4L70e vs. 6L80e behinc LS3 in '61 Chev
08-20-2013, 07:29 PM
#1
4L70e vs. 6L80e behinc LS3 in '61 Chev I'm debating which transmission I should consider. I'm not sure if there are issues with fitment. I'll have to check that.
Assuming I don't have fitment issues to consider, which tranny would you recommend I go with?
While the LS3 is a powerful engine, I don't anticipate racing. Of course, my foot will get heavy now and then, but I"m pretty tame now days. Fuel economy and longevity are more important to me.
Thanks for your thoughts.
Assuming I don't have fitment issues to consider, which tranny would you recommend I go with?
While the LS3 is a powerful engine, I don't anticipate racing. Of course, my foot will get heavy now and then, but I"m pretty tame now days. Fuel economy and longevity are more important to me.
Thanks for your thoughts.
08-20-2013, 11:12 PM
#2
Moderator
What PCM are you using to run the LS3? Does that PCM support the 4L70E?
I am still trying to figure out what stock computers are needed to support a 6l80E; I have read you need the BCM (Body control module) to interface the PCM to the TCM over the CAN bus. Who knows?
A 4L70E is just a late-model 4L65E with the Input Speed Sensor (ISS). Some vendors call it a 4L65E, some call it a 4L70E; just check if has the ISS.
In any case, I would suggest a 4L80E over the 6L80E; stronger and less computer complexities. And much smaller; the 6l80E is huge.
I am still trying to figure out what stock computers are needed to support a 6l80E; I have read you need the BCM (Body control module) to interface the PCM to the TCM over the CAN bus. Who knows?
A 4L70E is just a late-model 4L65E with the Input Speed Sensor (ISS). Some vendors call it a 4L65E, some call it a 4L70E; just check if has the ISS.
In any case, I would suggest a 4L80E over the 6L80E; stronger and less computer complexities. And much smaller; the 6l80E is huge.
Last edited by mrvedit; 08-21-2013 at 08:08 PM. Reason: Correction - a 4L70E is the newer 4L65E, not a 4L60E.
08-21-2013, 01:56 AM
#3
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LS3 requires a transmisson with ISS. A 4L65E can be modified to add one, but i'ts cheaper to install if installed when trans is being rebuilt. I know a couple of Trans builders on fourm have added ISS to 4L65E. 4L75E has it built in.
Two pin circled in RED are required.
GM performance parts sells harness with ECU, TCM, Correct throttle pedal, etc for LS3 conversions. There are also a number of Aftermarket Companies that will build you custon harness. If you are space limited and need to use LS2 MAF instead of L3 style they can handle that too. LS3/7 MAF likes 4.0" of straight pipe.
No Body Module is required.
I use LS2 style MAF on my LS3 project. Lost some Horsepower by doing it, but was space limited.
6l80E will require you to procure harness from aftermarket. GM Performance has not jumped into supplying harnesses for conversions at this time. That may change in the next couple of years.
Lot of info in both Autotrans section and in Conversions section here on LS1. Searching both sections would be a plus for you.
You need to take a close look at 6L80E gearing too. It has no 1:1 gear as 4th is 1.15 and 5th and 6th are OD gears. Rear end choice is critical based on weight of car. G8 Pontiac and Chevy's new SS both use 3.27 rear gear with 6L80E. 3.27 X 1.15 = 3.76 4th. Has two 1st gears also. They are for getting weight moving to save on fuel. Heavy car, while it will feel great with 6L's 1st & 2nd gear ratios, it can feel like a slug in 4th.
If you go with a 6L80E make sure you get one that uses a slip yoke are you will be spending money to convert if over. Also tuning is critical factor in life of transmission. Amount of HP & TQ the engine makes you plan on putting in front of a stock one may make cost of a built 4L75 or 65 with ISS look like a real bargain if it's more than 6L can handle.
