vettenoir

I'm currently upgrading my transmission from a Turbo 350 to a custom built 200-4R and am deciding on a torque converter. The car is road driven to/from all events (up to 300 miles) including Solo I and Solo 2, drag racing and maybe some lapping days.

The car has a 500-600hp 409 SBC, (power band up to 6500rpm) The car has a 3:31 rear end and will never see R-Comps or drag slicks, although it is going to have pretty sticky street tires (Kumho XS). I was wondering about an appropriate converter stall speed and whether or not to go for a multiple lock-up option, which I've heard /read can be advantageous for avoiding flashing the converter coming out of corners.

I've slalomed the car at many events with the setup in my signature and managed to be able to control the car fairly well with the throttle after some practice and never had any major problems.
Right now I'm thinking of a Vigilante 2500-2800 stall with lock-up only in 4th gear. (I definitely at least want this lockup for the long trips to/from the track.)

PS: Before you say I'm , I have no visions of winning any championships with the car, just having fun trying to drive it 'relatively' close to the limit in a safe environment.

2000BSME

I'm and auto driving road/tracking lap days kinda guy and I have no idea what you are talking about or why this is in the auto/roadracing subforum.

You may want to be a little more specific with your post/questions.

vettenoir

Okeedokee, we'll go for bullet form

Information I'm looking for:
- Recommended torque converter stall speed
- Is a converter that can lock up in 2nd and/or 3rd gear advantageous for auto-cross and road course applications?

Current vehicle specs:
- 500-600hp sbc: power band 1500-6500rpm
- 200-4R automatic
- 3:31 rear end
- Kumho XS street tires

Application:
- street driven, and driven to/from track
- auto-cross - main competitive venue
- drag race (2-3 times a year)
- lapping days (maybe...)

I hope this makes more sense.

2000BSME

well I guess I'm not that 'up' on autos like I thought I was...

I have a 300 rpm higher stall than stock converter (out of an astrovan, stock converter was imbalanced). I don't think that lockup will be beneficial, I think that it may be less 'hardy' than otherwise. I use a huge cooler, and a fan, and good air ducting, and still have trouble keeping temps below 250* on my short technical track (Barber Motorsports Park).

My advice for lap days is use the lowest stall converter that you can live with.

Still not sure what you are asking for, but I consider myself 'blazing' fast for an automatic (much faster than many modified vettes), and if you want to pm me or continue this thread as is, I would be glad to help, and I would be interested in bouncing ideas off of you if you are adept at lapping days, ... as that is really my only interest right now.

Aardwolf

I just had mine (700R4) rebuilt (again) and decided to go non-lockup. It wasn't difficult to convert over. The lock up feature adds an extra shift. That's extra time shifting that you don't need. You could use a manual lock up switch for long drives instead. I used a 2400 RPM stall, I didn't want the car to surge when getting back on the throttle. I think your 200 is similar to my 700 with the vent on the passenger top side of the case. My trans sometimes vents so plug a hose on the small tube and run that to a catch can or onto a fitting on the dipstick.

2000BSME

Oh, now I get it... how might I go about adding a switching for my lock function on my c5? Any ideas? I would like to disable for the track,... I have HP tuners, I bet that can help...right?

Aardwolf

I'm not familiar with C5 tuning or electronics. I can offer some insights from working on mine though. One, you can add a manual enable/disable switch. Two, you can use the chip tuning feature. On my chip there is a code that disables lockup after WOT. Just set that timer up a bit and you'll have it working the best. For example, I think I had mine set to 20 seconds delay after WOT to enable lock up.

vettenoir

Thanks for the information on the vent tube. I've never heard of that problem before, but will now account for it before it occurs.

Regarding converter lockup in 2nd and/or 3rd as well as 4th...
My transmission builder had heard of it and wondered if I was going to do it. I did a forum search before posting here and found this:

This is the thread:
http://forums.corvetteforum.com/auto...n-solo-ii.html
As this was the only post I found on the topic, I thought
would solicit other opinions here. Anyone else try this?



