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Any Mechanics aboard?
MrBallbaggins
Registered User regular
Registered User regular
Well, I have an '86 El Camino, with a 350 TPI out of an 88 Firebird and a 700R4 out of an 87 Camaro. The problem here is it's not wanting to shift from 2nd to 3rd, or from 3rd to 4th. If I stab the gas, it'll shift perfectly, but I don't want to go Ultimate Racecar Driver just driving to town and back. When I give it a normal amount of gas, it just kinda shutters as if it's stalling, but when I stab the gas it shifts perfectly. If anyone has experience with these transmissions, or has any suggestions on what it could be, I would really appreciate it. As a rule, I don't really work on anything myself unless it was made before 1981, just because I know what I'm doing there. But with any sort of fuel injection or 4 speed automatic transmission, I have no clue what I'm doing. I'm coming here before I take it to a mechanic because I'm hoping that someone else here has had the same problem and can offer me advice. As an incentive, if anyone correctly guesses the problem, then I'll buy them a beer. If they're the non-alcoholic sort, then I guess I'll get them some energy drinks.
Anyway, any advice other than "go to a mechanic" will be appreciated.
Thanks,
-Bildo
Anyway, any advice other than "go to a mechanic" will be appreciated.
Thanks,
-Bildo
MrBallbaggins on
0
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How's the fluid level? Is it brown or does it smell burnt?
First place I'd look is a vaccum leak.
The 700R4 doesn't use a vacuum modulator like the TH350/400s did. Line pressure is determined by the TV cable and the governor which runs off the speedo cable.
What stabbing the gas pedal is doing is raising the line pressure (the TV cable runs directly off the throttle butterflies). It sounds like at normal throttle you don't have enough pressure to properly shift. I can think of a few causes (in order of ascending seriousness):
1) Your tranny fluid is low or your filter is too gunked up to allow proper flow. If you haven't had the tranny serviced in a long time you might want to do that.
2) The governor is dying. It's got a little plastic gear that meshes with the speedo cable, it's not unheard of for the gear to grenade. Pretty easy fix, I believe all you have to do is drop the pan to replace it.
3) Your line pressure is fine, but your 3rd-4th clutch pack is dying. Stabbing the throttle is manhandling the clutch pack into working. You're gonna need a new tranny.
Well, I guess I'm going to check the governor tonight after I get off of work, hopefully that's the problem.
I forgot to mention earlier, the transmission has a B&M shift kit in it, if that could have anything to do with it.
First thought that comes to mind is the shift solenoid. But I'm not sure if the TH700-R4 has them, as it is still a primarily hydraulic transmission.
Second thought - 2nd and 4th clutch packs. There's a good chance that these are worn and no longer functioning properly, hence the reason you have to gun it (create more pressure) for them to activate. I'd put my money on this.
Either way, it's an internal fix requiring a good amount of work. If you're auto trans savvy, you could probably look up the info, order the parts and do this yourself if you have a place to mount the tranny outside the car. If not, I'd highly recommend taking it to a shop.
edit: Looks like I'm not the first one to suspect clutch packs...
No shift solenoid, the only electronic bit in the 700R4 is the TCC solenoid. I agree with you about the clutch packs, though.
You can have a shop replace them; I don't think it would be as expensive as getting a new tranny. [A little more research shows] the 3-4 clutch packs on the TH700-R4 are inherently weak and known for quick wear and failure.