4T65E Hard Shift-Solution

**jbamonte** · 12-20-2009

I have a 2001 Grand Prix 3.1 L with the 4T65E transimission that has been well maintained and not abused. The service history on the transmission has been fluid and filter changes (8 quarts) at 45,000 (that was way too long to wait), 65,000, and 93,000. At about 90,000 miles (Oct 08), the transmission experienced the first P1811 hard shift in traffic after traveling on the highway before the incident at 70-80 MPH on a 80 degree day. The usual temporary solution of shutting the engine off and restarting after 5 minutes temporarily solved the problem.

I have actively researched the issue over the past year and made some changes to the transmission to help improve and then eventually solve the problem. The reason for the post is to alert some of you that this issue can be resolved on a 4T65E transmission that is essentially functioning correctly, been well maintained, and does NOT have other internal problems. I have noticed in my research that many recommendations surround replacing the PCS solenoids, TCC solenoids, worn second gear clutch, all the way to most of the time, transmission replacement for ridiculous dollars (BTW-gmpartsdirect sells brand new 4T65E transmissions for $1,300).

From what I have read, the 4T65E's do not like heat and since the transmission acted up when hot, the obvious solution was to add the biggest baddest double stack transmission cooler that I could fit in the grill which I did (28,000 GVW) after the radiator cooling. This change greatly minimized the problem but it still occurred occassional on hot days. The next step was to totally have the transmission be cooled by the tranny cooler, by passing the radiator completely. BTW-There is no problem in the cold other than it takes about twice as long to get over 77 degrees for lockup.

The final solution was the ZZ performance shift kit for $30 that speeds up the shifts in the accumulator (easy to do if you can change your transmission fluid and filter) since the hard shifts occur due to shifts occurring too slow (over .65 seconds) and the computer tells the transmission to go to max line pressure since it thinks that there is something wrong due to the slow shifts. Obviously, with 100,000 miles on the transmission, parts get worn but there is still plenty of life in a well maintained transmission with the hard shift occurring because the springs in the accumulator becoming weak with age and mileage allowing slower shifts, some clutch wear that needs to be compensated with the shift kit (there is no adjustment for the 2nd gear clutch), and/or a bad solenoid (s) that again can be compensated with speeding up the shifts manually with the shift kit.

The tranny cooler and shift kit cost about $100 and now has 4,000 miles on it and has not acted up once since I installed the shift kit which does not make the shifts harsh (choose the milder spacer setting), just speeds the shifts up. The transmission shifts perfectly now under all conditions.

My point here is that many people are spending big dollars to fix a relatively minor problem as long as the rest of the transmission is in good working order. Recommendations by transmission places to replace the solenoids for $700-800 dollars only to have the problem occur again or to replace the whole transmission for $1,800-2,500 is criminal when the problem can essentially be addressed with a $30-60 shift kit.

I hope that this will help some of you with this problem.

**blueguy** · 12-20-2009

Triple Edge Performance - Home Page

Check that out. Also...a tune with upped line pressure with a shift kit with help things even further IMO.

**frugal** · 01-25-2010

Can you give us an update for your shift kit install. this seems like a simple solution to an exact problem a lot of us face. I thought that my pressure switch was going south but your symtoms mimic mine in every way. I would be more than willing to try this.

**bronzemist02** · 01-25-2010

I had the same problem and got my solenoid replaced along with the springs. Solenoid was set to shift a little bit harsher than stock and I haven't had a problem since. Was $375 for my complete solenoid and spring replacement with tax. Read the writeup on the zzp page for the product. Shift kit is not supposed to speed up shifts, it just changes the firmness and reduces wear on the clutches.

**jbamonte** · 01-25-2010

I have not exerienced the hard shift once since installing the shift kit. the shift does speed up the time between shifts by making the shifts firmer. I no longer have issue since installing the shift kit and tranny cooler-$100 for both-did it myself. Pm for more info.

**frugal** · 01-28-2010

I'm going to give this a try. I've noticed a few flared up shifts from time to time , which may indicate something hanging up and sticking, possibly triggering the max line pressure. It still works fine otherwise. I'm going to order this tommorow, i'll give an update after installation.

**jbamonte** · 01-30-2010

Frugal,

Let me know how you make out. My transmission has been perfect since I installed the ZZP shift kit and the trans cooler. It has been 2months since the shift kit was installed and everything is perfect. No hard shifts yet!!

