I like to shift my auto thru the gears and also downshift. Now it won't down shift unless it is in 'drive'. If I put it in drive, it works correctly. If I run it thru the gears and then come to a stop, it appears not to down shift to 1st. It feels like a washboard when I start up from a stop with it in 1st gear. It is like it is in 2nd or 3rd. Any thoughts.
Also am posting a coolant/temp issue. Any Help appreciated, Gary
It's a 95 LT1 with 70K.
Read thru this now and did not make myself very clear. If if put my car into 'D' everything works like it should. Upshift and downshifting as it should. On the flip side if I put it in 1st and then 2nd as speed increases and then finally 3rd and overdrive, it will not downshift as I decrease speed to a stop. When I come to a stop it appears not to have automatically gone back to 1st. Also, if I start out in drive and then try to down shift as I slow up to 2nd or 1st, it will not downshift.

 

Come on guys/gals. Any idea on the cure other than leave it in drive.

 

You're not supposed to downshift an auto while moving, it wears out the clutch bands which may be what your experiencing now. You can ask Pete K for help, he is the auto trans expert on here.

 

Rubbish. Shift it all you like.

The auto in your 95 is controlled by a few different shift tables, you can modify their values using a program called tunercat.

The shifts are calculated on a throttle position rated as a % against the speed of the vehicle in MPH.

Have a look at this table, i dont remember exactly what car i took this from, but i think it is a stock 1995 (not certain on that without looking) :


Youll see the first 3 columns are upshifts, at a given TPS%, it will need to exceed a given MPH to shift up. (eg. at 25% throttle, you need to reach or exceed 21MPH in order for the PCM to order the transmission to shift from 1st to 2nd)

The last 3 columns are downshifts, and at a given TPS% it will need to go below a given MPH to shift down. (eg. at 0% throttle, the PCM will not order the downshift from 2nd to 1st until youre at or below 10MPH.)

That is for automatic shifting only, obviously if you shift manually, it will shift when you give it the command with the shifter.

Ontop of all that, there is a shift pressure table, which governs the pressure of the shifts, again it is done on TPS% Vs MPH.

Here is a table for that:


As you can see, at 0% throttle, there is little or no real pressure applied. There is alot more to it, but youll see why you dont feel the downshifts at 0% throttle.

 

Thanks for the shifting info, but does anyone have an idea what the problem is??? Gary

 

Automatics have clutches and bands. Never heard of clutch bands.

 

If you say clutch and bands real quick, it sounds like clutchbands.

 

From what i can gather, and looking at the data in the two graphs, i dont believe you have an issue. From what i could see from your first post, it appears to me you have an issue with not being able to "feel" the downshifts.

As a further test, holding your throttle about 25% down, watch your speedo and see at what speed it shifts, note your RPM and youll be able to figure out what gear you shifted from and which it went into.

If youre saying that shifting the lever back to first and it is not shifting down, you may need to look under the car at the mechanical linkage between the shifter and the transmission.

Yep, and the band only grips the reaction shell in 2nd gear and in 4th gear. If it is up to the task at hand and serviced regularly, shift all you want to with complete confidence.

 

well it may or may not wear on the trans to manually down shift it,but i would think that it would wear the u-joints.

 

And don't forget about the exhaust tips.

 

Just for s&g's, do your upshift thing and, after coming to a stop, put it in neutral momentarily. See if it then starts out in first gear again.

Pure speculation, but I'm wondering if it could be slop in the linkage or out of adjustment. The theory being that the manual valve is being put in a position where it stays in the same gear. There could be other issues in the valve body also, such as wear, and dirt.

 

Actually, automatics have clutch packs....not clutch bands.....

2nd, I would listen to PeteK on transmission advice. He rebuilds them and knows how to make them tough.

3rd, upshifting is fine, downshifting could wear out your transmission faster and only downshift when your going under 50 IMO. If your doing 65 in D and then drop to 2nd, your going to be looking at a rebuild. Mine jerks hard when I downshift and upshift from first to 2nd manually in my automatic.

If you want to change your automatic manually, look into getting a shift kit that allows this. It will also help your transmission last longer. Faster harder shifts vs slow long shifts. See, less material is being rubbed on. Just my .02.

 

Mate for god sake , driving the car will wear it out, so you better stop doing that too. Leave it sit in the driveway and wash it every day, itll look great, and it wont wear out.

 

Ujoints don't just wear out like brake pads....If they did, I would have used up alot of them the past 5 years. Only replaced one time.

 

Thanks that sounds like a good idea. Gary

 

Mate i replaced mine when i fitted a DANA 44, after more than 90,000 miles of some hard, some reasonable driving, they were still tight as a drum and prefectly servicable.

 

I trust your judgement more than most. Just by your typing skills, I know you can back up the facts you say.

 

Thankyou sir

 

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i shift all the time as if it were a standard tranny..
last 3 yrs never had 1 problem...

 

As far as durability, is there a difference between manually downshifting while moving, and the trans automatically downshifting while moving? My car (93 LT1 auto) downshifts a gear when flooring the accelerator, from almost any speed. Sometimes I think it's going from 4th to 2nd, I'm not sure. Whatever the case, it's done from for almost 110K miles with no trans work (knock on wood).