The G6 version of the F40 (MT2) comes with a 3.55 final drive and a 3.77 1st gear, which provides a sump pulling 1st gear and isn't ideal with higher powered engine swaps. The low first gear is one of the criticisms for the F40, and FWD manual transmissions in general.
The F40 continues to live on in several Buick, Opel, Vauxhall applications and has versions with the following final drive ratios: 3.091, 3.348, 3.545, 3.762, 3.895, 3.909, and 4.176 (information courtesy of FieroWannaBe), but several of these final drives are only available over sees.
The 3.091 (F84) is an optional final drive in the F40 (MYJ) paired with the a20dth diesel engine in the Insignias (possibly other applications). Since it is optional, it takes some double checking to verify it has the proper final drive. I picked up my diesel F40 on eBay.co.uk and had it shipped to the US via TNT and Fedex.
Here are the gear ratios of both the G6 and the MYJ and the hybrid with the G6 gears 1-6 and the 3.09 final drive.
The pictures below will show some of the differences between the 3.09 transmission (dirty) and the G6 F40 (clean). High level the differences are: Bellhousing bolt pattern is different (and the MYJ bellhousing is deeper) Transmission mount bolt bosses are completely different Clutch line connection is different MYJ does not have a VSS provision Shifter assembly mounting flange are different (g6 uses 3 bolts, MYJ uses 2) MYJ gear side of the transmission case is more heavily reinforced with additional ribs as well as 2 additional bolts.
MYJ Bell housing. I used the vice grips to verify the 3.09 final drive. 1.92 turns of the input shaft = 1.0 turns of the tripod in 6th gear:
Transmission mount bolt bosses (MT2 bracket):
Different clutch line connection. Also notice the reverse gear sensor is moved from the shifter assy to the transmission case.
Shifter Assembly differences:
Additional Case Reinforcement (and 2 extra bolt holes) by the lower main shaft - gears 1, 2, 5 & 6):
[This message has been edited by fieroguru (edited 02-24-2019).]
To do the final drive swap, you have to open up the transmission and tear down the gear stacks on the Upper and Lower Main shafts as well as pull the ring gear off the differential.
These are the only 3 parts needed. The 3.09 final drive Upper & Lower Main shafts and the ring gear:
Here they are mocked up in the case:
Now, the 3.09 ring gear is smaller than the 3.55 one, so the VSS boss needed milled to move the VSS so it will work with the 3.09 gear.
There are no manuals for the F40 transmission, so needed to figure out what the factory preload was for the differential and both main shafts. So once the zero mile G6 F40 was torn down and all gears removed from the main shafts, I reinstalled the factory bearings to the shafts as shown below:
If you notice the center of the differential has a nut and washer sticking out of it. That is an expandable rubber freeze plug so I can spin the differential with a deflector style torque wrench and measure the preload. I did this with just the differential installed, gear side of the case installed and torqued. Once I had the differential preload, I took it apart, added the upper main shaft, reinstalled the gear side case, torqued and measured preload drag again. Then did it again with just the lower main shaft... That gave me 3 preload values that I would try to replicate.
I will keep the G6 differential, just install the 3.09 ring gear, so there is no change to the preload. However, both the upper and lower main shafts will have new bearings installed and will need to have the preload set for the new case using the same method detailed above.
There are no crush washers/spacers, all preload is set with shims between the gear side case and the outer bearing race.
Right now I am waiting on some additional shims to arrive as the lower main shaft was too loose and I needed some thicker shims. I pulled the races from the 3.09 case, but the spacers in that case were still not thick enough. I am also waiting for ARP bolts for the differential gear as well.
Originally posted by pmbrunelle: For those who don't know how to set up a gear-tooth type sensor, it should be as close as possible to the gear teeth, without rubbing.
You could also use a feel gauge to verify the current gap, them use a grinder to shorten the boss until you get the proper clearance. What I did was use my caliper to measure the OD of both ring gears, find the difference, divide by 2 and mill than amount off the boss - a little less than 1/8"
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Originally posted by pmbrunelle: What is your feeling regarding trying to duplicate the drag torque versus duplicating the "axial interference" distance?
If there was a similar special tool like the 282 and F23 getrag have, then I certainly would have purchased it and used than method. As of now, there are no service manuals on the F40 and no special tools available for rebuilding... so the preload drag will get me back within range and is better than not checking anything.