Anything can be made to fit, but a 6L80E can be a real problem if you want to run a low stance...LOL
I think I have 5.5" to 5.75" of ground clearance now by changing truck pan over to G8's shorter pan. Bad thing is pan still hangs below frame rails and that's not a good thing to have when front wheels have already cleared or clearing a nice speed bump in school zone or parking lot...
At least when your sitting parked, you get to tell people you have a 6 speed auto. Might want to adds paddles to help with that or a sign to put out in front of car...LOL
Two pin circled in RED are required.
GM performance parts sells harness with ECU, TCM, Correct throttle pedal, etc for LS3 conversions. There are also a number of Aftermarket Companies that will build you custon harness. If you are space limited and need to use LS2 MAF instead of L3 style they can handle that too. LS3/7 MAF likes 4.0" of straight pipe.
No Body Module is required.
I use LS2 style MAF on my LS3 project. Lost some Horsepower by doing it, but was space limited.
6l80E will require you to procure harness from aftermarket. GM Performance has not jumped into supplying harnesses for conversions at this time. That may change in the next couple of years.
Lot of info in both Autotrans section and in Conversions section here on LS1. Searching both sections would be a plus for you.
You need to take a close look at 6L80E gearing too. It has no 1:1 gear as 4th is 1.15 and 5th and 6th are OD gears. Rear end choice is critical based on weight of car. G8 Pontiac and Chevy's new SS both use 3.27 rear gear with 6L80E. 3.27 X 1.15 = 3.76 4th. Has two 1st gears also. They are for getting weight moving to save on fuel. Heavy car, while it will feel great with 6L's 1st & 2nd gear ratios, it can feel like a slug in 4th.
If you go with a 6L80E make sure you get one that uses a slip yoke are you will be spending money to convert if over. Also tuning is critical factor in life of transmission. Amount of HP & TQ the engine makes you plan on putting in front of a stock one may make cost of a built 4L75 or 65 with ISS look like a real bargain if it's more than 6L can handle.
Anything can be made to fit, but a 6L80E can be a real problem if you want to run a low stance...LOL
I think I have 5.5" to 5.75" of ground clearance now by changing truck pan over to G8's shorter pan. Bad thing is pan still hangs below frame rails and that's not a good thing to have when front wheels have already cleared or clearing a nice speed bump in school zone or parking lot...
At least when your sitting parked, you get to tell people you have a 6 speed auto. Might want to adds paddles to help with that or a sign to put out in front of car...LOL
08-21-2013, 07:14 PM
#4
poorhousenext...love your name ;-)
Really appreciate the input and detail.
AT this point, I'm thinking I do not want to go with the 6L80; I think the 4L80 is too big.
I've had trans guys I've talked to say:
All of those quotes are from different sources, all of which may be (but who not necessarily, who knows) trying to steer me to what they sell.
So all of that said, I'm debating between a 4L70, new, at around $2800 shipped; and getting a core locally, probably 4L60, and have it built to a 4L65. I have heard that can be done from multiple sources. I"m thinking that would be maybe 1K less thana the new 4L70, but not sure yet.
As I mentioned, I'm not racing. But the LS3 is fairly strong, 430, and I want a trans that will last. No racing, but I do get a lead foot now and then, for fun ;-)
Any thoughts now on build to 4L65 vs new 4L70 welcome and appreciated
.
Really appreciate the input and detail.
AT this point, I'm thinking I do not want to go with the 6L80; I think the 4L80 is too big.
I've had trans guys I've talked to say:
- You don't need anything larger than 4L65
- 4L65 and 4L70 are almost the same
- You should go with 4L70
- I can take any of them and build what you want. Give me a 4L60 core, and I can build it to a 4L65, or 4L70
So all of that said, I'm debating between a 4L70, new, at around $2800 shipped; and getting a core locally, probably 4L60, and have it built to a 4L65. I have heard that can be done from multiple sources. I"m thinking that would be maybe 1K less thana the new 4L70, but not sure yet.
As I mentioned, I'm not racing. But the LS3 is fairly strong, 430, and I want a trans that will last. No racing, but I do get a lead foot now and then, for fun ;-)
Any thoughts now on build to 4L65 vs new 4L70 welcome and appreciated
.
