I was wondering if it is ok to shift down to save breaks with this automatic tranny in my trans am?? I want to save my breaks till the winter (real low on funds), and I figure it should be the same as manual downshifting.. I have been doing this for 3 days now with no problems, the tranny shifts into 4th gear (OD) at about 60kph (sorry, i am Canadian), so when I am approaching a red light / stop sign, I put it into third first, and the rpm hardly moves, but I do feel it shift (very slightly and smooth), then at about 50kph I throw it into 2nd and this time the engine noticable increases RPM and noise level for about 1-2 seconds, but never over 2000 (which is very low of course), and the speed decreases real fast, in fact as fast as a light breaking job. The shift is still smooth, but noticable as I said.

Basically, is it safe to downshift an auto tranny (my tranny to be precise, my car is listed on the side) as you would do with a manual?? thanx in advance.

 

Not the way you are doing it, you will destroy the transmission. If you want to downshift this unit, you must first give it a little bit of throttle when you move the lever back, then you can let off the throttle to deaccelerate, repeat this for the 3-2 downshift. This is like double clutching a manual transmission, you have to "match" rpm's before you let off the throttle.

 

What causes it destroy the tranny? Excess heat, friction? Or is it that the hard parts can't take torsional the stress? I have downshifted my auto for years and never new that I was hurting my tranny. I won't be doing that any more.

 

I've always just downshifted an auto. Never done the throttle blipping thing you are talking about. This is pulling heavy loads and going down steep hills. I do and my dad has done it for years. I don't see how you can kill an auto. All your doing is engaging different bands and clutches. I believe 1 WOT upshift does 10X more damage than downshifting would do. Mine has 200,000 miles on it. I was pulling a 4,500 lbs trailer and downshifted at every big hill. I am going to keep downshifting it too. I would rather burn up a tranny then die or get hurt from a runaway vehicle when the brakes overheat.

If your brake pads are bad, I would fix the problem or your going to need new rotors too.

 

Yea, it never did seem to hurt mine either.

 

My recommendation would be to avoid the risk of extra wear in the transmission, save a few dollars up and do a brake job yourself. Regular replacement pads and shoes can be had for $15-20US a set, maybe $10-15 per rotor/drum to resurface (shop around for this one if you must get the best price, it can vary), and a few more dollars for some synthetic high temp brake grease for a front wheel bearing repack and caliper pin lube, and maybe a can of brake cleaner. Its a very easy job to do; it was the first car related job I had ever done & it was easy.

Of course, costs will go up if any other parts like the calipers, rotors, hoses, drums, etc. are bad--but but they're still not super expensive.

If you are having trouble scraping together cash for a brake job, call a few trans shops and price a transmission rebuild. I'm not trying to be a jerk: Imagine how much lower on funds you may be if you experience brake failure and can't stop. If there are two things I would ALWAYS keep in perfect working order on all my cars, its 1) steering and 2) brakes.

 

You're forcing it to shift to a much higher speed when the TV cable is fully retracted and line pressures are at a minimum. It's somewhat equivalent to upshifting at WOT with the TV disconnected.

 

I'm with 377Z... Whats the point in putting wear on a transmission that could cost upwards of $1000 to have rebuilt, when you can buy a set of brake pads for $20...

No offense, but this is just silly.. At the prices of gas, just walk once somewhere instead of driving and use that money you saved to buy brake pads...

 

If you're really broke, the bone yards will always have a half-way decent set that will work for $5.

Jim.

 

Yes it will damage the transmission. They are not made to do that.

 

if your brakes are gettin worn out its more of a saftey issue man go get a set of pads and put on there even if your rotors are bad or drums atleast put a set of pads on they may not last forever but you wont have to worry about it for a while .....i wouldnt take a chance at tearing up a transmission for a 20 dollar set of brakes .......

 

Sorry to bust your bubble. My GM manual says to downshift before going down a hill while pulling a trailer. It says nothing about having to match the Rpms before doing it.

 

Well, then your GM manual is instructing you to destroy your trans. It will do damage, and it will cause problems. Dont care what any manual says.

 

Apeiron spells it out for those who don't understand the basics of how a transmission works:

Official GM literature is not infallible. Or, if you prefer, its telling you what needs to be done, not the best way. Sometimes its plain wrong--as an example GM recommends that guided rocker arms are the correct replacement for all applications. Try them with guideplates. I'm sure many here can provide other examples where GM procedure can be improved upon. Now don't take this out of context--I'm not saying I'm smarter than GM or that they're always wrong, just that independent thought can be your friend.

Either way, the original question did not involve whether or not or how to downshift towing a trailer down a hill, the question was whether its a good idea to downshift to save brakes because the guy is low on cash and doesn't want to do a brake job. To me its akin to spending a dollar to save a nickel, and it amazes me that people will essentially argue a point that supports cheaping out on brakes, of all things.

 

You have a lit charcoal grill that you're cooking your dinner on.. Somebody sets a nickel on the grill under the open flame.. Sure, you could use your dollar bill to scoop it off and maybe get the nickel back, but more then likely, you'll just end up as the tard with a melted nickel and a burned-up dollar bill.. Hmmm...

 

Notice how I was the first to tell him to get his brakes fixed.

By the way the 700r4 uses a passage that gives full line pressure to the clutches when you downshift. If you don't believe me, try it. You will get a very harsh downshift with no slip at all. My 1983 will chirp the tires on a downshift into 1st @ 30 or so.

 

If you downshift the transmission before you start to go down hill, then that is different from downshifting while moving at speed. Yes, the line pressure does go up some when making a 3-2 or 2-1 downshift. The problem with this in one respect is that you do not know which size intermediate/reverse boost valve you have, the larger the better. Yes, some people have downshifted the transmission with little or no harm, others have with diasasterous results. The point is if you are going to "downshift" this unit, then do it the way I have mentioned to get the results you want without tearing up the unit.