Transmission not shifting
Thread Starter
Pro
Joined: May 2007
Posts: 609
Likes: 8
From: Round Rock TX
Transmission not shifting
Hey Guys,
I have a 77 vette that I put a B&M TH350 transmission in. The problem I am having is when the car is cold. I have to let it run for a long time before it will shift out of park into any gear. This does it when ever the car is started for the first time. I can run through all the gears and it will not engage into any of them. I run the car at 1500 rpms for a good 5 or 10 minutes then it will shift. It jerks the car alot when it first shifts but it will finally go. Now when I get it going, I have no problem shifting at all. It shifts just like normal. This only happens when the car has been sitting for a while.
I checked the transmission cooling lines and they are not blocked or colapsed.
Any ideas.
I have a 77 vette that I put a B&M TH350 transmission in. The problem I am having is when the car is cold. I have to let it run for a long time before it will shift out of park into any gear. This does it when ever the car is started for the first time. I can run through all the gears and it will not engage into any of them. I run the car at 1500 rpms for a good 5 or 10 minutes then it will shift. It jerks the car alot when it first shifts but it will finally go. Now when I get it going, I have no problem shifting at all. It shifts just like normal. This only happens when the car has been sitting for a while.
I checked the transmission cooling lines and they are not blocked or colapsed.
Any ideas.
Thread Starter
Pro
Joined: May 2007
Posts: 609
Likes: 8
From: Round Rock TX
Ok, it might be the vacuum module. I did some more research and kind sounds right. I have a pretty big cam in the car and very low vacuum. Less then 10Hg. So next question is I have read about getting a vacuum modulator that will work for cars with low vacuum but I can not find a type or part number. Has anyone seen this before?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
Your problem is not the vacuum modulator. You either have low oil level (until the oil is hot enough to expand and keep the pump from sucking air) or you have a sump intake problem. Auto tranny oil level is checked [and set] with engine running, not shut down.
Thread Starter
Pro
Joined: May 2007
Posts: 609
Likes: 8
From: Round Rock TX
If it is full then what can I do to check the sump intake? or do you mean pump intake?
Thanks
Aaron
Last edited by oneshot; Mar 13, 2009 at 09:29 AM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
Pump intake...sump intake...no difference; just semantics. Just drop the pan and check the pick-up tube for any problems with proper sealing: crack in the tube; loose/cut/hard sealring on the pickup tube; broken/cracked transfer tube from pump to block. It could also be a problem with the pressure regultor spring system in the oil pump. Either way, your problem should be in the engine sump area (if the tranny oil level is correct.) You haven't changed/replaced the tranny dipstick for any reason, have you?
Melting Slicks
Joined: Apr 2008
Posts: 2,623
Likes: 242
From: Russell Ontario
St. Jude Donor '09
I'd check the level first if it's not up-shifting try or check the modulator vaccum line , you can get adjustable modulator if need be. You can change a modulator valve in ten minutes. Ron
Thread Starter
Pro
Joined: May 2007
Posts: 609
Likes: 8
From: Round Rock TX
Pump intake...sump intake...no difference; just semantics. Just drop the pan and check the pick-up tube for any problems with proper sealing: crack in the tube; loose/cut/hard sealring on the pickup tube; broken/cracked transfer tube from pump to block. It could also be a problem with the pressure regultor spring system in the oil pump. Either way, your problem should be in the engine sump area (if the tranny oil level is correct.) You haven't changed/replaced the tranny dipstick for any reason, have you?
Thanks
Aaron
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
The pan wouldn't change the oil level requirement. Got to be oil level, suction tube, or pump problem [with the symptoms you described]. Add 1/2 quart of tranny oil and see if you get any change. 1/2 quart too much won't hurt anything. It may not fix it, but if it changes for the better, that's your problem.
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Thread Starter
Pro
Joined: May 2007
Posts: 609
Likes: 8
From: Round Rock TX
The pan wouldn't change the oil level requirement. Got to be oil level, suction tube, or pump problem [with the symptoms you described]. Add 1/2 quart of tranny oil and see if you get any change. 1/2 quart too much won't hurt anything. It may not fix it, but if it changes for the better, that's your problem.
Thanks
Aaron
1st Gear
Joined: Mar 2009
Posts: 1
Likes: 0
Mine was doing the exact same thing after I installed my crate motor. It was the darndest thing. I looked under the car and the vacuum hose had come loose from the modulator. I had to get some new hose and a small clamp and fixed the problem. Mine would take forever to shift gears. I have the TH400.
