1trucavalier Posted December 27, 2002 Report Share Posted December 27, 2002 I replaced my vaccume modulator and left the vent tube unplugged and the car drove like pure azzz! It hardly would upshift down shift or anything. Finally I said f-it plugged the modulator vent and the car shifts perfect WTF! Its was said that since its a turbo trans that its supposed to be unplugged so it can vent off the pressure but its so sluggish that there is no way you could possibly drive like that. Whats the deal someone shed some light :?: Quote Link to comment Share on other sites More sharing options...
eclipse5302 Posted December 27, 2002 Report Share Posted December 27, 2002 Well, The vac line comes down from the intake. It then connects to a T fitting / One way valve combo. The idea is to allow vac to the modulator, but once it comes on boost, it's pushed out of the lines via the one way valve. If you cap it, you are allowing the boost to go to a device designed only for vac. So you can picture it like this...the line goes down to the T, and one end of the T goes directly to the modulator. The other end of the T is a one way valve, which is closed on vac and open on boost. This is the end that is not connected to anything, and needs to be left open. It won't suck air or be a vac leak because it's a one-way valve. Only out, not in. Hope that helped. Jason Quote Link to comment Share on other sites More sharing options...
Jeff M Posted December 27, 2002 Report Share Posted December 27, 2002 If I could just add something here, and sorry Jason as I gotta add a correction to ya. The Check Valve "T" you guys are referring to does everything you state but it can also develop a leak, this is somewhat common for this Check Valve. GM does not sell the same exact one but Shawn or Chris (cannot remember who) found another Check Valve that will work as a functional replacement, GM part number 14056648. Also is if the Vac Mod is replaced with an adjustable unit, and the shifts are soft, then the VM needs to be adjusted to firm the upshifts but NOT the downshifts, it is a balance between the firmest upshifts with little or no firmness/hanging of the downshifts as you roll to a stop, and I say little only when the tranny is cold, there can be some, that will then go away once the tranny fluid warms! The adjustment is made via a very small flat blade screwdriver inserted into the vacuum line port of the adjustable VM, turn IN to firm the shifts/raise the tranny fluid operating pressure. Hope that helps. Jeff M Quote Link to comment Share on other sites More sharing options...
eclipse5302 Posted December 27, 2002 Report Share Posted December 27, 2002 Oh yea, I forgot about the valve leaking and the adjustable modulator...Thanks Jeff! The adjustable modulator is nice too, it allows adjustment of the shift firmness like Jeff said. I didn't really notice much difference until I rebuilt the trans though...when the trans was old it didn't help with firmness much at all. But what can someone expect from a trans with 150k? Jason Quote Link to comment Share on other sites More sharing options...
1trucavalier Posted January 6, 2003 Author Report Share Posted January 6, 2003 when you say valve you mean the little plastic piece thats connected to the the modulator via vaccume hose that also connects to the line going to your TB :?: Got another question? I just found a leak coming from my line up at the trans cooler. Does the line or trans keep or both need to keep a certain line pressure for the trans to shift correctly? When the car is cold the trans shifts fine but when it warms up it shifts sluggishly almost like its slipping which could be knowing these wonderful tranny's. I just need to keep it going long enough so I can get the 5-speed. I am going to replace the trans filter and that leaking line asaitstopsdamnsnowing! Quote Link to comment Share on other sites More sharing options...
eclipse5302 Posted January 6, 2003 Report Share Posted January 6, 2003 when you say valve you mean the little plastic piece thats connected to the the modulator via vaccume hose that also connects to the line going to your TB :?: Got another question? I just found a leak coming from my line up at the trans cooler. Does the line or trans keep or both need to keep a certain line pressure for the trans to shift correctly? When the car is cold the trans shifts fine but when it warms up it shifts sluggishly almost like its slipping which could be knowing these wonderful tranny's. I just need to keep it going long enough so I can get the 5-speed. I am going to replace the trans filter and that leaking line asaitstopsdamnsnowing! Yeah, thats what I meant by the valve. As for the line pressure thing, no a small leak in the trans lines won't cuase the trans to shift werid. You've probably got worn seals or clutches or something else. Are you looking for a 5-speed trans? I may be putting my complete 5-speed conversion on ebay soon...which includes the hard to find/make maunal turbo bracket. Jason Quote Link to comment Share on other sites More sharing options...
1trucavalier Posted January 7, 2003 Author Report Share Posted January 7, 2003 why not just sale it outright to someone on TGP or w-body board? Quote Link to comment Share on other sites More sharing options...
eclipse5302 Posted January 7, 2003 Report Share Posted January 7, 2003 I'm probably going to do that. I've got a lot of 3.1 turbo/manual parts that I may be selling soon. I took the engine and trans out of my Cutlass, and I might rebuild it or put in a L67. Not sure yet. Jason Quote Link to comment Share on other sites More sharing options...
