rpm drop at gear change??

what is a normal/acceptable rpm drop at gear change? my dart has a 8" 5200 stall ultimate behind the 512 and 1st to second shift drops 570 rpm and so does second to third,,does this sound about right? more info upon request.

I think about 1500 rpm drop is the norm but some drop 2k rpm.

That sounds about right Bill usually around 600 rpm for a tight converter

The two best converters I've run in my current car drop different amounts. The one that works best in the heat drops 600-700. The other is better in cooler weather, drops about 800-900.
Doug

What is your shift RPM?
I would try upping the shift rpm by 500 RPM and see if the RPM drop is the same as before If so that is all you are going to get with that tranny and converter
If it widens out the RPM drop then you need to think about what you want to do, shift it higher or take the converter out and have it work on so it drops the normal % RPM which should be around 1200 to 1300 RPM on a stock 1st and 2nd gear set in a 727 at or above 6000 RPM

We don't seem to have a clear opinion on this question. A range of 570-1500?
I'm trying to find the answer to this question myself right now.....3 converter changes and a rear gear change(don't know the result of the gear change yet)so far.
I have learned that a 300 rpm drop is not the answer......and a 600 rpm drop isn't quite the ticket yet either. In looking at some in-car camera shots of a SS/AH car on an 8.60ish run, it looks like around 1000 rpm drop or more seems closer.

Just to clarify this, I assume we're talking 3-speed's in everyone's reply?

Good INFO!!!!

The more the drop the looser the converter will be - i.e stall speed - if you shift below or near your stall speed you are going to see a bigger drop - every converter is different and no two are identical - its what works for your combo - only true way to know what converter is best for your car is to have a dyno sheet from the engine and have the converter built to the specs of your car weight, rear gear etc. - even then its still a bit of an art and S.W.A.G - I have watched Marco Abbruzi test ten different converters in his car in a single day - just to find the right one

my 8" vert dropped 600 on gear changes and calculated to 6% slippage behind my 408.

There is no single correct answer for this.
Every combo will have it's own requirement.

My opinion on the OP's combo......511, small heads and intake(std port window), not a huge cam...... Is that 570rpm drop is not enough.
I would think a 6500-ish rpm shift point, along with about a 1000rpm drop after shifting would work a bit better(assuming the reworked converter doesn't give up any multiplication or efficiency).


Member Wookie was fighting some converter issues last year with his Charger.

He had a couple of good you tube videos of the tac with the two different converters.
The first one you could see the motor was just driving right through it.
The second one really allowed the motor to work with the big mid-range tq numbers and had way more drop between gears...... Along with much better top end efficiency....... And the car was quite a bit quicker and faster as a result.

If it is a 727 with 2.45, 1.40, 1.0 gears then you are dropping 40% on the first shift and 30% on the second shift. If the engine speed isn't dropping that much then the converter is slipping. A speed sensor on the driveshaft will show exactly what is happening.

I was going to add look at the gear ratio differences and do the math on how much your motor drops RPM on each gear change, if it is less than you calculate it is probably falling below the converters lock up RPM

RPM drop on the gear change is a simple math problem using gear ratios and engine RPM to figure what driveshaft RPM should be IF the clutch or converter were direct drive with zero slippage. Slippage in the bellhousing makes the answer anything but cut and dried.

Shift points vs. converter stall/slippage is used as a tuning tool for some folks. Some want the RPM to fall back below the stall speed to get the converter back into torque multiplication a bit. Others want to stay above that point with engine speed. Depends on the combo and what you are trying to accomplish. Usually, with the correct converter for the application, a shift point 1000 to 1200 above stall speed - maybe a bit less with a 3 speed - is a good place to start.

Not only that, but you can take two converters from different suppliers that exhibit nearly identical characteristics(flash stall, drop between gears, slippage in high gear), and find they produce different ET's.

Of my own combos, the one I did the most experimentation with shift points on was the 383.
The best ET's with that came from shifting 1-2 @6000, 2-3 @6500, trap rpm 6900-7000 depending on weather.
This was with a 5400 flash stall converter.
The 1-2 shift came really quick, and would just put the motor back on the converter(400rpm drop). This was about .02 or so quicker than shifting the 1-2 @6500.

Shifting @7000 really felt awesome...... Like you were setting the world on fire..... But it never resulted in a good number on the time slip.
Shifting 1-2 @6000 felt like you just killed it..... But it always put up a good number.

Getting back into torque multiplication on the 1-2 change can help the engine recover. That's the theory, as told to me. Longer strokes, bigger cubes, flatter torque curves - it's not as helpful.

Same converter, same car, but with 5.13's instead of 4.56's...... And a higher strung 340 instead of the 383.
500rpm less flash stall, and if you shifted any lower than about 7200 the ET's fell right off.

I don't recall what the rpm drop was with that motor in the car, but the combination of less tq, higher rpm shifts(more converter lock up), and lower gear resulted in a much larger drop after the shift.
The best ET's with that combo came from shifting at about 7500.

That motor had about 65ft/lbs less tq, and it peaked about 500rpm higher than the 383.

I think you have that a little backwards....tighter converter will drop the rpm's more on the shift.

With some of the converter suggestions/results I've seen from some well advertised converter companies, I'm not sure I'd trust the newer kids on the block.

to add a little more info, the car has 4.56 gearing and 14X32X15 phoenix slicks, weight is around 3150# race weight, I launch off the T-brake at 3500 and shift at 6500, this is up from 6200 and resulted in a quicker ET and allowed the car to pull further down track, this info is is from using my LM-2 checking my AFR's,,,,which is another story.

Never liked a tight converter in anything. And just about everything I loosened up went quicker. But I shoe polish race. Car I been running drops 400 rpm at the shift.

I wouldn't have let that rascal live in my car more than one race, way to loose for me
Or is this a glide?
I've had the opposite experiences with a Art Carr 8 inch loose converter that drop less than 1000 RPM on the gar change shifting at 7000 RPM, it would flash to 7000 in 1st gear and drop back to 6000 RPM or so and then drop back to 6000 RPM on both gear changes, NOT GOOD
We ended up with a BM O69J nine inch in that car and it picked up .6 et and 5 mph
I've also had the same experience you have had with a looser converter in my old pump gas Duster, took out a tight 10 inch converter and put in a T/A SS Hemi 8 inch converter and picked that car up .23 in the 1/8 mile and 2 mph
If you don't test, you don't learn

No telling what gear ratios where in the car but if it was a serious SS/AH effort they probably were not stock.

This is an interesting thread but in my option if you are looking for the last bit of performance you are going to have to try a few converters. I would think a dyno sheet would help your vendor of choice a lot.

Good luck and keep us posted on your discoveries.

Bill