Hello Everyone! I'm in the market for a Fiero GT and would like to know if the V-6 engines and automatic transmissions are reliable. I really appreciate any and all information. Also, I read that parts for the 1988 model may be hard to find so kindly advise if what I read is or is not true. Again, thanks very much for taking the time to respond !
...would like to know if the V-6 engines and automatic transmissions are reliable.
Depends on your definition of "reliable". If all you want to do is to to put gas in the tank and drive... then buying an almost 40 year old car probably wouldn't be the wisest choice. It also greatly depends on the maintenance history of the individual vehicle.
Unless you're mechanically proficient yourself, or have deep pockets to be paying someone else to be doing the mechanical upkeep, you might regret buying a four decades old car.
Fiero only has TH125c for Auto Trans w/ different "final" gearing for model and trim level and fairly reliable if don't beat the hell out of them. Some Fiero have been swap to have 4T60 auto w/ Over Drive and ok too.
One issue is a solenoid valve to control Torque Convert Locking... Many unplug this because "old type" valve "breaks" and TC stays lock. In 4T60 and other, many ignore this wiring and never locks the TC.
No Lock hurts MPG and heats the auto trans more.
88 Fiero "big problem" is can't get brake and suspension parts. Was hard to get these parts 15-20 years ago and unobtainium now in most places.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Should the 2.8 give it up, the BM 3.1 and 3.4 engines are essentially the same blocks. Everything from the 2.8 bolts directly on. The 3.1 starter is on the correct side but the 3.4 will require drilling and tapping mounting holes on the other side using Rodney Dickman's starter relocation tool.
The 3.1 has the same HP as the 2.8 but more torque. The 3.4 has more torque and HP. My 87 has the 3.4 and my 86 has the Lumina APV 3.1.
With the automatic, you're locked into the one transmission without doing some mods to accept other automatics. With the manual transmission, you have a choice of 3 manuals that only require shifter, cable, transmission mount and slave cylinder bolt-ins.
You're registered on the Georgia Fieros message board. Come down to Marietta for the March 11 meeting and you can see a wide selection of options.
Hello Everyone! I'm in the market for a Fiero GT and would like to know if the V-6 engines and automatic transmissions are reliable. I really appreciate any and all information. Also, I read that parts for the 1988 model may be hard to find so kindly advise if what I read is or is not true. Again, thanks very much for taking the time to respond !
Off the cuff response, I think the Th125c is absurdly reliable. The only issues I've ever heard of people having, is the torque converter no longer locking up (usually not a mechanical but a sensor / switch problem).
I'll put it this way (no judgement). When I first got my Fiero back in 1996, I had the GX3, which has the 3.33:1 final drive (the highest gearing). MANY times... I ran at sustained speeds of 120 miles an hour. MANY times, I would put it in neutral, floor it, and then shift it quickly into drive to do a burnout. I did this MANY MANY times... before I was told (and learned) that this is the worst possible thing you can do for an automatic transmission.
I've beaten the **** out of that transmission... flooring it constantly... like, at every light. I was 18 when I got it, and stopped driving it when I was 21 becuase the engine blew and life took over. The only thing that in fact I never had problems with, in all 7 of the Fieros I've owned... was the automatic transmissions.
Per Patrick... yes, the cars are definitely 40+ years old now. And one of the things that happens is that the individual clutch disc material will degrade and break down. If you plan on running an older car at this point, I would recommend a rebuild, but they are solid, and very reliable.
Many people upgrade to the 4T60 though, because you get an extra gear, and better gearing through the individual gears. It's not a difficult swap.
EDIT: I was just corrected that the gearing for 1st, 2nd, and 3rd between the Th125c and the 4T60 are the same. The 4T60 of course just provides an additional gear for cruising which obviously helps reduce engine RPMs on the highway. I had a 4T60E in my GrandAm behind a TwinCam LD9, and loved that transmission.
[This message has been edited by 82-T/A [At Work] (edited 02-27-2023).]
Originally posted by 82-T/A [At Work]: EDIT: I was just corrected that the gearing for 1st, 2nd, and 3rd between the Th125c and the 4T60 are the same. The 4T60 of course just provides an additional gear for cruising which obviously helps reduce engine RPMs on the highway. I had a 4T60E in my GrandAm behind a TwinCam LD9, and loved that transmission.
