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03-09-2009, 07:24 PM | #1 |
Registered User
Join Date: Aug 2008
Location: Austin, Texas
Posts: 78
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can an auto trans 'drag' without failing outright?
It seems like my th400 has a lot of friction in forward or reverse gears. To go in reverse requires some pretty dramatic rpms to get it rolling. I dont have a tach to get true numbers... In forward it seems to require fewer rpms to start, but doesnt seem to shift at the proper point.
I just had the brakes redone and on the test drive the mechanic thought the brakes were grabbing. He checked it out and said they were fine. When I shift in reverse though, it seems that the rear squats a bit. Would that indicate a rear brake issue? Can an auto fail this way? Thanks for any info you can provide. |
03-09-2009, 08:21 PM | #2 |
diggertodd
Join Date: May 2005
Location: Athens, Illinois
Posts: 132
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Re: can an auto trans 'drag' without failing outright?
The sprag in your torque converter is going,
With your describing that your rear-end is squatting, your describing that it takes more brakes to hold the truck still? The sprag in your torque converter in basically a large ratchet wrench you spin backwards from the locking direction. This sprag allows the engine to idle without passing the converters fluid torque to the trans and shoving the truck when it is sitting still. The more it is damaged, and it will get worse - fast, it will quickly lock-up and damage the trans quickly. Just 2 cents worth from a drag racer who has banged his fair share of $900 torque converters. - diggertodd Last edited by diggertodd; 03-09-2009 at 08:23 PM. Reason: typo typo |
03-09-2009, 08:22 PM | #3 |
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Join Date: Jun 2008
Location: Jackson, Ca.
Posts: 674
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Re: can an auto trans 'drag' without failing outright?
Sounds like the pump is going or maybe even the torque converter, but usually the torque converter makes noise when it starts to die.
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Cable -K5 Blazer 2wd: 6.0 LQ4, 7875 Turbo, Tick Stage II Turbo Cam, Built 4L80e, RevMax Billet 3600, 9.5" 14 Bolt -Chevy 3+3 Crew Cab Dually: Cummins 12v P-Pump Swap, Compound Turbos, A2W Intercooler, NV4500HD, 4wd conversion, Radius Arms, Coilovers, Crossover Steering, etc Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=803608 |
03-09-2009, 08:48 PM | #4 |
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Join Date: Aug 2008
Location: Austin, Texas
Posts: 78
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Re: can an auto trans 'drag' without failing outright?
thanks for the replies.
When I shift in reverse and the back end squats, my foot is off the brake and there should be no pressure to the brakes at all. Are pumps and the sprag usually replaced during a rebuild? |
03-10-2009, 01:16 AM | #5 |
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Join Date: Jun 2008
Location: Jackson, Ca.
Posts: 674
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Re: can an auto trans 'drag' without failing outright?
Yes, both are "soft parts" and easily replaced.
__________________
Cable -K5 Blazer 2wd: 6.0 LQ4, 7875 Turbo, Tick Stage II Turbo Cam, Built 4L80e, RevMax Billet 3600, 9.5" 14 Bolt -Chevy 3+3 Crew Cab Dually: Cummins 12v P-Pump Swap, Compound Turbos, A2W Intercooler, NV4500HD, 4wd conversion, Radius Arms, Coilovers, Crossover Steering, etc Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=803608 |
03-10-2009, 12:02 PM | #6 |
Registered User
Join Date: Nov 2008
Location: grande prairie, alberta Canada
Posts: 49
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Re: can an auto trans 'drag' without failing outright?
did it do this before the brakes were repaired?
Have you jacked up the rear end, chalked the front wheels put it in nuteral and try to rotate the wheels by hand? |
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