Bob

mr.beachcomber

I've auto-xed my auto '89 (2.59 rearend) extensively and driven VIR only once in that car. The stock L98 and rear end ratio didn't have the beans to move the Vette out of the corners or around the course in overdrive (converter lock-up). In fact, 2nd gear gave me the best results both auto-xing and driving VIR although the later case overheated the tranny fluid. However, given the HP and torque your engine has along with the 3.31, I would stick with your present choice of the Vigilante mentioned above.

As mentioned in earlier posts, retaining a manual lock-up capability isn't a bad idea primarily since you have tons of torque available to pull the car out of a corner with a locked converter. (Locking the converter will reduce slippage and the attendant heat build up, but be sure to add a tranny fluid cooler to the mix.) Good luck and have fun!

2000BSME

I'm under the impression that WOT on a locked converter condition isn't good for the life of the tranny. What do you know about that? I thought locking was only for low rpm cruising and fuel efficiency, anything more and you will cause damage.

Allthrottleandsomebottle

I run a lock-up 3800 STI 2.1 stall in my 97' (500 RWTQ NA) with a Rossler 4l60E. Lock-up keeps the tranny temps down IF you have a long straight to use it on. I still manually shift at VIR
If I ran my car as a road racer, I would use around a 3-3200 and pick the STI stall
I do not baby it either

Aardwolf

I see a lot of drag racers locking the clutch. Some lock it up right off the line. From what I remember it's hard on the clutch to do WOT lock up. If you get a converter and want to do this I believe they make triple clutch lock up converters.

Locking the converter causes it to stop slipping. This makes less HP lost to the drive train. It can lug the engine or bring it out of your power band if done incorrectly. My stock system dropped the RPM 200.

Electronically lock up is turned off for WOT, I would think this would be for all years but I haven't done any later year tuning. If you can edit your computer chip, check the transmission settings. For example one of the tables for my year is TCC lock/unlock vs % TPS. I also see TCC unlock prevention threshold which is set to 76 MPH.

Solofast

Locking the lockup clutch all the time isn't a good idea since the clutch shouldn't be locked when you are shifting since it could put more shock loads into the shift clutches and that probably isn't a good idea.

The problem is the lockup clutch isn't really designed to transmit high torque. It's designed to carry the load at light throttle openings and when high torque is present it is designed to unlock. Not sure how much torque it can handle, but if it can't handle the torque, it's going to start to slip and go south pretty quickly.

The idea is great, if you unlock only at low speed and on shifts, but lock the rest of the time the converter won't heat up an life for guys running a automatic would be a lot easier since it won't generate a lot of heat. Driving the car would be a lot better since you can lift and control the attitude of the car a lot better, so there are good things that could result from a properly setup locku clutch. You just have to have a clutch that stout enough to take the full torque of the engine..

vettenoir

I talked to my transmission builder today. The Vigilante triple clutch lockup setup is what I'm considering. I can't electronically edit the lockup parameters, since the tranny isn't computer controlled (200-4R), but this is what we're looking into so far:
- no lockup in 1st gear - EVER
- manual switch to toggle lockup in 2nd & 3rd, when desired (not sure about WOT overruling lockup here...)
- lockup in 4th, but not under WOT.

Has anyone considered putting a 'clutch' button on the shifter to accomplish this? (Squeeze the button to disengage lockup when manually shifting)

Thanks for the responses.

Bob

mr.beachcomber

I apologize for the late response. (Didn't check e-mail for thread notification until this morning.) While it's true that converter lock-up was originally used for increasing CAFE mileage and by default, most applications from the factory applied lock-up during cruise situations and disengaged lock-up under WOT applications, there isn't any reason not to take advantage of this capability on track if the locked-up converter can handle the torque.

I'm no expert in racing auto trannies (I've only owned two auto-equipped Vettes over the years, the rest were manuals.) I think that talking with the converter manufacturer is the best path to take. After all, they should know the limitations of their product. With the HP/torque combination you've chosen, all components of the drive train need to be beefed up.

I see converter lock-up as an advantage on straights and those situations where unlocking the converter for the extra 200+ rpm is faster than downshifting to the next lower gear. (Similar to slipping the clutch in a similar situation with a manual transmission. A really old trick Corvette racers used back in the 70's.)