Last post on Feb 04, 2013 at 2:19 PM
You are in the Buick LaCrosse
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Buick LaCrosse, Transmission, Sedan
#29 of 92 Re: 2010 Buick LaCrosse Transmission Problems [waytoolaidback]
Oct 03, 2010 (4:55 am)
I am certainly hoping that you are the few with tranny problems. As to the third gear thing, 09 Malibu has issue. It is mostly a colder weather thing during the first couple of shifts. It has a long delay going into third when second is released. It feels like it is slipping, third clutch taking too long to fully engage, and the tachometer shows just that. AFAIK, this is the same tranny. It might have slightly different parts in some areas for controlling shift and also computer programming may differ some. Build would have been prior to AUG 09.
This worries me because it could be indicative of a problem leading to destruction of tranny. It might be indicative of an internal leak where there is no longer enough fluid flow to certain parts to build adequate pressure. Many of the circuits are in parallel and this could result in premature wear to bearings, gears, etc.
The part delay may not be unusual. Stocking parts is no longer a common practice.
If GM has determined the source of the issue, then they go back to transmission builder and then it moves on to their parts supplier if it is a manufacturing flaw. If it is a design flaw then you get a much larger circle of departments involved to come up with the fix.
Supposedly, every transmission leaving the build sight gets a runup test before being shipped to GM final line, vehicle assembly. I suspect they are not doing cold soak or hot run tests.
Older transmissions with lots of miles often displayed the first signs of failure by being slow to engage until they warmed up. Excess wear, cracked metal or rubber parts would cause internal leakage not allowing enough pressure to build.
If there has been a part change the transmission builder will get the new parts first.
#30 of 92 Re: 2010 Buick LaCrosse Transmission Problems [redriver1]
Feb 19, 2011 (8:08 am)
Interesting problem. Our Lacrosse is about 2 months old. We noticed from the beginning that the transmission acted odd. When decelerating the gear shift around 30 was not smooth. The car actually felt like it was applying the brakes. When the shift occured the tach would rev the drop dramatically.
This is not the smooth transition that we are use to in a buick.
The car has been to the dealer twice. Once for the first oil change and once for the trany. The technition believes that the calabration is out of sync. After the tune up it seems a little better but the problem is not completely resolved.
It will need to be watched.
That said, the car seems to operate well in every other aspect. Acceleration is fine and the ride is smooth and quite.
It is just this nagging hicup in the gear change at 30 mph.
#31 of 92 Re: 2010 Buick LaCrosse Transmission Problems [curtsinthezone]
Feb 19, 2011 (5:11 pm)
I'm not sure why but newer vehicles seem to have eliminated the over-run clutch in transmissions so that even in drive engine braking is compelled. Older vehicles often needed moving from drive or OD on the selector to start engine braking.
To me it would just make more sense to coast as far as possible and not bring engine braking into play unless perhaps the brake is applied.
#32 of 92 Re: 2010 Buick LaCrosse Transmission Problems [curtsinthezone]
Mar 03, 2011 (1:06 pm)
Please keep me updated on your situation.
GM Customer Service
#33 of 92 Re: 2010 Buick LaCrosse Transmission Problems [curtsinthezone]
Mar 04, 2011 (5:54 am)
I hope it is not a problem per say. There were similar complaints on Malibu as well as other pertaining to shift. I and some others came to the conclusion that the computer learns driving habits and self programs accordingly. Perhaps you are doing quite a bit of stop and go driving or have been recently? This style would seem to bring automatic downshifts more forcefully. If you drove where most of the time you were doing a long roll to the stop with only light braking near the actual stop it seems to use less forceful downshifts. I have yet to figure why they don't use an over-run clutch which would maximize the rollout and MPG.
#34 of 92 Reply: 2010 Buick LaCrosse Engine Braking[e_net_rider]
Mar 04, 2011 (4:05 pm)
Rider: Since our 94 pontiac B'ville we have noticed engine braking on hills where the car would "hold" the same speed for the most part. Very noticeable on newer vehicles i.e. 2010 Lacrosse. Personally, maybe due to getting used to it, I like the programming feature since you do not have to ride the brakes (in the smokies and on the Wheeling, WV Hill). Prior cars we did have to pull it down to a lower gear- like a manual to brake with engine. I agree it may help m,mileage by coasting but at what speed?
