Changing the Overdrive Shift Point
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Pro
Joined: Aug 2019
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From: Minford, Ohio
I will give that a try but right now I'm waiting for a new set of fuel injectors to arrive. Some of the old original ones are leaking. I just have one question, when the TCC lockup occurs does the rpm drop? The reason I think it is the shift point is because the rpm's drop and it feels underpowered. I must have a 2.59 differential because at 70 mph I'm only turning 1700 rmps.
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From: Glenbeulah Wi
I will give that a try but right now I'm waiting for a new set of fuel injectors to arrive. Some of the old original ones are leaking. I just have one question, when the TCC lockup occurs does the rpm drop? The reason I think it is the shift point is because the rpm's drop and it feels underpowered. I must have a 2.59 differential because at 70 mph I'm only turning 1700 rmps.
Try this, at 45 MPH when you feel the shift to overdrive pull the shifter back to drive, does the engine RPM increase with a noticable bump when you pull it to drive? If so you have shifted to overdrive, if not much really happens then the lock-up is what you are feeling.
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From: Minford, Ohio
In my 93 FSM on page 7A-15A-3 is a chart with different models of the 4L60 transmission and the speeds at which each gear shift takes place. I can't find any information about these different models. Does anyone on here know anything about these different models? There are 25 different models listed in the chart. There is one model HLM that shifts from 3rd to 4th at 56 - 63 MPH which would be perfect for me.
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In my 93 FSM on page 7A-15A-3 is a chart with different models of the 4L60 transmission and the speeds at which each gear shift takes place. I can't find any information about these different models. Does anyone on here know anything about these different models? There are 25 different models listed in the chart. There is one model HLM that shifts from 3rd to 4th at 56 - 63 MPH which would be perfect for me.
Depending on axle ratio you should have a YCM (2.59) or a YDM (2.73 or 3.07) transmission I'd think.
*** That's assuming originality.
Last edited by WVZR-1; Apr 24, 2020 at 09:37 PM.
Thread Starter
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From: Minford, Ohio
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From: Minford, Ohio
Thanks for all that info ihatebarkingdogs. I can't find any information on the model numbers that are listed in my FSM. That must be a well-guarded secret at GM! lol I think the best solution for me is to just put the shifter in D until I get on the highway. I get 27 mpg with it and I don't want to mess that up with a differential change. There is no DTC for the TCC in my 93 FSM.
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***See page 0A-5 in the FSM for ID location and explanation. (IHBD) - Don't look to be vertical to me!
Last edited by WVZR-1; Apr 25, 2020 at 04:17 AM.
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Thread Starter
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Joined: Aug 2019
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From: Minford, Ohio
I've been all over WV and the only flat stretch I know of is between Huntington and Charleston. I like to drive down to Elkins and take RT. 250 over to Staunton, Va. in the fall, beautiful dirve thru the mountains. I was hoping there was an easy adjustment on the 3-4 shift to change the speed at which it shifted but I guess not so the easiest thing is the 'D'.
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From: MotorCity
The easiest way to fix your annoyance if it is the TCC lock up MPH would be to contact Solomon from the link in post #5 and mail your PROM to him for a one time tune and have him increase the TCC lock up MPH and you would get a better tune as well then you could just swap proms in your ECM.
I have to agree with ihatebarkingdogs changing that 2.59 gear would make a huge improvement in torque and fun factor but might also might require some adjustments to the OEM settings in the ECM PROM to take full advantage of a gear change.
That was how I ended up having to sending mine to him I changed to a 4.10 gear and my speedometer among other things had to be changed.
I have to agree with ihatebarkingdogs changing that 2.59 gear would make a huge improvement in torque and fun factor but might also might require some adjustments to the OEM settings in the ECM PROM to take full advantage of a gear change.
That was how I ended up having to sending mine to him I changed to a 4.10 gear and my speedometer among other things had to be changed.
Last edited by 1Sin; Apr 25, 2020 at 12:43 PM.
Le Mans Master
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From: near the thumb in the mitten
The different transmission codes are for all the 700r4 (4L60) different applications from 4 cylinder S10 to the Fleetwood. The transmission codes are probably listed in a chart in a parts manual or used part interchange manual. Corvette likely only uses two; 1 for the 2.59 and the other for the 3.07.
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From: Minford, Ohio
The different transmission codes are for all the 700r4 (4L60) different applications from 4 cylinder S10 to the Fleetwood. The transmission codes are probably listed in a chart in a parts manual or used part interchange manual. Corvette likely only uses two; 1 for the 2.59 and the other for the 3.07.
Le Mans Master
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From: near the thumb in the mitten
Yes, The WTF were they thinking 2.59. Which is a sick joke anywhere but the flat lands. The optional G92 "Performance Axle" 3.07. IMO.The 3.07 should have been the base and a 3.42 the performance axle.
Drifting
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From: Orange, CA
Thread Starter
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Joined: Aug 2019
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From: Minford, Ohio
It's a great cruising axel and you can't beat the gas mileage with it but the acceleration doesn't exactly set you back in the seat. I had a 66 with the 327/350hp and a 3.73 axel, now that car would set you back in the seat.
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Drifting
Joined: Apr 2020
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From: Orange, CA
I saw that an RPO existed for GU2 but I couldn't find any information on production numbers, nor could I find any actual Corvettes listed with this RPO. Do you have any photos or information on such Corvettes?
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I don't need PHOTOS!! Trust me there's a GU2/G92 Performance Axle for Y67!!! If there weren't one I wouldn't have mentioned it!!! Look a little harder!
Last edited by WVZR-1; Apr 25, 2020 at 07:16 PM.