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| 4.9 engine and transmission swap discussion and research (Page 1/2) |
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fierobear
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JAN 14, 12:49 PM
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I’ve been having a conversation in a General section thread about someone’s low mileage 4.9 find, and instead of taking over that thread I want to continue the discussion here for doing the research for doing my 4.9 swap.
The current discussion is about automatic transaxles, and which one to use. It would seem that the transaxle that came with my 4.9 engine has the Deville 3.11 gears, which some say is bad gearing. It appears to be a 4T80E, and others have said they used a 4T60E, so I want to clarify which transaxle I should use with this swap.
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fierobear
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JAN 14, 01:04 PM
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Although I already have the engine for my swap, for reference I want to list the years and models you’d want for your 4.9. According to this link from olejoedad...
http://www.gmtuners.com/
...it says 91-94 Cadillac. My engine is a 93 Sedan Deville engine, so good. The transaxle, I’m told, has the 3.11 gearing, which I’m told is not the best. According to car-part.com this is a 4T80E, and I’ve seen some folks reference the 4T60E in their swaps. So I need some clarification as to which transaxle we should be talking about, since I will likely be looking for a used or rebuilt transaxle with beater gearing. I need your help here.
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fierobear
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JAN 14, 01:11 PM
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When doing a transmission search on car-part.com, these are the transmission options when looking up a 93 Deville...
This isn’t even showing a 3.11 ratio, but 2.97 and 2.93 (meaning even worse than the 3.11?)
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Will
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JAN 14, 01:32 PM
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The 4T80E was *ONLY* used with the Northstar. You definitely do not have that.
3.11 may refer to the combination of chain ratio and final drive... So a 2.97 final drive with a 1.05 chain ratio = 3.11. I'm not the expert on what parts were actually available or built, however.
3.11 is a lot of gear for a low-revving engine like the 4.9.[This message has been edited by Will (edited 01-14-2020).]
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olejoedad
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JAN 14, 01:33 PM
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The 4T80E was never used with the 4.9 V8.
The only transmission used with the 4.9 was the 4T60E.
The 4T60Ewas used with several GM engines.
It is easily identifiable.....
No throttle valve cable
Vacuum modulator
Electrical plug faces forward
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fierobear
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JAN 14, 01:45 PM
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Excellent information, guys, thanks.
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olejoedad
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JAN 14, 02:09 PM
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A friend had a Fiero with a 4.9 and the 85 - 86 four speed manual 3.65/1 differential.
He said the gearing was great, except for on the highway where the revs were too high.
He later changed to the F40, it was good except first gear was useless.
He later replaced the 4.9 with an LS3.
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fierobear
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JAN 14, 04:57 PM
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| quote | Originally posted by olejoedad:
A friend had a Fiero with a 4.9 and the 85 - 86 four speed manual 3.65/1 differential.
He said the gearing was great, except for on the highway where the revs were too high.
He later changed to the F40, it was good except first gear was useless.
He later replaced the 4.9 with an LS3. |
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Sounds like 3.71 should do the job.
FYI, under California smog I can’t use a manual transmission so I’ll be sticking with an automatic.
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Raydar
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JAN 14, 05:43 PM
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I would find a Seville or Eldorado trans (Or rebuild yours with a a chain/sprocket change.)
The 3.33 FDR came stock in the Eldo and Seville, IIRC. So it's already proven to work with the 4.9. (I hated my Deville 2.97s.)
A word of warning...
There are at least six different EEPROMs/definition files for the various 4.9 Cadillac vehicles. Most of the differences probably have to do with transmissions and their respective gearing / wiring / connectors, and the different years.
You will probably want to source the CALPAK (EEPROM plug-in) from the same vehicle you get the trans from, to ensure compatibility.
If you use the wrong program with the wrong trans, you will possibly find yourself running in "limp home" mode. That happened to me when I tried to run a non-compatible program in mine, while I still had the 4T60E.
(Others folks may have a better suggestion, or have more insight into what program works with which drivetrain. I welcome that input. That's all I've got.)
Edit - Here's another link from Sinister. Your 4T60E probably already has the 3.33 gears, but in order to realize that final ratio, you will need to swap in a 35/35 sprocket set. Yours probably has the 37/33 set.
http://www.gmtuners.com/ima...FWD_trans_ratios.pdf
This link tells you how to identify exactly which trans you have.
http://www.gmtuners.com/transmission/index.htm
| quote | Originally posted by fierobear:
Sounds like 3.71 should do the job.
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The 3.71 only came in the 4T80E. I promise that that's not what you have. Not if it came bolted to your 4.9.[This message has been edited by Raydar (edited 01-14-2020).]
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olejoedad
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JAN 14, 06:57 PM
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fierobear, even though the 85 - 86 four speed has a 3.65 differential, fourth gear is a 0.81 overdrive, dropping the overall final ratio to 2.96.
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