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Thread: 1975 Pontiac Trans Am (L75) 455 H.O. - the King Returns? (updated edition)

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    1975 Pontiac Trans Am (L75) 455 H.O. - the King Returns? (updated edition)



    1975 Pontiac Trans Am (L75) 455 H.O. - the King Returns?

    By Pete Dunton

    http://www.ericpetersautos.com/home/...3&Itemid=10787

    Automotive history as it has been written, 1975 will never be known as a banner year for muscle cars. The GTO, Chevelle SS, Challenger, and Cuda were among some of the most famous muscle car names to bite the dust by 1975. In 1975 the only Mopar muscle car names that remained (had become Chrysler Cordoba clones) - the Plymouth Road Runner and Dodge Charger, which had sadly become underpowered luxury barges with pillowy seats. Ford had completely given up, the Mustang by 1975 was know as the Mustang II and based on the Ford Pinto platform. Though it was a sales success it was as far from a muscle car as a car could venture. The availability of only 4 and 6 cylinder motors for the 1975 Mustang II, was a big reminder of this fact. The Torino had also grown to almost Thunderbird proportions however it still packed a V8 under the hood. Sadly the Torino's largest displacement V8 was a 351 Cleveland that was very light on the horses. AMC was also out of the muscle car business by 1975. At GM things also looked grim. Oldsmobile still had a 442 and a Hurst/Olds and Buick still had a Gran Sport but these cars were so detuned, that their decals and emblems were the only similarity to their predecessors. Chevrolet also threw the white towel in the ring, by 1975 the largest displacement V8 in the Corvette was a 350 CID V8. The Camaro had dropped so far in performance and to add insult to injury, Chevrolet even dropped the Z28 from the Camaro lineup for a couple of years starting in 1975.

    Pontiac was also feeling the pinch like every other U.S. auto maker with the new EPA mandated emissions standards for 1975, lower compression motors that started in 1971 for GM (EPA mandated that all 1972 cars run on unleaded fuel, hence no more high compression motors), skyrocketing insurance rates, and the after effects of the 1973 OPEC oil embargo. Pontiac not one to give in to adversity, had beaten the odds up until 1975. The mandated lower compression engines had killed just about every high performance motor by 1972. Pontiac continued as if nothing happened and just converted to high performance low compression V8s. Pontiac high performance low compression V8 motors were so good that they could propel an almost 4,000 lbs Trans Am in the mid to high 13 second to low 14 second 1/4 mile time range. These motors were the 1971-1972 455 (CID) H.O. V8 (rated at 330 gross horsepower/300 net horsepower) and the 1973 and 1974 SD (Super Duty) 455 (CID) V8 (rated at 310 and 290 net horsepower respectively). As an example in 1973, Hot Rod Magazine test drove a factory stock SD 455 powered 1973 Trans Am and obtained a 1/4 mile time of 13.54 seconds at 104.29 mph. This was faster than most of the high compression muscle car motors from the muscle car golden era. Pontiac seemed to be leading no matter what the odds were up until 1975. It seemed the new for 1975 EPA emissions mandates which choked the engines with a single catalytic converter, EGR valve, and a maze of new vacuum hoses under the hood had finally put Pontiac's back against the wall.

    Pontiac announced in late 1974 that a L78 400 CID V8 would only power the 1975 Trans Am. This seemed like good news since the competition's V8s were much smaller in displacement, but the 185 net horsepower rating of the L78 brought any muscle car fan back to the cold hard reality that things had changed drastically from the previous years. The good news was that the Trans Am by 1975 was skyrocketing in sales, even though the Trans Am was detuned it still was faster than it's competition. And the buying public was taking note of this fact and voting with their dollars. Trans Am sales were skyrocketing for a reason. Even as muscle cars had waned in popularity the Trans Am provided fantastic handling and good performance all wrapped up in a stylish muscular shape. The 1975 Trans Am was a carry over from the successful 1974 Trans Am restyling. The only real changes in styling for 1975 were the front parking lights (which moved to the front grilles) and a new wrap-around rear window.

