Mump 1302 Late Model Corral
Mark Houlahan
Tech Editor, Mustang Monthly
December 18, 2012

On Restriction

In the article on '87-'93 climate control (How To: Renew '87-'93 Climate Control Systems, October 2012 issue), author Jim Smart referred to a restrictor in the supply side heater hose. I have an '84 Mustang LX convertible with 56,000 miles that I just replaced a heater core on. When was the restrictor first used and are they available? It looks like the tapered end is toward the water supply. Can I use one in my '84? Thanks in advance, you have a great magazine.

George Martin
Pittsburgh, PA

The small restrictor, formally known as a "flow control," was first used in the '87 model year SSP Mustangs. These special service Highway Patrol cars often were optioned with silicone hoses as well, but the flow control was used no matter what hose type was installed on the car. One of the most knowledgeable guys we've ever had the pleasure of meeting when it comes to the SSP Mustangs is Jim Dingell of Performance Parts Inc. (; 703/742-6207). Jim tells us that the SSP cars got the restrictor first, but that some '93 Mustang Cobras also had one. The original intent of the restrictor was to decrease coolant flow to prevent heater core failure and reduce heater core "thumping" from the pulsing of the coolant flow. The original is a metal part with a plastic insert, which Performance Parts Inc. carries in limited quantities. The all-metal restrictor often seen is actually from the Thunderbird/Cougar and even used in some trucks. The '96-'04 Mustang used a similar all-metal restrictor as well and is what some companies sell for the Fox Mustang.

One other thing to note is the location. The factory installed the restrictor in the larger 3/4-inch heater inlet hose at the heater core end of the hose (closest to the firewall). As the hoses aged and softened, the restrictor would sometimes shift and block coolant flow further. Ford issued a TSB that stated the restrictor should be relocated to the opposite end of the same hose (the engine side of the 3/4-inch heater hose) to reduce heater core noise and a hose clamp used to prevent the restrictor from moving. As you correctly surmised, the tapered end is inserted into the hose first. Even though your '84 didn't come with the restrictor originally, it certainly can't hurt to install it, as replacing the heater core is NOT a fun job in the late-model Mustang.

Need a Rest?

I have a '89 5.0L Mustang convertible. Where can I locate a replacement rear armrest? Where is a good place to look for them? Are they reproduced?

Jim Day
Via the Internet

It's been a while since we've been in the back seat of a Fox convertible (hold your jokes until the end people!) and we were kind of scratching our heads at the word "armrest" until we Googled an image. Oh yeah, we remember now! The '83-'89 Mustang convertible had a narrower quarter trim panel with an actual padded armrest separating the upper vinyl panel from the carpeted lower panel. Ford changed the trim panel design in 1990 when they relocated the speaker to the upper panel with an integrated power window switch, ditching the armrest pad.

Like most interior trim items, these armrest pads have long been out of the Ford part's system. A quick search of eBay (writing this in mid-November 2012) showed two different auctions; one for just the armrest pads and one for complete trim panels with the armrest pads installed. So with some patience you should be able to find serviceable used ones, even it does mean having to have them dyed to match your interior color scheme. Keep an eye on the auction sites and put a word out on your favorite Mustang forums.

We spoke to a couple of late-model parts manufacturers about the armrest pads (as the '87-'93 armrest pads for the door panels are reproduced) and were told that the convertible armrest pads are "on the radar." There's still a ton of parts to be reproduced for the Fox-era Mustangs and these companies are looking at what's in demand. With '83-'89 convertible production of around 184,000 vehicles versus just over one million coupe/hatchback Mustangs during the same model years, you can see that convertible specific parts often take longer to come to market due to lack of demand. As new Fox-era reproduction parts hit the market, we'll let our readers know.

Let us hear from you. Send your late-model Mustang questions or comments to: Late-Model Corral, c/o Mustang Monthly, 9036 Brittany Way, Tampa, FL 33619, or email us at