1993 corvette speedometer calibration
Thread Starter
Intermediate
Joined: Sep 2016
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From: NW Indiana
1993 corvette speedometer calibration
Hi I have a 1993 corvette 4 speed automatic with 2.59 gear, tire size 285/40zr17,switching to 3.73. read a lot of the threads on the subject, was curious if any one had had problems with computer system, shift points, abs/asr, throwing any codes etc. I've seen basically 3 options, change speedometer gear set to 15 / 45 and vss, the electrical speedometer calculator you can wire in. Then from Howell industries, H9293 computer chip for your ecm. my question is which would be the best option. couldn't find anything on the computer chip, it seems to be the simplest of the 3 options? but 250 dollars. electronic calculator seems to be most flexible if you want to change tire or rear gear in future, around 200 dollars. then changing speedometer gears and vss removing transmission housing and c beam seems like a lot of work and around 170 dollars. only want to do this once, most reliable set up. Thanks For Your Help In Advance John.
Team Owner
Joined: Sep 2003
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The VSS required for the 15/45 is a very hard find and likely expensive. These days I'd think the electronic ratio converter the least expensive and considered quite reliable. There ain't no PROM/CHIP that will correct odometer. Driveability - there's always issues. ABS/ASR I'd think no issues.
Why such a 'steep' gear? Sounds silly!
Why such a 'steep' gear? Sounds silly!
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From: N.E. Ohio OH
Finalist 2020 C4 of the Year - Modified
Here is a discussion about a converter box
https://www.corvetteforum.com/forums...alibrator.html
here is the box
https://www.ecklerscorvette.com/corv...1984-2004.html
update: there is something about Eckler's site that links don't work like other websites, the part nbr is 25-108502-1.
https://www.corvetteforum.com/forums...alibrator.html
here is the box
https://www.ecklerscorvette.com/corv...1984-2004.html
update: there is something about Eckler's site that links don't work like other websites, the part nbr is 25-108502-1.
Last edited by drcook; Aug 5, 2020 at 06:04 PM.
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Finalist 2020 C4 of the Year - Modified
http://www.atrol.com/era.htm
http://www.atrol.com/order.htm
Last edited by drcook; Aug 5, 2020 at 06:08 PM.
Thread Starter
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Joined: Sep 2016
Posts: 30
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From: NW Indiana
One of the reasons i asked the group, about options where to find out the most viable option. I just heard about 2 days ago about Howellefi.com Part number H9293 LT1 ecm. wrote them haven't heard back from them, My understanding is you give them your tire size, rear gear what transmission they make a chip for you guaranteed money back, was just asking if anyone have heard of them or there technology? As far as going to 3.73 I read a lot of post of people that did this and was by far best power adder you could do. I want to take a moment to thank everyone for there help, If I hear back from Howell i'll relate what they said.
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From: N.E. Ohio OH
Finalist 2020 C4 of the Year - Modified
The advantage of the adapter is that if you don't like the gearing, you can go to something else without a chip reprogram.
For what is worth, I have the optional 3.07 gear ratio in my '96. It will bark the tires going from 1 to 2 just fine (at this point, same'ish HP as you have). The 3.07's will wake the car up, not as drastic a jump as going to 3.73's. You need to consider the end result and usage of your car before changing it that drastically. Do you drive a lot on the highway ? etc.
Going around 3.45 range would be a big improvement also.
I am going to 3.33's, but I have a Dana 44 rear that I am rebuilding. Took me a long time to find the 3.33's. I also have a new Sonnax carrier that changes the 1st and 2nd gear ratio and makes the 4L60E a close ratio transmission (or closer) (for when I rebuild the entire drive line in the spring). The "final drive ratio" in 1st is still going to be very close to what it is right now with the 3.07's, but 2nd,3rd and even OD (4th) are going to be closer together and I won't lose much off the top end for highway driving (55 or better) which is where we spend 95 % of our driving time (we live in the semi-country and right in between 4 major highways).
For what is worth, I have the optional 3.07 gear ratio in my '96. It will bark the tires going from 1 to 2 just fine (at this point, same'ish HP as you have). The 3.07's will wake the car up, not as drastic a jump as going to 3.73's. You need to consider the end result and usage of your car before changing it that drastically. Do you drive a lot on the highway ? etc.
Going around 3.45 range would be a big improvement also.
I am going to 3.33's, but I have a Dana 44 rear that I am rebuilding. Took me a long time to find the 3.33's. I also have a new Sonnax carrier that changes the 1st and 2nd gear ratio and makes the 4L60E a close ratio transmission (or closer) (for when I rebuild the entire drive line in the spring). The "final drive ratio" in 1st is still going to be very close to what it is right now with the 3.07's, but 2nd,3rd and even OD (4th) are going to be closer together and I won't lose much off the top end for highway driving (55 or better) which is where we spend 95 % of our driving time (we live in the semi-country and right in between 4 major highways).
Drifting
Joined: Oct 2004
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From: Hawaii
1993 has the 4L60 (non-electronic) transmission. 1994-1996 has the 4L60E (electronic) transmission.
Shift points on the 1993 is set with weights and springs, which is a pain in the azz. Speedo calibration is set with one of the methods stated above. Correct gears, and VSS or electronic converter box.
1994 to 1996 with the electronic transmission, the speedo/ shift points can be set thru the PCM, electronically.
Shift points on the 1993 is set with weights and springs, which is a pain in the azz. Speedo calibration is set with one of the methods stated above. Correct gears, and VSS or electronic converter box.