**frugal** · 02-03-2010

I just ordered the kit from ZZP. I dont know when i will be able to do the install but it will be soon i hope. I'ts the wifes van and when it goes into this harsh shift mode it really freaks her out. i have been carefully observing the cause of the harsh shift. what i have noticed is that when everthings cold , there is no problem and the transmision shifts fine. as the car warms right up, I notice the shifts between 1-2, 2-3 get a lot of delay, and even a little shudder. if you are on the throttle it will flare and shudder and cause a really delayed engagement of the next gear. this must be when the PCM calculates a shift over the prescribed time of .65 sec. When you come to a complelete stop thats when the pressure goes up, causing all this fun. I am guessing that the accumulator springs are either weak or the pistons are just not moving freely in their bore causing all this mayhem. My hope is the nothing is broken, just dirty, a quick install of the bushings and washers and a cleanup should remedy this. fingers are crossed as I am only thinking hypothetically here. but your explanation and solution to the problem sound a lot better than a rebuild right now. i recently did a service and did not find anything out of the ordinary in the pan or filter. what i find to be really strange is that when the car is cold, everything works perfectly. good strong clean shifts with no delay.

**jbamonte** · 02-08-2010

Like I stated above, with the ZZP shift kit installed and with a 28,000 lbs GVW trans cooler installed which does all of the transmission cooling now (no lines into the radiator), I have had zero problems since early December 09. I used the 1/2 inch spacer recommended by ZZP on the 1-2 spring in the accumulator and also a 1/2 inch spacer on the 2-3 spring in place of the 3/4 inch spacer recommended by ZZP on the 2-3 spring since I wanted to have the softest shifts that could fix the problem which it did. I would have tried the 3/4 inch spacer on the 2-3 spring if my set up did not fix the problem. My transmission has 100,000 miles on it. I think that your assessment that the springs in the accumulator weaken with age and heat is correct and the reason for the hard shift problem in these transmissions most of the time, not the PCS solenoid replacement recommended by many trans shops and very expensive, assuming everything else is in good condition in the tranny which in my case, I knew was correct. Change the fluid to Dexron VI (Supertech frm Walmart is the cheapest), change the filter, and I would recommend the biggest tranny cooler in the grill separate from the radiator which heats up the fluid unnecessarily, and I expect 10's of thousands more miles from my 4T65E. Let us know how you make out!

**josemolina2008** · 02-15-2010

I have this same problem and this looks like a very low cost way to fix the problem so my questions are as follows.

1) Is it hard to do the shift kit install? This is coming from a person that knows almost nothing about transmissions.

2) Again is it hard do put in the trans cooler independently from the radiator?

**jbamonte** · 02-16-2010

Putting the shift kit into the transmission is easy IF you know how to drop the pan and replace the transmission filter, which is easy for a competent back yard mechanic. Once the fluid is out of the pan and the filter is removed, there are about 6 bolts to remove the accumulator which is visible and easily accessible once the pan and filter are removed. Once the accumulator is removed from the car, there a few bolts holding the two halves of the accumulator together and when removed the accumulator comes apart. Inside are the 2 pistons and springs for the 1-2 shifts and 2-3 shifts, clearly marked on the housing of the accumulator. Putting in the shims is easy and put it all back together. Do a search about shift kits like I did and you will find detail explanations with pictures on how to do it or send me a private message with your e-mail address and I will send you the instructions with the ZZP kit that I used.

As for the tranny cooler, the toughest things are removing the plastic splash card under the front of the car to gain access to the grill area and then just cutting the 2 trans lines going into the radiator to by pass the fluid being cooled by the radiator and afterwards the cooler mounted in the grill. Most coolers have everything that you need if you buy the one I did, at least, a Long double stack cooler.

Like I said before, zero issues since the cooler install and the shift kit. Let me know if you need my instructions and I think that I have the pciture instructions, that I got off the internet or this site, before I did the install.

**frugal** · 04-13-2010

Hard shift update Finally!
Upon reading jmamonte"s post, i concluded that I was willing to give this a try. I ordered the kit from ZZ Performance, then became bogged down with other life's issues, I finally installed the kit and have no more Hard-shift. It does shudder shift 1-2 when hot, but this is usually when the hard shifting would start. I had previously installed a small stacked plate cooler and am contemplating buying a larger one with a fan. I wish I knew how to over ride the cooling fans to turn on earlier, I think they are programmed to turn on at 230'F. ( any Ideas?) Maybe I'll just do a full overrideso their always on. So those trannys run HOT!!! And the hard shift issue only occurs when hot! I know that I am only buying myself some time before a rebuild. I had recently done a service and am using transynd ATF fluid (Good stuff thanks Allison!) Thanks Jmamonte your posts just bought me some valuable time. I was actually contemplating getting my wife a Toyota Sienna ( yuck). I'will give future updates as the ol Montana van is a real work horse, 232000 kms (145000miles) so we'll see how long this goes.

**rynoman03** · 04-13-2010

If you buy an aftermarket PCM or have your PCM tuned you can have the fans turn on whenever you want and forever long as you want. But the aftermarket PCM's turn the fans on at 180 i believe.

**frugal** · 04-14-2010

Tuned like with an aftermarket chip, or have it hooked to a laptop and parameters changed? I might just jump the wires for full time fans.

