I think its an adjustment thing but I'm really not sure. I drove my car from seattle back to where I was moving (bout 60 miles from seattle) and on the highway I shifted it into OD. My transmission is a 700R4 with a shift kit, whole shebang, 2400 stall, etc, and a 4th gear vacuum lockup set up (tranny shop put it in, I odn't know how it works). Anyway, on the drive back, when I first shift it into OD it lugs and stays right around 1500-1800 RPM like it always has, but then if I hit the gas a bit more, and it shifts back into third, then let off, it sort of seems like it.....half way shifts back into OD and seems like it has more power in the 4th gear now. Is it in 4th gear and the OD just hasn't locked or how does that work? It feels alot different. If any more explanation is needed, lemme know and thanks in advance.

 

I would say its the lockup not functioning correctly.

Its shifting to 4th(OD) like it should but the lockup doesnt engage giving you that 1:1 ratio between the engine and tranny.

 

Thats kinda what I thought. Is this something that will hurt the transmission?

Thanks for your SPEEDY reply

cheers

 

In the long run if you dont have a trans cooler it will cause problems, If the converter doesnt lock you always have that slippage and it causes heat to build up and that heat can kill a tranny. Also doesnt do you any good for fuel economy!

 

Not so worried about the economy but its got a hefty tranny cooler already thanks!

 

Sounds to me like it may be functioning properly, just not adjusted right.

If you kick it down to 3rd, and then maybe its locking up the TC in 3rd but not shifting back into 4th because you have your foot into the accelerator to the point that a shift into 4th is not going to happen (would require changing the TV plunger and sleeve), and that "shift" you are feeling is actually the TC locking up and not a 4th gear upshift?

Or maybe it is shifting from 3rd to 4th and not locking the TC back up yet because the vacuum controller is not getting the right vac signal from the intake yet, and could use some adjustment?

You need to figure out which situation is happening first, then take it from there.

 

I would say its alot more likely that its not locking up when it shifts back to 4th.

It seems to be functioning correctly in the sence that it unlocks and downshifts when you stomp on it but it just wont lock up again. or something like that...

It could be a cracked vacuume line giving the sensor a weak signal, vaccume line is connected to a 'ported' source instead of manifold vaccume or depending on what 'kit' is actually installed, it may be adjustable and just not set right.

 

Its not going into lock up. It has the vacuum controlled lock up mechanism, and it hasn't fully been adjusted correctly cause of other changes that are being made to the car (cam is huge too, doesn't have alot of vacuum)

thanks