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Is there an automatic transmission that can handle a LS7 by JCircs
Started on: 04-05-2014 06:41 PM
Replies: 30 (1774 views)
Last post by: fieroguru on 04-09-2014 10:56 AM
JCircs
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Report this Post04-05-2014 06:41 PM Click Here to See the Profile for JCircsClick Here to Email JCircsSend a Private Message to JCircsEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have a 575hp LS7 engine that is attempting to jump into the trunk of my Fiero, is there an automatic that can handle it?

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[This message has been edited by JCircs (edited 04-05-2014).]

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Report this Post04-05-2014 07:04 PM Click Here to See the Profile for SnapperheadClick Here to visit Snapperhead's HomePageClick Here to Email SnapperheadSend a Private Message to SnapperheadEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by JCircs:

I have a 575hp LS7 engine that is attempting to jump into the trunk of my Fiero, is there an automatic that can handle it?



Use a worked over built up 4T65E with a trans controller like PCS. That trans has been holding 1000hp at the track.
Vince

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Report this Post04-05-2014 07:20 PM Click Here to See the Profile for firebossClick Here to Email firebossSend a Private Message to firebossEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by JCircs:

I have a 575hp LS7 engine that is attempting to jump into the trunk of my Fiero, is there an automatic that can handle it?


NOPE...and you should be ashamed for even asking.

So as your Penance you should give the engine to me and we will forget about this....
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JCircs
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Report this Post04-06-2014 12:05 PM Click Here to See the Profile for JCircsClick Here to Email JCircsSend a Private Message to JCircsEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fireboss:


NOPE...and you should be ashamed for even asking.

So as your Penance you should give the engine to me and we will forget about this....


I am ashamed, sorry come get your motor. Lol
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Report this Post04-06-2014 01:05 PM Click Here to See the Profile for StreetRod4Send a Private Message to StreetRod4Edit/Delete MessageReply w/QuoteDirect Link to This Post
You could build a 4t65e hd with a GMR 1 inch chain rated between 800 and 1200 hp, that would be the biggest expense for the trans but you might need an adapter plate to bolt it up. If you do need an adapter plate I would use a 4t80e out of a Caddy, which are extremely strong to begin with
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Report this Post04-06-2014 09:35 PM Click Here to See the Profile for infinitewillSend a Private Message to infinitewillEdit/Delete MessageReply w/QuoteDirect Link to This Post
.

[This message has been edited by infinitewill (edited 01-05-2016).]

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Report this Post04-06-2014 09:43 PM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
Email Don Kraus and get the SPECs on his 65E he had built for his LS swap. Gonna need to spend just as much on the trans as u plan to on the swap cause it will not be cheap...

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Report this Post04-07-2014 07:58 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by StreetRod4:
If you do need an adapter plate I would use a 4t80e out of a Caddy, which are extremely strong to begin with


That transmission is too large to fit along side any LS(x) based engine (wide, deep skirt design), can't line up the input shaft to the cranshaft due to the side of the block hitting the side of the transmission.
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Report this Post04-07-2014 08:15 AM Click Here to See the Profile for GrantmanClick Here to Email GrantmanSend a Private Message to GrantmanEdit/Delete MessageReply w/QuoteDirect Link to This Post
JCircs, that must mean a turbo 3.4/4T60 will be hitting the mall?

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JCircs
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Report this Post04-07-2014 09:48 AM Click Here to See the Profile for JCircsClick Here to Email JCircsSend a Private Message to JCircsEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Grantman:

JCircs, that must mean a turbo 3.4/4T60 will be hitting the mall?



Grantman you'll be the first to know, I hate to speculate but that's what I'm doing right now. I really am happy with my setup now and I'll probably just stay with it, to be honest it seems like a very expensive swap even with me already having the LS motor on hand. If selling my setup as a complete dropout with 4t60, ECM and intercooler would get me within a couple of grand I would consider it but it seems like it would be quite a bit more then that. So for now I'm just kicking the tires.
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Report this Post04-07-2014 10:50 AM Click Here to See the Profile for JustinbartSend a Private Message to JustinbartEdit/Delete MessageReply w/QuoteDirect Link to This Post
You should get a corvette and put that engine in it.

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Report this Post04-07-2014 10:54 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Sell the LS7 and use the proceeds to install a LS4 with some upgrades.
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Report this Post04-07-2014 10:59 AM Click Here to See the Profile for troyboyClick Here to Email troyboySend a Private Message to troyboyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:

Sell the LS7 and use the proceeds to install a LS4 with some upgrades.




