So I'm working on a transmission swap for my 2006 Cobalt SS and my hair keeps falling out. Every turn is a new problem and I've not even gotten all the parts yet! I thought I had the plastic shifter base but now realize I have the wrong one. <sigh>

Here's the one that shows up on the OTTP web page:

I thought I had the right one, purchased it from Ebay, but nope... strike one!

I found one I think IS the right one here:
2013 Buick Regal Manual Transmission Shift Lever - 55486394 | Stingray Chevrolet, Plant City FL (oemgmpartscenter.com)

Does anyone know if this is correct?

Thanks, Dave.

 

Ok, so Ryan at ZZP gave me a thumbs up on this one in less than 12 hours! I'm buying a long tube header from them and they were kind enough to identify this shifter base for me.

Damn, they actually have great customer service.

I might post more trials and tribulations here if anyone is interested.

 

Keep posting because almost ever person I've heard make the 6 speed swap have had issues.

Also please type out the part numbers since links can die.

 

So the part number for the plastic shifter base is: 55486394

For anyone interested, there's a series of 5 videos that piece together the F40 transmission swap on YouTube.
1. Removing front axle assemblies:
2. Remove the subframe:
3. Remove the transmission:
4. Parts list:
5. Install clutch and first drive.

 

Here are some parts that make up the kit. I finally got mine installed and it’s running nicely! You can obtain all these parts in a kit from OTTP or ZZP. I got mine from OTTP. Wasn’t impressed with Josh’s customer support. The guy seems to be a one man show there, has no time for customers and if you bug him too much, he’ll screen your calls. Unfortunately, ZZP hasn’t offered the transmission for over a year now. It could be available elsewhere but I’ve not looked.

Shifter cable P/N: 24270798
Product Details | SimplePart (gmcarpartsonline.com)

CV Intermediate shaft P/N: 22910265
Buick Regal Cv intermediate shaft (front) - 22910265 | GM Car Parts Online, Cincinnati OH

Axle bracket P/N: 13228250
2011-2017 GM Bracket 13228250 | OEM GM Parts (gmpartsoutlet.net)

Transmission bracket (Saab P/N: 13228255
13228255 - Genuine GM Bracket-Trans Mount (gmpartsgiant.com)

Obtain shorter, driver side axle from The Driveshaft Shop (great customer service)
The Driveshaft Shop | Home Page - Driveshaft Shop

This does not include all the items necessary, but it’s a start.

 

Some feedback on this - the transmission itself is smooth but I notice a bit of vibration now. The brackets used on the original transmission have rubber bushings to eliminate engine vibration being transmitted to the vehicle. The kit has a few brackets with no bushings which bolt directly between the transmission and body so there's a bit of additional noise now that I don't care for. Sounds like there's something wrong with the car to be honest. When I have time, I'll look to add rubber bushings to those brackets somehow.

 

Cobalts tend to be VEEEERY bad about transmitting NVH, so I'm not surprised.

 

So I'm still having one minor issue with this transmission swap. Cruise control doesn't work in 6th gear. It works in all the other gears. I've talked to a shop that does tuning here and they weren't able to help. I've also contacted OTTP and Josh said he'd heard of this once but didn't know anything else. It's now at a performance transmission shop but we're stumped.

There are no codes that might affect it. One possibility might be the RPM's are too low for the speed - perhaps there's something set up in the computer that looks at RPM and if the expected RPM differs from actual, it may disengage cruise control. But what that is and how it might be changed is what I'm looking for.

Any suggestions would be appreciated!

 

I have the same issue with 5th gear on my F23 XFE swap - both the F23 XFE 5th and the F40 6th are much longer than the F35 5th. I'm 98% sure that it's an issue with the expected load and is something that either isn't available for adjustment in the PCM or it's in the BCM and is equally unavailable for adjustment.

In short... I think you're going to have to live with it.

 

Thanks for the comment USMC. I brought the car home from the transmission place tonight, no different than when I took it in. I've seen a lot of folks with similar issues on the internet not with Cobalts but with just about everything else such as Corvettes and whatever car this is:

Cruise control issues after 6MT swap (audizine.com)
It's mentioned on here that

Quote:

There are maps that control this, I can't recall off the top of my head what they're called but I've seen them discussed on nefmoto.

Quote:

You would need to modify the above mentioned maps in the ecu so that the car knows what rpm/mph/load should exist for your 6th gear/final drive. Haven't ever actually done this so don't have the info in front of me or recall where to easily find it.

Quote:

The issue is that on a manual the only way for an ecu to know what gear the car is in is to calculate it from speed and rpm. Once you swap out parts, change final drive, change from say a 5spd to 6spd or change to something with a taller 6th then the ecu can't do its calculations right and will not let you activate cruise, or as soon as it tries to go up a hill realizes load is way off and cancels it.

Quote:

But yes his actual question- to make the cruise function you need to edit the file in the ECU to get the ecu to understand 6th gear and calculate the speed vs load. I did it in the old days on MK4 golf. I built. But I just copied what the TDI group guys had already done, they're the real hackers.

I don't think it has anything to do with load on the engine. That would have to be calculated from things like mass air flow, but it seems to me, going up and down hills will change that drastically and that never forces the cruise control to cut out, or at least I've not seen that happen. On one car I drove with an auto, I put it in the manual control mode and forced it to stay in top gear while going up some small hills. The engine wasn't powerful enough to maintain speed and it dropped off by at least 10 mph, but it didn't kick the cruise control off..... thinking about that, I'll have to test that out at low speed in 5th. Maybe tomorrow...