08-21-2013, 08:05 PM
#5
Moderator
A well built trans from one of the sponsors, e.g. FLT will be much stronger than a factory 4L70E. Consider for example FLT's Level-5 4L65E/4L70 for $2300 plus core charge:
http://www.finishlinetrans.com/trans...meDuty4L65.htm
A bunch of members here run the FLT Level-5 at 600+HP.
Here is a good description of the differences between a 4L60/4L65E/4L70E:
http://www.trutechtrans.com/Topic-1-00-08.html
According to that a 4L70E is a later model 4L65E with ISS.
(I will therefore correct what I said earlier.)
I am glad you are no longer considering a 6L80E. poorhousenext made an excellent and informative posting, but was very diplomatic about the 6L80E gear ratios. I won't be - they suck for light/medium weight cars. I considered purchasing a Pontiac G8, but after driving one with a 6L80E I found the gear ratios awful. The car leaped in 1st gear and then bogged down in 2nd gear. IMHO the 6L80E is only suitable for vehicles over 4500 lbs.
Note that GM performance sells their "LS3 Connect and Cruise" kit with a 4L65E (really a 4L70E):
http://www.chevroletperformance.com/...train-systems/
Only the supercharged LS3 kit has the much stronger 4L80E.
http://www.finishlinetrans.com/trans...meDuty4L65.htm
A bunch of members here run the FLT Level-5 at 600+HP.
Here is a good description of the differences between a 4L60/4L65E/4L70E:
http://www.trutechtrans.com/Topic-1-00-08.html
According to that a 4L70E is a later model 4L65E with ISS.
(I will therefore correct what I said earlier.)
I am glad you are no longer considering a 6L80E. poorhousenext made an excellent and informative posting, but was very diplomatic about the 6L80E gear ratios. I won't be - they suck for light/medium weight cars. I considered purchasing a Pontiac G8, but after driving one with a 6L80E I found the gear ratios awful. The car leaped in 1st gear and then bogged down in 2nd gear. IMHO the 6L80E is only suitable for vehicles over 4500 lbs.
Note that GM performance sells their "LS3 Connect and Cruise" kit with a 4L65E (really a 4L70E):
http://www.chevroletperformance.com/...train-systems/
Only the supercharged LS3 kit has the much stronger 4L80E.
08-21-2013, 08:26 PM
#6
Thanks for that, and the links.
I have no core, so looks like the L5 rebuild would be about the same as the new stock 4L70. Looks like hte L3 4L60e would cost me around 2K with core.
I'm not sure the 4L60e, at L3, wouldn't be enough, given my planned use. I will drop them an inquiry.
I'm trying to keep the tranny to close to 2K. But...if I really am very well advised to consider beefier, I will spend the $.
My '04 LS1 in my '56 is a stock 4L60e, and is working well. Of course, the LS1 is lower in HP. Been running it for about 8 years. Although, only about 25,000 miles on it.
I have no core, so looks like the L5 rebuild would be about the same as the new stock 4L70. Looks like hte L3 4L60e would cost me around 2K with core.
I'm not sure the 4L60e, at L3, wouldn't be enough, given my planned use. I will drop them an inquiry.
I'm trying to keep the tranny to close to 2K. But...if I really am very well advised to consider beefier, I will spend the $.
My '04 LS1 in my '56 is a stock 4L60e, and is working well. Of course, the LS1 is lower in HP. Been running it for about 8 years. Although, only about 25,000 miles on it.
Last edited by ewingr; 08-21-2013 at 09:18 PM.
08-21-2013, 09:11 PM
#7
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I agree with mrvedit on a built 4L6/7 over a new stock 4L7. I think it would be worthwhile for you to look at trans vendor supplying core Vs you. If you have to ship it to them cost could be same, less, or just little more, not to mention you buying a 4L core that's not rebuildable.
If you go with a built 4L6/7, go with someone with a known reputation for building a good strong 4L6/7 transmission. Make sure when you install trans converter is seated properly and use a good trans cooler.
