Lock-up VS. Non Lock-up Torque Converter
 

I have an 89 I'm swapping my 6 spd for an auto. I want a good smooth shift, but still be able to put my foot in it every once and a while.

What are the advantages and disadvantages of each?

If lock-up than what RPM range torque converter?

I can see no advantage to a non-lockup TC save possibly for full out racing.

I think a 2,400rpm lockup TC will give stronger than stock launches with very good manners around town and excellent highway mileage.

Thanks.

I'd like to get some more opinions on this too. I just had my transmission out for a complete reseal job and took it to a shop supposedly specializing in hi-perf 700R4's and after they pulled the pump to replace the seals and front bushing he had me bring my converter over to have him look at it and he determined the lockup clutch was going out in it by spinning it with a dummy shaft and showing my how it would get tight. Long story short he talked me into putting in a new pump and opening up a feed circuit and because my motor is pretty stout (haven't dyno'd it yet but it should be over 400 RWHP) he said I would be better off going to a non-lockup converter. He said the engine would be more responsive because the non-lockup converter was lighter and with the weight savings of 32lbs off the back of the crank you would feel it and he was right about that. I went ahead and went the non-lockup route and now the engine definitely gathers RPM's quicker then before. He told me if I did not lug the converter which I don't and there wouldn't be much of a difference in trans heat which so far seems to be the case by my gauge it really didn't go up much if at all. I'm going to build a later 700R4 this year though from the ground up and would like to know the pros and cons from some experts about weather or not to go lockup or non on my next one.

i would like to know what you guys have to say about this topic also! ill bee keepin an eye on this thread! I just hard wired mine so it locks up when it shifts into 4th only seems to work fine for me :yesnod:

Same here , my trans builder also mentioned the possibilty of trashing the clutch lining if hitting it with enough torque while still in lockup.

Remember;
the TCC is a economy measure.Nobody worried about the % slippage when they were driving "glides" and TH400's.
Also with the mod to delete the lockup I believe you get full flow to the trans cooler all the time; which you only get when the convertor is locked in std setup.
That is the reason why it is recommended you have the TCC working if you have a stock trans; it can overheat if it doesn't go into lockup mod due to partial flow to the cooler.

My opinion is simple.
Racecars use non lock up converters. Street cars use a lock up converter.
Lock up converters producle less heat because the internal slippage goes away when locked, and most are locked in 3rd and 4th gear, depending on model year.

I have a 9.5 inch "race" converter in my 700r4 that has a lock up plate, and works well. It is 14 pounds lighter than a stock converter, and performs like a race converter at the strip. It allows the engine to spin up faster due to it's light weight, and will allow me 2 mpg more on the highway than a non lock up converter would. Your trans guy needs to step into the 90's. Non lock up converters ruled the streets when dual point distributors were the latest bolt on.

I'm running a 406 solid roller motor. My converter of choice has a lock up. I have a switch that I use to lock and unlock the converter.

I will tell you that under full throttle, I lock up the converter in 2nd at 5,000 rpm. There is a very noticable difference in the pull with the converter locked. No slippage. Pulls hard!

lol.......yeah I remember how cool dual points were, that's why I always had a single point set-up before electronics were available.
Since you don't clean your PM's out I'll post here. How hard is it on parts to have the TC lock at WOT (somewhere before the stripe done either manually or ecm)?
*to the OP sorry, don't mean to jack the thread*

Mick,
I didn't realize the pm box filled up again, but I will delete a few soon.
I am only aware of the raybestos 500 hp friction material for the lock up plate. Although it is rated for 500 hp, there is wiggle room. I have a few of my converters out there that are locking them on the back half of the 1320, and are on there 3rd year without lock up friction lining failure.
Guys like you and me know that we build stuff with a shorter fuse, and they wear out quicker. Considering that most hard core guys that run 700r4's freshen them every 3 years or so, I never worried about frying the friction material on the lock up plate.
I guess that is a rambling way to say:
Not too sure:D

I run a 700r4 with a TCS 3500 RPM stall. The lock up is on a switch. I have run a 7.72 without the TC locked and 7.9's in the 1/8mi with the lock on. It does not engauge in 1st but does in second and it is very noticable change when it is locked. Sometimes I lock it in third right before I shift and it seems to give me a slight boost. I generally do not lock the converter except in 4th when I am on the freeway. I did not weigh it but it was lighter than the stock TC. I notice every time it is locked it is like a manual transmission feel. The extra rpm's prompted me to stay with a lock up TC. Seemed like the best compromise for me.

