[Shrunken_Head]

I am planning on putting LS376/480 into a '55 convertible. Who has installed a six speed behind an LS? How much cutting of the trans tunnel is required.

If I decide to go with a four speed auto, would there be any disadvantage to going with a non-electronic transmission? I would save a few $ by not needing a computer and harness for the trans.

 

[57den]

I put the same combo in an AME frame and a 57 body. No modifications were needed to the tunnel except the spot weld seam between the firewall and tunnel. It just needed to be trimmed about a 1/2 inch.

Den

 

[Shrunken_Head]

I put the same combo in an AME frame and a 57 body.

Den

Would you say the engine position would be relatively the same in the stock frame and the AME frame?

 

[Chevynut]

I put the same combo in an AME frame and a 57 body. No modifications were needed to the tunnel except the spot weld seam between the firewall and tunnel. It just needed to be trimmed about a 1/2 inch.

Den

WOW. That's hard to believe :confused0006:. A 6-speed automatic is a HUGE tranny. Most people even have to cut the tunnel with a T56.

 

[57den]

I posted photos perviously of the installation with only very minor cutting. I was surprised that the motor fit without altering the firewall at all. The only cutting was the tunnel spot weld seam. There is about an inch clearance between the tans. and tunnel.

The LS3 combo is only about 6 inches longer and the transmission is about the same height of the powerglide.

Should be able to search this site for the posts. Under LS section maybe?

It you want I can repost the pics.

Den

 

[Chevynut]

I posted photos perviously of the installation with only very minor cutting. I was surprised that the motor fit without altering the firewall at all. The only cutting was the tunnel spot weld seam. There is about an inch clearance between the tans. and tunnel.

The LS3 combo is only about 6 inches longer and the transmission is about the same height of the powerglide.

Should be able to search this site for the posts. Under LS section maybe?

It you want I can repost the pics.

Den

According to the post comparing the engines and trannys on one of your threads, you said the tranny was a 4L60E. That's not a 6-speed.

Nice build, though :tu

I put a 4L60E in a 57 and it also only reqired trimming of the tranny tunnel seam. But a 6L80/85 is a lot bigger.

 

[Rick_L]

"I would save a few $ by not needing a computer and harness for the trans."

Wouldn't there be an acceptable LSx controller that could control both of them?

I don't know whether LS3s are available with that 6 speed auto or not, but I would think the controller from a truck could do the job. It might not be "plug and play" as far as doing it yourself, but I would think that an outfit like Speartech could fix you up.

Myself, I'd never put a non-computer controlled automatic behind an LSx engine. Having the pcm control both is one of the big advantages of these engines.

You seem to be all over the place with your questions. One sentence, it's a 6 speed, the next, it's an analog transmission. How about the 4 speed which is right in the middle? The pieces exist from the factory to do that one.

 

[NickP]

Here is a link from LS Tech regarding an LS coupled to a 6l90 install into a 68 Camaro.
http://www.ls1tech.com/forums/conversions-hybrids/898899-6l80-6l90-into-68-camaro-does-go.html

 

[Shrunken_Head]

Thanks for the link and info so far.

I know my post looks wishy washy, but I'm trying to get some informed opinions. Unfortunately GM does not have a harness and ECM which will control this engine and the transmission. I would have to get a separate controller for the trans ($1,000 plus - ouch) or have an all-in-one solution made by someone like Speartech. Bottom line, if it looks like it would be too difficult to install the six speed, then I would have to weigh the pros and cons of an electronic 4 speed over the non-electronic. :confused0006:

 

[55ChevDelray]

Thanks for the link and info so far.

I know my post looks wishy washy, but I'm trying to get some informed opinions. Unfortunately GM does not have a harness and ECM which will control this engine and the transmission. I would have to get a separate controller for the trans ($1,000 plus - ouch) or have an all-in-one solution made by someone like Speartech. Bottom line, if it looks like it would be too difficult to install the six speed, then I would have to weigh the pros and cons of an electronic 4 speed over the non-electronic. :confused0006:

The big differences is the gearing of the 6SpdAuto vs a 4 spd. I would think it would be the same difference as 4 spd manual vs a 6 spd manual. I'd rather have a 6 spd over a 4spd. It gives agood combination of a low first gear and nice overdrive for cruising. The 6L90 is not an impossible trans to retrofit into a tri-five, although not an easy plug and play. The LS3 and 6L90 is not a GM combination at this time, but there are private companies that can make it work, Speartech for one. (GMPP is working on it) I'm not aware of anyone that has a combination of an LS3 and 6L90 on this forum that is functional, or at least that someone has shared that info. The 6L90 is a monster tranny, I just can't see it fitting without some modification to the tunnel.