Also, most of the work to do this swap can be accomplished with basic/inexpensive tools, with the exception of access to a press.
Speaking of special tools... there are a few inexpensive tools that can be used, but they need to be modified slightly.
The first task you will need to do is remove the gear side bearing from the main shafts. I used a small 4 jaw puller with a 1/2" button head bolt in the hollow portion of the shaft. Additionally, the legs of the jaws were modified to make them thinner. I used a grinder to remove material from the backside to make the point thinner.
Snap ring pliers and piston ring expander pliers helps as well. Each main shaft has 2 of these snap rings to remove. They are quite strong and a little bit of a pain... I used the snap ring pliers to get the snap ring out of the groove, then I used the piston ring expander to pull them off the shaft.
Harbor Freight gear puller. There is a VSS spacer sleeve (the Buick versions have a VSS ring on this spacer) that is pressed on and you need this tool to remove it. This is the tightest press fit of any part on the main shaft. I will add a better pic showing the gear puller setup on this sleeve, but for not these pics will do.
Couple of 4x4 blocks, a 2x4, and a hammer. This last gear set on both the upper and lower shafts is press fit to the shaft, but can easily be knocked free by placing the assembly as shown, resting the 2x4 on the end of the shaft, and a couple of hammer blows.
The middle gear set on the lower main shaft that can be removed with 2 pry bars or long screw drivers .
Under the gear set removed by pry bars is a different locking mechanism. There is an outer ring holding two half moon pieces with a locking tab that fits into the hole.
For installation, get a piece of 1 1/2" black pipe. I used a 9" one, but it would be handy to have several shorter lengths so you don't have to keep lowering the press table.
A couple of handy tips...
When you are pressing the splined sections of the syncros onto the shaft, use you hand and raise the gear that is under it, spin it until it snaps into place and once the gear is engaged with the syncro, then press the assembly down while making sure to keep your fingers out of the way. If you don't do this alignment step, you will not be able to press the syncro hub down far enough... you will also bend the ears on the outer syncro cup and have to take it all apart again to fix it...
Also, the bellhousing side bearings protrude past the end of the main shafts. So all pressing operations need to have a spacer or a couple of washers to properly support the shaft. As the press makes contact with the shaft, I made it a habit to spin the lower bearing to ensure it wasn't seeing any of the press load.
To adjust the main shaft bearing preload, GM put shims behind the outer bearing sleeve. To make any adjustments, you have to pull the outer races. I used a harbor freight pilot bearing puller, but with a few mods. The legs of the jaws were significantly ground down to basically form a point. Most of the material was taken off the bottom, but I did file a slight angle to the top as well. I also ground down the cross shaft to right next to the o-ring grooves. This allows the tool to fit in the pocket for the upper main shaft. Stock pilot bearing puller: Modified one:
[This message has been edited by fieroguru (edited 08-24-2017).]
Originally posted by KissMySSFiero: You do amazing work on these cars. But you're documentation is hands down better than anyone's I've ever seen. Thank you for that.
Thanks! IMO Bloozberry is the best documenter with Jazzman a close second. I am somewhere further down the list.
Originally posted by Raydar: Amazing. This is pretty much the first thing that I have ever heard about an F40 that might make it worth my trouble to install. Thanks!
Thanks! It will likely be an additional $1000 to the cost of the F40 and the initial swap, but I think this final drive change will improve my 1/4 mile performance and allow me to break 30 mpg on the interstate. Not sure how many others will do the same, but this thread will help them if the want to do it.
Thanks! It will likely be an additional $1000 to the cost of the F40 and the initial swap, but I think this final drive change will improve my 1/4 mile performance and allow me to break 30 mpg on the interstate. Not sure how many others will do the same, but this thread will help them if the want to do it.
I wonder if the pieces might be sourced individually, if even from a European vendor.
Regardless... is this a service you might be interested in providing? Or is this simply a "how I did it"?
Thanks! It will likely be an additional $1000 to the cost of the F40 and the initial swap, but I think this final drive change will improve my 1/4 mile performance and allow me to break 30 mpg on the interstate. Not sure how many others will do the same, but this thread will help them if the want to do it.
Are you selling them with the final drive already changed out?
Cracking open a transmission is like brain surgery to me, only more difficult.
Originally posted by Raydar: I wonder if the pieces might be sourced individually, if even from a European vendor.
