Seems like all those fluids are around the same price. Any reason not to use 58404 on a more mild power application such as near-stock LS4?

They all work... so for most applications, it really doesn't matter which one you run. It might be best to stick with the GM fluid.

If you plan to drive your car in the sub 40 degree temps, the heavier weight fluid options make the shifter more difficult to move on cold mornings until it warms up. They also likely will reduce your mpg slightly.

I switched to the Redline Shockproof as I am aproaching near twice the rated touque through the F40, and the shockproof line is designed to help in these extreme cases.

Hello to everyone, new user here.

This thread was the main source of info for F40 3.09 conversion and I am glad that I found it. I am doing conversion for my Alfa Romeo 156 2.4 JTDm 20V which has 3.54 F40 gearbox. From Ebay I bought 3.09 gearbox from Opel-Vauxhall Insignia 2.0 CDTi "ECOFlex". I read that you are not sure in what cars are 3.09 gearboxes. I found that only "ECOFlex" Opel-Vauxhall Insignia's have that gearbox and Astra K with B16DTU engine. So it is easier to find the gearbox by specific car model searching ECOFlex only.

I also bought another Alfa's F40 gearbox, because housings are not the same, and I am using the car daily, so when I finish conversion I will just put modded F40 to the car.

Also I tried to measure shim preload, and gap between outer bearing ring and the gearbox's housing by putting soldering wire between, putting the 3.09 bearings and 3.09 gear set in 3.54 housing, tightening and tapping top of the housing with rubber hammer, and then removing everything and measuring thickness of the soldering wire. I am hoping that this was good method. Now I will do the same one day when I have time, but everything stock with both gearboxes.
I am aiming for 0,05-0,12mm preload but I will find out when I put all back together both gearboxes with stock gear sets. Shims that I have now are: for diff: 1,00mm, 1,05mm, gear set: 1,10mm x1, 1,15mm x2, 1,20mm x3.

On the images are info where to find 3.09 gearbox on which cars and the current gap measurements between bearings and the housing (3.09 gear set in 3.54 housing with 3.09 bearings). Measurements were min and max measure that I got, need do it maybe once more for consistency and taking the average.

I hope that this info will help.

[This message has been edited by fikuna45 (edited 06-03-2025).]

The numbers on your image are the thickness of the solder after your fit-check assembly?

Does anybody know what are the torque specs for the diff ring gear bolts? Thanks

@Will Yes, numbers on the image are thickness of solder wire after fit-check assembly, without shims of course. Solder wire was 1.5mm in diameter.

Hello,
It was a good idea to use solder wire to determine the shims.

I also bought a used F40 to change the final drive for my car.
The used F40 has 3.091 final drive with only 110k kilometers milage. All the gear ratios would be suitable for me. So I will intend to swap the cases of the F40 gearboxes, since the case of the 3.091 gearbox is slightly different to my F40 with 5.545 final drive.

I wonder whether it is easy to pull out the outer tapered bearing races from the casing of F40 without any damage?
Should I use an expensive bearing puller which has wide surface (see picture)?

Since I reuse the races and the shims, I want to avoid damaging anyone of them.

On the picture I point out the places of outer races for better understanding.


Best regards,

I used modified inner bearing puller like one @fieroguru used. But mine was broken after several attemps. I grinded off too much of material.

So I used hand impact bearing puller with a modified hook (Flattened and near perfectly rectangular so it can go and grab underneath the bearing edge ) and then I hammered out left and then right side alternately little by little until bearing popped out. I did this twice for shim side bearings, and none fo the bearings was damaged nor it had any scratches.

Bearing seat had few minor scratches at the beginnning only until I managed to do it properly.

Of course best way is to use wide bearing puller, because then you are reducing the risk of damaging anything.

Thank you for the response.
Today I opened the donor F40. Really interesting to do such kind of projects

I will start also with a budget tool for bearing races pulling.
Will I require a press to install the outer bearing races?
Or I can just use a piece of wood and a hammer?
Best regards,