Never know what you may decide to do in the future with engine upgrades so trans want need to be built too. Since you are not planning on racing you might want to stay conservative on Converter stall. Just go for a great driver with the 61.
I think you would have had a lot less of a problem installing a 4L80/85 than a 6L80...LOL
I have a modified geared trans based off 4L80/85 in same body style car as the one with 6L80E. Just had to provide a little more room so wire harness plug could be installed along with bump out on passenger side of tunnel for trans cooling lines. Lot less time and money to mod body Vs what had to be done to fit the one with the 6L80.
If you go with a built 4L6/7, go with someone with a known reputation for building a good strong 4L6/7 transmission. Make sure when you install trans converter is seated properly and use a good trans cooler.
Never know what you may decide to do in the future with engine upgrades so trans want need to be built too. Since you are not planning on racing you might want to stay conservative on Converter stall. Just go for a great driver with the 61.
I think you would have had a lot less of a problem installing a 4L80/85 than a 6L80...LOL
I have a modified geared trans based off 4L80/85 in same body style car as the one with 6L80E. Just had to provide a little more room so wire harness plug could be installed along with bump out on passenger side of tunnel for trans cooling lines. Lot less time and money to mod body Vs what had to be done to fit the one with the 6L80.
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08-22-2013, 01:15 PM
#8
I'm now thinking I may get a core 4L60e and have a local transmission guy build it. I've used him a couple times over the years, and seems to be good. He built up a 700R4 I put behind my 350 with a B&M street blower a few years ago.
Now, I need to be sure I get teh right core. They want 300-500 for them aruond here.
I've found a guy on Craigs list that has one out of a '99 Chev Pickup for a couple hundred. Any ideas if that would bolt up to the LS3? I'm guessing that if the bell housing is a 6 bolt, it would work.
[EDIT]
Ok, what I'm hearing from someone I spoke to here locally, is that I would need a 2003 or later trans. Or, if I get an older one, I need to be sure to get one with a removable bell housing so that i can purchase teh correct bell housing.
Makes this route a little more difficult.
Now, I need to be sure I get teh right core. They want 300-500 for them aruond here.
I've found a guy on Craigs list that has one out of a '99 Chev Pickup for a couple hundred. Any ideas if that would bolt up to the LS3? I'm guessing that if the bell housing is a 6 bolt, it would work.
[EDIT]
Ok, what I'm hearing from someone I spoke to here locally, is that I would need a 2003 or later trans. Or, if I get an older one, I need to be sure to get one with a removable bell housing so that i can purchase teh correct bell housing.
Makes this route a little more difficult.
Last edited by ewingr; 08-22-2013 at 01:30 PM.
08-22-2013, 05:41 PM
#9
Moderator
You need to indicate what PCM you have.
Late model 4L60E/4L65E do NOT have a 3-2 downshift solenoid and do not have a manifold pressure switch. These changes took place somewhere around 2007/2008.
Therefore, if your PCM is 2008 or later, you need to get a 2008+ trans.
Also, as mentioned earlier, the trans has to have a Input Speed Sensor, IIRC, this started around 2005 and was universal by 2007.
Since 2008+ transmissions typically are still under factory warranty, local trans shops have very little experience with them and don't realize how much changed.
I have personally switched transmissions from 2008+ to pre 2007 operation, from non ISS to ISS, but it required changed valve bodies, pumps, stator shafts, electrical harnesses, sometimes machining parts and incredible cooperation from the local GM parts department. I do it for my own education; you won't want to.
Therefore, if you go aftermarket, you will need to get a 4L65E/4L70E that not only is ISS but has the latest valve body which uses a mechanical shift switch (instead of manifold pressure switch) and does not have the 3-2 downshift solenoid.
Late model 4L60E/4L65E do NOT have a 3-2 downshift solenoid and do not have a manifold pressure switch. These changes took place somewhere around 2007/2008.
Therefore, if your PCM is 2008 or later, you need to get a 2008+ trans.
