89fast5oh

I have a 2600 stall Edge 9.5" street converter behind the 383 EFI and 3.23 rear gears.

The TCC low speed lockup in the tune are as follows:

Low Speed Limit For Low Gear Lock To Unlock Transition: Stock-27mph - Modified-50mph
Low Speed Limit For Low Gear Unlock To Lock Transition: Stock-28mph - Modified-55mph
Low Speed Limit For High Gear Lock To Unlock Transition: Stock-33mph - Modified-50mph
Low Speed Limit For High Gear Unlock To Lock Transition: Stock-35mph - Modified-55mph

The speed limits in my town are 30mph and 35mph on the longer stretches of road, which are only a few miles long, lol.

So my converter is never going into lock up, which I read is very bad for the transmission in 4th gear. Should the tune be adjusted so the converter locks up? or at those low speeds/RPM is it fine to not lockup?

Fast355

iTrader: (2)

Transmission cooler? Trans temp gauge? My gut feeling says you are fine. Alot of factory trucks do not lock up until 40+ MPH in 4th. My buddies 454/4L80E crew cab dually did not lock the converter until 65 mph.

If its only a few miles at a time and you have a good cooler added in after the in-radiator cooler you will be fine. What hurts them is putting power through them for miles at a time when they are not locked. Think of a truck towing a trailer with an underpowered engine and the owner leaves it in OverDrive. The converter has to unlock to multiply torque in overdrive to keep the truck rolling, building a massive amount of heat.

If the cars are wired the same way as the trucks, they have a temperature switch mounted to the valve body that forces lockup at higher temps. The 1992 4L60 aka 700r4 in my 83 G20 had the temp switch when I was still running TBI on it. With a 2,600 rpm converter it would sometimes force lockup right after the 1-2 shift until the transmission cooled back down. IIRC that switch was tied to the TCC solenoid and 4th gear pressure switch ground. It was normally open and closed when the trans approached 200°F bypassing the ECMs normal lockup logic.

Kingtal0n

https://www.thirdgen.org/forums/tran...ml#post4600583

Something about converter lube. Main thing is watch trans temp in the pan. Trans temperature over 175*F = BAD.

Kingtal0n

Oh ****

http://67-72chevytrucks.com/vboard/s...56&postcount=5
Clinebarger and probuilt are the two top transmission experts in the world. Clinebarger helped me build a couple transmission already successfully. I trust his words more than anyone else. I would suggest based on what hes says here to ensure your transmission uses lockup as needed. Don't F around with planetary lube curcuit.

Orr89RocZ

iTrader: (20)

i would change it back, there really isnt a need to run unlocked once at speed. My 383 would run easily at 25-30 mph locked up so no reason not to use lock up.
Or atleast set the high gear lock up lower so if you cruise around in 3rd it will not lock til 50 but in 4th it wil
for drag race you can set the unlock prevention threshold to a higher mph so it never locks under throttle. Should run quicker that way. In all my combos i never ran better with it locked. For dyno, set it low mph so it stays locked for max power to wheels. As long as converter is designed for it, which the Edge should be. Ive had 3 of them lol

Fast355

iTrader: (2)

Really depends on the specific combination. Short runner intake and decent cam will have it in cam surge until atleast ~1,500 rpm. That gets really annoying very quickly.

As for locked vs unlocked, I have had slight MPH and ET improvements locking slightly above peak torque (+200 rpm), and dragging it back close to peak torque again. Once the converter locks the acceleration improvement is noticeable.

You could actually feel the surge in power when the 4L85E converter locked behind my old L31 in my Express. Locked at about 63 mph in 2nd. Which was about 3,800 rpm, it would drop it back to 3,500. Engine made peak torque at ~3,400. To find the specific point where locking it will help requires a a chassis dyno and unlocked and locked pulls. Generally at slower input speeds the converter is still multiplying torque and at some point the converter will stop providing added multiplication and become less efficient transfering power unlocked. You want the converter to lock where the power curves cross. Generally speaking on the few I have tested that crossover point is around 1,000-1,500 rpm higher than the stall speed. When you force the converter locked you want the engine rpm on the side of the curve where the locked converter is putting down more power. Lock too early and it will bog the engine and slow the vehicle briefly. The engine rpm going into 3rd and 4th was still higher than that crossover point so I kept the converter locked when the trans upshifted. It was a pretty harsh shift even with 6,200 lbs of tall geared van taming it. Several times I datalogged 2-3 mph of tire slip going into 3rd shifting with a locked converter.

