So I just recieved an Si/EX (92-95) tranny for my weak *** CX engine. The seller is a great guy, but apparently he never used it and he bought it from another guy... So the problem is I don't know if it's a Si or an EX tranny, or which year it is. I'm positive it is the tranny for a Z6 engine though, only due to the P20/B000 stamp located above the filler plug.. (as mentioned in Mista's tranny page )

Since I now have the tranny lying on the garage floor, I was hoping I could get some help identifying the gear ratios.. I saw a picture somewhere showing that if you turn the mainshaft in a certain gear, you should see the differential spin a certain amount along with it.. And you can tell the approximate gear ratios just by spinning the mainshaft. I hope that makes sense!

Please, any help is appreciated. Can't find any batteries for this damn camera, so I can't seem to get any pics... (I could use my cell phone, but it sucks)

 

this is for the cable driven trannies. you just differentiate by final drive since 1st gear is the same on all d series.




isnt 92-95 Si and EX trannies the same??? youve already identified it by the p20-b000

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tyson &raquo;</TD></TR><TR><TD CLASS="quote">
isnt 92-95 Si and EX trannies the same??? youve already identified it by the p20-b000</TD></TR></TABLE>

some were out there a rumor was started that the SI and EX trannies were different, i have yet to see any one prove it though.

 

hmmm my resource says the difference is in 5th gear...

"0.750 Si HB & Del Sol Si / 0.702 for 2dr & 4 dr"

interesting.

so i guess you can stick it in 5th and calculate the difference in rotations.

 

Thank you Tyson! That's exactly the diagram I was looking for! After spinning the mainshaft 10 times it looks like it has the 4.25 FD along with the 3.25:1 1st gear. So it's definitely a Si/EX tranny.

Now all I need to figure out is which 5th gear does it have?

Like you said (Tyson), I could use the same technique to figure out the 5th... But I'm not exactly sure how I would calculate it?

 

Maybe try putting it in 5th, counting the turns and dividing by the known final drive.

 

Hmmm.....

Well let me tell you what I just tried. Before I begin, you should know that I'm a dumbass when it comes to math. I'm in college taking GE classes right now, but I've been putting off math because I'm so retarded.

Anyway.

So I just tried this method.

I counted how many mainshaft turns it would take for the axle input to make one complete revolution in 1st gear. It took ~13.8 turns.... I then multiplied the Si/EX 1st gear ratio (of 3.25) by the FD ratio of the Si/EX (4.25) and I got 13.8125 - which is exactly how many mainshaft turns it took for the axle input to make one complete turn.

SO, according to this weak sauce theory. If my tranny is an Si tranny, it should take 3.1875 mainshaft turns in 5th gear to make the axle input turn once. If my tranny is an EX tranny, it should take 2.9835 mainshaft turns in 5th gear for the axle to turn once.

Let's see if this works....


Modified by MrTodd at 2:40 PM 10/31/2005

 

HeY i WAs riGHT!!

I ended up spinning the mainshaft (in 5th gear) ~2.95 times to make the axle input spin once. Turns out I have an EX tranny!


I totally just learned something new, but I'm sure there are plenty of other people on this board that have figured out methods similar to this. But according to this, you can identify ANY tranny's gear ratios without taking it apart. Hopefully someone else can benefit from this as I have.

Thanks again for the help everyone!

 

no problem.

now id like to see someone with a known Si tranny check if 5th gear is any different...

 

the Si/EX tranny's have the same 5th gear. the oddball is the del sol with the z6 motor has the .750 5th gear. i've got one of each in case you were wondering.

nate - likes the .750 5th but wishes it were in the racecar and not the dd, though the dd did just pull 38-40mpg doing 85+mph on the highway