1985 corvette shifting gears when cold issue automatic
Thread Starter
Intermediate
Joined: Feb 2016
Posts: 41
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From: Vancouver BC
1985 corvette shifting gears when cold issue automatic
When the car is cold and I put it in reverse or drive, it barley moves. Just like trying to move a manual with the clutch almost all the way in, it revs but barely moves. Giving it more throttle doesn't make it move much faster. Once it warms up shifts and moves fine.
Last edited by pavich91; Feb 10, 2018 at 08:49 PM.
Melting Slicks
Joined: Feb 2003
Posts: 2,677
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From: Saskatoon Sask.
Did both conditions appear at the same time or one sometime after the other? How many miles on the trans?
Thread Starter
Intermediate
Joined: Feb 2016
Posts: 41
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From: Vancouver BC
Car has 85000km
Melting Slicks
Joined: Feb 2003
Posts: 2,677
Likes: 811
From: Saskatoon Sask.
PS: If you continue to make it "crawl" at 2000 RPM, this condition will not be your only problem.
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Thread Starter
Intermediate
Joined: Feb 2016
Posts: 41
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From: Vancouver BC
So I will ask my question again. Did both conditions(in forward and reverse) appear at the same time or did one condition manifest itself before the other? It makes a difference.
PS: If you continue to make it "crawl" at 2000 RPM, this condition will not be your only problem.
PS: If you continue to make it "crawl" at 2000 RPM, this condition will not be your only problem.
After abiut a 5 min warm up it moves normally.
Last edited by pavich91; Feb 10, 2018 at 12:16 PM.
Le Mans Master
Joined: Jul 2004
Posts: 6,227
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From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
As soon as i start it up, If i put it in drive it does it, if i put it in reverse it does it. Or vise versa. And just giving an example that no matter how much gas i give it still crawls. I dont keep revving it up to get out like a kid driving a 5spd mustang lol.
After abiut a 5 min warm up it moves normally.
After abiut a 5 min warm up it moves normally.
If it sits for more than a couple days, the transmission will slip at startup. Let engine run 15-20 seconds, then put into gear and it's normal.
I sure wouldn't be giving it more gas if it's slipping
Last edited by Cruisinfanatic; Feb 10, 2018 at 12:46 PM.
Thread Starter
Intermediate
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From: Vancouver BC
No. I don't give it gas. I let it warm up before I move it. Just tried one time to see what happens.
Le Mans Master
Joined: Jul 2004
Posts: 6,227
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From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Melting Slicks
Joined: Feb 2003
Posts: 2,677
Likes: 811
From: Saskatoon Sask.
As soon as i start it up, If i put it in drive it does it, if i put it in reverse it does it. Or vise versa. And just giving an example that no matter how much gas i give it still crawls. I dont keep revving it up to get out like a kid driving a 5spd mustang lol.
After abiut a 5 min warm up it moves normally.
After abiut a 5 min warm up it moves normally.
...........did both conditions, forward and reverse appear at the same time???
Thread Starter
Intermediate
Joined: Feb 2016
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From: Vancouver BC
OK, I will try this one final time and then I give up. The first time you noticed this, did it do this in one position(forward or reverse, take your pick) but it was OK in the other direction? Then after a period of time, the other direction also developed this condition? OR
...........did both conditions, forward and reverse appear at the same time???
...........did both conditions, forward and reverse appear at the same time???
Lol, sorry. It happened both directions at the same time
Intermediate
Joined: Sep 2017
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From: Dataw Island SC
It's been a while and I can't remember for SURE, but I think the 700R4 mechanicals are based on the TH350. If this is like I remember, you're experiencing a low/reverse clutch slipping. If it's at start-up/cold like you describe it's likely the seal leaking and not allowing the low/reverse clutch to engage. As things warm up the seal expands and the piston will engage the clutches. Very common TH350 failure point.
If it does it like cruisinfanatic experiences it might be just a leak-down issue that requires fluid pressure to restore. However, if it happens every cold start, I hate to say it, but plan on pulling the trans for a rebuild. It's not going to get better and every time you engage 1st or Rev you're damaging the seal even worse, plus eating the low/reverse clutches. Eventually, probably sooner rather than later, you will lose 1st and reverse altogether.
As a last ditch effort, drop the pan and change the fluid and filter. Inspect the pan for clutch material. If it's clean you might get some more life from it with some driving TLC. If you see clutch material it's done for.
Any transmission experts feel free to correct me - it has been more than a few years since I've been inside one. My memory isn't what it used to be.
If it does it like cruisinfanatic experiences it might be just a leak-down issue that requires fluid pressure to restore. However, if it happens every cold start, I hate to say it, but plan on pulling the trans for a rebuild. It's not going to get better and every time you engage 1st or Rev you're damaging the seal even worse, plus eating the low/reverse clutches. Eventually, probably sooner rather than later, you will lose 1st and reverse altogether.
As a last ditch effort, drop the pan and change the fluid and filter. Inspect the pan for clutch material. If it's clean you might get some more life from it with some driving TLC. If you see clutch material it's done for.
Any transmission experts feel free to correct me - it has been more than a few years since I've been inside one. My memory isn't what it used to be.
