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Reading all this I'm beginning to think that the rebuild was not
done to "old world standards" :cry:
 

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Discussion Starter · #62 ·
the 2nd gear in these trannys are not the best.( remember its a german tranny,, and they might still have some hurt feeling after the last war lol ).. before you put new oil in the tranny, flush it out with paint thinner... stuff the rear of the car in the air.. stuff it in 3 or 4th gear.. rotate the rear wheels so the drive shaft will rotate.. do a lot of rotations. let sit overnight..drain all the thinner out...then refill with correct oil
Right but the whole point of rebuilding the tranny was the fix he second gear crunch. It's got a new synchro, dog gear and everything. Everything was pretty straight forward too so unless I got a defective synchro, I'm not sure what could be wrong with the gearbox that would solely be causing this.

I also filled it with redline 75w-90NS at the rebuild so the fluid should be good...
 

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Discussion Starter · #63 ·
Yeah, that didn't seem right to me. A lot of folks (including me) have installed slave cylinders over the past few years, and this is the first I've heard of that being an issue.



Something doesn't make sense here. If the clutch was engaging with your foot almost all the way up before the mod, then it seems like you had plenty of throw and were getting plenty of clutch disengagement when you pushed the pedal. Extending the rod should've increased the throw such that the engagement point would move UP, not down, right?

Am I misunderstanding something here? If the clutch was releasing near the top, there's no way you should've gotten gear grinding with the clutch all the way down. That suggests you had plenty of clutch throw and no slave problem.

Reverse will always grind from neutral on a Spider unless you wait a few seconds to shift after pushing the pedal down. Second will typically grind if you shift too fast, or on downshifts. I'm not sure you had a clutch disengagement problem to start with: can you clarify how you determined that?
Not exactly, as the longer rod isn't pre-engaging the clutch at rest, all it does is give you more total clutch travel per pedal press. Your pedal travel stays the same but you get more for each press. This means more distance between the extremes and the clutch disengaging point moving towards the middle rather than the extrememes.

I'm still suspicious as a new clutch should disengage by the floor...

As for determining it was the clutch, when second and reverse would engage the car would shudder as if I was trying to send power to the wheels. At first I had quite a bit of air in the slave as I didn't bleed it with the nipple at 12 o clock but now all the air is out. There was still play so I kept tracking down play issues until I got to where I am now. The clutch didn't feel right either with engagement so that was another give away.
 

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Hydraulic travel does not increase every time you depress the clutch. Once the air is out, the rod will just allow the t/o bearing to touch the pressure plate. The only way to increase travel is to lengthen the master cyl rod raising the pedal moving more fluid and then increasing slave throw. Good luck
 

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Discussion Starter · #66 ·
Reading all this I'm beginning to think that the rebuild was not
done to "old world standards" :cry:
This was the first tranny I've ever rebuilt so I don't put it past me to have messed something up, that being said I did follow the shop manual for everything and took my time, and quite frankly everything was simple enough, I'm not sure where I could've messed up. I used all new synchros, new dog gear for second, and modded first gear for the crunch from neutral fix. Once everything was sealed up I filled it with redline 75w-90NS.

In other words, I'm sure I could have messed something up, but what could be messed up that could only cause 2nd to crunch and not the others. The rest of the tranny shifts like a dream and makes no noise what so ever. Any gear misalignment would whine, gear selector issues and first would be unusable, etc. It really feels like it did before I rebuilt it, which makes no sense as the synchro and dog gear are brand new... Unless one of these some how broke during the install.

My last theory is maybe some transmission fluid spilled out from the breathers/ top of the tranny so the fluid is a little low? The tranny hasn't leaked from any of the seals.
 

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Discussion Starter · #67 ·
Hydraulic travel does not increase every time you depress the clutch. Once the air is out, the rod will just allow the t/o bearing to touch the pressure plate. The only way to increase travel is to lengthen the master cyl rod raising the pedal moving more fluid and then increasing slave throw. Good luck
Increasing the length of the clutch slave rod does this, it has more rod to push giving it increased travel. I was just trying to describe how lengthening that rod doesn't raise the engagement point but actually will shift it to the middle.
 

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This was the first tranny I've ever rebuilt so I don't put it past me to have messed something up, that being said.............

