Guest beauchase Posted June 12, 2012 Share Posted June 12, 2012 Our 1990 Reatta down shifts hard or even jerks a tad while shifting from Over Drive to Drive or from Drive to Overdrive while running 45 to 50 MPH in hilly detrain. I recently performed a pan drop service. Fluid level is good. All other shifting is very smooth both going up and coming down. The shift from Over Drive to Drive is also smooth on level detrain. Of course the quick fix is to place the shifter in drive while in hilly detrain. Just wondering if there is a something I can do to smooth this guy out. ffice:office" /><O:p></O:p> Link to comment Share on other sites More sharing options...
DAVES89 Posted June 12, 2012 Share Posted June 12, 2012 Take a look at the transmission shift modulater. The hose that connects it to a plastic tube may be bad. However my experience has always been the most noticable shift is downshifting from second to first. Link to comment Share on other sites More sharing options...
KDirk Posted June 12, 2012 Share Posted June 12, 2012 Second that, and check the vacuum modulator itself. If you disconnect the vacuum line and transmission fluid drips out, the diaphragm is shot and the modulator needs to be replaced. I just did this on the 88, and the difference has been quite remarkable. It now shifts nice and smooth, previous one (original Holley part) clearly was not working right as most up and downshifts were harsh to varying degrees. Thankfully, this is an inexpensive part. KDirk Link to comment Share on other sites More sharing options...
Guest beauchase Posted June 26, 2012 Share Posted June 26, 2012 I finally got the chance to check the Transmission Vacuum Modulator hose and have a look to see if any fluid would drip out of the modulator itself. Hose is in like new condition and there is now fluid in the modulator. I even turn to hose connection down towards the ground. Nothing… I hate to swap the current modulator for no reason. Any other suggestions? Thanks…. Link to comment Share on other sites More sharing options...
Ronnie Posted June 26, 2012 Share Posted June 26, 2012 Do you have the large, stock modulator or do you have the small modulator? The small modulator valve can be adjusted for how hard you want the shift to be. It controls both up and down shifts.The small ones are available in The Reatta Store at ReattaOwner.com for less than $20. Look in the Engine & Transmission category.Small valve Link to comment Share on other sites More sharing options...
Guest beauchase Posted June 26, 2012 Share Posted June 26, 2012 Do you have the large, stock modulator or do you have the small modulator? The small modulator valve can be adjusted for how hard you want the shift to be. It controls both up and down shifts.I currently have the large OEM Gray AC Delco modulator. I’ve considered the Pro-King Automatic Transmission Vacuum Modulator available at Advance for $15.49 but am leery on how to adjust the modulator. Any moral support on the adjustment of a Transmission Vacuum Modulator. </SPAN> Link to comment Share on other sites More sharing options...
Ronnie Posted June 26, 2012 Share Posted June 26, 2012 When you get the one from Advance I'm sure they can tell you how to adjust it. Link to comment Share on other sites More sharing options...
jonlabree Posted June 26, 2012 Share Posted June 26, 2012 Clockwise will tighten up the sgifts. (less slippage)Counter clockwise will loosen them up more slippage) Link to comment Share on other sites More sharing options...
Guest beauchase Posted June 26, 2012 Share Posted June 26, 2012 Clockwise will tighten up the sgifts. (less slippage)Counter clockwise will loosen them up more slippage)Just like that, seems simple enough and inexpensive enough to give it a try. I’ll let you know…</SPAN></SPAN> Link to comment Share on other sites More sharing options...
Guest beauchase Posted June 27, 2012 Share Posted June 27, 2012 (edited) Clockwise will tighten up the sgifts. (less slippage)Counter clockwise will loosen them up more slippage)Pro-King Automatic Transmission Vacuum Modulator purchased from Advance and installed. Shifting up and down is harsher than ever in all gears. My problem was Over Drive to Drive or from Drive to Overdrive. No matter which way I turn the modulator it makes no difference in the harshness of the shifts. There are three dimples on the modulator. I have made a complete turn in both directions a dimple at a time with no noticeable adjustment. Hmmmm…Perhaps one of those high dollar Gray AC Delco modulators is advised. As infothe original one that I removed this evening was a Holley. Any thoughts? <o:p></o:p> Edited June 27, 2012 by beauchase (see edit history) Link to comment Share on other sites More sharing options...
DAVES89 Posted June 27, 2012 Share Posted June 27, 2012 I bought one of those tranny shift modulators also from Advance. Never could get it right. Took it out, went to Gibson's and took the factory unit out of a Buick Park Ave. Installed it and never looked back. At the time a new unit at the dealership was over $100.00. Didn't want to spend that much as I had spent a lot of money getting the Red in shape. Still in there and cost less then $20.00. Link to comment Share on other sites More sharing options...
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