Regardless... is this a service you might be interested in providing? Or is this simply a "how I did it"?
So far I haven't found the GM part numbers for the 3 components... I am more curious as to how much I like this upgrade for my car. Doing this upgrade for others isn't in the plan at this point as my cost w/o any labor or markup is going to be pushing $1000. Add in being paid for my time and marking up the parts, it won't be cheap...
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Originally posted by jscott1: Are you selling them with the final drive already changed out?
Not at this time. Right now it is a proof of concept exercise for my personal car.
Originally posted by lou_dias: Would it have been easier to just use the other transmission complete?
Not even close... Different bellhousing pattern, so it would require an adapter plate. Bellhousing is deeper, would require a different flywheel or a custom spacer and possibly require new axles (or moving the engine = reworking all engine mounts). Different transmission mounts front and rear. Different shifer bracket Different clutch line connector Require a unique VSS solution (3.09 transmission doesn't have one) End result would only gain the ratio benefit in 3rd - 6th gears, as you would be going from a 3.77/2.04 1st and 2nd to a 4.17/2.13
The ARP bolts for the differential ring gear came in, so I ran a tap down the threads to clean them, added some locktite and torqued the ring gear down (yes, I know I should install a LSD, but they are $1200 and I don't want to spend that kind of $$$ until I know I like the 3.09 gearset):
With the shafts tore down, I checked the drag torque for the preload on each shaft. The lower main one needed a shim (that I had to order), but it arrived as well. Once the preload was set, the 3.09 shafts were reassembled with the zero-mile gears and syncros from the 3.55 transmission. I also cleaned up the flanges and cases and have everything ready to go back in the case.
The ARP bolts for the differential ring gear came in, so I ran a tap down the threads to clean them, added some locktite and torqued the ring gear down (yes, I know I should install a LSD, but they are $1200 and I don't want to spend that kind of $$$ until I know I like the 3.09 gearset):
Did you have traction issues with the V8?
I'm not sure that ARP bolts on a ring gear are necessary.
When I "rebuilt" my Muncie, I took note of the no. of bolts, bolt circle diameter, bolt class (10.9). I estimated that the torque transmission capacity of the friction joint between the ring gear and diff carrier is about the same as the torque transmission capacity of the wheel-to-hub friction joint. So from the factory, the ring gear friction joint was well sized; neither a weak link, neither overkill.
The transmission as been assembled. I gave the gears and shafts a bath of transmission oil as I placed the shafts into the case, then I put the rest of the 3 quarts into the transmission and probably rotated the input shaft 200 times as I worked through the gears to make sure everything work. Then I set it on its end for several hours to ensure the oils gets everywhere it should be.
Then I drained the transmission oil back out, cleaned the transmission, used some self-etching primer, and then some aluminum engine paint. I didn't paint my first F40 and after 4 years of sitting outside the case has started to oxidize and not look good.
[This message has been edited by fieroguru (edited 08-25-2017).]
This thread is pure unadulterated sweetness!!! I've read it 3 or 4 times so far and studied each of the pictures intently. Thank you. You are the path finder I needed.
I have been casually searching for just this info for a couple of years but hadn't found anything yet. I need at least another year on the engine before working on the trans. However knowing what I will have for a final drive gear will help me choose the right cam for my setup. How ever I would like to go the other way from you. I think I need a lower gear because my motor will sort of be low torque, high revs. So a 4.1 or even a little lower. Maybe 4.45!
So now I have spent two long nights searching the web, starting with some of the info you provide. Even copying and pasting from this thread to the search bar.
I have started to get answers to some more of my questions. And maybe those of others who wish to mod an F40.
Somethings I found; A FWD Opal Antara can have the 4.176 gear set,(RPO code MXS) Alpha codes 2Z, AKC, AVM But don't know how to use the codes to get the correct trans. Any other cars? Can anyone help me find where to get the info I need.
The tapered roller bearings are 32010x. GM shims for the diff start at #24465757 for 0.85mm (.033inch), and then each number higher increases by 0.05mm. (.002inch) Are they the same the other shafts?
Wavetrack helical gear type limited slip differential part number is: 57.309.190WK.
