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lmmoquin 09-02-2017 11:49 PM

A Six Speed?
Hello everyone. I'm wondering at the probability of a new transmission. I know that it would require a LOT of things, but bare with me. My thinking is that, in a perfect world, you might be able to get away with putting the 6T40 transmission from the Chevrolet Sonic into an Astra since both cars use the 1.8l transverse Ecotec engine. The Sonic is a smaller car, so it's transmission should fit? I'd love to hear any thoughts on this.

nicolas_p 09-04-2017 12:46 AM

Re: A Six Speed?
I would be very interested to see if this was possible aswell or even the m32 from the 6 speed in the 2.0l in europe

TDA 09-05-2017 09:17 AM

Re: A Six Speed?
I'm no help as far as getting it done... but it makes sense.

Taking an Astra on the highway gets you less MPG than expected. In 5th at ~55 it's cool and will report high 40s MPG. But if you start getting up to 65-75mph, MPGs plumit to the mid to low 30s. Sure sign that another gear is needed for high speed highway driving. :(

Having the 6-speed would help explain our funky reverse position as well...

AstraFasta 09-05-2017 07:14 PM

Re: A Six Speed?
Some European boards discuss the 18xer engine possibility with a 6-speed swap (Astra and Vectra).

One of the issues is the very low power of the engine.


RobD1517 10-29-2017 04:01 PM

Re: A Six Speed?
[QUOTE=AstraFasta;2253814]Some European boards discuss the 18xer engine possibility with a 6-speed swap (Astra and Vectra).

One of the issues is the very low power of the engine.


The use of 6th gear being only good on the "motorway" translates to me the motorway is higher speed. I don't know about y'all, but I'm at highway speed as much as I am 35-50 mph. 50+ in 6th in my mind would be perfect, just depends on the gearing the 6 speed has.

I've done some research myself into the matter, but I don't think the 6 speed the Vectra uses is available over here is it? I know the bolt pattern on the Cruze and Sonic 1.8's are different from the z18xer, or atleast it appears that way atleast.

fdryer 10-29-2017 05:27 PM

Re: A Six Speed?
There may be some issues not mentioned besides physical dimensions for direct bolt on of this six speed auto. Early Saturns used the single PCM to run the EFI system and xmission. Electronic controlled xmissions became the next generation of xmissions. Later models required two separate modules, one for the engine and the other for the xmission, due to more sophistication. Add a third module, the body control module, and Saturns evolved along with other cars in sophistication. The problem of addressing a different xmission from another car may require asking the technical questions of whether or Astra electronics can recognize a foreign xmission and accommodate the extra gears to shift the extra gear two a stock Astra xmission doesn't have.

Will the stock ECM and TCM (transmission control module) need one or both modules (if Astras have two or three modules) updated (if they can) or if they need one or both modules from the other car to make this Astra one off workable. Then the question whether or not the other ECM/TCM will run the Astra engine. Like any complex project, the devil is in the details. To discuss some factors involved in engine/xmission relationships, the engine computer either controls xmission shifts or relegates this control to a separate xmission control module with both ECM and TCM communicating with each other at all times. Engine management deals with all the sensors needed to make an engine run. To make electronically controlled xmissions shift up and down requires more programming to use the same engine sensors like map, throttle position, spark timing, coolant temps, etc. And add xmission sensors to this mix. A lot goes on just running the EFI system. Add xmission programming and things get more complicated and thanks to engineering on many levels, we have 5, 6, 7 and 8 speed xmissions for us shiftless drivers. While a little slow to understand the need for more gears in autos, it didn't occur to me the extra gears allows for quicker off the line acceleration (lower gearing) for things like stoplight racing or more importantly short on- ramps on older roads as well as one or two over drive gears for better fuel mileage at higher speeds while cruising. Separate engine and xmission management systems working together. Xmission shifting looks at engine rpm, load (map sensor) throttle position, coolant temps and spark timing, some factors a xmission control module examines, including the xmission input/output speed sensors to make correct shifts whether stop light racing or granny driving.

If some of this seems a little overwhelming, it isn't when considering what actually goes on with electronics needed to monitor our lead foot while driving in every weather condition our cars, trucks and SUVs are subjected to. And I haven't added abs, tc, and stabilitrak.......

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