When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I just bought an automatic 1981 corvette and when I attempt to accelerate from a standstill, the engine revs will go up as normal but I won’t go anywhere and eventually I start to slowly accelerate. Also, when eventually at speed, if I want to overtake someone, there is barely any acceleration. Does anyone know of this issue or how to resolve it? Thanks.
First. Check fluid level in trans. Top up as necessary.
And if trans is still slipping badly. Take it to a automatic transmission shop.
Clearly your trans is slipping badly. And if you had no idea I'm thinking rebuilding an automatic transmission might be above your skill level. Not to worry, it's above most people's skill level.
Thanks for responding so quick! I initially thought it was slippage but wasn’t sure because there are a few other possible reasons why the transmission is acting how it is I just wasn’t 100% sure. I will take it to an automatic transmission specialist soon.
Welcome to the Forum. Please post a photo of your car!
As @4-vettes pointed out, the most likely problem is that you are low on transmission fluid. Your car now behaves like a modern soul-crushing automatic.
Although unlikely in 1981, count your pedals. If you have three, you may need a new clutch.
Timing can really wake these cars up, but it seems that the issue right now is the transmission.
I bought a 1981 14 months ago,and even though it’s a eight cylinder,it is as slow as a turd,lol....I guess that’s why I tore mine apart,so if you’re exspecting it to burn the tires,It won’t.I think it was 190hp. So,not sure if this is original with all the smog stuff,but if you need any parts for engine,let me know,I also have the dual snorkel for it like new,as I was planning on using it,but when I replaced the heads,intake and carburetor so,had to change air breather,and even with that,had trouble shutting the hood,had to end up putting shims under it to raise the hood a little.
I bought a 1981 14 months ago,and even though it’s a eight cylinder,it is as slow as a turd,lol....I guess that’s why I tore mine apart,so if you’re exspecting it to burn the tires,It won’t.I think it was 190hp. So,not sure if this is original with all the smog stuff,but if you need any parts for engine,let me know,I also have the dual snorkel for it like new,as I was planning on using it,but when I replaced the heads,intake and carburetor so,had to change air breather,and even with that,had trouble shutting the hood,had to end up putting shims under it to raise the hood a little.
Excuse me? You shimmed the hood up? Instead of dropping the airfilter down?
Seriously? And how exactly does that work in practice. So when you drop the clutch and the engine goes up and to the right. Does the airfilter then smack the underside of the hood?
How does the hood look not lined up with the fenders?
This is indeed a unconventional approach.
Some might consider a drop base air filter. Others like myself might consider a high rise hood. Some even a bolt on or graft on hood scoop.
But shim the hood up. That's thinking outside the box.
Well,I have the lowest drop base breather base on it,and as for the fit,it was lower than the fenders anyway,and there was already shims on it and I added some and raised the hood,I guess maybe 1/8 in,just enough to clear everything,so ordering a new hood,having it painted,instead of adding shims which took 5 minutes,if that’s out the box,I’ll take out the box,oh and the shims were like $10.00 dollars for shims,now exactly how much is a hood,oh and painting it also,what maybe $1,000.
Simple fix sounds like low fluid, easy enough to check. Otherwise it's the bands probably need replacing, not something typical for the DIYer to accomplish.
If not too bad, there are some additives you can try as a temp fix.
Well,I have the lowest drop base breather base on it,and as for the fit,it was lower than the fenders anyway,and there was already shims on it and I added some and raised the hood,I guess maybe 1/8 in,just enough to clear everything,so ordering a new hood,having it painted,instead of adding shims which took 5 minutes,if that’s out the box,I’ll take out the box,oh and the shims were like $10.00 dollars for shims,now exactly how much is a hood,oh and painting it also,what maybe $1,000.
well your explanation makes some sense. Of course one would assume that your hood was correctly fitted in the first place. Most are. But that's what I get for assuming.
Still begs to question 2 things.
1. The Engine is rubber mounted, unless you have converted it to solid mounts as well. But if somewhat stock. The engine is rubber mounted. So under hard acceleration the engine will lift and pitch right. If your under hood clearance is that tight. Your first burnout should also give you a nice Star crack right above the air filter wing nut.
2. A super low drop base air filter is likely to limit air flow. This can cause multiple issues.
And your correct. Putting on a new hood with paint and all is far more expensive than a couple shims. I'm thinking my hood with paint was at least double your estimate 20 years ago. So even more now.
Hello! Sorry I didn't get back to responding I accidentally responded as a private reply instead of a thread post. I have checked the transmission fluid and seems to be full and fresh color. I also threw in some Lucas stop slip to see if it make a difference nothing changed. Like 4-vettes said, I pulled the vacuum modulator and it seems to be in good condition but I have a new one coming hopefully tomorrow that I am going to test out. I will have pictures of the old one soon. If it turns out to be the bands, I would be somewhat shocked because the car only has 50k miles on the odometer and the previous owner said the car drove and accelerated fine before I bought it. Thanks for all of your responses so far btw. I have some
pictures of the car now attached here if your interested. Definitely needs a paint job and its in a temerity shop now.
Last edited by Landon H.; Jun 7, 2023 at 10:56 PM.
Reason: adding text
Me, I think it's an easy decision. Rip out that slush box and put in a manual trans of your choice. Get some decent rear gears in your diff and build your engine for more power.
simple.
See how good I am at spending your money?
Oh.
I know, this isn't helpful if your on a budget.
Lesson 1. Never buy a sports car with a automatic transmission.
I just changed out the transmission fluid, vacuum modulator, filter and gasket for the trans today. None of that even helped but instead made the situation worse. I can’t even barely move forward anymore in any forward gear but reverse seems to work oddly. The fluid is right at the full mark while hot and everything else is hooked up so I’m thinking the transmission is just shot and needs replacing or rebuilding. Sorry I couldn’t get a video but imagine your in 1st gear but it drives like your in neutral.
No, the previous owner said that the car drove and shifted fine before I bought it which is weird because I have only had the car for a month and all I have done is the brakes and transmission fluid change, and vacuum modulator etc. Nothing has been tampered with in the engine bay exempt for there being no belt on the A.I.R pump. The most confusing part is that the car shifts like butter but there is just 0 acceleration.
No, the previous owner said that the car drove and shifted fine before I bought it which is weird because I have only had the car for a month and all I have done is the brakes and transmission fluid change, and vacuum modulator etc. Nothing has been tampered with in the engine bay exempt for there being no belt on the A.I.R pump. The most confusing part is that the car shifts like butter but there is just 0 acceleration.
pull air cleaner and take a closeup pic of throttle side of carb
Here are some pictures of the side of the carb. Let me know if something seems fishy because I don’t know what it’s supposed to look like if it’s broken or damaged.
it is mounted upside down in the bracket, no big deal but the adjuster tab
should be on top.
press tab in, push black round point plastic the cable goes thru in.
open throttle to full and black plastic piece that was pushed in will extend.
tvs is now adjusted.
verify cable is connected properly to trans.
81 corvette acceleration issues
