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| Build update - 4T80 3800 Turbo (Page 3/10) |
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LFiero67
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FEB 05, 02:30 PM
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| quote | Originally posted by DimeMachine:
Enjoying this thread - thanks for sharing the process !! |
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👍
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Trinten
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FEB 05, 10:17 PM
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I've had a few conversations with Brandon his build. He said the only issue he's had with his 4T80 was the first one chewed itself up due to a long 2-3 shift. He flipped the 2-3 piston on his subsequent transmission and hasn't had any issues since. Not sure if you have done that or not.
Also, Will, I did not realize that there were fine splines vs 'standard'(?) splines! How do you go about finding this information? (I want to make sure that the axles I'm going to be ordering don't just fit, but fit properly - sorry for the slight high-jack).
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LFiero67
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FEB 05, 10:47 PM
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| quote | Originally posted by Trinten:
I've had a few conversations with Brandon his build. He said the only issue he's had with his 4T80 was the first one chewed itself up due to a long 2-3 shift. He flipped the 2-3 piston on his subsequent transmission and hasn't had any issues since. Not sure if you have done that or not.
Also, Will, I did not realize that there were fine splines vs 'standard'(?) splines! How do you go about finding this information? (I want to make sure that the axles I'm going to be ordering don't just fit, but fit properly - sorry for the slight high-jack). |
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I have modified the 1-2 and 2-3 accumulators and increased the size of the feed holes in the spacer plate to firm up the shifts. Won’t know how it works until it runs. The 2-3 shift is notoriously lazy on the 4t80, so hopefully these changes will help keep the clutches alive.
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LFiero67
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FEB 05, 10:49 PM
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LFiero67
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FEB 05, 11:02 PM
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Picked up some new bolts for the engine to transmission. The flange of the 4t80 is thicker than the 4t65.
Drilled, tapped and added a M10x1.5 x 35mm bolt in extra 4T80 hole to replace the bolt that is in the cut off ear of the block on 4t65.
Bit of cleanup to do on the engine bay, and I will be ready to test fit the drivetrain in the car.[This message has been edited by LFiero67 (edited 02-05-2022).]
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Trinten
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FEB 06, 12:28 AM
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Nice! And thank you for posting the info and pics on the valve mods you did!
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OldsFiero
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FEB 07, 07:05 AM
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100% of the 4T80's that came into my shop needing major repair were due to a badly slipping torque converter clutch. The lip separates on the metal clad turbine shaft seals in the channel plate. I would change them while trans is out. The Delco numbers are: 24201991 and 24201992.
Trans part suppliers such as Transtar, WIT, ect should have them. If you search by part number, they show up on Rock Auto also.
Marc
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LFiero67
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FEB 07, 10:06 AM
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| quote | Originally posted by OldsFiero:
100% of the 4T80's that came into my shop needing major repair were due to a badly slipping torque converter clutch. The lip separates on the metal clad turbine shaft seals in the channel plate. I would change them while trans is out. The Delco numbers are: 24201991 and 24201992.
Trans part suppliers such as Transtar, WIT, ect should have them. If you search by part number, they show up on Rock Auto also.
Marc |
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Absolutely correct!
Changed both seals while I had it apart, as well as the common worn bushing that supports the driver side output shaft.
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OldsFiero
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FEB 07, 04:29 PM
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LFiero67
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FEB 12, 12:41 AM
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Over the last week or so, my son and I have been busy. I removed the remaining portion of the trunk that I no longer used, cleaned the cv joint grease from the 1000 axles I’ve broken lol. Added a 1x2 cross bar for support, masked and painted the engine bay.
Yesterday I replaced the old rubber -6AN fuel lines with PTFE lines so hopefully there will be less fuel smell.
Finally this evening, the 3800 and 4T80 were bolted to the subframe and installed in the car. Need to build a new rear manifold and hot side as the stock 3800 rear manifold interferes with the transmission, and it will be nearly ready to fire.
Anyone interested in a bolt on turbo setup? Will probably look to sell the ported rear manifold which has been modified for 4 bolts to the turbo adapter with wastegate output. Accepts a T3 turbo and 44/46mm wastegate. Can probably include a 3” or 4” down pipe as well.------------------
10.007 @ 135.54MPH. <-- Video
Best 60' 1.42
Best mph 138.82
Billet 6262 Precision turbo, PT1001 intercooler, ST1 cam, 140lb springs, comp pushrods, HV3, stock L32 bottom end and heads.
Old M90 XP Cam time -
11.425 @115.60
1.543 60'
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