Supporting Vendor
Joined: Oct 2004
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It's been a while and I can't remember for SURE, but I think the 700R4 mechanicals are based on the TH350. If this is like I remember, you're experiencing a low/reverse clutch slipping. If it's at start-up/cold like you describe it's likely the seal leaking and not allowing the low/reverse clutch to engage. As things warm up the seal expands and the piston will engage the clutches. Very common TH350 failure point.
If it does it like cruisinfanatic experiences it might be just a leak-down issue that requires fluid pressure to restore. However, if it happens every cold start, I hate to say it, but plan on pulling the trans for a rebuild. It's not going to get better and every time you engage 1st or Rev you're damaging the seal even worse, plus eating the low/reverse clutches. Eventually, probably sooner rather than later, you will lose 1st and reverse altogether.
As a last ditch effort, drop the pan and change the fluid and filter. Inspect the pan for clutch material. If it's clean you might get some more life from it with some driving TLC. If you see clutch material it's done for.
Any transmission experts feel free to correct me - it has been more than a few years since I've been inside one. My memory isn't what it used to be.
If it does it like cruisinfanatic experiences it might be just a leak-down issue that requires fluid pressure to restore. However, if it happens every cold start, I hate to say it, but plan on pulling the trans for a rebuild. It's not going to get better and every time you engage 1st or Rev you're damaging the seal even worse, plus eating the low/reverse clutches. Eventually, probably sooner rather than later, you will lose 1st and reverse altogether.
As a last ditch effort, drop the pan and change the fluid and filter. Inspect the pan for clutch material. If it's clean you might get some more life from it with some driving TLC. If you see clutch material it's done for.
Any transmission experts feel free to correct me - it has been more than a few years since I've been inside one. My memory isn't what it used to be.
Melting Slicks
Joined: Feb 2003
Posts: 2,677
Likes: 811
From: Saskatoon Sask.
Someplace you have a hydraulic leak/lack of oil that, under cold conditions, it is not allowing the forward clutch or the reverse input clutch to fully hold. The fact that they both started doing this at the same time indicates that it is in an area that is common to both circuits rather than individual lip seals or D/O rings. Since you say that it is OK once warmed up, that leads me to think it is a seal becoming more pliable when warm and then doing its job or expansion in an area that “reseals” itself. The pump comes to mind. So does the seal around the filter neck. Could be numerous other things without any one thing being obvious during an inspection. If you are not prepared to remove and rebuild, start with a filter and fluid and check the torque on all the valve body bolts. Make a decision on your next move after that - live with it or R and R.
Melting Slicks
Joined: Feb 2003
Posts: 2,677
Likes: 811
From: Saskatoon Sask.
It's been a while and I can't remember for SURE, but I think the 700R4 mechanicals are based on the TH350. If this is like I remember, you're experiencing a low/reverse clutch slipping. If it's at start-up/cold like you describe it's likely the seal leaking and not allowing the low/reverse clutch to engage. As things warm up the seal expands and the piston will engage the clutches. Very common TH350 failure point.
If it does it like cruisinfanatic experiences it might be just a leak-down issue that requires fluid pressure to restore. However, if it happens every cold start, I hate to say it, but plan on pulling the trans for a rebuild. It's not going to get better and every time you engage 1st or Rev you're damaging the seal even worse, plus eating the low/reverse clutches. Eventually, probably sooner rather than later, you will lose 1st and reverse altogether.
As a last ditch effort, drop the pan and change the fluid and filter. Inspect the pan for clutch material. If it's clean you might get some more life from it with some driving TLC. If you see clutch material it's done for.
Any transmission experts feel free to correct me - it has been more than a few years since I've been inside one. My memory isn't what it used to be.
If it does it like cruisinfanatic experiences it might be just a leak-down issue that requires fluid pressure to restore. However, if it happens every cold start, I hate to say it, but plan on pulling the trans for a rebuild. It's not going to get better and every time you engage 1st or Rev you're damaging the seal even worse, plus eating the low/reverse clutches. Eventually, probably sooner rather than later, you will lose 1st and reverse altogether.
As a last ditch effort, drop the pan and change the fluid and filter. Inspect the pan for clutch material. If it's clean you might get some more life from it with some driving TLC. If you see clutch material it's done for.
Any transmission experts feel free to correct me - it has been more than a few years since I've been inside one. My memory isn't what it used to be.
Oil Producer
Joined: Apr 2014
Posts: 9,368
Likes: 2,735
Arbee helped me with my 85 when the trans grenaded. ended up replacing it with an $150 86 trans with 20k miles on it from a wrecker in edmonton. amazing results.
i did not have your symptoms. i did have a leaking dipstick grommet. id recommended following arb on this and id be dropping pan to assess fluid and filter oring. they can be a behatch if stuck up there. my finger wouldnt fit. i asked my wife to crawl under the car which i had raised and she came through.
good luck with trans and dont be too discouraged, there are ways to replace with known good replacements from wrecker if money is tight like it was for me at the time.
i did not have your symptoms. i did have a leaking dipstick grommet. id recommended following arb on this and id be dropping pan to assess fluid and filter oring. they can be a behatch if stuck up there. my finger wouldnt fit. i asked my wife to crawl under the car which i had raised and she came through.
good luck with trans and dont be too discouraged, there are ways to replace with known good replacements from wrecker if money is tight like it was for me at the time.