I recently purchased a used 06 Denali XL and I noticed it shifts harder than I would like. When I compare it to my OBS k3500 which you can hardly fell it shift between gears under 3k RPM. so I am going to get a full flush and have the trans filter changed and use AmsOil plus a Mag-Hytech deep Pan. Is there anything else I should do? Like have the shift solenoids replaced or anything else?
Other steps when flushing a transmission
- Thread starter abishoff
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JBTJ
Member
I would not do a flush, but rather just a fluid replacement. Drop the pan replace the filter and top back off. Then remove the top tranny line on the radiator passenger side. You can get a brass fitting the will screw into the radiator from the auto parts store. Then connect a 5 or 6 foot piece of 3/8th's rubber hose to it and run to a milk jug marked off in one quart increments. Start the engine and let if fill up to the 3 quart line. Turn off motor and dump out old fluid, then add 3 quarts to the dipstick fill tube. Repeat this process till you get fresh clean ATF running out. Then reconnect the tranny line to radiator. Takes 12 quarts or so and maybe 15 minutes to do.
Ok thanks? Any thoughts on why its might be shifting hard? I'm sure that trans fluid has never been changed but I was also wondering if there are any parts on the trans that I should replace while I have the pan dropped?
Wake
Full Access Member
I'm looking at a trans issue myself.
A few months back I felt a surging while driving under light throttle in 4th gear with the TCC engaged. Shifting back to 3rd eliminated the surging.
A few weeks ago, I lost all engagement on the transmission at about 40 mph. I coasted to the side of the road and when I came to a stop it shifted into first and I proceeded to drive home and it was just fine. I've driven it a few hundred miles since then and never had the problem reoccur.
I read about a product called DR Trans you can get at Advance Auto and it seemed to get good reviews in curing the surging I mentioned with my first symptom. No more surging issues there in the few hundred miles I've driven it.
Still worried about the loss of engagement I decided to drop the pan and change the fluid and filter. This trans is a Jasper rebuild with maybe 20K miles on it, but out of warranty due to time. So the trans was clean when I dropped the pan. No problems where it looks like the trans is eating itself.
I've been reading a lot about the valve body though. Seems that it is considered the most overlooked item when rebuilding a transmission. Problems with the shift solenoids, and one other big one is the TCC actuator bore being worn and out of round leading to eventual trans failure.
I'm contemplating buying a new/remanufactured valve body and seeing if that cures my problem.
I also have a harsh/late 1-2 shift and see a lot of times it is related to the TPS in the throttle body on the intake going bad.
mattluttrell
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I second this method. It was extremely simple. My only variation was that I used around 16 quarts and pumped it in fairly fast with a bucket pump. I had my wife turning it on and off. It really only took about 20 minutes. Was a cheap and easy preventive maintenance.
JBTJ
Member
Hard shifting could be due to the simple fact that the filter is getting plugged up and therefore not getting the proper amount of flow through the transmission. Old and worn out ATF will also cause this problem as it no longer has the lubricating properties as it does when new. Since that you feel the filter and ALL the fluid has never been changed, chances are this is causing the shifting problems.
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