Why are the 90 AODs slow?

MTTod

Registered User
I've seen quite a few posts saying the 1990 AOD SCs are the slowest models. Why is that? Is it the tranny or the engine or what?

I have an 89 XR7 and it does seem to have a lot quicker throttle response and power off the line. Normal or just my SC motor?

No one has seriously discussed buying my XR7 motor so I'm starting to think of keeping it and putting it in my SC. Good or bad idea?
 
I don't think that my 90 SC AOD is slow. It will outrun a stock Mustang GT. Of course my 90 isn't totally stock either.

I also have a 95 5-speed and it does not seem much faster than my 90.
 
Could be alot of reasons. What rear end gear do you have.

In my case it was motor failure. When I first got my SC I could rip and tear and burn'em up but as time went on and I started losing compression in the cylinders the power went down drasticly. In the end before the big KABOOM. I was running with 2 dead cylinders. It ran like a 6 cylinder but It felt Like a 4 cylinder. Have you done a compression test?
 
Both cars are totally stock. The SC has had the HGs replaced, the XR7 hasn't been opened up and has about 30K more miles. 155K total and the tranny is pretty bad. The SC tranny is good.

Both are AODs so they have the 3:27 rearends. In the mid to upper RPMs the SC pulls about as hard but the XR7 feels lighter and quicker off the line. Like I said, the XR7 is a lot faster revving too.

The SC has Bridgestone Potenza RE730s on it. They don't squeal at all. It's funny smoking the tires and only hearing the engine. :)The XR7 has some basic highway treads on it. They howl.
 
Alot of what you are experiancing can be explained by the tolorances the engines were built by. The factory has an allowable tolorance range on every critical part in the engine.
The short of it is that some engines are built better by the factory because the tolorances are much better on that engine verses the engine that the tolorances werent so good on, but still within the limits.;)
 
seems to me that maybe ur SC has a problem. Maybe you need to rip apart the block open and check what the hell is going on inside ur engine. I have a 91 AOD . I have outran anything that has reved its engine at me.

I think that you should rip your block open and make sure that your TV cable is set correctly. Also you might wanna replace the AOD oil and the filter. You need to take time and check it out.
 
The XR-7 feels lighter, because it IS lighter! The SC has the body clading & that huge rear window.

68COUGAR
 
Doesn't sound like there is anything wrong if you can still smoke the tires. I would dyno both of them and see what you've got.

BTW, I've never heard about 90 AODs being slower...but I've heard about them being faster. Last year 4 of the top 5 cars in this club were 90 AODs

David
 
If the Cougar is lighter it's no more than 50 lbs. My XR7 weighed 3960 with me in it (165lbs at the time). On a car that old there can be many reasons why the car is or may seem slower. I wouldn't fret about it.
 
If the Cougar is lighter it's no more than 50 lbs. My XR7 weighed 3960 with me in it (165lbs at the time).
I just weighed my SC with me (195 lbs) and it came in at 4090, so that's 100 lb difference :p

Like others have said, there are numerous contributing factors for why your 90 may be slower than average.
 
I don't necessarily think there's something wrong with my SC. I had just seen different people saying the 90 AOD was the slowest model year SC, maybe it's just an opinion. Driving my XR7 made me think there might be something to it though so thought I'd ask.

I know there will be variations in performance even in new cars. Tight or loose tolerances in various drivetrain components add up to overall gains or losses in performance. Add 100K miles of driving and you need to look at how hard it was driven, how well maintenance schedules were adhered to, etc, etc.

As far as how to actually check it out there's really no way I can. I doubt there's a dyno within 300 miles of me and I haven't found a shop yet that even knows the 3.8 SC motor exists! Pretty much everyone I called said the same thing... "Supercoupe... isn't that the turbocharged 4 cylinder?" Nope... thanks... bye. (Small town) I'd race the two but my wife would never keep her foot in it long enough to actually compete. :rolleyes:

I'm probably going to sell the SC in the spring anyway. I'm tearing down the XR7 this winter and hopefully it'll roll out this coming spring. A new toy to play with. :D
 
Kurt, I don't think that's too valid. You and Dave N have some - um - heavy stuff in your - um - cars. :D If you look at the article in MM&FF this month, you see a number of cars weighed at the same scale at the same track.

Gary 3885- no aircond.
David 3706- Mine HAS been lightened. (no sunroof either)
Mine stock 3960
Bill 4010
Chris 4046
Ricardo 3910
Ron 4060
Ken 3982

These are all with driver and some had some significant stereo equipment. Like I said I think the Cougar may be about 50lbs lighter, but total weight has more to do with options like JBL, added stereo, sunroof, folddown rear seat, gas in the tank and stuff like that.

Some others:
Anthony 4001 lbs
Fast 92 3879lbs

There's more, but you get the idea.

I have a moonroof cut out of the car. Maybe I should weigh it but I know that it is heavy as hell. I'd guess 60-75 lbs with all the bracing, wiring and hardware.
 
You and Dave N have some - um - heavy stuff in your - um - cars
Are you calling us FAT? :) Anyway, I would suspect there are bigger weight differences between leather and cloth interior and power and manual seats than a base XR7 vs base SC (whatever weight is shed with the little glass on the XR7 is probably gained on the extra metal of the truck lid). I didn't even think about the moon roof weighing that much.

Looks like I'm going to have to weigh my XR7 to convince myself. Although, it has lost some weight in what's rusted away :rolleyes:
 
My SC has every heavy option you can imagine. Leather, dual power seats, JBL sound with sub woofer, moon roof, fold down rear seats and if that wern't enough these 17" X 9" chrome cobra Rs are much heavier than stock wheels.

I'm really not looking forward to the extra 100 pounds the rollbar is going to add. I'm on my version of the atkins deit (down from 245 to 220), but I'll never get skinny enough to have a race weight under 4100 lbs. with the rollbar.

David
 
Thats why you should let me make a few passes w/ it Dave. You saw what I did to Diddy's timeslip. I ran his best times in that car. 14.6@92 I believe. Damn near stock. Too bad he didn't let me race that car at the shootout, I'd have cleaned house.

So my offer still stands next time I'm in town. :D
 
I would recommend looking at the connections on the IC tubes....make sure they're up to snuff..

Put in a K&N panel filter and that might give it some pizazz.

The 89 5-speed I recently got seemed to be dogging it until I put the panel filter in and added just over 1 bottle of SC fluid. Actually after I added the bottle of fluid I thought it got somemore pull to it.
 
Think I'm gonna pull the XR7 motor and sit on it till I find a worthy transplant victim... unless someone comes up with cash!

The SC runs fine as is so it should sell this spring. I'll get it cleaned up and detailed this winter, wrap it up tight and wait till the snow melts to put the FOR SALE sign in it.

Going from a white/red 1990 SC to a black/red 1989 XR7. I hate trying to keep black cars clean... maybe I oughta rethink this.
 
I read someware on this board that with the flip down rear seat & leather
seats,that it weighed 40 more pounds that the cloth seats with non flip down
seat.

randy
 
Well thank God Randy! I have cloth nonfold down rear seats......
...Woo hoo Thats 40 lbs I dont have to worry about!!!!:D
 
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