Also, as mentioned earlier, the trans has to have a Input Speed Sensor, IIRC, this started around 2005 and was universal by 2007.
Since 2008+ transmissions typically are still under factory warranty, local trans shops have very little experience with them and don't realize how much changed.
I have personally switched transmissions from 2008+ to pre 2007 operation, from non ISS to ISS, but it required changed valve bodies, pumps, stator shafts, electrical harnesses, sometimes machining parts and incredible cooperation from the local GM parts department. I do it for my own education; you won't want to.
Therefore, if you go aftermarket, you will need to get a 4L65E/4L70E that not only is ISS but has the latest valve body which uses a mechanical shift switch (instead of manifold pressure switch) and does not have the 3-2 downshift solenoid.
08-22-2013, 07:13 PM
#10
Getting over my head.
I don't have a PCM yet. So, does what you're saying get resolved if I get the right pcm, or do I just need to get a layer model transmission?
I appreciate the input.
I don't have a PCM yet. So, does what you're saying get resolved if I get the right pcm, or do I just need to get a layer model transmission?
I appreciate the input.
08-22-2013, 07:16 PM
#11
[Edit]
It really sounds like I need a newer transmission because of the IIRC in any event
[Edit2]
I suppose it bears asking if there is a good reason to get a newer model transmission even if a correct COMdies fix mthe issues brought up
It really sounds like I need a newer transmission because of the IIRC in any event
[Edit2]
I suppose it bears asking if there is a good reason to get a newer model transmission even if a correct COMdies fix mthe issues brought up
Last edited by ewingr; 08-22-2013 at 07:32 PM.
08-22-2013, 07:54 PM
#12
08-22-2013, 08:10 PM
#13
Moderator
First, I should add that I have NOT actually tested a pre '08 trans (with pressure manifold switch) with a 2008+ PCM, but the significantly different shifter switch makes me think it is wired very differently from the manifold switch.
This picture of my 2010 4L60E is a bit fuzzy, but shows the new style internal shifter switch, the ISS connection and the missing 3-2 downshift solenoid.
The valve body and internal harness wiring are quite different from a pre-2007 trans. (I swapped to a 2005 Valve body to make this trans work with my 2002 PCM.)
I don't have the knowledge to recommend a particular PCM for your LS3, but I'm sure others on this forum do. I would pick a PCM that is best for your engine and future plans, and then select a compatible trans. I suspect some builders like FLT can supply a 2008+ compatible trans. Or perhaps some newer PCMs can be programmed to support an older 4L60E; I don't know that.
With all these complexities, I can understand your inclination to just buy a brand new 4L70E to reduce the chance of problems. I would check with (owner) Chuck at FLT first. Or perhaps sponsors Performabuilt or RPM can post a definitive answer here. (And correct me if needed.)
This picture of my 2010 4L60E is a bit fuzzy, but shows the new style internal shifter switch, the ISS connection and the missing 3-2 downshift solenoid.
The valve body and internal harness wiring are quite different from a pre-2007 trans. (I swapped to a 2005 Valve body to make this trans work with my 2002 PCM.)
I don't have the knowledge to recommend a particular PCM for your LS3, but I'm sure others on this forum do. I would pick a PCM that is best for your engine and future plans, and then select a compatible trans. I suspect some builders like FLT can supply a 2008+ compatible trans. Or perhaps some newer PCMs can be programmed to support an older 4L60E; I don't know that.
With all these complexities, I can understand your inclination to just buy a brand new 4L70E to reduce the chance of problems. I would check with (owner) Chuck at FLT first. Or perhaps sponsors Performabuilt or RPM can post a definitive answer here. (And correct me if needed.)
08-22-2013, 09:17 PM
#14
Where I'm at really, is, can I make a pre-2003 4L60e work fine, assuming a good build, and then knowing which 4L60e it is so that I can get a correct PCM.
What you wrote earilier about the IIRC and all left me thinking that getting a 4L60E that is older was really the wrong thing to do.