    Diehard Pontiac fans were still clamoring for more cubic inches, especially since Pontiac still made the Pontiac 455 V8, which was an option on the bigger Pontiac B-body, G-body, and A-body cars. Pontiac finally saw the error of their ways after the 1975 model year had started and decided to offer the L75 455 CID V8 from the bigger Pontiacs, which was rated at 200 horsepower. The good news was when the L75 was ordered the following were manditory: a limited slip 3.23 rear axle, a Borg Warner Super-T10 4-speed manual transmission, dual chrome twin splitter exhaust outlets, "low back pressure" muffler, and front sintered metallic brake pads. All of these items with the exception of the Super-T10 could not be ordered on any other '75 Trans Am or Firebird. Since the L75 455 had come out of the bigger Pontiacs it came as no surprise that it produced plenty of low-end torque, 330 lbs/ft of torque at a very low 2,000 rpm. However due to the restrictive heads and a grandma type cam, the compression ratio was a very low 7.5:1. This meant a L75 Trans Am ran its best on 87 octane gas and began to run out of steam once it went beyond 3,500 rpm. Even with the L75 engine being a very low compression motor choked of power, performance was very good for 1975. Car and Driver Magazine obtained a 16.1 second 1/4 mile time at 88.8 mph which was almost a full second faster than the '75 Trans Am L78 400 which took 16.8 seconds to make the same run. The 0-60 mph time of the '75 L75 Trans Am was 7.8 seconds, which happened to be a full 2 seconds faster than the '75 L78 400 powered Trans Am. Even though the L75's performance figures paled in comparison to the figures of the previous years, The L75 Trans Am still beat the competition in performance. Even the lighter weight (than the Trans Am) 1975 Corvette could only obtain a 16.4 second 1/4 mile time and a 9.6 0-60 mph time making the Trans Am L75 the king of the streets for 1975. And if that was not enough for L75 Trans Am buyers back in 1975, it was very easy and cheap to almost double the horsepower with a few engine upgrades and bolt on parts, since what you had was a choked D-port 455 just begging for a hot cam, high performance heads, exhaust headers, etc.

    The 1975 L75 455 Trans Am was a wise move by Pontiac since it kept the Trans Am on top as performance king. This trend continued until the end of the 1979 model year when the last W72 400 powered Trans Ams left the assembly line. The mistake Pontiac made with the '75 L75 Trans Am was marketing the package as the 455 H.O. All L75 equipped Trans Ams received the "455 H.O." decals on the shaker hood scoop, which allowed critics to take a cheap swipe at Pontiac. And rightly so, since the '75 L75 Trans Am was at least 2 seconds slower in the 1/4 mile than the 1971 to 1972 Trans Am 455 H.O. The L75 option carried over to the '76 Trans Am with the same mandatory limited slip 3.23 rear axle and 4-speed transmission. Pontiac did learn their lesson by 1976, the package had just a "455" decal on the shaker hood scoop.

    For 1975 only 847 L75 455 Trans Ams were produced mostly due to the late 1975 model year introduction. By 1976 the L75 Trans Am option was much more popular with sales going over 7,500 units. The 1975 Trans Am L75 455 kept the Trans Am on top in terms of performance for 1975 and kept the momentum going. And things kept getting better for the Trans Am as the 1970s progressed. For that alone the 1975 Trans Am L75 455 deserves its recognition in the annuals of muscle car history. So in the final analysis the King did return after-all in 1975.


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    Re: 1975 Pontiac Trans Am (L75) 455 H.O. - The King Returns? (updated edition)

    I have always liked the '76-'76 TAs... not the fastest or most powerful, but still had the big engines and some unique-to-these-years touches/options.

    Nice write-up!

    PS: I'm not 100 percent sure of this, but I recall the splitters were at first only available with the 455 HO package, which also included sintered metallic brake pads....

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    Re: 1975 Pontiac Trans Am (L75) 455 H.O. - The King Returns? (updated edition)

    Eric,

    Yeah those '75 - '76 T/As are special. Thanks for catching my error, you are correct the splitters where only available on the L75 T/A for 1975. And you are correct front sinthered metallic pads were also part of the L75 option which I failed to mention. I'll make the appropriate changes to the article.


    update.. changes made to the above and the main article on front page. Thanks again.

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    Vulture of The Western World Eric's Avatar
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    Re: 1975 Pontiac Trans Am (L75) 455 H.O. - The King Returns? (updated edition)

    You bet!

    One of the things that really sets apart those '75-76 cars (in my opinion) is the combination of unusual/vivid colors, final availability of the 455 V-8 (and the final use of cubic inch call-outs on the shaker - "400" and "455" vs. the subsequent "6.6 litre," etc.), "one-year-only" exterior cosmetics for both years (grilles/front end and rear end treatments) and the relatively low production, esp. of cars with the 4-speed stick and either 400 or 455 V-8.

    I prefer the '76s because their exterior shape is "cleaner" (the '75s have that black rub strrip on both the front and rear end fascias) and also because Carousel Red is my favorite color ( Brewster Green and Goldenrod Yellow - another '76 color - are also high on my list)!

    I like all second-gen TAs, though... and if I had Jay Leno's money and time, one of the projects I'd like to do would be to restore an '80 Turbo Trans-Am pace car (white/charcoal) to show quality cosmetics, but replace the 301 with a professionally built turbocharged, intercooled and fuel-injected 455 backed by a 200R4 OD transmission. A turbo 455 should be capable of producing at least 500 pounds-feet of torque (stock, with carburetors, these engines were making 400-plus lbs.-ft.) and 320-plus (real, rear-wheel) horsepower with a mild street cam.