**jbamonte** · 04-14-2010

Originally Posted by frugal

Hard shift update Finally!
Upon reading jmamonte"s post, i concluded that I was willing to give this a try. I ordered the kit from ZZ Performance, then became bogged down with other life's issues, I finally installed the kit and have no more Hard-shift. It does shudder shift 1-2 when hot, but this is usually when the hard shifting would start. I had previously installed a small stacked plate cooler and am contemplating buying a larger one with a fan. I wish I knew how to over ride the cooling fans to turn on earlier, I think they are programmed to turn on at 230'F. ( any Ideas?) Maybe I'll just do a full overrideso their always on. So those trannys run HOT!!! And the hard shift issue only occurs when hot! I know that I am only buying myself some time before a rebuild. I had recently done a service and am using transynd ATF fluid (Good stuff thanks Allison!) Thanks Jmamonte your posts just bought me some valuable time. I was actually contemplating getting my wife a Toyota Sienna ( yuck). I'will give future updates as the ol Montana van is a real work horse, 232000 kms (145000miles) so we'll see how long this goes.

I installed 2 double stack 18,000 GVW tranny coolers one on each side under the bumper that do not run the transmission line through the radiator, the coolers do all the cooling. I choose that route since the radiator cooler will never get the trans fluid temperature lower than the coolant temperature which runs between 185-210 on my car on the gauge. I have not had a hard shift problem since the installation of the ZZP shift kit with the coolers since the fans run very often in the hotter weather with the A/C on and pull air over the cooler in the warmer weather. Obviously, winter driving is not a problem with the trans fluid running cool enough. I mounted the coolers in the grille above the lower bumper intakes and below the dual snorkel intakes up higher so you cannot see the cooler from the front of the car. I chose this location to protect the coolers from road debris and to lessen the cooling effect slightly in the extreme winter since they would not be exposed to direct cold air while the car was moving in the winter. The fans pull the air through the coolers in the summer with the A/C on. No issues in 6,000 miles of driving so far and the tranny shifts perfectly normal but my trans with 100,000 miles was not abused and the fluid was changed with filter 4X over its life. In my case with my setup and based on the condition of the tranny in general, I expect this setup will allow the transmission to run ten of thousands more miles with no problem from the hard shift issue as long as no other issues develop. Total cost for 2 Long double stack 18,000 GVW coolers and the ZZP shift kit was about $150. The coolers will also greatly extend the life of the tranny. I use Dexron VI and change the fluid every 20,000 miles or 3 years. Less is better!Hope that helps!

**harrydunn** · 04-27-2010

Originally Posted by frugal

Hard shift update Finally!
...I finally installed the kit and have no more Hard-shift. It does shudder shift 1-2 when hot, but this is usually when the hard shifting would start...

Bummer. I was onboard with this until you stated the 1-2 shudder is still there. I've got the typical 15-25 mph 1-2 shudder and the nice "whine" sound. If I go ahead and step on it a bit, shifts great.

Oh heck, maybe I'll just try it. If it got rid of the whine, that would be a small victory I suppose.

Your thoughts?

**frugal** · 04-28-2010

Its worth a try, the shift kit is just some plastic dowels, you could easily just make one, take apart the accumulators and place the dowels on the rods,( it just limits accumulator piston travel) I could scan and email instructions as to where the dowels go. i personally couldn't believe i paid money for some small plastic dowels , but it worked for me. i find that the tranny only shudder shifts when hot in stop and go driving, i have a tranny cooler albeit a small one, I want to get my fans to turn on sooner but discovered that this is controlled by the PCM. I could wire in something but that's a lot of hassle. Could get the PCM retuned to turn on fans at a lower temp. (overkill Motorsports) Maybe i'll install one of those tranny coolers with a fan from B&M. the real fix is a rebuilt trans from a specialist like triple edge performance,

**harrydunn** · 04-28-2010

Mine only shudders around town when hot so it doesn't sound like I would benefit much. My former 2000 Bonneville and now 2001 Grand Prix have both been very disappointing with regards to their transmissions. I love the engines however. Roll with the punches I suppose.

**jbamonte** · 05-06-2010

Getting Warmer weather in the Northeast (6,000 miles now and counting) and still no hard shift problems since the fluid and filter change, ZZP shift kit and dual double stack 18,000 GVW coolers with the radiator trans cooling lines by passed!

**Blacknight02GT** · 05-07-2010

Hello, i have had this exact same trans problem occurring only in warm weather or once with 5 ppl in my car on a stop and go drive. Once you shut the car off and turn it back on its fine again. My problem first started occurring after I had my trans fluid flushed and filter replaced at 55k miles. It only did it on hot days in long drive times, until late September I got my coolant flushed and the weather got cooler and the problem seemed to disappear until now with the warm weather i noticed it acting up again.. after going all winter with NO PROBLEM. I'm so frustrated with this. Do you guys think my car could have the same problem? Would this shift kit help it stop? How much have u driven in hot weather with this "fix"? UGHH I dont' know what to do about this. I'm pissed.