Everyone has their own opinion but I would not pass up a nice 88 GT due to fear of parts availability:
The 88 brake master cylinder is not available but the 84-87 master cylinders are. The difference between them is 1/16" of an inch different piston diameter. Most people would have a hard time telling the difference The Fiero store has remanufactured brake calipers. Rock auto has caliper rebuild parts including the piston. If push come to a shove there are options to install calipers from other vehicles The brake rotors are readily available Rock Auto and The Fiero Store have struts and shocks The Fiero store has polyurethane bushings for front and back Rock Auto and The Fiero Store have ball joints The sealed hubs for the front are not available but Rodney Dickman sells greasable hubs that use tapered roller bearings.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
I've had 3 cars with the THM125C (2 Fieros and 1 Grand Am), and relatives have had 3 more (all 2.2L Cavaliers). Out of all 6 of those cars, the only one that had a transmission failure was a Cavalier that had been the first car for 4 consecutive teenagers over it's entire life. It died at only 120K - but 4 teenage owners. This was also the lightest of all the cars (a very low optioned 2 door Cavalier) with a 2.2L producing less torque than the 2.5L Duke or the 60V6. I'm going to dismiss that failure as probable abuse or neglect.
Unlike some automatics, the THM125C has a dip stick, so if the owner is attentive enough to check it, it may tend to be better maintained than those that don't have one.
My current 86GT has the automatic 3.33, it's up to 230K miles now and still works perfectly. This is the only one of those 6 cars that was a V6, the others were all 4cyls. But as I understand it, the V6 transmissions are built up a little more from factory to handle the extra torque, and so I don't think their track record is any different in the V6 application.
Many people never change the fluid and filter in an auto trans. If you do buy an auto Fiero, it should probably be done. My car came with the lockup TCC connector unplugged, and when I plugged it in, there was a shudder. That cleared up after I did a couple fluid changes.
The big con for the THM125C is that it doesn't get good highway mileage because it doesn't have overdrive. If you cruise at 75-80 it will cost you. It turns about 3500rpm@75mph with stock wheels and gearing.
In California I was getting 22-24mpg depending how I drove. I was in the rural foothills so most of my miles were cruising (lots of elevation changes though). I would guess I was probably hitting 25mpg when strictly on a highway at a conservative speed (65 or less), but of course these cars don't have a dash gauge to tell me that, all I know is the final mileage per tank.
Now that I'm in Florida I've been getting like 19-20mpg but I blame it on my short trips, and the increased desire to punch it either from restless boredom or merging into suburban traffic. Something might also be falling out of tune.
Given the age of these cars, a heavy weighting should be placed on the condition of the car, most especially whether the frame is rotting (look under the trunk carpet). The best car you find might not be the one that has the options you want. But as far as reliability concerns, I don't think the 3spd auto has any. It's a solid transmission - just lacks overdrive.
In California I was getting 22-24mpg depending how I drove. I was in the rural foothills so most of my miles were cruising (lots of elevation changes though). I would guess I was probably hitting 25mpg when strictly on a highway at a conservative speed (65 or less), but of course these cars don't have a dash gauge to tell me that, all I know is the final mileage per tank.
Now that I'm in Florida I've been getting like 19-20mpg but I blame it on my short trips, and the increased desire to punch it either from restless boredom or merging into suburban traffic. Something might also be falling out of tune.
This has me thinking too...
I have a 2002 Crown Victoria LX-P74. It's a cream-puff as they say. I basically got it in 2004 from my grandfather (when he passed away), who bought it new. I've done a number of things to it, but it has a 2.73:1 final drive gear ratio, which I've left. The transmission... I can't remember, is a 4-Speed. When I lived in Florida back just prior to ~2011, I was getting ~28mpg... which is quite good for a 5,000 pound car with a 4.6L V8 engine.
Absolutely nothing has changed on the car since 2011, except that I've changed the tires, and changed out the fluids. The car still only has like 50k miles on it as it sits, and sometimes I go 6 months without driving it... but it now only gets around ~25 miles to the gallon on the highway.
There's been some more obvious changes in the fuel that we now use today, versus what we used 10 years ago... but I'm wondering if that seems to be more of what's going on? I'm unable to get more than 25 miles to the gallon.
Originally posted by 82-T/A [At Work]: This has me thinking too...
I have a 2002 Crown Victoria LX-P74. It's a cream-puff as they say. I basically got it in 2004 from my grandfather (when he passed away), who bought it new. I've done a number of things to it, but it has a 2.73:1 final drive gear ratio, which I've left. The transmission... I can't remember, is a 4-Speed. When I lived in Florida back just prior to ~2011, I was getting ~28mpg... which is quite good for a 5,000 pound car with a 4.6L V8 engine.
Absolutely nothing has changed on the car since 2011, except that I've changed the tires, and changed out the fluids. The car still only has like 50k miles on it as it sits, and sometimes I go 6 months without driving it... but it now only gets around ~25 miles to the gallon on the highway.
There's been some more obvious changes in the fuel that we now use today, versus what we used 10 years ago... but I'm wondering if that seems to be more of what's going on? I'm unable to get more than 25 miles to the gallon.