:iagree: 100% thats what I got in mine.

Pete, thanks....I recall you mentioning that when I bought mine. So far, mine feels great it actually flashes a tad higher (which is good), and no complaints here. I was considering playing w/locking it somewhere about 10mph below my 1320 mph.
If I get 3 years that would be good, more than likely by then I'd be tearing it down and going through the set-up.

Mick,
I suspect that the reason that yours may flash a wee bit higher than planned is because the builder may have knocked a few hp off your projected numbers. Most guys build less power than they claim, so the builder takes a guess at what the "real" number will likely be.
Your combo did everything you hoped it would regarding power, and may have exceeded your goals, if I recall correctly.
Bet you cant wait for the snow to melt.

I have not seen this posted yet so i will go ahead and post a bit of info i have been taught and has yet to fail me.

If you fry a transmission (IE: clutches burn up or gears blow) replace the torque converter. When they go the friction material polutes the converter and if you dont replace it or flush it PERFECTLY it will kill the life of your rebuild.

Pete, in the world of performance parts it is rare when someone conservatively estimates hp....it was a pleasant surprise.
Yeah, it will be nice when the white stuff, and the salt goes away. I am still doing more, new radiator is in, and working towards the n2 stuff....hopefully it will be a good season. (maybe you'll get a chance to clear your pm's...lol):cheers:

This is an area where I've done some experimentation. Last season, I had a 500+ HP 383 LT1 installed into my 92 A4. As part of that project, I got the appropriate ALDL connector cable, software to log and interpret engine performance, software to edit bin tables for chips, and chip burning hardware. This has allowed me to experiment quite a bit with many aspects of tuning, one of which is the vehicle speed where the TC locks up. See sig below for list of mods.

I burned several chips, differing ONLY in the speed of the TC lockup, and tested them at the track. I looked at three speeds: 47 MPH, 75 MPH, and 95 MPH. For point of reference, I go through the eighth mile at about 90 MPH, so in the first two settings, the TC locks up before the halfway point. My results indicated that the 75 MPH setting consistently gave me the best times, almost a tenth better than either of the other two settings.

Part of this is due to the fact that my engine is a stroker, which makes more torque at low RPM than stock engines, due to the mechanical leverage of the longer rods. So, it's to my advantage to get the engine back to a lower RPM as the TC locks up. The point is that every engine and gearing combination has an optimum speed for TC lockup, and it will vary depending on both the engine design and the gear ratio. By pre-burning several chips with only this one change and making multiple passes with each, you can assess the best setting for your own car.

My .02. I use a vigilante 5 disk lock up converter in my 84 bracket car and lock the converter up right after the 1-2 shift. My car runs approximately 2 tenths faster in the quarter with the converter locked up. In my case as in the other forum member, the car does pull strongly. This allows me to use a .430 rear gear and go through the lights at 6500 at 126mph. I make over 250 runs per year and have my converters freshened up every 2 years with never a problem. 10.58@126

Attachment 48160871

I was wondering if MTVettes Locking up of the torque converter at 75mph coincided with the 2-3 gear change. That would go along with what 383vett discovered. Seeing as I will be running a 4L60E and a FAST transmission controller it will be easy to make that adjustment. So to cut to the chase, 1st and 2nd gear unlocked and 3rd gear locked. Also 4th locked if I run that fast. Thanks for the information. ;)

That is a pretty huge gain (imo) from just locking the conv. I thought there would be some gains, guess I'll just have to figure out the right spot.
I have a couple of questions for you, Did you use one of the available "calculaters" to determine or attain a starting point ? Does the amount of slip in the converter become a consideration for the lock up point ?