If all is required is that I get the correct PCM to work with the older 4L60, and with the LS3, it would seem to me I should be able to use the '99 chev truck 4L60e.
I'm going to drop in inquiry about that to John at Speartech and see what he says.
What you wrote earilier about the IIRC and all left me thinking that getting a 4L60E that is older was really the wrong thing to do.
If all is required is that I get the correct PCM to work with the older 4L60, and with the LS3, it would seem to me I should be able to use the '99 chev truck 4L60e.
I'm going to drop in inquiry about that to John at Speartech and see what he says.
08-22-2013, 11:17 PM
#16
Appreciate your input.
So, if I understand you correctly, if the one I mentioned earlier for a 99 pickup was from a V6 instead of v8, I should not use it. Even if I'm having it rebuilt, because it won't have a 300mm input shaft. (I presume that is not a normal item to change in a build, and maybe can't be changed). Can that be measured without taking the transmission apart? Is it the shaft the Torque Converter mounts on? If I measure it, would
]
Conversely, I can use any 4L60 if it meets these specs: from a V8 (verifiable by measuring input shaft); the bell houseing is 6 bolt with a top center bolt at 12:00 o'clock; and I can know the year of the transmission so I can get the correct PCM. (Could a part number on the tranny tell me that?).
Have I got this right now? (appreciate your patience and help).
Note: I did try some research/googling. Found some threads with same topic of input shaft,and I find contradictory information. This exercise is beginning to feel like a hard to win, or must be lucky, situation.
[Edit]
I found this interesting article.
There are so many different variables. I've had folks again, selling rebuilt 60's and 65's tell me that those would be better than a stock 70. The input shaft speed sensor on the 70 may be something that should be a consideration.
At this point, maybe I would be wiser, and possibly face less difficulty, if I just buckle and get a new 70.
So, if I understand you correctly, if the one I mentioned earlier for a 99 pickup was from a V6 instead of v8, I should not use it. Even if I'm having it rebuilt, because it won't have a 300mm input shaft. (I presume that is not a normal item to change in a build, and maybe can't be changed). Can that be measured without taking the transmission apart? Is it the shaft the Torque Converter mounts on? If I measure it, would
]
Conversely, I can use any 4L60 if it meets these specs: from a V8 (verifiable by measuring input shaft); the bell houseing is 6 bolt with a top center bolt at 12:00 o'clock; and I can know the year of the transmission so I can get the correct PCM. (Could a part number on the tranny tell me that?).
Have I got this right now? (appreciate your patience and help).
Note: I did try some research/googling. Found some threads with same topic of input shaft,and I find contradictory information. This exercise is beginning to feel like a hard to win, or must be lucky, situation.
[Edit]
I found this interesting article.
There are so many different variables. I've had folks again, selling rebuilt 60's and 65's tell me that those would be better than a stock 70. The input shaft speed sensor on the 70 may be something that should be a consideration.
At this point, maybe I would be wiser, and possibly face less difficulty, if I just buckle and get a new 70.
Last edited by ewingr; 08-22-2013 at 11:48 PM.
08-23-2013, 09:32 AM
#17
Well, the rebuild is all moot now.
I had a fella in the Chevy Talk forum direct me to Berger Chevrolet in Minnesota. Said he got a really decent price from them on a new one.
Called Berger, and it is reasonable, I'm out of state, so no tax, free shipping. A new 4L70E is on order from them.
An interesting note: I called my local Chevy dealer, and they said only thing available was a rebuilt...price was only $150 less, but then they had a $700 core charge. Lordy.
Thanks for all the input guys.
I had a fella in the Chevy Talk forum direct me to Berger Chevrolet in Minnesota. Said he got a really decent price from them on a new one.
Called Berger, and it is reasonable, I'm out of state, so no tax, free shipping. A new 4L70E is on order from them.
An interesting note: I called my local Chevy dealer, and they said only thing available was a rebuilt...price was only $150 less, but then they had a $700 core charge. Lordy.
Thanks for all the input guys.
