Stock Rim specs and Axle Bumper Removal safe? -

Mustang II Section The more economy minded, compact Mustangs which were offered from 1974-1978

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Old 05-28-2015, 02:10 PM   #1
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Join Date: May 2015
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Default Stock Rim specs and Axle Bumper Removal safe?

Straight to the point first, I can find loads of specs and information pertaining to the stock rims and such for 1979's and up as far as their backspace and offsets, however trying to find anything for the 1974-1978's is pretty much impossible and there are conflicting statements from owners that don't appear to confirm anything nor seem right considering. So If anyone happens to be able to point me in the right direction for SPECIFICALLY what those values should be... that's be great and appreciated.

The other question i have is regarding the rear axle rubber bumpers that "hang" from the unibody frame of the car to prevent the axle from making sudden and direct contact with the frame. This is related to the rim issue. I've been search high and low for some 15" rims that'd fit the bolt pattern, center point of the axle. The reason for the 15" rims is due to the fact that finding any "decent" 13" tire is basically obsolete and impossible for the stock rims that would have been on the car, and no, don't bother directing me to sites or places that sell a 13", I'm not interested, I want a permanent solution.

Suffice it to say The only ones that matched up were a set of Mustang FoxBody rims from i believe a 1989 that have the correct center/bolt pattern. The issue is that the rim is deep, as in that the inner wheel well becomes a rubbing hazard, Actually HAS become a rubbing hazard. Suffice it to say, I'd have enough clearance if i remove the bolts that hold the rubber axle bumper in place.

Now removing those seems like a bad move, but let me bring you up to speed. I've installed a set of 5 leaf General Spring leafs and a set of Monroe 5854 Shock. Now if you know anything about the shocks, you'll know that the part number is not for a mustang but for a toyota corolla, and the reason being is the standard shock for the mustang II wouldn't be long enough to accommodate the extra lift of the vehicle in the rear end, however these are the ONLY shocks that fit the distance, absorbing requirements, and the travel distances not to mention bolt up EXACTLY the same aside from only having to mount the upper stud and then cut off exactly 3/4" to 1" from the stud so it clears properly (they are very long studs). These shocks come with bumpers built into them so if they over extend, there is no issue, and their shortest point prevents the axle from ever traveling fully to the frame anyways, making those rubber bumpers redundant. The leaf springs were designed to give a 2 and 3/4 inch lift to the rear end, which it definitely did, likely more due to being new springs that need to be broke in.

However I'm concerned about if the place the rubber bumpers are attached to serve as structural integrity of some sort. Though they don't appear to be attached in any secure way (basically a bolt that self threads into the plate without a nut of any type. There are 2 that are on the wheel well and one that threads in from the bottom. I figured removing these bolts would sort my issue for sidewall clearance.

As it stands, with the vehicle not in motion on a level surface, i can bearly fit my pinky finger between the bolt head and the sidewall of the tire. Removing the bolts would give me basically twice the clearance. There is definitely rub with the bolts in as evidences by the tire showing scrapes. Obviously going to a small tire would solve this issue, but I'd prefer not to.

The other option is using wheel spacers, however I would prefer to avoid this specially since there is a very good chance that this car will be making a return to the drag strip, not to mention the numerous issues that plague wheel spacers on just daily driving situations, I don't feel like watching my rear wheels fly past me prior to likely flying off the road into a huge wreck.

The only alternative to this is tracking down some rims that have a more ideal offset/backspacing so the wheel is at least 1/2" to 3/4" away from the inner wheel well vs the 1/4" it currently is. If you're wondering what tire i've on the 15" rim, it's a 235/60R15 Cooper Cobra tire. I know these fit very well, and there is plenty of outer wheel well left for it, I could likely get away considering the lift the car already has, with a 295/50R15 even but no point in bother with that until i fix the current dilemma i have.

A Brief History of the car...

I've been working on this car with what little cashflow i have, a few hundred dollars per year making improvements, repairs and overall just making it drive-able.

I've a 1978 Mustang Cobra II that was bought brand new off by my mother whom still owns it today. While she did drive it for a few years, due to family related issues, it had to be sold which was sold to a cousin of hers that then raced it for about 10 years before she ended up selling it to some bar owners kid to which, destroyed it within 2 months, rebuilt what was left of it (engine mostly) then destroyed it again. From there it shuffled around a few peoples hands quickly before somehow ending up in a slough slowly rusting to death as an entirely totaled vehicle. My father made it his mission for their 25th anniversary to track down that exact car with the exact VIN number and bring it back to it's former glory with well, as little cash as he did as well while trying to keep it hush hush, it was to be a 5+ year project with no paper trail for my mother to figure out.

Suffice it to say, when he managed to find the car in a slough, he had his dreams mostly dashed due to the last owners having taken a side grinder to all the racing stripes and exterior, it looked horrible, dinted, broken parts, missing parts.. complete trash. Then he opened the door and found an immaculate and still complete interior, granted aged but still very usable.

The primary task for the car was to make it road worthy enough to pass safety and such even just barely. Basically the cars appearance would be the next thing on the chopping block as being made to look original and new, Combined with my fathers investment into finding mustang IIs to salvage replacement fenders and other parts from that were found to be in better shape, a combination of 3 vehicles were used to select the best of the best from. So while the body looked pretty much immaculate , along with the from factory malformed front spoiler that all the cars had, she looked precisely like what she looked like sitting new on the lot in 1978, minus the low sitting rear end and a few other mechanical/suspension related issues that made the stance of look off.

Due to the previous owner(s), destroying the vehicle, the engine had been blown several times and overheated horribly, further disassembly of the engine determined that whomever rebuilt it last, placed the WRONG gaskets/seals in it which completely blocked numerous of the water ports which obviously resulted in a total meltdown. The heads/block and everything were blued from the heat and scared up badly. Basically destroyed with no real benefit of trying to repair. Considering it was just a typical V8 302 5.0L 2 barrel carburated engine that came with it, my father decided to salvage a 1984 Mustang GT V8 302 H.O. 4 Barrel and drop it in. Surprisingly the 3 speed Auto in the vehicle (i know, not standard, no bother fussing) was in mint condition and not a single sliver of filings found. The rear end though without the limited slip, uses a 2.79 ratio, and is swapable. However with the standard 13" rims and the changeover required to match the newer engine to the tranny, for whatever reason the 100km/h required a 3500rpm engine speed. With the larger 235/60r15's however, the 100km/h travel speed has been reduced to about 2800rpm. We had the rear gear ratio checked twice as 2 different location in which they both counted the teeth themselves. They don't get it.

The rear suspension is probably the most expensive fix i did by myself entirely on the floor (no hoist/lift) and took me a few days to do. After pulling out the W shaped original leafs, I was glad i did it simply due to the fact that out of the 4 leafs per side, only 1 was actually a single peice, the other 7 leafs had broken in half long ago, surprisingly having had put many miles on the car, lucky they hadn't just randomly spread out after hitting a bump and destroying a tire in the process, Lucky.

Additionally the mechanic that originally dumped the 84 engine in the car neglected to plug the giant ports on the spacer plate between the intake and the carburator which resulted in hard starting, and nearly impossible idling. When i decided to investigate (when i was allowed finally)... i discovered those ports and plugged them, but already determined a significant amount of dirt and debree had been sucked in and collected. Cleaned it up best i could, it's burning a bit of oil and runs a little rougher than it should but so far for the 300,000+ km that is on the engine... can't complain otherwise. Front suspension needs some work likely next, but i wanted to replace the tires as the old ones are past the wear bars. Just running into this little hitch.
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