Ramanstud

I have a newly installed BowTieOverdrives transmission and Pro-built converter:

The TCC will lock up in 4th gear only. Not 2nd or third under any circumstance. I am heading out now to do some testing per the GM manual but I've already tried to jumper the ALDL terminals to "test" the lockup and it did nothing.

Anyone have any insite to save me some time on this one? I'm supposed to drive 900 miles in about 6 hours...

CFI-EFI

The TCC lock up is commanded by the ECM. If it used to lock up in 2nd, 3rd, and 4th, with the old trans, then the difference is in the new trans. Since it locks in 4th, you know It's working. I'm guessing that it is a "feature" of the new trans. Before wasting time trouble shooting, *I* would consult with BowTieOverdrives.

RACE ON!!!

JrRifleCoach

The TCC is suppose to only lock up in 4th gear. Touch the brake pedal or travel at speeds below (approx) 40 MPH and the TCC unlocks. You can jump the ALDL to force a lockup when in 2nd gear or above. This is not recommended for daily driving due to the pressure exerted on the TC lockup clutch.

Good Luck

If the test you performed was negative then someone maybe someone forgot to hookup the harness connector on the trans.

Ramanstud

well the TCC is definitely supposed to lock in 2nd, third and fourth - it's just forced to always lock up in 4th gear even if the ECM fails to tell it to - right?

Well I can't say I've been real pleased with BowTie on this one: not only did they ship the wrong tailshaft housing, but I called in trans pressures and the guys like "well, those seem a little low..." I tell him I'm running the stock/OEM GM TV cable and it's a vette - he then changed his tune and said it was fine. Just makes me suspicious, especially since my order form says "corvette" on it.

Oh well.

dgoodhue

It definately does lock up in 2nd & 3rd as suggested by others. I think that it doesn't has to lock in 4th gear, the TCC solenoid is electric and I can't see how the mechanical tranny would be able to lock it manually. Most of the when its a TCC issue, it isn't locking at all and its a wiring/brake adjustment issue.

CFI-EFI

In order for the TCC to lock, the TCC solenoid has to be energized. The only way it can be energized is by the ECM. It CAN'T lock in 4th gear "automatically", it has to be commanded. Hydraulics prevent the TCC from locking in 1st gear. I am suggesting that Bow Tie ODs may have trans "set up" not to allow TCC lock up until 4th gear. Have you asked them?

RACE ON!!!

Ramanstud

Yes, CFI I just called them - and I am unbelievably pissed off right now. I'm trying not to lose my temper but I'm running on the ragged edge. BowTieOverdrives.com builds their transmissions to lockup in 4th gear only - so with a 3000RPM stall converter guess how well that works in town?

Conveniently, neither their website nor their staff mentioned this "little" caveat when I ordered. this is an remarkably important detail when you advertise your transmissions as an OEM or better-than-OEM replacement. So if there is an OEM characteristic that is no longer functioning, you'd think they'd bother to tell me about it BEFORE hand. Needless to say, I've never even heard of tranny's without the 2/3 lockup.

The guy on the phone laughed at me when I asked him why it wouldn't lock up in 2nd/3rd gear; he says "all the aftermarket transmissions are set up that way." As if that's supposed to be comforting to me. I am NOT very happy at all with the way this worked out. I will post a new thread on my BowTieOverdrives.com fiasco, so that other Forum members will be aware of this issue before they decide to order a BTOD transmission and can plan accordingly.

Jloshotz

Wow raman, i'm sorry to hear the way this is coming together here, i see what you were saying now. I wonder if they are correct in saying ALL aftermarket 700Rs are set up this way. Surely someone else will add thier .02 here. I'll keep checking back; i really hope you get a fairly simple fix to this situation in one form or another.

crheinish

Raman, I know your PO'd but ask them what they do to stop the 2-3 lockup and have it reversed locally.

flyersfan1088

700R4's never locked up in 2nd. 3rd and 4th only.
My money says your tranny is working exactly as Bowtie wants it to. Later 4L60E's only lockup in 4th (according to my tranny guy) When performance trannys are built, it is common to cut out the 3rd gear lockup, leaving only 4th. Call or email Bowtie to alleviate any concerns.

JrRifleCoach

If you want the TCC to lockup in all gears except 1st, bend a heavy duty paper clip to jump A & F on the ALDL connector. "A" is the top far right hand port and "F" is the top far left hand port.

Thats all you need to do.

conv90

On my 90 (not a 4L60E) and on all others chip i read, there are routines for TC lock vs. mph. They are for "low gears" and "Hi gears".
Hi gears is always OD and lower gears are 2 and 3.
If I want the lock occurs at 40 mph in 3 I change this table, if i want it locks at 55 in OD i will change the speed to 55 in the Hi gears.
So definitively the 4L60 LOCkS also on 2 or 3.