If it sits a long time that might be having a negative effect, especially on the fuel system. You could end up with a misbehaving injector, for example. My nephew had a Town Car for a while. Those are such roomy and comfortable cars, they put other modern cars to shame. Unfortunately his went downhill for various reasons (not the car's fault).
I noticed the mileage drop as soon as I moved. California does have it's super-special unique formula for whatever reason, so I'm sure the gas I'm using now is different in some way. I'd be surprised if CA gas has a higher energy content, but even if it does, for paying half the price in FL I'll take that trade. I immediately noticed I'm making more power here, which I assume is just because of lower elevation.
I did mess with the tune on my Fiero years ago, so maybe it doesn't work as well at this elevation, but I plugged a laptop into it once since moving here and didn't notice anything looking different than it did in CA. I want to convert my car to a 7730 ECM. I have most of the parts, just need to get going on the project. It might get better mileage with that.
There's a station nearby that sells ethanol-free. Unfortunately it's 93 octane premium also - so it costs too much extra for me to bother trying it. I wish somebody sold 87 octane ethanol free, I'd be more interested in running that.
If it sits a long time that might be having a negative effect, especially on the fuel system. You could end up with a misbehaving injector, for example. My nephew had a Town Car for a while. Those are such roomy and comfortable cars, they put other modern cars to shame. Unfortunately his went downhill for various reasons (not the car's fault).
I noticed the mileage drop as soon as I moved. California does have it's super-special unique formula for whatever reason, so I'm sure the gas I'm using now is different in some way. I'd be surprised if CA gas has a higher energy content, but even if it does, for paying half the price in FL I'll take that trade. I immediately noticed I'm making more power here, which I assume is just because of lower elevation.
I did mess with the tune on my Fiero years ago, so maybe it doesn't work as well at this elevation, but I plugged a laptop into it once since moving here and didn't notice anything looking different than it did in CA. I want to convert my car to a 7730 ECM. I have most of the parts, just need to get going on the project. It might get better mileage with that.
There's a station nearby that sells ethanol-free. Unfortunately it's 93 octane premium also - so it costs too much extra for me to bother trying it. I wish somebody sold 87 octane ethanol free, I'd be more interested in running that.
Yeah, I can't remember if I mentioned it above, but I ended up having to replace the fuel pump. But that was after it sat for 3 years... literally having never been run. I put in some fresh gas, put in a new battery, and it wouldn't turn over. I changed out the fuel pump (I don't remember why I thought that was the problem), and it fired right up. At the time, there was also a relay inside the cabin that was sticking, as I heard it clicking on and off. But I drove it for a couple of days, and all the problems went away. Obviously, I had to get new tires too, hahah.
I drove it maybe once every couple of months for three years... basically put like 500 miles on it that year. And then took it from Fort Lauderdale to San Antonio... where it basically sat again for 4 years. I started it only a few times a year. I love the car, I really do... it's awesome, but it's so huge that when I'm getting around, the last thing I want to do is drive a gigantic battleship. To be completely honest, if it wasn't for the fact that it was my grandfathers... I would have sold it already. But I can't bring myself to do it.
The 7730 is a pretty sweet ECM, lots of features that you can enable, like a knock sensor, better MAP, and other features. The communication baud rate of the system is significantly faster too than the original Fiero ECM... like, significantly more powerful. You can also run an open-loop oxygen sensor too, which is nice.
They do actually sell 87 Octane, ethanol free, here in Florida. It's at select Race Track gas stations. Obviously not all the pumps have it, but there's usually at least one pump. My parents live in The Villages, and every time I go there, I fill up with ethanol free gas.
Originally posted by 82-T/A [At Work]: They do actually sell 87 Octane, ethanol free, here in Florida. It's at select Race Track gas stations. Obviously not all the pumps have it, but there's usually at least one pump. My parents live in The Villages, and every time I go there, I fill up with ethanol free gas.
I'll have to keep an eye out for that. I haven't normally been going to Racetrack stations, but there is one nearby I should check. At least I think it's Racetrack - I can never keep Speedway and Racetrack separate in my mind.
On my 1985 SE V6 (W/ Manual trans) I was getting 20 around town and 28 on the highway. At the ripe old age of 15 (Car age), I swapped in a getrag- and a 3.4 F-body block...I then was getting 19/30.
By the way, my 1999 Firebird Formula (Automatic) got 30.4 MPG on a trip from CA to Oklahoma City...I was doing 70-75 the whole way and had the AC running (Except early morning). The car only had 2000 miles on it when I started that trip. When I told a co-worker at the CG air station, he became very angry- his Volvo wagon could only get 23 MPG highway driving.
I wish there was a light 4 speed automatic for the Fiero- but all the 4 speed autos weigh a lot more...
