transmission shifts hard

Help! I recently purchased a 2000 Silverado LS extended cab 4x4 5.3 motor and automatic transmission. Approximately 70,000 miles on it. After driving for a while ( highway driving with very little stops and starts) Normally it happens after approximately 1 1/2 hours when I stop at a stop sign orred light and pull out the transmission shifts hard in the first 2 gears almost like a horse is kicking the truck. Clunks on downshift also. Sometimes the service engine light comes on also with a manufactures tranmission code (checked at Advance Auto Parts), If I shut the truck off and sit for a minute or 2 the transmission is fine for a while again.

With that "Few" miles have you changed the tranny fluid and had a once through so you know what you started with???

Just a thought...

I recently bought a 2000 Silverado Z71 4x4 ext cab and had the same problem on a road trip. Thought I'd never even make it thru an intersection and everyone was honking at me to get out of the way (that's usually me doing the honking!). Kept looking back to see what had dropped out of the bleepin' truck.

Dealer came up with OBD code P1870 (transmission slipping) and they told me I need a new transmission...~$2,500. Apparently this is very common in these trucks and GM is aware of it. Chevrolet told me today to get the transmission replaced and they will "consider" partial reimbursement. I volunteer for a doberman rescue and am not happy about this, especially since I had the truck checked out before buying it.

Maybe I should've bought the Ford!

Hate to tell you this, but the same thing can happen with a Ford, Dodge or any other truck. I'm not defending the job GM did building your truck, just being realistic. Also if you bought the truck used, who knows what the previous owner did with it. Anytime you buy a used vehicle, you inheirent the maintenance and driving habits of the previous owner(s).

True, there is always a risk when buying pre-owned, which is why I took what measures I did. Having not asked the Ford and Dodge dealerships how often they see the issue, I can only speak to what I have heard from local Chevrolet, independent and tranny shops...this is a common problem on the Chevy trucks. My Discovery and the Ford Explorer I had never had this type of problem, and the Explorer had 135k on it. There are more Chevy complaints at NHTSA, too. It wouldn't be such a biggie if I didn't make frequent long trips.

There have been quite a few problems with these tranys, very few require replacement. Poor seperator plates and valves in valve body most common problems. There have also been some electrical issues. Cost far less to replace these than new trans. Myself, I needed saperator plate as when then trans heated up, the check balls would stick in the plate causing pressure loss. The PCM reads the loss of pressure, and ultimate slipping, and raises it causing the hard shifts. Cost me $180 for new plate, shift kit and Corvet servo. Good luck.

These hard shift issues and code p1870 are most frequently cause by the TCC valve bore in the valve body wearing and the trans looses pressure, this cause the pcs to boost line pressure to compensate, hence the hard shifts and code, further diagnosis is required here, but there is an AM repair kit for the VB that will correct this condition.

Hate to tell you this, but the same thing can happen with a Ford, Dodge or any other truck. I'm not defending the job GM did building your truck, just being realistic. Also if you bought the truck used, who knows what the previous owner did with it. Anytime you buy a used vehicle, you inheirent the maintenance and driving habits of the previous owner(s).

VERY TRUE!!!!! after 3 weeks I had to replace the fuel module!!!!

My truck currently has 62,000 miles on it and I was experiencing a rough 1-2 shift (along with the famous chevy clunkeritis disease). I bought a bottle of Slick 50 ATF conditioner. I put the bottle in yesterday at noon and noticed a difference on the ride home, and both ways today, smooth shifts, no more slip and hops. I recommend this to anyone who is having a rough shift problem. Here are a few words of advice with the application of this product though...

The bottle says "Caution. May Take 10 Minutes for Application"
Don't think they lie. I did. It honestly took me 15 minutes to dump the entire bottle into the tranny. All I can say that this stuff resembles is molasses in the middle of January. It comes out about 1 oz per minute, and it's sticky as hell. Another word of advice, DONT USE A FUNNEL LIKE THEY SAY TO!!! That 10-15 mins is now more like 25-30. Just aim and have a rag ready. Oh, and don't do it when it's windy. The stuff strings like hot glue and cotton candy.

My truck currently has 62,000 miles on it and I was experiencing a rough 1-2 shift (along with the famous chevy clunkeritis disease). I bought a bottle of Slick 50 ATF conditioner. I put the bottle in yesterday at noon and noticed a difference on the ride home, and both ways today, smooth shifts, no more slip and hops. I recommend this to anyone who is having a rough shift problem. Here are a few words of advice with the application of this product though...

The bottle says "Caution. May Take 10 Minutes for Application"
Don't think they lie. I did. It honestly took me 15 minutes to dump the entire bottle into the tranny. All I can say that this stuff resembles is molasses in the middle of January. It comes out about 1 oz per minute, and it's sticky as hell. Another word of advice, DONT USE A FUNNEL LIKE THEY SAY TO!!! That 10-15 mins is now more like 25-30. Just aim and have a rag ready. Oh, and don't do it when it's windy. The stuff strings like hot glue and cotton candy.

Sounds like motor honey...

Ok, you have my curiousity??? And thick stuff does what for you???? Possibly build up gunk? Made your shifting parts stick and get stuck sooner when you might really need what???

I really am curious what a thick material will do in the long term...