Orr89RocZ

iTrader: (20)

His combo should be fine, i believe its similar to my old combo and maybe slightly smaller cam. Mine was 383 hsr with 230/245 .600” 109 lsa cam. Lugged fine with 3.42 gear.

i played extensively with my combo and never seen anything et wise. Two combos actually. Bolt on hsr intake L98 and my 383. There was no surge in acceleration, actually the opposite. It lugged the converter down and slowed car down. Tried peak torque, just after, redline shift rpm, first gear, second gear. No results other than maybe a mph, mostly nothing.

so i guess it depends on how much converter you have and what it stalls at. Mine was 3600 and car could have had 4000-4500 to be faster. Maybe under stalled locked up would not help. Might help an overstalled car

89fast5oh

Thanks for some great replies. Sorry it too me 2 weeks to get back to this.

I forgot to say in the first post that I have a Probuilt Automatics Street/Strip 700r4.

I have no surging while driving, it drives very smooth. I'm sure with a lower lock up speed I wouldn't have any issues.

I don't drive the car much, and when I do its very light throttle around town stop and go doing 30mph. I haven't gone on the highway yet and if I am driving on the 40mph road I have the shifter in D not OD.

I don't have a cooler yet, but ordered this one and will install it. It has a 180 thermostat setting.

https://www.summitracing.com/parts/der-13950

Vader

The factory TSB from 1986 raised the lockup point in 4th gear to 41 MPH (from 28 MPH). That should easily be safe for a stock TH700-R4.

AlkyIROC

For a good race converter, stall speed shouldn't have any more than a 10% slip when driving above the stall speed.

For a street converter, running a higher stall speed helps performance because it gets the engine quicker into the powerband. While cruising however, you are normally driving below a performance converters stall speed. This increases slippage and creates heat in the transmission oil. A lockup converter helps reduce or eliminates this slippage. Not saying it's going to hurt anything since performance converters have been around a lot longer than lockup converters have. The key is to make use you have a good aftermarket trans cooler to keep the oil temp down. Although they all work, I never liked the cheap tube and fin style coolers. Stacked plate is more compact and efficient.

The lockup converter will also slightly increase fuel mileage since the converter isn't slipping, the engine rpms will be lower. Generally they'll lock up at a cruise speed however as soon as you start to accelerate/decelerate, they are suppose to unlock.

89fast5oh

As a follow up to this, This week I just changed lock up speeds to the factory prom settings. The car did not like this. With the current tune I am getting engine stumbling while cruising if I try to gently accelerate or even maintain speed.

I have had this tip in stumble since day one and a locked up torque converter is magnifying it. I will be changing the TCC lock up speeds back to the higher MPH until I can get this running right.

I will also add what torque converter I am running since I never mentioned it before. It is a 2400-2600 stall 9.5" Street Edge lockup converter specd out by Dana Wilkes.

Fast355

iTrader: (2)

As I said it is combination specific. My 383 does not like being locked until ~1,500 rpm. While it has the power to pull at a lower rpm it is not necessarily happy doing it. The 383 surges and bucks under load a bit. It is amplified by the vehicle weight. My converter is a custom built stock diameter 4L80 converter that flash stalls at 2,800.

89fast5oh

The surge and buck is something I've dealt with on my 408W Mustang LX 5 speed for years so I know all about that. On that car it is very harsh. On my 383 Camaro there is zero surge and buck.

BUT something to ponder as I just discovered it for myself..

I was playing around with a new tune I made off of the APYP bin. It has a ton of spark advance in the table. about 10 degrees more through the curve and like 40 degrees off idle. With the stock APYP spark advance table, the Camaro bucked and surged like crazy. I went back to the spark advance provided by Tuned Performance and zero bucking surging.

I think the surging/bucking definitely results from improper timing values at low rpm cruise.

I am investigating more so I can apply what I find out to the Mustang tune to try and get rid of that bucking and surging.

Kingtal0n

Many vehicles I've tuned that have difficulty at low rpms with surging bucking trailer hitching are fixed by adjusting injector phase to spray post Exhaust valve close (SOIT just after closed exhaust valve)

For example my mild cam 5.3L Will buck and surge cruise 1500rpm with factory SOIT but easily smooth and fixed with retarded (later) SOIT

Fast355

iTrader: (2)

EOIT, Timing, Fuel mixture, Open/Closed loop made no difference in my case. If its down around 1,200 rpm and gets a load on it, the thing bucks. It acted the same with a carb as it does with EFI. At 1,200 rpm it had a noticeable pulsation or hunting. At 1,500 rpm it will take a load smoothly. I delayed lockup to keep it at 1,500+. That 300 rpm increase gives me something like 20 hp more to move the weight and the unlocked converter under its stall speed adds some torque multiplication.