    The result would be spectacular. I would guess a mid-high 12-second quarter-mile car (n drag tires) with a top speed of 160-plus. In other words, quicker than a new Mustang GT500 and close to a new Z06.

    Only much better looking and a helluva lot more fun to drive!


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    Re: 1975 Pontiac Trans Am (L75) 455 H.O. - The King Returns? (updated edition)

    Eric,

    Very well said. You are right the color combinations on the '75-'76 T/As really added to their appeal. Another thing that helped these cars was they could be ordered with a lot of different options. Most of the '75-'76 T/As I have seen are very well equipped very rarely do you see the stripper when you do its a nice show piece. For the earlier Trans Ams there seemed to be more strippers and its harder to find the "loaded with options" examples.

    There's a guy that I know - Brad Bunger who has been turbo charging low compression 455s for the last few years. It started off as a project that sparked his interest, he told me the response to his original project was overwhelming with many wanting to do the same on their T/As especially those with '80 -'81 turbo cars. He built fantastic performance on a shoestring budget. You may have seen the writeup on his project in HPP a few years back:

    http://www.highperformancepontiac.co..._am/index.html

    Speaking of the '80 Indy Pace Car Edition turbo Trans Am, there was one for sale here in No-Va in 2004 for $7,500. It was a preserved low mileage original. The exterior was perfect along with the white interior. I should have bought it because the price was very low and it was in such nice condition.

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    Re: 1975 Pontiac Trans Am (L75) 455 H.O. - The King Returns? (updated edition)

    Quote Originally Posted by Pete
    For the earlier Trans Ams there seemed to be more strippers and its harder to find the "loaded with options" examples.
    There's a reason for that, Pete. Most of the people I know who bought pre-75 TAs ordered them as "go fast" cars -- meaning no AC, no power windows, no power door locks, and none of the other options that added weight. Weight is the enemy of performance. The reason many of these guys ordered TAs in the first place was because the death of other muscle cars left the Trans Am as the last game in town, and they wanted to most bang their buck could get.

    For some reason (perhaps the lousy performance offered by catalytic converter cars) that began to change in about 1975. Few people were willing to spend the time/effort required to roll back the performance losses to emissions controls by doing heavy-duty wrench work, and the TA began to assume a more symbolic status, particularly with the advent of the factory T-tops. Pontiac continued work on the 400 motor and upped the output for a couple of years, but EPA and CAFE regs caused the end of Pontiac 400 production in 1978 (the final 79 400/4 speed engines were actually produced in 78). In the final couple of years, style overcame substance for the gen 2 F-body from the standpoint of the die hard performance enthusiast.

    We all had high expectations for the 301T, but the decision to use the SBC as the corporate engine for the gen 3 cars put a stake through the heart of that hope.

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    Re: 1975 Pontiac Trans Am (L75) 455 H.O. - The King Returns? (updated edition)

    Rick,

    Very well said. It was a sad day for performance, and Pontiac did the best they could under the circumstances as you mentioned. GM then cancelled 301 production at the end of the 1981 model year, killing any hope Pontiac had of dominating its GM brothers with a future 301 turbo - instead Buick got the opportunity.

    Do you remember the mid 1980s how all the auto magazines were saying that the next generation Firebirds & Camaros would be at best V6 powered and may even be front wheel drive? Ford initially planned the fox bodied Mustang to be a fwd 4 and 6 cylinder powered car. However when gas prices dropped in 1986 and stayed low during the late 1980s, and rwd Mustang sales were very strong - Ford decided to keep producing the Mustang and released this fwd (Mustang replacement) car as the Ford Probe. Also Mustang fans appartently flooded the phone lines in Dearborn, which sent them the message to keep the Mustang rwd.

    BTW - what happend to Trans Am Country - the forum and website are gone. Is it coming back?

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    Re: 1975 Pontiac Trans Am (L75) 455 H.O. - The King Returns? (updated edition)

    TAC has crashed again. Mr B tells us that he changed servers, and apparently things didn't go well. In the meantime we're all hanging out over at 78TA.com (http://www.78ta.com/smf/index.php) -- I'm a moderator over there, so drop by and join the party!

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    Re: 1975 Pontiac Trans Am (L75) 455 H.O. - The King Returns? (updated edition)

    Rick,

    Sorry to hear about TAC's server crash. Hope they are back online soon. I just signed up over at 78ta, thanks for the invite.

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    Re: 1975 Pontiac Trans Am (L75) 455 H.O. - The King Returns? (updated edition)

    Pete -- I set you up with access to the TAC refugee room over there today -- it's down at the bottom of the forum index page.

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    Re: 1975 Pontiac Trans Am (L75) 455 H.O. - The King Returns? (updated edition)

    Rick,

    Thanks for setting up the access, I'll stop on by.

    Pete

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