, appreciate it. I checked the width of my 8.8 and by swapping out the drums to discs, we should be right on the money for fitment. I went with SR Performance upper and lower control arms for a 4 link setup which are the same size as the original 4 link arms which came out of the donor car, so it should drop right in (well up). It looks like my rear axle (as it was a 4 link hookup) has the right mounts already installed on the axle.

Couple images we have. The axle if it works out is getting blasted and cleaned up so it looks new, new lines, etc etc.
[You must be registered and logged in to see this image.]

I have kicked around changing my gear ratio as its currently a 3.08 which should be decent, but then I read people suggest going to a 31 spline vs 28 (which I currently have). Your offer is tempting, I live in Toronto...let me noodle it....

31 spline is stronger and if these cars were heavy with a lot of tire on it then it would be necessary but unless you put slicks on it and launch it at 6k rpm I think you will be ok. One of the reasons people upgrade the axles is because if you stay with the drum brakes and you break the axle it will come shooting out of the rear end as they are only held in by a little C-clip washer in there. With disc brakes the disc would keep it in there as the caliper would not allow it to fly off in the worst case scenario. Switching to 31 splines requires a new carrier like an Auburn Posi or another one that accepts the 31 splines. BTW, I like that suspension set up, looks great.

Cheers Bwdz!

We're (well my son and I are, wife is tired of boxes of parts arriving haha), excited about it, figured as we're starting from ground zero, might as well do it right and give the MX a few decent upgrades as we build. Our plan is to use the car as a daily driver in the summer, have a bit of fun with it and take it to local car shows and meetings.

Hi Bwdz, as you have an 8.8 thought I'd ask a question. You'll notice on my image above showing the axle, it still had the Quad Shock installed which runs on a 45 deg angle approx from the axle mount to the rear of the car. On the MX there isn't any mount for this and considering the 4 link setup, I don't know that i need it and therefore can remove those mounting brackets? Or should we weld in an attachment, not sure what purpose they serve if you have 4 link, with independent shock behind axle and spring in front....

There are different kinds of 4 links that use different shock set ups. Mine is just links in front and coil over shocks behind it so it required all custom brackets. You only need the shock brackets that you will actually use so if those are extra or in the wrong spot just go ahead and cut them off.

One other note. If you didn't already spend a bunch of money on parts for your rear end you can get one out of an Explorer with a better gear ratio and disc brakes already on it, they go for about $100 so way cheaper than any one part you buy for yours or go with one out of a SN95 Mustang but you will still only get crappy gear ratios but 5 lug axles and disc brakes, again for under $200 on those.

Rear end looking awesome. Now we have 5 lug hook up with disc brakes. SR performance upper and lower controls arms for a solid 4 link hook up, now kicking around what to do for rear spring on lower control arm to shock installed on backside of axle up to frame.

Planning to go with QA1 as really like their stuff, but looking at frame, I might have to weld in a support plate below the round tube on the frame to mount an upper spring perch so we can support a QA1 spring mounted between the lower control arm perch and the frame....hmmm.

I found the enclosed picture in the owner forum, and that is pretty much what we're going for on the rear, the question is the metal bracket that the spring mounts into on the frame, looks like this was fabricated (sorry, don't recall where i got the picture from, but its most helpful on this build).

Pic: [You must be registered and logged in to see this link.]

You might want to check Viking Shocks.  All of their shocks are double adjustable for rebound and compression.  Just like QA1, they are available in several valve setups and some can even have the entire valve setup changed by you to another valving range so that you don't have to send them back for service.  They have multiple mounting configurations available also.

Since it sounds like you will be fabricating shock and/or spring mounts, you might also want to think about coil over units.  The springs are available in more rates than the Mustang parts, which are actually too stiff anyhow.  DrJ had a nice write up on his thread about this.  Now is the time to do it, before you get the car assembled.

Just my dos centavos.

MC247,
We're in Georgetown, ON. Sebring MX c/w 8" 'Auburn' posi & 3.23 gears. 275/60 x 15 rears. Would be good to meet you @ a cruise night.
JimboQuick