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BillSF49 | 94 automatic - soft shift | ||
Guru Newb
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I have owned my 94 LT1 auto since 2002. I used to get a second gear scratch when i stood on the throttle. It was a firm shift. Now, over the last several months, I have noticed that it is very soft, kind of like an old buick. the shift just slides into the next gear. It is very uneventful. I haven't had any changes to tires or tuning. It just seems to have gone "soft".
Does this sound like a big problem? I would appreciate any suggestions. Thanks, Bill |
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Posted on: 2008/5/22 12:10
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Notorious | Re: 94 automatic - soft shift | ||
Elite Guru
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It could just be showing it's age but the 4L60E can have pressure loss problems that can be fixed w/o an entire rebuild. My original trans didn't shift as I liked either so I installed a B&M Shift Plus unit. It's cheap and easy to install and boosts shift pressures electronically, as can be done with a PCM reprogramming. My stock trans worked good for several years after until I installed a stroker engine, that finally killed it.
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Posted on: 2008/5/22 13:02
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1Fast04Vert | Re: 94 automatic - soft shift | ||
Elite Guru
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Time for a fluid and filter service???? Does the fluid smell burnt, look discolored, etc?
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Posted on: 2008/5/22 14:13
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_________________
2004 Vert. 475hp. Built by Vengeance Racing |
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BillSF49 | Re: 94 automatic - soft shift | ||
Guru Newb
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Actually, yes, I have it changed regularly, probably more often than I should, it is a nice cranberry color.
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Posted on: 2008/5/23 4:41
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CasetheCorvetteman | Re: 94 automatic - soft shift | ||
Elite Guru
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Yep, the band is rooted.
You can never change auto trans fluid too often. |
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Posted on: 2008/5/23 11:35
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aapple | Re: 94 automatic - soft shift | ||
Guru Newb
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Quote:
How are the other shifts? Are they also a bit softer, or do they still work the same? The band in the 700/4L60E operates 2nd gear and 4th, so usually, if there is a band issue, it will effect both 2nd and 4th...unless there is a problem with the servo. The servo(located on the pass side of the trans) is actually two separate servos...one section operates 2nd, the other operates 4th. You can have a sealing ring problem on the 2nd servo that will make the 1-2 shift mushy, but not effect the 3-4 shift. There could also be a problem with the 1-2 accumulator, located inside the pan of the trans. Usually, if the accum. spring breaks, it causes harsh shifts, but...if it hangs up the accum. piston, it can cause a soft shift. Soooo many possibilities here... ![]() |
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Posted on: 2008/5/26 14:33
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Matatk | Re: 94 automatic - soft shift | ||
Webmaster
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Wow...good info. Are you going to be our trans go-to-guy?
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Posted on: 2008/5/26 15:50
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_________________
2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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BillSF49 | Re: 94 automatic - soft shift | ||
Guru Newb
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All other shifts are still the same, no issues at all, it is just that 1 to 2 soft shift. Everything else is good. So, should I check for leaks on the passenger side trans? This is good info, i was immediately thinking worst case scenario. It would be nice to know there may be some alternate maybe less costly solutions. Thanks,
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Posted on: 2008/5/28 22:28
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aapple | Re: 94 automatic - soft shift | ||
Guru Newb
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You wouldn't see any leaks from the servo externally...at least none that would cause the soft shift. Don't get me wrong, the trans may have an internal problem, but I prefer to eliminate the easy stuff first.
In this case, I would remove the servo, and check the sealing rings for the 2nd gear part of it. If the rings were good, I'd have to start digging into the valve body or accumulator for answers. Of course, once you get the pan off to check that stuff, the pan itself will help with further diagnostics. If there's a ton of crap in the pan, it's time for a rebuild anyway. If the pan is fairly clean, and only has minor "varnish", and no major chunks, then I'd check the accumulator for a damaged spring or accum. piston. The center hole of the accum. piston can and does wear out, making it egg-shaped, which allows the 2nd gear fluid pressure to bleed off. It's very common to see the piston messed up, as it is to see the spring broken. Both are easily replaced. If the accum. looks okay, then it's time to remove the valve body, and see if there are any stuck/sticky valves. After that...well...it's time to pull the unit. Have you scanned the ECM to see if there are any codes in it? Sometimes that can point you in the right direction, too. The trans in the '94 is electronic controlled...don't see a lot of issues with the solenoids that would cause only one shift problem, but it could happen if the EPC(electronic pressure control) solenoid is gunked up, and not responding quickly enough. hth |
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Posted on: 2008/5/29 4:09
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