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Need help from a trans builder on 2-3 shift

Old Feb 12, 2005 | 10:50 AM
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Default Need help from a trans builder on 2-3 shift

I have the TransGo 4L60E-HD2-B kit installed in my '02 camaro ss.
It has a stock converter, the car is stock with just a lid and loudmouth exhaust.
The problem is with the light throttle 2-3 shift, it's too soft or overlapping second (if thats the word). It feels like it slows down for a split second befoe it completes the shift, rpm does not rise, it drops.
Now at higher throttle it's fine and all shifts are firm and quick. It's just at lower throttle 2-3 is weaker than the others.

I do have HP Tuners and changed the shift time and duration, didn't mess with the pressure charts.
With a gauge the max line pressure, usually right before shifts hits 250 psi.
Same with a stall test 250 psi max.

The transmission has never been out of the car.

The shift kit specs are...2 band adjust shims, the servo cover will push in approx. 3/16" with this set up.

It has a 700R4 1-2 accumulator which is shorter than the stock one and it has one washer.

The fourth accumulator feed hole has been blocked with a plug.

It has the factory vette style servo and the new .500 boost valve from the kit.

Plate hole sizes are ....A 3rd .110; B second .093; E fourth .110, All others are .093 as instructed in the kit.

I'm wondering if the third accumulator feed that pushes the band off needs to be modified, if so what hole is it?
Or does the problem need to be addressed properly by pulling the trans out and adjusting the 3-4 clutch?

Anyone know if the typical 3-4 factory clutch clearance is too big?

What should I do to get the 2-3 shift firm and short?
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Old Feb 12, 2005 | 01:18 PM
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Do a little test to see if the problem is in band release or in 3-4 clutch apply. In drive accellerate at a rate where you get a 1-2 shift at about 20mph. After the shift punch it for a 2-1 downshift. If the engine lugs and the trans stays in second for a moment then you can focus on the band.

If the band is not releasing quickly enough for the 2-3 shifts you will feel a moment of fourth gear in between second and third. If it's only doing it at low throttle it's not a danger to anything, but if you feel it with moderate throttle or WOT it will burn the 3-4 pack up prematurely.

Check play on band:
The TransGo comes with shims for the second apply piston. You say you've got two in there. The instructions describe how to use a screwdriver to wiggle the band back and forth from the bottom to check it. Make sure that is right.

There are a few other things that can screw up the synchronization, but start with that I think.
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Old Feb 12, 2005 | 02:18 PM
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James,
I can tell you it shifts fine in the tests you describe.
The servo shims are the big ones, I've seen the ones that go around the apply pin in place of the spring, I don't have these, mine has the spring still and an inner spring from the kit. These shims are the ones that are the same diameter as the servo itself.
Even with two I thought by wiggling the band and also by pushing the servo cover in that it was too loose. (the two ways I check).
But 1-2 is quick.
2-3 at hard throttle is perfect, but it's real lazy at low throttle.

This is the first 4L60E that I put a kit in, I've done several 700R4's with the transgo 2&3 kit but those were built from cores and I would be sure the 3-4 clearance was close to .040.
They always had a strong 2-3 shift. Maybe this is leading me to believe the 3-4 clutch clearance is too big.
But now I'm starting with a low mileage car that I really don't feel like taking the trans out of, and from what I hear the stock clearance is in the .040-.100 range.
I'm also prepared for the honest truth, if you think I should start from the inside out and get the clutches right, then I'll do that. Thanks.
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Old Feb 12, 2005 | 02:55 PM
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Does the part throttle 2-3 shift feel like a bind? In other words, do you have the sensation of your head being thrown forward slightly when this happens? Let me know?
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Old Feb 12, 2005 | 03:55 PM
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Originally Posted by Pro Built Automatics
Does the part throttle 2-3 shift feel like a bind? In other words, do you have the sensation of your head being thrown forward slightly when this happens? Let me know?
Yes exactly!
But, it's not as bad as it may sound. It doesn't feel like it lets go because the rpm doesn't flare.It feels more like the car slows down for a split second during the 2-3 shift.
Now if shifted manually it does ok.
And it does it only at normal throttle maybe up to 25% tps. It's very annoying to me and I'd really like to make it feel right.
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Old Feb 14, 2005 | 04:44 AM
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The 2nd gear release hole needs to be enlarged from .093 to .110, and at the same time the 3rd gear apply hole needs to be enlarged from .093 to .125 with a 12" torque converter. If you are using a 10" or smaller torque converter the 2nd gear release hole needs to be enlarged from .110, to .120 the 3rd gear apply hole needs to be enlarged .155. Also enlarge the 4th gear feed to .125 with 12" TC, and to .155 with 10" or smaller TC. If you have any questions on this, call me at 800 7763288 anytime past 11am PST. This should solve the 2-3 shift problem. If you have a "flare" on the 2-3 shift, then differeny settings are needed.
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Old Feb 14, 2005 | 06:05 PM
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Thanks ProBuilt.
I don't have a manual though and don't know which is the second release hole. I would give you a call but it might be difficult to explain so I put the plate instructions page on my website HERE.
I'm assuming the holes they label as 2nd, 3rd and 4th are feed holes.
Which is the second release?
Thanks for taking the time to help me, I do appreciate it very much.
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Old Feb 14, 2005 | 10:20 PM
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The "D" hole is the 2-4 band release hole.
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Old Feb 15, 2005 | 05:56 AM
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Thanks, I'll let you know how it works out.
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Old Feb 16, 2005 | 10:05 PM
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Dana from Pro-Built is a class guy. He has been a big help to me in getting my trans rebuilt. Since he's in Cali and I'm in NC the work was done locally. We bought the parts from him. He spent a lot of time on the phone with my tranny guy. It's over a year Dana and it's still is running great.
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Old Feb 17, 2005 | 08:14 PM
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Well it didn't help. I drilled the holes as instructed. Shifts are more firm, but it still slows down a second before it hits third.
It only does this at low throttle and I don't like it because it's softer than the rest of the shifts.
Now there is one spot in the low throttle range that it will shift perfect.
High throttle shifts are all firm.

Now as far as the 2-4 band adjustment.... ProBuilt mentioned in another post that using both servo shims is not common, I had to use two to get it right.
But I took those out after drilling the holes and driving it for about 35 miles and nothing much has changed.
I don't know what to do now. If I had the time I would pull the trans out and look at the 3-4 clutch clearance.
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Old Feb 18, 2005 | 05:53 AM
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OK, I changed the upshift pressure modifier for 2-3 using HP Tuners and it seems to shift good now.
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