But just let me know when you want to sell it, I'll be glad to take it off your hands
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Report this Post04-07-2014 11:46 AM Click Here to See the Profile for bmwguruClick Here to visit bmwguru's HomePageClick Here to Email bmwguruSend a Private Message to bmwguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
You should keep your car and buy my gold GT with the 3800s/c that I took you out for a ride in.

Dave

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Report this Post04-07-2014 12:09 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
500hp isnt much for a mostly stock 4t65e. The torque output is pretty low from a ls7 compared to some of the stuff ive ran through stock transmissions. If weekly drag racing isnt your goal, then you wouldnt have any problems with a stock or mild upgrade on a 65e.

 
quote
I am in this exact situation right now. 500+ hp at the flywheel from a highly modded LS4. There are 3 areas that concern me the most: the input shaft prone to breakage, ZZP is now reproducing the 1" chain, the 3rd gear clutch packs are well documented as a weak link on the 4T65eHD's. I have a Torsen LSD and I am sure. Spirited driving is going to grenade my trans.


Input shafts are not so much a weak spot as they are just a failure after a stretched chain and bad driving habits... Just because Don broke his you shouldnt have anything to worry about if your crank centerline is the same as your transmission input shaft....

I think you are really underrating the 65e here. Also a LSD upgrade is NOT suggested in a fiero application.. I am sure it will cause you handling and increase the potential for shock loading the chain/input shaft. 3rd gear issues are related to power applications approaching 750hp using nearly stock transmission pressures, and power levels reaching 1000hp in modified pressure transmissions. No 500hp application will have issues with 3rd gear slipping in a fiero, even less in a low torque situation like a LSx.

[This message has been edited by darkhorizon (edited 04-07-2014).]

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fieroguru
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Report this Post04-07-2014 04:19 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
The LS4's don't have much challange killing the 4t65 but most of their failures start in the torque converter vs in the other transmission hard parts.
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Report this Post04-07-2014 05:18 PM Click Here to See the Profile for JohnWPBClick Here to visit JohnWPB's HomePageSend a Private Message to JohnWPBEdit/Delete MessageReply w/QuoteDirect Link to This Post
Not that this will help in your situation, but for all those Automatic Transmission Nay-Sayers....

Tom Mccann dominated Islip speedway's NASCAR modified division for a year with an automatic transmission. The next year they were banned. It's got to make you think

Also a bit more information found on the Interweb.....

 
quote
Anytime a car is faster than an 11.0 or so, it's VERY difficult to keep up with an automatic. A properly built automatic, with C4's, TH400's and Powerglides being the most common.
Please do not be the typical ignorant car drivers who think Manuals are the end all be all of drag racing. Look up what the local guys are running in their 1000hp Mustangs, Novas, Camaros, and Mopars.


Sure, a manual transmission ca be TONS of fun, and offer more of the "feel for driving" for sure. However, there are some of us that prefer automatic transmission. I prefer having both hands on the wheel on a nice winding road at high speed. Not having to downshift and up shift at every little corner and sharp curve.

Again, it is a matter of preference, and guess what, for someone to not like exactly what you do, no matter how much it may bug you.... that's just too bad

[This message has been edited by JohnWPB (edited 04-07-2014).]

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Report this Post04-07-2014 07:44 PM Click Here to See the Profile for Jims88Click Here to Email Jims88Send a Private Message to Jims88Edit/Delete MessageReply w/QuoteDirect Link to This Post
This 6T75 looked promising.

http://www.fastfieros.com/t..._hydramatic_6t70.htm

I wish there were a recent update on this thread.

//www.fiero.nl/forum/F...2/HTML/119430-3.html

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Report this Post04-07-2014 09:19 PM Click Here to See the Profile for FFIEROFREDClick Here to Email FFIEROFREDSend a Private Message to FFIEROFREDEdit/Delete MessageReply w/QuoteDirect Link to This Post
I made sure to make a brace to connect the end of the trans to the side of the engine.
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Report this Post04-07-2014 10:01 PM Click Here to See the Profile for drattsClick Here to Email drattsSend a Private Message to drattsEdit/Delete MessageReply w/QuoteDirect Link to This Post
"Input shafts are not so much a weak spot as they are just a failure after a stretched chain and bad driving habits... Just because Don broke his you shouldnt have anything to worry about if your crank centerline is the same as your transmission input shaft".... l've broken a stock input shaft a 300M, and a GM racing shaft. The centerline has been suggested as my problem. How would I check that? Stock ls4s break input shafts. I think that my GM racing shaft never got hardened as it twisted before shearing at the same point as the others. At a minimum I would upgrade the input shaft and chain. I'm being pretty conservative with my driving at this point.

