2nd to 3rd shift at DE

[Tut]

Did a DE at BeaveRun (near Pittsburgh) this weekend. Turns 10 and 11 are very similar to the toe of the Boot at the Glen. I would downshift into 2nd just before entering the uphill turn to the right. As I accelerated up the hill I would shift to
3rd. As the weekend went on I began to have difficulty making a smooth shift to third. There was no grinding, etc. I simply could not get into 3rd unless I paused briefly in neutral as I went from 2nd to third. When I did that things were fine. Usually have no problem with shifting. Was I simply rushing things too much in the heat of battle? Is this "normal vehicle function", or am I looking at a developing issue?

I have new bushings, etc., for the shifter. Also new motor mounts. Planning to install them before I go to the Glen in October. Haven't bitten the bullet for the wevo G50 transmission mount upgrade, or got the wevo shift coupler.

I won't go into the car dying during the last run of the day in turn 10. Had to leave it there to get fixed. Think the fuel pump took a dump. Thankfully two buddies were with me with their cars, so I had a ride (4.5) hours home.

Thanks.

[IROC]

I doubt this is of much help, but I have had this exact same problem happen to me twice - albeit in a mag-cased 915. The first time it was due to what I figure was excessive heat build-up due to insufficient gear oil. Topped off the gear oil and the problem went away. The second time was due to a loose shift coupling (at the coupling between the seats). Tightened the set screw (which had backed out) and the problem went away.

[aston@ultrasw.c]

x2 on checking and adjusting the linkage. Install the new bushings you have.

When I adjusted the linkage on a high mileage 85 in accordance with the manual: 3 and 4th was not great. Then I played around a little and tweaked the coupling this way and that. I was able to find a position where all gears engaged without any bulking.

Other stuff is to "blueprint" the shifter as described in the tech section. This was another big improvement, as was adding a helper spring to center the shifter in the 3/4 plane. Someone makes a kit but a spring from ace hardware with a little ingenuity and you can figure it out.

It will seem like you are doing a bunch of insignificant things but they all add up to a great shift.

However, your GB may still have an internal prob. Drain the oil through a strainer and look for metal pieces.

[Porsche_monkey]

How miles on the tranny? Might be time for a tear down...

[Matt Monson]

Did the problem go away once the tranny had cooled down and was being driven home or the next day?

[Tut]

Monkey,

59,xxx on the car/tranny


Matt,

Unfortunately, I didn't get to drive the car home. The fuel pump died on track. Had to leave the car there to be repaired, as home was 4.5 hours away. While the car was still running, if I slowed the shift down, with a brief pause in neutral on the way from 2nd to 3rd, there was no balking.

Mobil 1 75w-90 in the tranny, by the way.

[Porsche_monkey]

Higher mileage and I would say it needs a rebuild. At 59,000 I would hope the problem is outside the tranny, not inside.

Shift coupling or engine mounts maybe. I guess you need to remove the shift linkage, rebuild it what's worn, re-set the shift and hope it works better next time.

Could be a synchro issue if that doesn't solve it.

[ChrisBennet]

Originally Posted by Tut

Monkey,

59,xxx on the car/tranny


Matt,

Unfortunately, I didn't get to drive the car home. The fuel pump died on track. Had to leave the car there to be repaired, as home was 4.5 hours away. While the car was still running, if I slowed the shift down, with a brief pause in neutral on the way from 2nd to 3rd, there was no balking.

Mobil 1 75w-90 in the tranny, by the way.

Try Swepco. Synthetics are said to be too slippery for these transmissions.
-Chris

[Porsche_monkey]

I missed the synthetic part. Chris is correct.

I would drain it, dump in Castrol and try that. Switch to Swepco when you are sure the tranny is okay.

[175K911]

Originally Posted by Tut

Mobil 1 75w-90 in the tranny, by the way.

Definitely loose the Mobil 1. I tried that back in the early 90's and hot shifting on the track was nearly impossible. Might be passable for street but not for track duty. Loose it and put in Swepco.

Also as others have suggested, check all 4 engine/trans mounts. The chassis is really torqued in a high rpm 2nd gear turn and if the engine/trans is moving even a small amount, could make it tougher to shift. Several of the tracks I run (blackhawk, Mid-O, VIR, Autobahn etc) require 2nd in several places, with a shift to 3rd before the trackout. 4 new Sport trans mounts from our host, and fresh Swepco 201 made a noticable difference.

[Tut]

Chris and Monkey,

The Swepco suggestion is opposite of what I've read about G50s. See Tyson's comments in this thread:


http://forums.pelicanparts.com/showt...hreadid=245911
__________________

[s5uewf]

I think people are assuming you have a 915 trans and you seem to have a G50.

You should be using Mobil 1 and never use Swepco in that trans. I use Mobil 1 in my 1988 G50 and it works fine.

I have gone to semi solid/poly trans mounts and wevo engine mounts and it did make my shifting better at DE's and on the street - not much more noise or vibration, either.

I have had to replace my cup bushing under the stick shift before - it was worn and cracked and was preventing me from being able to shift correctly. You may want to take a look at the shifter mechanism under the center console. The rear linkage for your G50 is at the end of the tunnel near the rear seats. I don't think there is a lot to do back there except check it. If the linkage is solid then I would not mess with it.

Are you sure your clutch is disengaging all the way? That could make shifting hard.
Maybe youneed to bleed your slave cylinder on top of the trans (reach up from underneath). It is hard to reach but may need a check - especially if youhave been flushing your brakes before DE's etc. - I think the clutch uses the same master reservoir as the brakes and you may ahve introduced air into the line there. I'd check this as part of your diagnosis.

The G50 is supposed to be quite solid and more robust than the 915, so I'd look for external causes given no grinding, etc.

good luck

[Porsche_monkey]

I thought it was a 915. My error. I guess 87's are G-50's?

And I automatically assume transmission issues are 915 related.

[175K911]

I thought it was a 915 too. Just didn't read the original post thoroughly enough. Can't speak to fluids, but the engine and trans mount suggestions still stand.

[Tut]

Yes, it's a G50.

Thanks for the input.