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Left rear sags 68 coupe

1084 Views 2 Replies 2 Participants Last post by  deeuutee
Hi All, I have owned this car for a few years, last month I changed the wheels for a wider and slightly taller set. First time out I noticed it was rubbing over bumps, but only on the left rear. That's when I realized for the first time that the left rear was lower that the right, by about an inch.

Having had this problem years ago with a Buick, the first thing I did was put the rear up on stands and measured the front, but there was no difference there. With the Buick after stuffing around trying to find the problem at the back found it had two different front coils, the stiffer one was pushing the opposite corner down.

But that wasn't the case with my Mustang. The front springs were changed a couple of years ago for a lowered set, but I didn't change the rears because they had sagged enough the sit the car level - from the side anyway.

So I got a new set of lowered rears and had a suspension shop fit for them for me because I just didn't have time. When I went collect the car, it was outside in the middle of a downpour and I didn't have a chance to look at it, but noticed straight away on the way home it was rubbing but still only on one side. Sure enough, it still has the lean to the left.

I called the suspension shop, and they have suggested removing one spring and cold re-arching it to fix the problem. There will be a cost ($230) for this procedure, but they say no charge for r&r and wheel alignment. It occurred to me it would be cheaper to buy a set of lowering blocks and only fit one side.

I have done a bit of searching on this site and other places, and found a few others who have had the same problem, but couldn't find any posts with a solution.

Anyone able to offer advice?


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I don't quite understand, Taller and wider tires but the rear end is lowered? 1st gen mustangs (64-68) had clearance problems in stock configuration. That's why so many fastback have the inside of the wheel well hammered flat or even cut out.

I don't know what condition the current springs and shackles are in, but at $230.00 to re arch one spring. your are close to the price of a pair of new springs at factory height from a lot of dealers.

Did you just buy new springs or just lowering blocks? Not sure what you are trying to say. But if the springs are new i'd demand the installer/supplier fix it at no charge, someone made an error.

There are rear shackles available in various lengths, perhaps making the low side longer would bring the car back to level? also some outlets have single leafs for a spring pack that you could add to the low side only. As far as rear end alignment the spring has a pin or button in the center. this lines up with the hole in the rear perch so its hard to screw that up.

Does the car perhaps have gas charged shocks and one is defective? In my 30 years in the classic mustang biz. I've seen lots of cars sag on the Drivers side, its because most use of the car is done with just the driver in the vehicle, and men drive more miles than women so we are talking about 150-225 pounds on the average american male over 40 years time, of extra weight on that side. That's why the battery and spare tire or on the opposite side on most fords.
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The previous wheels were 14x6, and now they are 15x8 and the rears are a slightly taller tyre. The slight rubbing is not a problem and I fully expected that I would need to get the guards rolled to fix that.

I supplied new 1" lower rear springs (mid-eye) and shackles to the installers as they were happy to do just the fitting, and since Mustang springs are not readily available in Australia I had a cheaper and easier source. It also has new (two years ago) springs in the front and new (not air) shocks all round.

Probably it has sagged from use as you say, but new springs should have fixed the problem. I had a chat with the installer and he told me that before he fitted the springs he compared the arches and they were within a couple of millimetres but he fitted them so the better one was on the sagging side.

I don't think adding a leaf is a good idea as it will change the spring rate on that side. Cheaper to get a set of lowering blocks than longer shackles too.

You are correct, I can get a new standard height spring for $185 so cheaper than re-arching, but a set lowering blocks is $72. And you are right someone did stuff up as they should have checked the heights before calling to tell me job's done.
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