LSJ Supercharged Ecotec Swap (Page 2/45)
Joseph Upson MAY 19, 02:35 PM

quote
Originally posted by wftb:

if you get rid of the jackshaft assembly,will the stock fiero axles fit right in ? as i understand it ,the jackshaft is just to help eliminate torque steer ,not a problem with a rear drive car .nice build ,keep the pics coming !



No, this tranny takes the same axle spline configuration as the F40, they are both originally Saab transmissions and more than likely the F35 has the same offsetting of the final drive carrier that calls for different length output axle stubs at the tranny, in other words you can't fully insert an axle shaft in the right side of the transmission so the jackshaft would be manditory.

[This message has been edited by Joseph Upson (edited 05-19-2007).]

ccfiero350 MAY 20, 12:07 AM
Joseph is correct, the fiero axles will not fit into the jackshaft or the transmission either. Good news is the cobolt axles fit the fiero hubs. The F23 transmission will except the fiero splines. I think both F23 & F35 are wider at the differantial and would make the long fiero axle too long.

At this point I could use 2 RH cobolt axles to make the swap work. I'm hoping the LH cobolt axle is a little shorter. I'll should be getting one next week.

The published torque ratings of the new transmissions.

F23 5-speed 170 ft-lbs
F35 5-speed 258 ft-lbs
F40 6-speed 295 ft-lbs
I not sure what the getrag is rated as, 170 ft-lbs?

Does anybody know if the F40 have the same bell housing bolt patern as the F35 & F23?

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yellow 88 GT, not stock
white 88 notchie, 4 banger

Joseph Upson MAY 20, 12:57 AM

quote
Originally posted by ccfiero350:

Joseph is correct, the fiero axles will not fit into the jackshaft or the transmission either. Good news is the cobolt axles fit the fiero hubs. The F23 transmission will except the fiero splines. I think both F23 & F35 are wider at the differantial and would make the long fiero axle too long.

At this point I could use 2 RH cobolt axles to make the swap work. I'm hoping the LH cobolt axle is a little shorter. I'll should be getting one next week.

The published torque ratings of the new transmissions.

F23 5-speed 170 ft-lbs
F35 5-speed 258 ft-lbs
F40 6-speed 295 ft-lbs
I not sure what the getrag is rated as, 170 ft-lbs?

Does anybody know if the F40 have the same bell housing bolt patern as the F35 & F23?




The jackshaft is the only thing that properly inserts into the right side of the F35 and F40.
Both Cobalt axles will be the same length, it would defeat the purpose of the Jackshaft for them to not be. As for the tranny torque ratings, I believe they can be increased because they are based on a max vehicle weight as high as 5000 lbs particularly for the F35, I believe that's why GM lists a max gearbox torque and max engine torque for the transmission so that the two combined do not exceed the strength of the gearbox, the lighter the load that has to be moved the less stress on the gearbox. So subtract the weight of the Fiero from the max weight the transmission is rated for, calculate the # of lbs per lb/ft for the max weight the tranny is rated for, then divide that into the difference of the vehicle weights and you should be able to add that to the above rating for your application. I believe it was near 350 lb/ft for the F40.

The Saab F40 may have the same bellhousing as the Cobalt. The G6 version of course has the V6 pattern.

[This message has been edited by Joseph Upson (edited 05-20-2007).]

Fierobsessed MAY 20, 03:58 AM
Are you saying that the F35 axles (with the half shaft) may work with the F40 and the Fiero Spindles? That would be nice. A little O/T, but it would be nice
wftb MAY 20, 06:49 AM
the fiero axles fit right in to the F23 and are the right length .the slight difference in width is made up for by the amount of in and out movement available on the stock axles .there are 3 of us who have done this already .i doubt that the fiero getrag is rated the same as the F23 .even if it was ,its still 20 years older .use the F23 and save all the rebuilding costs.
Joseph Upson MAY 20, 08:10 AM

quote
Originally posted by Fierobsessed:

Are you saying that the F35 axles (with the half shaft) may work with the F40 and the Fiero Spindles? That would be nice. A little O/T, but it would be nice



The F35 and F40 are both Saab Transaxles originally and take the same axle spline configuration. The intermediate shafts are different in GM cars but the same on the Saab, the Cobalt has a female ended intermediate shaft like the Saabs, the G6 uses a male ended intermediate shaft so you would have to make a mounting plate for the Cobalt intermediate shaft to work properly with the F40 mounted to a non Ecotec engine which will not have the mounting bosses for the Ecotec intermediate shaft in the proper location.

The other issue which has been aluded to already is the axle length, You may be able to get away with using the complete axle set from the Cobalt on the F40 in the Fiero by repositioning the assembly since the F40 axle output seal is 2 inches closer to the left frame rail and one inch further away from the right frame rail in the Fiero compared to the Getrag, so positioning it one inch further to the right will leave you with about 1" less plunge depth but that all depends on the drivetrain assembly height on the cradle and the length of the axle with the Fiero outboard joint cup installed since the bearings, cage and race are interchangeable. If the Cobalts joining axle is 32 spline instead of 33 like the G6s you can swop the complete Fiero outboard joint on to the axle.

Fiero wheel base 93.4"
Cobalt wheel base 103"
G6 wheelbase 112.3"

Thanks for what you have posted here CCFIERO350, it has helped the F40 swop along tremendously due to what I suspected and have now confirmed through your posts after finding that both transmissions were original Saab units and used the same intermediate shaft on some Saab cars.

[This message has been edited by Joseph Upson (edited 05-20-2007).]

FieroWannaBe MAY 20, 04:03 PM

quote
Originally posted by Joseph Upson:
Fiero wheel base 93.4"
Cobalt wheel base 103"
G6 wheelbase 112.3"





those stats are irrelevant for the transmission, you looking for track width, even then scrub radius and offset effect it.
Joseph Upson MAY 20, 05:09 PM

quote
Originally posted by FieroWannaBe:


those stats are irrelevant for the transmission, you looking for track width, even then scrub radius and offset effect it.



Those specs are not intended to note the transmission but the fact that the axles are different lengths because of it. I was intending to list the actual track specs and got it all mixed up and listed the wrong specs.

Here are the widths that will better represent the actual track
G6 70.4
Cobalt 67.9
Fiero 68.9

I hope to acquire some Cobalt axles this week for some comparisons in hopes that they will be the right length for the job.

[This message has been edited by Joseph Upson (edited 05-20-2007).]

Dennis LaGrua MAY 20, 05:17 PM
Very Interesting and informative post! High technology lightweight engine with great horsepower potential but IMO a difficult swap for the experts. Makes you wonder if Fieros would be using an Ecotec if they were being made today. Looking forward to hearing about the road tests.

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

ccfiero350 MAY 20, 08:58 PM
I don't think it's all that diificult, it's just uncommon. Roger is selling kits now and the 2.2L ecotec and F23 are very common place and can be had in the $500 range.

I think after a few of these get done and along the way, refined parts, procedures and knowledge base will increase in quality and affordabilty. And it will become more common then the Quad 4 swap before long.

One of the main reasons for doing the 4 banger is that at 2.0L I will race in a class that I may have a chance at winning something. And the LSJ engine and LSD transmission combo really are just incredibable.

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yellow 88 GT, not stock
white 88 notchie, 4 banger