 

[drpepper]

i'm using a L76/480 and 4L70 in my 61 belair. i picked up an ecm and tcm for an 07 trailblazer ss on the tbss forum for $125 shipped. there are guys on the forum selling them all the time. i really didn't see the need for 2 more gears. the 4L70 Ls combination is proven and dependable and fit like a glove. just my 2cents.

 

[57den]

Sorry Guys, I forgot my tranny is a 4l/60e converted by TCI to a 6 speed.
I guess I need learn how to read better.

 

[BO185]

Sorry Guys, I forgot my tranny is a 4l/60e converted by TCI to a 6 speed.
I guess I need learn how to read better.

You mean the 4l80, as thats what TCI uses to make there six speed.

I am planning on putting LS376/480 into a '55 convertible. Who has installed a six speed behind an LS? How much cutting of the trans tunnel is required.

:confused0006:

As in speed 6sp you mean auto 6l80/90 or T56 manual??

If you mean the 6l80/90 the TCM is built into the trans it self so all you need is the trans harness.

If I decide to go with a four speed auto, would there be any disadvantage to going with a non-electronic transmission? I would save a few $ by not needing a computer and harness for the trans.

The disadvantage of the non electronic 700r4 is is you have a drive by wire Thottle body there is no provisions for the TV cable

 

[joeelutz]

I would highly recommend you go with the 4L60E or 4L80E and let the factory PCM control the transmission. Otherwise go manual!

 

[BO185]

I would highly recommend you go with the 4L60E or 4L80E and let the factory PCM control the transmission. Otherwise go manual!

If its an LS3 the OP is talking about then it is a Gen IV and they need a separate TCM for the automatic transmissions. And a ECM for the motor. The TCM is internal to the 6l80/90's and external on the 4l60,65,70 and 4l80.

Again I would go 6l80. :biggrin:

 

[Hamman]

The 6L90 is not an impossible trans to retrofit into a tri-five, although not an easy plug and play. The LS3 and 6L90 is not a GM combination at this time, but there are private companies that can make it work, Speartech for one. (GMPP is working on it) I'm not aware of anyone that has a combination of an LS3 and 6L90 on this forum that is functional, or at least that someone has shared that info. The 6L90 is a monster tranny, I just can't see it fitting without some modification to the tunnel.

Brian, How is your 6L90 going? I'm doing a similar thing with 55 ba 2dr. LS+6L90. I'm still working on body. I've got minitubs and a new floor so will have to cut that for the trans. I'm using a mastmotorsports ECM and harness and theirs talks to the trans. Would be good to stay in touch with your progress as you're probably ahead of me!

 

[55ChevDelray]

Brian, How is your 6L90 going? I'm doing a similar thing with 55 ba 2dr. LS+6L90. I'm still working on body. I've got minitubs and a new floor so will have to cut that for the trans. I'm using a mastmotorsports ECM and harness and theirs talks to the trans. Would be good to stay in touch with your progress as you're probably ahead of me!

At the pace I'm going, you may be done before me. I have been looking at Mastmotorsports ECm as well. It's my fallback if GMPP doesn't come out with something.

Are you using a stock frame?

 

[Hamman]

At the pace I'm going, you may be done before me. I have been looking at Mastmotorsports ECm as well. It's my fallback if GMPP doesn't come out with something.

Are you using a stock frame?

Chris Sutton - StreetRodGaraGE is building me the chassis. I'm on the other side of the world so building a car certainly has its challenges. And I'm converting from Left to Right Drive.
I've found some CAN Guages that work with the MastMotorsports ECM
www.livorsi.com under "off road". They look like an easy hook up, although will have to make my own dash cut-out as they are slightly different sizes than the dash inserts sold by Danchuk etc...

 

[BO185]

Doesn't Mast have gauges as well?

 

[Hamman]

Doesn't Mast have gauges as well?

YES
This is where mast gets them from - here you can see all the colour combniations etc.... and they are real helpful - gave me all the correct part numbers etc...