ALLT4

Man, it really sounds like the wrong wiring internals were installed or pressure switch. Some were N.O. some were N.C. this is the pressure switch that controls fourth gear lockup. If it's the wrong one the ECM might be all confused. Also I believe there is a temperature switch in there that won't allow lockup untill the transmission is warm enough. Most folks throw that one out or short it out of circuit.

BTO should know this though and the correct pressure switch should have been installed. Short of fourth gear lockup I believe the ECM should be handling 2nd and 3rd lockup regardless of what type of pressure switch is in there.

Not only that but if there is a different convertor installed the pressures could be all different and again the ECM might be all confused.

I'm speculating and just offering things to think about.

rodj

Bowtie have just wired it through the 4th gear switch in trans so it only operates in 4th
Hot wiring the control circuit will make no difference.

JrRifleCoach

Sounds like the 2nd Gen C4's have a different set of OD commands for gear selections vs speed. This jumper trick is good for the earlier years.

crheinish

Now that I think about it I am not so sure you should have lockup in 2nd and 3rd gear. I know my 93 only locks in 4th and I have no problem with that. I am running a 2800 Vig, 3.73 gears, no shift kit and stock 700r4 with a trans cooler.

Ramanstud

Well there are a lot of differing views / thoughts building up in this thread.

To reply to the post about contacting BTO, well I did (see other post) and it was basically a Tough Luck situation. At the very end of our conversation the manager suggested I "swap internal wiring harnesses and see if that works." So who knows what valve pressures and all that have to do with it.

I don't yet know what actually has to be changed to allow a 2nd/3rd lockup from the apparent standard of no 2nd/3rd lock up, but it may just be a wiring issue in the trans itself. Obviously transmission co's are not modifying the ECMs (thank god) to change it's behavior.

Another issue compounding my woes is that the 2-3 and 3-4 shifts are delayed (3000-3500 RPMs) under slight to part throttles, causing me to have to cruise around town in the 2500-3500RPM range. Only when I hit 50mph + will it shift down and become reasonable again. Per BTO's advice I've been trying to address the TV cable adjustment and accelerator linkages to make sure everything is on the up and up. I've tinkered without success. Perhaps the higher stall is an issue, but others are running 2800's without pause so I am reluctant to outsource blame to the stall speeds.

Two seperate people from BTO gave me two different responses when I inquired about all of these events, so I can't say I have much faith in their advice at this point anyway.

I'm having a bad week.

Pete K

Are they willing to refund your money? If that possibility exists, the couple hundred in return shipping may actually be worth it. I had a bad dealing with an engine builder 8 years ago. I spent so much time and effort in trying to correct every issue that i almost went broke and insane. If i were in your shoes I might consider that option if it is possible. Also, if you paid on a credit card, they may be of help. Sorry man, I feel your pain.
PS I have a few books floating around regarding 700's and the wiring differences. I will sneak a peek and see if I cannot make heads or tails out of it. I am confused regarding what gears are locking up and why. I intentionally locked mine up in fourth gear only. i thought the stock 87 box only locked up in 3rd and 4th but cannot be sure. I will dig in the books a bit.

Ramanstud

Thanks for your assistance, Pete.

Well at this point I've installed and driven the transmission due other issues and constraints on my part. So in that sense I think I've "assumed ownership" at this point and I would more quickly buy another $200 converter as a quick fix rather than eat the money in shipping, argue extensively with BTO and then still be out a transmission and a month's worth of wrenching (and NO, during my dialogue with BTO there wasn't a hint of an offer of resolution in any manner - it really was me explaining my issues and them not believing me... they honestly thought I was making this **** up at one point. then their implying that it was my own fault because I don't know any better, etc, we really never got down to whether or not they would actually offer a refund).

I will make this one work in one way or another, and hopefully it's built as well as their previous rep would suggest. Besides, I will provide the benefit of the doubt and say that BTO probably builds a quality transmission that would work very well in specific applications - but Corvettes (specifically early C4s) are not necessarily one of those applications due to the inconsistencies we've hashed out already. And you know how I feel on the PR side of things.

I read your other post on the valve bodies regarding TCC lockup, and I think I will call BTO back and try to get a straight answer out of them on what has to be done to get the lockup functioning back. It is obviously frustrating, as they previously told me to basically crap shoot my problems with the harness switch and left it at that. Maybe the valve bodies don't need to be changed?

Perhaps I'm in a holding pattern until I'm able to pull the pan later this week. If the wiring harness is different at all, it will be short work to see if it affects anything.

crheinish

What brand converter are you running?