#35 of 92 Re: Reply: 2010 Buick LaCrosse Engine Braking[e_net_rider] [crankeee]
Mar 06, 2011 (7:24 am)
I generally don't ride in very hilly or mountains. Older vehicles with override clutch would positively engage when pulled from D(OD) position. It seems these 6 speeds are not as good at engine braking when applied. Even pulling down a gear or more they are hesitant to engage depending upon speed and engine RPM, so it is necessary to apply brake to get you within the allowed range for that gear. That is if you want effective engine braking for a high grade.
Obviously coasting without engine braking should help MPG at any speed, assuming the engine efficiency is not horrible at idle. Rollout of newer vehicles can be very lengthy without any braking. A tap of the accelerator can move you a long way. This is much the principle that those who competed for most mileage on a vehicle used in contests. Most did use standard transmission, but once they got it rolling at the desired speed, they'd clutch and kill engine, allowing a long rollout. When speed decreased to the desired point, they'd pop clutch and restart to increase speed again. There are some that competed locally and got 100 miles on a gallong.
#36 of 92 Reply: 2010 Buick LaCrosse Engine Braking[e_net_rider] [crankeee] [e_net_rider]
Mar 06, 2011 (8:40 am)
Newer , jointly developed 6-speed is obviously programmed for economy preference with fast upshift and slow to downshift in my experience. We use the tap up tap down for really big grades, but as you have posted the new on board diagnostics appears "to learn" your driving mannerisms and the car becomes gradually easier to drive IMO. I have read about flashing or reprogramming certain transmissions and computers to take out the initial bugs (we had it done once and that car was very driveable and economical forever after. Big key with the Lacrosse 6-speed and the higher revving 3.0/3.6L DOHC engine family is to keep the RPMs up on big hill climbs. At 80 MPH, the car will climb all but the steepest, at 70 it lugs due to lower RPMs and as speed drops off it shifts down and then back up searching for economy. Very frustrating to some drivers who do not use tap system at all. At 55-65 the car gets phenomenal MPG (31-33) on level road if gas gets to $5 that may be tolerable. BTW- per new oil change forum -what interval are you using?
#37 of 92 Re: Reply: 2010 Buick LaCrosse Engine Braking[e_net_rider] [crankeee] [e_net_rider] [crankeee]
Mar 13, 2011 (8:48 am)
My opinion of the engine braking is that it is not very good on this vehicle. I was reminded of that yesterday as I cruised back across the Savannah River. A very high bridge allowing largest containter ships. As you come to the bottom and exit into Savannah, there is a 25MPH curve. As I crested I started downshifting, all the way to 1st. Engine was revving quite high and it was not slowing me much so I still had to brake a lot. I suspect that it has to do with VVT and that it is not moved to an engine brake solution. That is it is more like a diesel when coasting until you employ the Jake as far as engine braking. On the 3.6 it might be for pollution reasons or they just did not add effective engine braking timing to the valve train.
#38 of 92 Re: Replace transmission filter or flush [mrrogers]
Mar 31, 2011 (6:37 am)
This is a very old post I'm replying to, but felt it necessary.
There is some discussion about replacing older transmission fluids with the newer Dexron VI synthetic. By now dealers should know, but DIY may not be aware.
When the newer first came out it was listed as backwards compatible but Ford & GM apparently had enough issues that they came out with a bulletin saying not to do it. The apparent issue was that clutch plates started coming apart on older transmissions, pre- the year that they started coming off the line.
It is possible the newer transmissions had new clutch plates or that it is the effect of having previously been worked and soaked in the older formulation. If it was the plate construction, presumably newer synthetic compatible plates would be available for rebuild, at least in transmissions that spanned the changeover.
I did get by with a change from whatever was in the 96 Aurora transmission at 125K to AAMCO synthetic, off the shelf. I drained, filled, then disconnected cooler line to allow it to pump new fluid from pan forcing old from torque convertor out the disconnected line. I'm sure I got at least a 90% change. And I saw no bad from 20K miles, except the solenoids seemed to be going bad which was common with older fluid.
Although this was occurring around the same time that most transmission shops would not change fluid if you were around 70K and had never done it before, I do not know if changing to synthetic influenced that decision.