[This message has been edited by dratts (edited 04-07-2014).]

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Report this Post04-07-2014 11:34 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:

The LS4's don't have much challange killing the 4t65 but most of their failures start in the torque converter vs in the other transmission hard parts.


Considering there are probably 3 4t65e LS4 fieros out there... what makes you say this?

 
quote
"Input shafts are not so much a weak spot as they are just a failure after a stretched chain and bad driving habits... Just because Don broke his you shouldnt have anything to worry about if your crank centerline is the same as your transmission input shaft".... l've broken a stock input shaft a 300M, and a GM racing shaft. The centerline has been suggested as my problem. How would I check that? Stock ls4s break input shafts. I think that my GM racing shaft never got hardened as it twisted before shearing at the same point as the others. At a minimum I would upgrade the input shaft and chain. I'm being pretty conservative with my driving at this point.


I cant say much to your failures but ive been putting alot of power through alot of weak input shafts in the auto cars ive built and driven. For example formula's 500hp+ fiero has made over 30 moderate hard launches at the track without issue so far on I believe a 300m input shaft and 7/8 chain. I did almost as much as he has on almost as much power with a $40 150k+ mile transmission in my fiero...

[This message has been edited by darkhorizon (edited 04-07-2014).]

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Report this Post04-08-2014 03:36 AM Click Here to See the Profile for Steven SnyderClick Here to visit Steven Snyder's HomePageClick Here to Email Steven SnyderSend a Private Message to Steven SnyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Darkhorizon, the 4t65 is the stock transmission for the LS4. There are TONS of issues even in the w-body.

EDIT: just noticed you said 4t65e not HD.. I don't think fieroguru is talking about the "e", but rather a stock 4t65hd.

[This message has been edited by Steven Snyder (edited 04-08-2014).]

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Report this Post04-08-2014 01:05 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Steven Snyder:

Darkhorizon, the 4t65 is the stock transmission for the LS4. There are TONS of issues even in the w-body.

EDIT: just noticed you said 4t65e not HD.. I don't think fieroguru is talking about the "e", but rather a stock 4t65hd.



All 4t65 transmissions are "e" transmissions. And all 4t65e transmissions that came mated to the LS4 or the Supercharged 3800, are the version with the HD diff. The Torson diff can be installed in either one, and it's simple enough to install the OEM HD diff on a non-HD version.

And yes, it's pretty easy to destroy a stock trans with a stock LS4 in the W-body cars, especially when they are being weekend warriored at the drag strip.

But still, put the money in to build a hardened one to handle 700+ ft-lbs and it shouldn't have a problem with an LS7.
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Report this Post04-08-2014 02:01 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by darkhorizon:
Considering there are probably 3 4t65e LS4 fieros out there... what makes you say this?


Every LS4 came from the factory with a 4T65E-HD and the LS4 specific transmission is the only version of the 4T65 family that has the starter mount to be used on an LS7 engine (which is what this thread is about). I figured everyone knew what 4T65 came with the LS4 and I tried to save some key strokes (which I have now more than made up for).

How well one of the early 4T65E that came along side the non-supercharged 3800's would hold up to the LS4 is unknown as they there has never been a swap using one of them. That transmission doesn't have the needed starter mount.
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Report this Post04-08-2014 04:24 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
The hd lettering means nothing for a fiero... the load on the diff is 1/4 what it would be in a fwd.

I was saying there are few automatic fiero swaps out there to say that torque converters are failing so easily. What about the fiero swaps is causing the torque converters to fail over high powered 3800 swaps?
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Report this Post04-08-2014 06:37 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by darkhorizon:

The hd lettering means nothing for a fiero... the load on the diff is 1/4 what it would be in a fwd.

I was saying there are few automatic fiero swaps out there to say that torque converters are failing so easily. What about the fiero swaps is causing the torque converters to fail over high powered 3800 swaps?


I was referring to all the failure in their stock platforms. Here is just one thread where they are trying to keep track of them with the members who have them.
http://www.gmls4.com/index.php/topic,33.0.html
The guy who purchased mine locally was on his 3rd transmission... so it is clear to me that the LS4 is not a good match for the 4T65E-HD.