6 speed Quaife F25/35 Gear set There is nothing Saab specific here. The kit was developed to fit the Cobalt SS and similar F35 cars. it just happens to fit in the F25 cases also. For the NG900/9-3 and 9-5 it is a straight swap. For the 9000 94-98 since the trans mount is part of the end case that is changed you have to fabricate a new mount assembly. This is just the gear set and you need to have some extra parts from Saab to make it all work. The final drive can be selected from the few that we have from 4.05 std in 9-3/9-5, 4.45 and 3.82 so you can move the gearing around. You will need to have the ring and pinion as a set. Not the easiest to swap but still an option. More at https://www.genuinesaab.com/psi/gearbox.htm
OK so there not saying they have gears for the F40 in this article. but they do have small parts for the F35. The F40 too??? Used parts? I may have to call to see.
A 6speed Quaife F35? £3,165.00 gear set only. A new mortgage would be needed.
A slip of your finger I think. To verify the 3.09 final drive 1.92 turns of the input shaft = 1.00 turn of the tripod in 6th gear:
Some scrap yards list the final drive ratios, other don't. To make sure it is the right one, you need to PM or call the scrap yard and have them verify the final drive ratio.
I have the part #s for most of the bearings and shims and will post them later this afternoon.
Right now I am building a cross bay support bar as I plan to start dropping the stock F40 later this afternoon.
Upper & Lower Main Shaft - Gear Case End: Koyo 32007-JR-3YD (35mm ID, 62mm OD, 18mm width)
Upper & Lower Main Shaft Shims - go behind the gear case bearings. The part # goes up or down by 1, the thickness of the shim changes 0.05mm. 24461944 = 0.80mm (thinnest) ... pattern continues 24461949 = 1.05mm 24461950 = 1.10mm 24461951 = 1.15mm 24461952 = 1.20mm (thickness specified on tear down documents) 24461953 = 1.25mm 24461954 = 1.30mm 24461955 = 1.35mm ... pattern continues 24461966 = 1.90mm (thickest)
[This message has been edited by fieroguru (edited 08-27-2017).]
Just click on the assembly (like Upper Main Shaft): http://www.wholesalegmparts...&ukey_category=19405 and it will show you the drawings with part call out numbers as well as most of the GM part #s for the individual parts.
Here is the engine support bar I fabbed up. The end brackets use a factory hole in the strut towers to lock into position. There is a leg that rests on the upper frame rails as well. The cross bar bolts to both end brackets and has adjustable hooks to raise, lower or tilt the engine.
Pay close attention to the bolt holes used for the chain. If you relocate some of the stock studs to these holes and put a chain on them, then the transmission can be lifted with the top bell housing flange surface parallel to the ground (which is how it is when installed). It also allows the transmission to be nearly perfectly vertical which helps when it comes time to line up the holes. Lastly the lifting hook is not in the center of the bellhousing flange, which is a great thing because that is where the cross bar is positioned. With this offset position you can use a cherry picker to lift the transmission into place while the engine is supported by the cross bar.
Here I set the transmission on a creeper to slide it under the car, then hooked it from above with the cherry picker.
The transmission with the 3.09 final drive is now bolted to the LS4, but I still have lots of things to reconnect. I am hoping to finish it up after work on Monday or Tuesday.
The LS4/F40 Fiero is back together and I took it for a 10 mile shakedown run.
I wasn't really getting on it, but I do like the new feel of 1st gear. Overall I found myself running 1 gear lower than before - so where I would previously been running say 5th, I am now running 4th. I didn't make it to the interstate, but the car will cruise at 55 mph (phone GPS) at 1480 rpm in 6th just fine.
I still need to align the car and change the speedo settings in the tune. In the next several days I will continue to do shakedown runs in town and might take it on the interstate. This coming weekend, I want to get on the interstate and drive about 250 miles to check if there is any change in fuel economy.
Originally posted by fierogt4e: I think I need a lower gear because my motor will sort of be low torque, high revs. So a 4.1 or even a little lower. Maybe 4.45!
So now I have spent two long nights searching the web, starting with some of the info you provide. Even copying and pasting from this thread to the search bar.
I have started to get answers to some more of my questions. And maybe those of others who wish to mod an F40.
Somethings I found; A FWD Opal Antara can have the 4.176 gear set,(RPO code MXS) Alpha codes 2Z, AKC, AVM But don't know how to use the codes to get the correct trans.
Stateside cars with other final drives are: 2002-2004 Saab 9-3 Aero 6 speed has a 3.895 2009+ Buick Regal Turbo Has a 3.765
[This message has been edited by FieroWannaBe (edited 08-30-2017).]