But I could see RPM and speed needing to be on a 'map' so to speak. If they're outside of the map, then perhaps Chevy feels there's a safety reason to disengage cruise control. Sixth gear would certainly be out of any 'map' that might exist in the computer (PCM or BCM?).

Does HP Tuners allow you access to those 'maps'? I wouldn't even need to add a 'map', just change the values in 5th gear to 6th gear. After all, we only drive with cruise control on, in the highest gear so ditch the others and just have it work in 6th, right.

I might try a Chevy dealership next. I'll post what I find out...

 

HPTuners does not grant access. And I think it's based on calculated load, which is kind of what they're saying. I was able to get mine to work for about a day while initially tuning my car for E85. Even then though, if the car started going up a hill and the load on the engine increased (such that it needed more power), it would kick the cruise control off. If I hit resume while at a lower speed than what it was set - it would engage for a second and then kick off.

Also, VW/Audi controllers are very different. I have a cable that lets me edit almost any VW/Audi body controller that's on the car. Can't do that on a GM.

I would advise against a Chevy dealership for a handful of reasons. Mostly because you'll just be throwing your money away. They're going to want to reflash the ECU or BCM. They really don't have a lot of capabilities for something like this.

I'd love the ability to either edit more PCM tables or edit the BCM... but neither is an option. A lot of us tried for years to get HPTuners to open up more table. And I searched for a long time to see if anyone had developed BCM editing software like VCDS, but there's nothing.

 

Well that sucks.... I tried cruise control today in 5th gear at very low RPM and under load. At 1100 RPM, it ran fine, even up a minor hill. Boost (intake manifold) pressure was 10" Hg vacuum. I then tried it around 1200 RPM and up a much more significant hill. It basically put the pedal to the floor and went to 5 psi boost and kept going. So at least from that experience, it tells me that low RPM and high load doesn't kick off the cruise control. So if load is higher in 6th gear, I can't see how it's going to shut off cruise control. I suspect it's just RPM and speed that it looks at to verify those match some existing expectation.

Good to know. I figured there were differences but that sucks...

Ok, I suspect you're right. I'm not finding anything either. So how about this. I know there's a value that can be changed in the program that adjusts the speedometer and it operates off the speed sensor that's on the transmission. I guess there's a different number of teeth on the ring with this 6 speed transmission so that value in the code has to be adjusted to make the speedometer accurate, and I understand I can use HPTuners for this. Changing it to reflect the actual speed obviously isn't going to help, but I wonder what would happen if I changed the value so that in 6th gear, it outputs the same speed as if I were in 5th gear. If I did that, if the speedometer and RPM matched, then it would essentially 'think' I was in 5th gear and cruise should work, right?

The speed on the speedometer would obviously be way high. I think at 60 mph, RPM has to read about 2250 for it to think it's in 5th gear but in reality, I'd be going 74 mph. I could change that value and verify cruise control works in 6th gear.

Problem then is, the speedometer is reading way too low. So the next thing would be to change the speedometer so it read correctly. I understand a speedometer is basically a stepper motor that rotates the needle on your speedometer. There may be 2 ways to adjust the speedometer. The first would be to use a calibration adjustment on the gage itself if it has one. The second would be to adjust the input electrically by adding some circuit to the wires going into the speedometer. Like yourself, I'm a mechanical engineer and have electrical engineering friends that might be able to do that. So once this circuit is spliced into the wires going into the speedometer, it would accurately reflect the speed I was going but the computer would still think I was going much slower.

The only other problem I see is if the speed pickup on the transmission is used for something other than the speedometer and cruise control. If it is, I'd need to figure out what that was and what impact that had. I won't speculate what I could do to get around that issue before it's identified. But if all the speed sensor is used for is to operate the speedometer and cruise control, then I don't think there could be another issue.

Any thoughts on that? Thanks for your time.

 

Had the 6 speed for 4 years now. My tuner got the speedo working dead on, no clue what he did. Cruise does not work in sixth as well, messaged briefly with other f-40 folk about this seems common issue.

 

Thanks Flatgod. What year is your Cobalt?

 

I assume the guys with the cruise not working in 6th are all running the regal ones? And the guys that have had it working are running the saab versions? I know the Saab has closer to stock 6th gear than the the talk Buick ones.
my car has always kicked cruise off on fairly steep hills if it’s unable to accelerate to maintain speed at a reasonable load. I assumed it was a load calculation doing this. Maybe it is just a speed rpm calc.

 

I think it would be worth playing with the speedo values to trick it and see if that helps.
Or alternatively try it at a higher speed and see if it will allow it.

 

Thinking back... it might be speedo related, as I seem to recall that when mine was working intermittently, I was trying to dial in my speedo to perfection. I might try flashing a couple different values later on just to test it out. I'm guessing it's load + RPM + speed. There must be a formula that it calculates... if the load goes over what it thinks it can generate at a given speed & rpm, it kicks it off? Or, a preprogrammed "Expected Load" that is based off of actual speed & RPM... and if there is a certain %-difference when compared with the actual load.

And it definitely might be a Regal F40 thing, slap. The Saab F40 and the LNF F35 have the same output gear ratio in 5th/6th. My F23 XFE and the Regal F40 also have very similar output ratios in 5th/6th, but the Regal is longer.



These numbers are based on 235/40R18 tires.

 

My transmission seems to match the Regal one. Of course, right now I've not adjusted the speedometer so although it's actually ~ 80 mph at 2500 RPM, the speedometer is reading closer to 87 @ 2500 RPM.

I think I'll have a look at adjusting/lowering the speedometer reading to 80 mph and then lower to see if cruise control starts working again. Might need to adjust it so it reads close to what 5th gear used to look like (3000 RPM @ 80 mph). Should be interesting...

 

It's an 2006 Redline.