Tranny gurus step inside....lock-up issues
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
Tranny gurus step inside....lock-up issues
Alright, here's the scoop, and keep in mind I'm a transmission moron so please use small words! I installed my custom built tranny and 9.5" 2500 stall converter a while ago, and have put about 800 miles on the car since.
I'm having overdrive issues (not engaging unitl 65 mph) and I figured, perhaps, it was something with the ecm not allowing the lock-up to engage. However, we adjusted the 4th gear lock-up with the dyno tune, and no change (changed from 47mph to 40mph) . It was then that I realized I also should have a 3rd gear lock-up function (set at 38mph).
The car continues to stall all the way until OD finally engages at 65 mph. I can tell you, it's getting a little frustrating stalling at 55 mph in highway traffic in 3rd gear.
Any of you gurus have any suggestions?
I did the install myself, and all wires/harnesses are indeed plugged in. The speedo reads correctly, so the speed sensor must be working. I have tried adjusting the shifter cable, and haven't seen any changes.
Thanks in advance!
I'm having overdrive issues (not engaging unitl 65 mph) and I figured, perhaps, it was something with the ecm not allowing the lock-up to engage. However, we adjusted the 4th gear lock-up with the dyno tune, and no change (changed from 47mph to 40mph) . It was then that I realized I also should have a 3rd gear lock-up function (set at 38mph).
The car continues to stall all the way until OD finally engages at 65 mph. I can tell you, it's getting a little frustrating stalling at 55 mph in highway traffic in 3rd gear.
Any of you gurus have any suggestions?
I did the install myself, and all wires/harnesses are indeed plugged in. The speedo reads correctly, so the speed sensor must be working. I have tried adjusting the shifter cable, and haven't seen any changes.
Thanks in advance!
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
You need to change your governor weights to heavier weights or you need heavier springs in the governor. The governor controls the shifting of the transmission the computer only controls the lock-up of the torque convertor. B&M sells a governor calibartion kit and it takes a few trials to usually get it dialed in.
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
You need to change your governor weights to heavier weights or you need heavier springs in the governor. The governor controls the shifting of the transmission the computer only controls the lock-up of the torque convertor. B&M sells a governor calibartion kit and it takes a few trials to usually get it dialed in.
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Alright, here's the scoop, and keep in mind I'm a transmission moron so please use small words! I installed my custom built tranny and 9.5" 2500 stall converter a while ago, and have put about 800 miles on the car since.
I'm having overdrive issues (not engaging unitl 65 mph) and I figured, perhaps, it was something with the ecm not allowing the lock-up to engage. However, we adjusted the 4th gear lock-up with the dyno tune, and no change (changed from 47mph to 40mph) . It was then that I realized I also should have a 3rd gear lock-up function (set at 38mph).
The car continues to stall all the way until OD finally engages at 65 mph. I can tell you, it's getting a little frustrating stalling at 55 mph in highway traffic in 3rd gear.
Any of you gurus have any suggestions?
I did the install myself, and all wires/harnesses are indeed plugged in. The speedo reads correctly, so the speed sensor must be working. I have tried adjusting the shifter cable, and haven't seen any changes.
Thanks in advance!
I'm having overdrive issues (not engaging unitl 65 mph) and I figured, perhaps, it was something with the ecm not allowing the lock-up to engage. However, we adjusted the 4th gear lock-up with the dyno tune, and no change (changed from 47mph to 40mph) . It was then that I realized I also should have a 3rd gear lock-up function (set at 38mph).
The car continues to stall all the way until OD finally engages at 65 mph. I can tell you, it's getting a little frustrating stalling at 55 mph in highway traffic in 3rd gear.
Any of you gurus have any suggestions?
I did the install myself, and all wires/harnesses are indeed plugged in. The speedo reads correctly, so the speed sensor must be working. I have tried adjusting the shifter cable, and haven't seen any changes.
Thanks in advance!
When you say stall, do you mean that the engine shuts off when driving down the highway at 55 mph?
As far as the late shifting, it is possible that you have a governor problem. You can swap the governor from your old trans, and see if it solves it. Before installing it, clean it well with carb cleaner and dunk it in fresh atf. It is unusual for a governor to affect 1 gear only, especially 4th, but I have seen stranger things. Something to try that is free, and may solve it.
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
I have a few beers in me, so I do not quite understand.
