When I downshift my 700r4 ( I have a bm rachet shifter) will it damage it? It redlines third gear at about 100 so if im going slower than that can I downshift?

 

good question i wanna know that answer to?

 

If it's a factory build then yes. How soon is anyone's guess. The reason being is that it's very hard on the clutch packs. Eventually it's going to wear them down which will lead to slipping. My understanding is if you build a high performance unit that you can downshift it as long as you give it a little bit of gas prior to doing so to help your high performance clutches last longer.

 

ok so my 700r4 didn't come with the b&m ratchet shifter but it also didn't come with the shift kit so if i had the shift kit upgraded torque converter it should be ok

 

This is exactly how i ruined my 700r4. ly downshifted into 2nd at 90mph at the track, whoops...

 

SO BASICLY we shouldn't downshift our 700r4's then

 

please don't tell me u were in 4th

 

So I can do it just not at high rpm? I wanna be able to downshift on the highway.

 

Why?

 

wow, i've hit 100 in 2nd before without a problem (only turning 5500 rpm)

 

Not everybody has 2.73 gears though...

 

I've got a problem with that statement/assumption (downshifting an automatic while moving will damage it).

My problem is that if it were true, then stomping the gas and forcing an automatic downshift would damage it as well.

The only difference being the fluid passages used to effect the shift:
Stomping the gas uses the TV passages, while downshifting uses others.

The internal trans action is still the same and it ends up in the same state. Some still say that you must have higher pressures to force the clutches in harder during such a shift and that automatically happens when you floor it, but not when you move the shifter to D from OD. I can get that, but if that were even the case than your OD->D manual downshift would just take longer and slip longer, generating heat which is generally bad for the transmission.

Some have said this is bad on the sprag, which is the only thing that I can see as being true. It is not moving and suddenly is now going x RPMs. That can wipe out a part.

SO does anyone have an actual true reason for why forcing a manual OD->D downshift is bad?

 

I always downshifted both my camaros for a few years without a problem. Just cruising around town, down shifting into second didnt seem to hurt it any. It wasn't until i went to the track and downshifted from D to 2nd at 90+ mph and i heard a thud, never worked right since. I have 3.42 gears so 90 mph in 2nd is not a good thing. Live and learn, now i have a 6 speed so im happy!

 

good point.

I personally do not see why it would hurt anything as long as you do not hit dangerous RPMs and you don't shift into gear while the engine is at a high rpm.

 

Chiming in... I thought the same.... but more recently, I think the judgement call needs to take into account things like the age of the internals and how hard it's being driven.

I had a 66 Mustang with a C4 automatic that I shifted manually to hold it in first or second gears almost constantly, but it had been rebuilt. I never had an issue.

When I moved on to my 88 Firebird with a 700R4, I expected similar behavior that I had with the C4 in my Mustang, and got it (although I manually shifted sparingly, not constantly). For reference, the Firebird had 138K on it when I bought it, with no known tranny rebuild or maintenance history, but seemed to function without issue.

I've put 15K miles on the Firebird since I bought it and until last week, I could easily force a downshift from 4->3, 3->2, and 2->1 with no issue; the trans would instantly downshift and under no application of the gas pedal, the tach indicated an increase in RPM that was expected. Now, when I do the same, the tach floats down to a high idle unless gas is applied. And also, now if I accelerate at WOT (like getting onto the highway) I have what I feel like is excessive RPM flare between shifts the shifts feel like a long overlap). In fact, I don't even think it'd be possible to ever chirp the tires under a WOT acceleration (not that I would anyway, just saying to illustrate the issue of wear or possible damage).

Mind you, I don't beat on the car - downshifting was done to either make engine braking possible coming down hills and off highways, or to make driving in rush-hour traffic easier (instead of flooring it to get a kick-down).

My car still flawlessly winds through the gears under modest acceleration and also automatically downshifts at the designed shift points (such as a 4->3 downshift at 35 mph when going up a hill).

I'd be curious for anyone to weigh in on what I'm experiencing btw