1994 to 1996 with the electronic transmission, the speedo/ shift points can be set thru the PCM, electronically.
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Thread Starter
Intermediate
Joined: Sep 2016
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From: NW Indiana
Thanks for the input, it looks more like ill be going with the converter box, being the 1993 trans shift points are set with weights and springs does changing rear gears effect that.at all? Thanks again for your input.
Racer
Joined: Jun 2020
Posts: 274
Likes: 43
From: Vestavia Hills, AL
Hi I have a 1993 corvette 4 speed automatic with 2.59 gear, tire size 285/40zr17,switching to 3.73. read a lot of the threads on the subject, was curious if any one had had problems with computer system, shift points, abs/asr, throwing any codes etc. I've seen basically 3 options, change speedometer gear set to 15 / 45 and vss, the electrical speedometer calculator you can wire in. Then from Howell industries, H9293 computer chip for your ecm. my question is which would be the best option. couldn't find anything on the computer chip, it seems to be the simplest of the 3 options? but 250 dollars. electronic calculator seems to be most flexible if you want to change tire or rear gear in future, around 200 dollars. then changing speedometer gears and vss removing transmission housing and c beam seems like a lot of work and around 170 dollars. only want to do this once, most reliable set up. Thanks For Your Help In Advance John.
Thread Starter
Intermediate
Joined: Sep 2016
Posts: 30
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From: NW Indiana
can only wish I would be done by this weekend, it will probably take me another month or so. I'm not a very good mechanic, if it wasn't for 2 of my friends that have really fast cars, you tube and this group I wouldn't even be able to try any of this.
Thanks to All John
Thanks to All John
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Joined: Apr 2016
Posts: 4,648
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From: N.E. Ohio OH
Finalist 2020 C4 of the Year - Modified
can only wish I would be done by this weekend, it will probably take me another month or so. I'm not a very good mechanic, if it wasn't for 2 of my friends that have really fast cars, you tube and this group I wouldn't even be able to try any of this.
Thanks to All John
Thanks to All John
Drifting
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From: Orange, CA
Racer
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From: Indianapolis
John-- Any update? I'm switching to 3.54 gears myself. Did the ECM from Howell work out well? I'm considering the PCM fo NC unit--but I've no feedback on how well it operates.
And if you don't mind me asking, where did your differential from (assuming you swapped pumpkins rather than actually going in and changing the ring and pinion)?
Thanks,
Ronn
And if you don't mind me asking, where did your differential from (assuming you swapped pumpkins rather than actually going in and changing the ring and pinion)?
Thanks,
Ronn
Thread Starter
Intermediate
Joined: Sep 2016
Posts: 30
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From: NW Indiana
John-- Any update? I'm switching to 3.54 gears myself. Did the ECM from Howell work out well? I'm considering the PCM fo NC unit--but I've no feedback on how well it operates.
And if you don't mind me asking, where did your differential from (assuming you swapped pumpkins rather than actually going in and changing the ring and pinion)?
Thanks,
Ronn
And if you don't mind me asking, where did your differential from (assuming you swapped pumpkins rather than actually going in and changing the ring and pinion)?
Thanks,
Ronn
Race Director
Joined: Jan 2012
Posts: 17,062
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From: United States
3.73 gears are fun, especially when you have traction, until you do a long drive. Not the worst though. If I were to do it again, I would have went to D44 with 3.45 gears, vice 3.73...
With my 396LT1 (93 Vette), I would love to have the 3.33 gears installed. I have them on the shelf in the garage... Time, changing gears in transmission for speedo..
With my 396LT1 (93 Vette), I would love to have the 3.33 gears installed. I have them on the shelf in the garage... Time, changing gears in transmission for speedo..
Thread Starter
Intermediate
Joined: Sep 2016
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From: NW Indiana
Hey guys finally got the 3:73 gears in and took my 93 for her first ride. Its about 45 degrees here tonight, tires cold, road cold, what a difference no traction 1st or 2nd. very responsive, what I really like is no more droning sound from driving in OD at about 40 mph, the whole car just seems smoother, ran it up to 70 mph don't have my electronic ratio adapter wired yet so don't know how fast i was really going but no one was passing me on a 4 lane highway. No regrets hear would do it again, I don't take my car for long rides, this year I only put a little over a 150 mile on here and really enjoyed the ride. biggest issue I would think is to get it to hook up, that will be for next year and warm weather. Need tires any ways, I want to thank everyone for there help, Thanks and Happy Thanksgiving to the group
John
John
Racer
Joined: Aug 2020
Posts: 362
Likes: 81
From: Indianapolis
Sounds Fun! I'm having my 3.55 installed now. I decided to go with the physical gear from Exotic Muscle rather than the box to keep the odometer correct (at least I think the gear will keep it correct). Keep us updated on your process of choosing tires--that's my next purchase as well ;-)
Congrats!!!!
R
Congrats!!!!
R
Hey guys finally got the 3:73 gears in and took my 93 for her first ride. Its about 45 degrees here tonight, tires cold, road cold, what a difference no traction 1st or 2nd. very responsive, what I really like is no more droning sound from driving in OD at about 40 mph, the whole car just seems smoother, ran it up to 70 mph don't have my electronic ratio adapter wired yet so don't know how fast i was really going but no one was passing me on a 4 lane highway. No regrets hear would do it again, I don't take my car for long rides, this year I only put a little over a 150 mile on here and really enjoyed the ride. biggest issue I would think is to get it to hook up, that will be for next year and warm weather. Need tires any ways, I want to thank everyone for there help, Thanks and Happy Thanksgiving to the group
John
John