Is GM crazy????
01-01-2005, 08:55 PM
#21
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True Car Nut
Here is a copy of the email I sent to Andrew Schreck at GM. Hopefully it elicits responses regarding the 4T65'* reliability issues. Let me know what you guys think of this, and tell me what else I failed to mention. I am far, far from being a transmission guy, so if I left something out please tell me. Thanks!
Mr. Schreck-
I just got through reading two very interesting articles on the General Motors website. The first article, from which I obtained your contact information, was from August 2004 and described the prominence of the 2-litre Ecotech engine at the Bonneville Salt Flats. The second was about the Hydramatic 4T65 transmission and its use in the GM Racing Pontiac Sunfire. Due to your apparent involvement in the Ecotech racing program (which powers the Sunfire), I am interested in whatever information you may be able to give me about the tranmission used in that project.
I am an active member of the Bonneville Club (www.bonnevilleclub.com), a collection of car enthusiasts who drive Pontiac Bonnevilles and other 3800-powered GM models. As you know, current production Bonnevilles use the 4T65-E and 4T65 HD transmissions, which explains my interest in the Hydramatic project. The club has many members who, including myself, modify our motors to gain extra performance from our cars. The problem many of us run into is the durability of both the 4T60 and 4T65 transmissions. Many times when power numbers exceed 275 or 300 horsepower with the stock drivetrain, transmission reliability issues are encountered. There is much debate about the "weak link" in the drivetrain, and some members conjecture that transmission failure can ultimately be averted with the replacement of the torque converter and differential with higher-strenth aftermarket units. Nobody is quite sure which stock components have sufficient strength to handle high power applications and which ones do not. What we do know is some members have destroyed differentials (often ruining the rest of transmission), and many of us suffer from increasing levels of transmission slip as the years go by.
My request of you is to provide us with some definitive answers. The article about the Hydramatic 4T65 seems to indicate that a stock 4T65 may be able to take a considerably high horsepower and torque input with the substitution of an aftermarket torque converter and limited-slip differential. This would be very refreshing if it is accurate, as the only viable transmission options currently available to us seem to be expensive transmission overhauls. We have never come to a solid conclusion about the reliability of our transmissions, and your expertise will be sure to clear the air on many of the issues.
Thank you for taking the time to read this letter. I look forward to hearing back from you regarding this issue, and I would request that you share whatever you can about the 4T65 and even the 4T60, if possible. If you are not the correct person to address questions about front wheel drive transmissions, I would ask that you please forward this email to a colleague who may be able to shed some light on this topic. I would also like your permission to post your response to my question on the Bonneville Club website. Thanks again, and have a great new year.
-Ben Eichelberger
I just got through reading two very interesting articles on the General Motors website. The first article, from which I obtained your contact information, was from August 2004 and described the prominence of the 2-litre Ecotech engine at the Bonneville Salt Flats. The second was about the Hydramatic 4T65 transmission and its use in the GM Racing Pontiac Sunfire. Due to your apparent involvement in the Ecotech racing program (which powers the Sunfire), I am interested in whatever information you may be able to give me about the tranmission used in that project.
I am an active member of the Bonneville Club (www.bonnevilleclub.com), a collection of car enthusiasts who drive Pontiac Bonnevilles and other 3800-powered GM models. As you know, current production Bonnevilles use the 4T65-E and 4T65 HD transmissions, which explains my interest in the Hydramatic project. The club has many members who, including myself, modify our motors to gain extra performance from our cars. The problem many of us run into is the durability of both the 4T60 and 4T65 transmissions. Many times when power numbers exceed 275 or 300 horsepower with the stock drivetrain, transmission reliability issues are encountered. There is much debate about the "weak link" in the drivetrain, and some members conjecture that transmission failure can ultimately be averted with the replacement of the torque converter and differential with higher-strenth aftermarket units. Nobody is quite sure which stock components have sufficient strength to handle high power applications and which ones do not. What we do know is some members have destroyed differentials (often ruining the rest of transmission), and many of us suffer from increasing levels of transmission slip as the years go by.
My request of you is to provide us with some definitive answers. The article about the Hydramatic 4T65 seems to indicate that a stock 4T65 may be able to take a considerably high horsepower and torque input with the substitution of an aftermarket torque converter and limited-slip differential. This would be very refreshing if it is accurate, as the only viable transmission options currently available to us seem to be expensive transmission overhauls. We have never come to a solid conclusion about the reliability of our transmissions, and your expertise will be sure to clear the air on many of the issues.
Thank you for taking the time to read this letter. I look forward to hearing back from you regarding this issue, and I would request that you share whatever you can about the 4T65 and even the 4T60, if possible. If you are not the correct person to address questions about front wheel drive transmissions, I would ask that you please forward this email to a colleague who may be able to shed some light on this topic. I would also like your permission to post your response to my question on the Bonneville Club website. Thanks again, and have a great new year.
-Ben Eichelberger
01-02-2005, 01:45 AM
#26
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Originally Posted by fantastic88
I didn't know that guys running 12s even still had the 4T65E. Doesn't a smaller pulley, ehaust work, and rockers usually finish them off?
My moms SSEi has ~125k on it, is midly modded and has been since it was almost new, and it has the original tranny and its just fine *knock on wood*.
Since they only use those trannys for a few runs, I can imagine that with just heavy duty imput/output shafts, and a different differential that it can easily handle that kinda power.
Shawn
01-03-2005, 08:55 AM
#28
Senior Member
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Originally Posted by macho_mike21
very intelligent email. It would be hard not to reply to that.
while we have lots of car nuts here, that would love to answer those questions, the biggest problem we have with answering something like that is liability.
that said, i figure about a 35% chance you'll get any sort of a meaningful response. 75% that you'll get a response at all.
as for the tranny, it'* really funny, but do you guys realize that the 4t65 is the most reliable tranny that gm offers? according to jd power, in 2004, was by far more reliable than any other gm tranny.
strange.
of course, that it'* reliable at normal power levels doesn't matter too much when you're not at normal power levels, now does it?
good luck getting an answer. if you don't get one, let me know, and i'll go knocking on some doors, and see if I can't find out for you.
<edit>
which RPO do you guys have for your tranny? i count 5 different 4t65'* from the data i'm looking at right now...
01-03-2005, 10:24 PM
#30
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which RPO do you guys have for your tranny?
MN3 / MN7 - with 258 mm torque converter - */C 3800 . Mine is MN7 for my SSEi 2.93 ratio.
I can only assume that the 3 codes refer to the 3 final gear ratios available 2.86, 2.93 and 3.05