I have a D36 on a automatic early 1986 corvette. I took it to my trusted mechanic and he checked the fluid. It was a little low. He showed me so he was not lying and it was nasty looking. It was original with 145,xxx miles on it. I said change the fluid and check all the parts. He did and everything looked great! He even checked u joints ect...I get it back and it doesn't want to accelerate as fast. I talked to him and he checked it over for free and said the only thing it "MIGHT" be is that the old fluid was so thin and low and used that it made it slicker. He said he highly doubts it but it's possible. Im stumped. He said let it break in for a little bit thru some heat cycles. What do you guys think? No sounds, grinding, gas mileage loss or anything. Maybe his guess is right. He offered to redrain it, check it again and fill it back up for free but I declined.

He also did a FULL tune up. Plugs, wires, distributor cap, rotor button, oil change, cleaned my injectors, flushed my brake system, cleaned my maf, new coil, cleaned the throttle body, checked the transmission, differential, inflated my tires, checked brakes/pads/lines/rotors., new air filter, flushed the cooling system and put a new radiator cap on with new hoses and thermostat, fuel filter, and a few other minor things. Runs GREAT!!! Just doesnt accelerate as fast. I know it's because of the differential. Transmission is fairly new and he checked it over. Just can't figure it out...I still think the fluids thicker and thats why.

 

Just curious why you would think that? To me it seems like the least likely cause for poor acceleration considering the other tune up work, just my take.

 

New fluid does not create drag in the differential. I'd put my money on something wonky up front. Either that, or maybe the hand-brake is partially engaged.

 

with both posts above. Differential fluid viscosity is the least likely reason your car doesn't perform. Check timing and all the other components that were replaced.

 

hmmm...
So you know that electric, maf, and TB all have been altered (all performance related), and the guess is that the new rear end fluid is what is slowing your car down now, compared to before?

 

I agree. You are barking up the wrong tree.

 

wrong tree for sure.
your rearend was in dier need of new fluid

 

When you said FULL tune up I crossed the D36 off the list. I would have all that was done in the tune up looked at again.

 

This is a gag, right?

It couldn't possibly be the diff oil. You could fill it up with tar and not notice any difference in acceleration.

 

I would have another mechanic check the tune up. Something is wrong there.

 

The first thing that comes to mind is timing.
Could be crossed wires etc..Does it have a miss at all?

 

What kind of plugs did he use? I recommend using the NGK

 

Sounds like the throttle cable was not reset. You can do this yourself:


It sounds like the TV cable is set incorrectly. Fix this IMMEDIATELY or it will fry the trans. On the throttle body there is a "D" shaped button where the throttle and TV cables connect. Push it in and the press the cable back into the housing until it is fully seated. Now, open the throttle by hand until it is all the way open (you will hear a ratcheting sound). The TV cable is now set correctly.

As quoted in an earlier post by Frizlefrak

 

I think someone is getting a chuckle out of this.

 

I sure hope this is a joke,