1trucavalier Posted January 8, 2003 Author Report Share Posted January 8, 2003 L67 is exactly what I was thinking about. If my 3.1T goes for any reason then I am going to replace it with the L67. I found 37 in my local area ranging from $700 (high mileage)-2200. If I can score one for $1000 then when I pull the motor for the 5-speed swap the 3.1L is not going back in. Its worth in in the long run because the aftermarket on the 3800 far exceeds the 3.1L. Quote Link to comment Share on other sites More sharing options...
1trucavalier Posted January 8, 2003 Author Report Share Posted January 8, 2003 Oh yeah last night while trouble shooting for 2 hours in 25 deg weather to find out why out of the BLUE :shock: why I didn't have a trickle of power to the car (no lights, igniton bell etc.....) I found that my battery didn't even a trickle of acid/water in it. After that I found that my tranny to cooler lines are leaking at the connection on the drivers side supply/return and the supply to the cooler is leaking also. I could have shifting problems because there isn't enough tranny fluid. What I don't understand is it doesn't leak in my driveway at all. I monitor that big time for oil/tranny/coolant and check it at least 3 times a week. I am going to just replace the tranny filter, pan gasket and lines and see how it runs. Quote Link to comment Share on other sites More sharing options...
eclipse5302 Posted January 9, 2003 Report Share Posted January 9, 2003 Well, there is a chekc ball in the trans, and if it's not pumping fluid I can't imagine it would leak too easily (ie in the driveway). If you need to replace those lines you might find that they are no longer made. But, if you need to fix the leaking lines you could cut the metal bands off (with a cutoff wheel) of the ends of the lines and install heavy duty SS clamps (If you look closely at the ends of the lines you will know what I am saying). Thats what I had to do with my TurboSTE because the lines were no longer made. It's still holding today. Jason Quote Link to comment Share on other sites More sharing options...
1trucavalier Posted January 9, 2003 Author Report Share Posted January 9, 2003 i already did that on the cooler side when i replaced the stock radiator with the griffin unit. My tranny fluid now no longer goes through the radiator. I just cut the nipples/ends off and put RTV just inside the lines and then double clamped them. I am going to have to do the same to the other side thats leaking. There should actually be plenty of tranny to cooler lines available because the n/a 3.1's have the same tranny line to radiator set up just a longer radiator. Quote Link to comment Share on other sites More sharing options...
eclipse5302 Posted January 9, 2003 Report Share Posted January 9, 2003 Yeah, you're probably right...I was thinking about the extra cooler the TGP has. Beccause of the extra cooler all the lines are different.\ So you don't run your trans fluid through the radiator? Do you have a trans temp gauge? Do you let the car idle for extended periods of time? You'd be surprised how much you actually need the fluid to run through the radiator. When I reinstalled my trans, I bypassed the radiator. I soon found out why GM runs it through the radiator... My trans temp gauge went up to 230 degrees for only the 5-10 minutes I was in a drive through getting food (long wait). I started to understand what GM was thinking when I saw my coolant was only 185 degrees. You see, at idle / slow speeds the external cooler cannot cool the fluid (no air). This is when your radiator cooler comes in to play. The trans fluid is never above the coolant. Once I re-hooked up the radiator cooler my trans fluid never exceeds 180 degrees. And you would think running the fluid through the radiator would heat it up. It doesn't. When you are moving, there is air running over the external cooler. The fluid is also moving fast...which means it moves fast through the radiator cooler, and at high speeds your air cooler is much more efficent than your radiator cooler. Sorry about the long post... Jason Quote Link to comment Share on other sites More sharing options...
1trucavalier Posted January 9, 2003 Author Report Share Posted January 9, 2003 never thought of getting a guage but that POS is getting trashed anyway so I am not even going to bother. Its 5-speed or nothing. This is my first and last automatic. I must have been smoking at the time. I was going to run a B&M with fan but of course there is no use now. Quote Link to comment Share on other sites More sharing options...
Chris A Posted January 10, 2003 Report Share Posted January 10, 2003 i already did that on the cooler side when i replaced the stock radiator with the griffin unit. My tranny fluid now no longer goes through the radiator. I just cut the nipples/ends off and put RTV just inside the lines and then double clamped them. I am going to have to do the same to the other side thats leaking. There should actually be plenty of tranny to cooler lines available because the n/a 3.1's have the same tranny line to radiator set up just a longer radiator. I keep forgetting to verify this, but I think the TGP uses bigger lines than the other wbody's. 3/8 to 5/16 i think. Quote Link to comment Share on other sites More sharing options...
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