When you say stall, do you mean that the engine shuts off when driving down the highway at 55 mph?
As far as the late shifting, it is possible that you have a governor problem. You can swap the governor from your old trans, and see if it solves it. Before installing it, clean it well with carb cleaner and dunk it in fresh atf. It is unusual for a governor to affect 1 gear only, especially 4th, but I have seen stranger things. Something to try that is free, and may solve it.
When you say stall, do you mean that the engine shuts off when driving down the highway at 55 mph?
As far as the late shifting, it is possible that you have a governor problem. You can swap the governor from your old trans, and see if it solves it. Before installing it, clean it well with carb cleaner and dunk it in fresh atf. It is unusual for a governor to affect 1 gear only, especially 4th, but I have seen stranger things. Something to try that is free, and may solve it.
I'm right there with you....with the beers, I mean.
When I say stall, I mean the engine revs to a greater degree than the power is transfered to the wheels. Essentially, what I would describe as what a stall converter would do, but seems to be overriding the lockup programming of the ECM, at least in 3rd gear. Maybe I'm just misunderstanding, and this is a normal function...but seems strange in the mid 50 mph's.
Would replacing the governor with the stock one affect any of the other performance aspects, or strengths of the tranny? And, by the way...where the hell is the governer, anyway?!
Other than this issue, this trans is flat awesome; mild shifting under light load, incredible shifting under power. And I'm not afraid to lay the boost on it either.
Ahhhh.....time for a refill!
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
I swapped out the governors last night. Although I don't think I've got the cover as absolutely tight and seated as it should be (I had it tight enought to prevent leaks, but didn't have anything that wouldn't damage the cover), about 1/16" from being flatly seated, the swap was pretty easy.
I haven't had the car on the highway yet, but I was able to run her up, and cruise, at about 57 mph, still without OD engaging. I did notice that the stock large spring rate from original governor was much heavier than the one in the new tranny.
I'm not sure if the improper seating of the cover would prevent the upshift from 3rd...but by not running it on the highway to see if the 65mph shift is still in play I just don't have alot of info.
I haven't had the car on the highway yet, but I was able to run her up, and cruise, at about 57 mph, still without OD engaging. I did notice that the stock large spring rate from original governor was much heavier than the one in the new tranny.
I'm not sure if the improper seating of the cover would prevent the upshift from 3rd...but by not running it on the highway to see if the 65mph shift is still in play I just don't have alot of info.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by silver86
I haven't had the car on the highway yet, but I was able to run her up, and cruise, at about 57 mph, still without OD engaging.
RACE ON!!!
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
I'll take her around the block and double check this evening. If I'm going by what I can recollect (and I'm pretty sure this is the case), I'm only getting two shifts and the 3rd shift is occuring at ~65mph.
Drifting
Joined: Jun 2001
Posts: 1,704
Likes: 459
From: Mass Mass
Here are the stock tables for an 88 ABTS bin.
The 86 (I might have it around some place) probably looks similar.
Can you look at your bin?
Is your coolant temp coming up over 120F or maybe disconnected?
The 86 (I might have it around some place) probably looks similar.
Can you look at your bin?
Is your coolant temp coming up over 120F or maybe disconnected?
Le Mans Master
Joined: May 2003
Posts: 5,362
Likes: 3
From: Delray Beach FL
I guess this is the possible easy way out, but you could put a B&M Torque Converter Lockup Switch in your Vette. Gives you the ability to have it lock up at any speed between 30 and 90 mph. You would no longer have to worry about the computer doing the shifts. I use one in my Monte Carlo SS (got rid of the factory computer in it). Don't know if I am going to need one in my Vette, once it is done, though. Just another idea. 
Last edited by QuikZilver; Apr 17, 2008 at 05:19 PM. Reason: English not too good. LOL! Corrected..
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
Only two shifts....so OD is not engaging unitl elevated mph. Governor has been replaced with the one from the original trans.
I don't have a way to pull the BIN info., unless I can do it with datamast.
I don't have a way to pull the BIN info., unless I can do it with datamast.
Racer
Joined: Jul 2002
Posts: 466
Likes: 0
Don't want to hijack the thread but if my dad's vette's od is slipping, could it be that the torque converter lock up is not locking up at all? (or maybe partially) and it's slipping, because i tought that the clutches were slipping?