There are around 12 or so LS4 4T65E-HD swaps completed and running and at least 4 of them had the transmission rebuilt during the swap, so failure rates on bone stock transmissions will be hard to get. However, this thread isn't about a bone stock LS4 swap into a Fiero, it is about an LS7 being bolted to the LS4's 4T65E-HD and that is just asking for trouble.
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Report this Post04-08-2014 09:20 PM Click Here to See the Profile for drattsClick Here to Email drattsSend a Private Message to drattsEdit/Delete MessageReply w/QuoteDirect Link to This Post
Well I haven't given up. I haven't had my ls4 on the dyno yet, but it should be in the close neighborhood of your 575 hp ls7 and Darks car. I always think of his car and say "I think I can, I think I can". Some differences are: I have an 11" wheelbase stretch and when I weighed it at the dump with 1/2 a tank of gas I was 3400 lbs.
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Report this Post04-08-2014 10:12 PM Click Here to See the Profile for menderSend a Private Message to menderEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by darkhorizon:

The hd lettering means nothing for a fiero... the load on the diff is 1/4 what it would be in a fwd.

Heavy FWD = 2200 lbs on the drive wheels (static); 1800 lbs static in a Fiero: not 1/4. Plus weight transfers onto the drive wheels in a Fiero and off the drive wheels in a FWD, so very likely that peak load will be higher in a Fiero.

[This message has been edited by mender (edited 04-08-2014).]

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Report this Post04-08-2014 10:48 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by mender:

Heavy FWD = 2200 lbs on the drive wheels (static); 1800 lbs static in a Fiero: not 1/4. Plus weight transfers onto the drive wheels in a Fiero and off the drive wheels in a FWD, so very likely that peak load will be higher in a Fiero.



"load" isnt the concern. The diff is stressed in traction "events" commonly found in FWD that are rare in fieros.

 
quote
it is about an LS7 being bolted to the LS4's 4T65E-HD and that is just asking for trouble.


I really dont see why its asking for trouble. As mentioned before ive built more than a few cars making more power than this LS7 will be (most likely less than 500 due to exhaust considerations), and the transmission has never suggested to be a problem.

Weight is a big difference going from a 3900lb FWD car to a 2800lb rwd car.
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Report this Post04-09-2014 07:37 AM Click Here to See the Profile for FormulaSend a Private Message to FormulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
just dont let it downshift at full throttle and it shoud be fine (DH's advice for my car and it has been fine - I even hotlapped it 12 times in a tournament). I have the zzp 4t65e-hd trans.

[This message has been edited by Formula (edited 04-09-2014).]

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Report this Post04-09-2014 10:56 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by darkhorizon:


I really dont see why its asking for trouble. As mentioned before ive built more than a few cars making more power than this LS7 will be (most likely less than 500 due to exhaust considerations), and the transmission has never suggested to be a problem.

Weight is a big difference going from a 3900lb FWD car to a 2800lb rwd car.


To my knowledge you have never used the LS4's 4T65E-HD in any of your swaps. Other 4T65's certainly, but never the LS4 specific one.

What I am trying to say is that not all 4T65E-HDs are created equal.

The one behind the LS4 from the factory has known issues with the torque converter clutch and transmission temps and it probably stems from the chain ratio, final drive and stall speed used to help the 4T65E-HD live behind an engine that exceeds is rated tq capacity. I also think GM tweaked the TCC lockup logic and TCC lockup line pressure to keep it engaged at higher torque levels to improve fuel economy. Many of these issues likely are not present it the 4T65E-HD that you have ran with 3800's.

Since the easy way to run the LS7/4T65E-HD is to keep the LS4 ECM, TCM and 4T65E-HD, then most of these issues will also be present in the swapped application. Heat will likely be less as it will be easier to move the car and the converter will see less stall under normal driving, but the configuration of the transmission and the tune within the TCM will remain the same and I think that is where many of the issues originate for the LS4 specific 4T65E-HD.

There have been far to many LS4 4T65E-HD failures to ignore them just because you have never had an issue with your non LS4 4T65's (HD or non).

Once the LS4's 4T65E-HD has been rebuilt by TEP, the transmission for the most part becomes issue free for the next 100K miles like they should have been from the factory, but there have been a few people snap the input shaft on bolt on cars when driven agressively with sticky tires.

This is why many of the guys swapping LS4's into fieros are having the transmissions built by TEP during the swap.
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