how to: itr tranny rebuild and upgrade

[Black R]

pic for reference:





Unfortunately, that spacer is a sleeve and spacer combo that rides on the mainshaft with needle bearings between it and the gears (inside of them). Besides, even if I were to spacer the 4th gear up on the mainshaft - that would present a problem because the teeth on the bottom of 4th have to mesh with the syncro and sleeve set...

No, it appears that either ATS requires a different sleeve on spacer for 4th and 5th gear - OR just that 4th gear on the countershaft is very wrong somehow.....

I have emailed Yasu @ ATS/ ACROSS and await his reply.....


Here's what he says:

That gap is I think normal.
The old 4th had a slightly different dimension. The gap between 4th
and 5th was 4.2mm for the old model and the gap for the current ones
is 1.2mm.You can run them, but as I mentioned the old 4th is not strong enough.
I would suggest to purchase a new 4th which is reinforced with temper
shot and which is slightly different dimension.

Best regards,
Yasu

[Black R]

I got a chance to swing by Galaxy Machine and my friend Jenson helped me out there.....

First we checked the oem 4th gear on the mainshaft side (left) vs the ats one (right).
Now it is clear to see why ats decided to redo the gear and have a new part number... the clearances are totally wrong for this thing... :crook:



fwiw, the new ats 4th gear has a gap to 5th of 1.2mm versus the 4.2 that you see here. :crook:


Next you can see the countershaft side ats 4th gear on the left vs the oem itr 4th gear on the right... the dimensions are almost identical. Just a different number of teeth makes the ats 4th gear have a more agressive ratio:




Even though 4th gear on the mainshaft side is the part that's wrong, there's really nothing we can do to it without screwing up clearances somewhere else... so we look to the countershaft side 4th gear piece and see if we can't modify it to make up for the problem...

Solution: machine it down at the underside of the gear where it's really just a spacer anyway... THEN space 5th gear on the countershaft to line up again once 4th is at the correct height.

So here's 4th countershaft piece getting material removed from it:



See the tiny carbide bit?


Grinding:


And now the spacer is going to get made from some steel stock:




Machining the spacer now:


Removing burrs from both pieces:





And since we had to disassemble and reassemble it several times to check clearances, it kept getting easier to do...

Now what? Well it's still not perfect like I'd like it, so I may have another go at it. Total material that needed to come off was 3mm. I think only 2mm came off because the measurements on the machine were thrown off... why? Well the gear is so hard that it actually eats up the bit. This throws off the measurement on the machine. We had to have a couple of tries to get it this right. It's better to take off too little than too much and have to space it back up.

Here's how it sits now:


I'd estimate that 4th and 5th will still be a bit off once the spring clip pulls up on the countershaft when it's in the case. I'm going to double-check the clearances again and we'll have another go at it to get it perfect. =)

We're getting there though - and if worst came to worst I could get it all back together and drive the car like this. But of course I want it dead solid perfect!

[Black R]

Oh, here's the ratios of the gears if you're curious:

1st = 3.077
2nd = 2.105
3rd = 1.652
4th = 1.308
5th = 1.033

1st -> 2nd = 0.684
2nd -> 3rd = 0.784
3rd -> 4th = 0.792
4th -> 5th = 0.790

0.784 * 8500 = 6664 rpm

rpms will be between 6600 - 8500 the whole way (except 1st -> 2nd)

actually, the rpm drop will be moved to a higher window - as the rev limiter is 9500... A 9200 shift point should land it around 7200 in all of the upper gears.


Compare this with the jdm and usdm gearing...


usdm itr:

1st 3.2310
2nd 2.1050
3rd 1.4580
4th 1.1070
5th 0.8480
final 4.40


jdm itr:
1st 3.2310
2nd 2.1050
3rd 1.4580
4th 1.0340
5th 0.7880
final 4.7860

[Black R]

More progress:

Machining the 4th gear another mm or so:





Measuring the inner ring of 5th gear on the countershaft side for a custom spacer...



J, making cnc program to do a new snap fit spacer to keep the correct distance between 4th and 5th:









Then he sets up the cnc machine and the bits that will be used:



























Custom spacer done (17-4 stainless steel):





Checking the fitment:



Final once-over on the gear to get the burrs off:



Finished:

[Black R]

Here's some more info on the tranny and gearing + costs.....

B18c5 tranny with ATS final drive and ats 1,2,3,4,5 gearset:

Gear Ratio Final MPH @ 9200 RPM @ 80 MPH

1 - 3.077 - 15.18 - 42.2 - 17423
2 - 2.105 - 10.35 - 62.0 - 11879
3 - 1.652 - 8.13 - 78.9 - 9334
4 - 1.308 - 6.46 - 99.3 - 7410
5 - 1.033 - 5.08 - 126.3 - 5827
Axle ratio - 4.929
Tire diameter - 23.44" (I did this with a 205/50/15 tire as an example.)

ATS gear ratios can be found here:

http://www.a-t-s-usa.com/ats-p...shtml


Here's an online calculator, so you can do your own comparison's:

http://www.xse.com/leres/ss/calculator.html


Cost, iirc was something like ~$800 for the gearset from a 'reputable' individual seller; but I couldn't use 1st because it was for a 4.4 final. So I had to buy a new ats 1st gear for 4.9 final ($350) and I also had to machine the 4th gear down and modify it. My buddy did those modifications for free, but I gave him a few $ for his trouble anyway. New, the gearset is in the $1200 range iirc, but then again MFactory sells a similar gearset for a lot less $. I'd look into that if I had it to do all over again.

Bearings, syncro sets, seals, and shift forks, etc, ended up costing me over $1k by the time it was all said and done.

The ats 4.9 final drive and ats lsd I already had from before I blew up the clutch. So if you wanted to have a full ats tranny like this, you're looking at a lot of $ retail.

Is it worth it? Probably not. :P

[Black R]

update:
















































well it's done! Right after finishing the install, I went to fire it up and check everything and noticed the radiator was squirting out a little fluid...

So I got hooked up with a new radiator from MainStreamPerformance.com and installed it.

I adjusted the clutch throw (by adjusting the cable) and nearly had a heart attack when it wouldn't go into any gear..... luckily I just needed to adjust the cable a little tighter. *whew*

Well I drove it 60 miles that evening... in lower rpms the drop between shifts is only 500 rpm's.

I cruised home at 70mph (5150rpm).

I'd say it's not *that* agressive.....

[Black R]

i'll try to go back and put up the final pics as well as all the thanks to Craig (AssPenny) for the picture hosting through http://www.we-todd-did-racing.com, Galaxy Machine for the machining of the gear, Len @ Baranco, Mike and Charles @ http://www.mainstreamperformance.com, Ben (IN VTEC) for his support and help, and of course Willard and everyone else here who contributed.

I've had a chance to daily drive the car for a while and rip on it down the hwy with some friends, street tune it a bit, autox an event, and even take the motor to ~10k...! It's safe to say that it's working well!

I'll refine and get a final version up with torque specs in a bit. :thumbup: and thanks again!