I have put a few more miles on the new transmission and I really like it! It is quite enjoyable around town and works great on the interstate.
To put it in perspective at 75 mph, In 4th gear, the engine turns 3000 rpm, which is essentially the same as having the M17 4 speed. In 5th gear, the engine turns 2400 rpm, which is 100 rpm less than the Isuzu 5 speed, 260 rpm less than the Getrag 282, and 380 rpm less than the F23. In 6th gear, the engine turns 1965 rpm, with is about 575 rpm less than the Isuzu, 700 rpm less than the 282 Getrag, 825 rpm less than the F23, and nearly 300 rpm less than the 3.55 F40.
I have a 3 day weekend, so I should be able to get a fuel economy test done sometime during the next several days!
I have put a few more miles on the new transmission and I really like it! It is quite enjoyable around town and works great on the interstate.
To put it in perspective at 75 mph, In 4th gear, the engine turns 3000 rpm, which is essentially the same as having the M17 4 speed. In 5th gear, the engine turns 2400 rpm, which is 100 rpm less than the Isuzu 5 speed, 260 rpm less than the Getrag 282, and 380 rpm less than the F23. In 6th gear, the engine turns 1965 rpm, with is about 575 rpm less than the Isuzu, 700 rpm less than the 282 Getrag, 825 rpm less than the F23, and nearly 300 rpm less than the 3.55 F40.
I have a 3 day weekend, so I should be able to get a fuel economy test done sometime during the next several days!
Wow! That's impressive!
How does it feel, coming out of the hole? (I'm sure you used to just blow the tires away, with the other FDR.)
You gonna go for 200 MPH? (Based upon calculated speeds/RPM, you probably could have done it before now. Would you be drag limited? Or just limited by your own self-preservation instinct?)
[This message has been edited by Raydar (edited 09-02-2017).]
Normal takeoff from a 4 way stop is improved as the car can reach a faster speed (and go further through the intersection) before I shift into 2nd at 2500 to 3000 rpm. For a slightly more aggressive part throttle launch, I can still break the rear tires loose, but car gains more speed while they spin. Anywhere in 1st gear full throttle results in instant wheel spin.
The car is primarily setup for autocross and daily driving, I haven't spent much time or effort finding the best setup for drag racing. My front shocks are currently set to full stiff, and they should probably be full soft... but adjusting them requires removing the shock. The rear springs are 425lb/in, which is probably a little stiff (and the rear struts are set full stiff as well - but can be adjusted with the turn of a knob). The tires normally have 38-40 psi, and probably need to be below 30. Lastly the 18" 30 series tires probably need replaced with some 16" slicks or drag radials...
As for top speed... I have had the car to about 135 but the front end starts to get pretty light. It needs more aero work to go faster - like a splitter for the front, but I already scrape the rubber air deflector getting into the driveway (I might need to try something like this: http://www.bridjit.com/). There was a standing mile event held about 20 miles away at the closed air base in Rantoul. I am hoping there was enough interest to hold the event every year or two as it would be a great opportunity for further testing and development.
Normal takeoff from a 4 way stop is improved as the car can reach a faster speed (and go further through the intersection) before I shift into 2nd at 2500 to 3000 rpm. For a slightly more aggressive part throttle launch, I can still break the rear tires loose, but car gains more speed while they spin. Anywhere in 1st gear full throttle results in instant wheel spin. ... As for top speed... I have had the car to about 135 but the front end starts to get pretty light.
Originally posted by FieroWannaBe: Did you happen to take any of the teeth count/diameters of the gears while you had the transmissions apart?
3.55: 78 tooth ring gear and 22 tooth pinion. 3.09: 68 tooth ring gear and 22 tooth pinion. The tooth pitch on the 3.09 is physically larger. The difference between the two ring gear diameters was less than 1/4", but I didn't measure the difference of the pinion gears, but the 3.09 ones were certainly larger in diameter.
Here are the 3.55 components - notice the edge of the pinion gear teeth relative to the bearing. The diameter of the pinion gear is smaller than the bearing OD.
Here are the 3.09 components - the edge of the pinion gear teeth are close to flush with the OD of the outer bearing race (which is 80mm).
[This message has been edited by fieroguru (edited 09-08-2017).]