I got to give you credit. A transmission rebuild I would never attempt.
Scares the hell out of me...
 

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Not exactly, as the longer rod isn't pre-engaging the clutch at rest, all it does is give you more total clutch travel per pedal press. Your pedal travel stays the same but you get more for each press. This means more distance between the extremes and the clutch disengaging point moving towards the middle rather than the extrememes.
I don't think that's right. If you install a longer slave rod, the total slave rod travel (how much the end of the rod moves) doesn't change: pushing the pedal to the floor gives you the same throw in the rod. What changes are that the minimum point and the maximum point both move rearward by the same 5/16".

With a longer rod, the clutch lever arm starts out closer to the release point (because you're already engaging it that extra 5/16" or whatever at rest). So with a longer rod it should take less throw on the pedal to reach that point and disengage the clutch, and the engagement point should move up, not down.

Anyway, if the clutch was really disengaging at the top of the pedal as stated, then the slave throw doesn't appear to have been the problem: you had plenty of extra pedal distance to fully disengage it. I think you may have been chasing the wrong problem.
 

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Here's a way to think about it: let's say you lengthened the clutch slave rod by a lot, like an inch or something. With a rod that long, the clutch would be disengaged with the pedal at rest: the clutch lever arm would be in the same position it would be with a normal length rod and the pedal on the floor.

Again, longer rod moves the engagement point up, not down.
 

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Discussion Starter · #72 ·
I don't think that's right. If you install a longer slave rod, the total slave rod travel (how much the end of the rod moves) doesn't change: pushing the pedal to the floor gives you the same throw in the rod. What changes are that the minimum point and the maximum point both move rearward by the same 5/16".

With a longer rod, the clutch lever arm starts out closer to the release point (because you're already engaging it that extra 5/16" or whatever at rest). So with a longer rod it should take less throw on the pedal to reach that point and disengage the clutch, and the engagement point should move up, not down.

Anyway, if the clutch was really disengaging at the top of the pedal as stated, then the slave throw doesn't appear to have been the problem: you had plenty of extra pedal distance to fully disengage it. I think you may have been chasing the wrong problem.
While what you're saying makes sense and was my same thought at first, the fact that this didn't happen disproves it. The way I see it is that the clutch isn't engaged in either instance (lengthened or shortened), but the rod does rest on the clutch regardless (Think like brake pads on your calipers), as such the minimum point is the same , only the maximum point changes. If I did lengthen it enough to engage the clutch at rest then yes, the minimum point would have changed, but since I still have some play if I push in on the rod it hasn't. Since the lengthened rod still has travel to push back into the slave, the total travel is greater as the rod is just starting a little closer to the slaves cylinder. That's at least how it makes sense to me. With visual inspection, the clutch is getting pushed farther in than it used to.


Either way, the question still exists:
1) The clutch and flywheel are both brand new, the clutch should engage close to the floor, why didn't it?

And even if the disengagement was not the problem, poor clutch engagement was a problem and this did solve it.
 

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Discussion Starter · #73 ·
On the topic of disengagement, how far back should the clutch fork be in the bell housing when the clutch is disengaged? mine still has about 1/8th in to go before it would hit the bell housing.
 

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If you want the clutch to release off the floor shorten the master cylinder rod. This will also lower the pedal. Good luck
 

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draw the free body and force diagram and you will see what is happening. Ive never had a fresh clutch (with the arm adjusted correctly) release at the floor. I would never want that.

Remember that the rod throw is completely defined by the master cyl piston travel. Now, if the fork needs to take up some slack prior to getting into the sweet spot of beginning deflection of the spring arms, you are wasting some of the throw. Thats the idea here - by making the rod longer, it will take up some of the free slack == and it sure doesnt have to be much to have an effect
 
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Discussion Starter · #76 ·
Exactly this, thanks for explaining that better than I could. As for the pedal engaging near the floor, I don't want this either, however, a new clutch is thicker therefore would have less "space" between engaged and disengaged, so the engagement point should be closer to the floor then the old worn clutch.

Before the rod modification the brand new clutch was engaging at the end of the pedal travel, why?

I'm certainly not the first to replace a clutch so what caused this issue in the first place. The mod I did moved the pedal engagement to somewhere good but why was I the first to run into such a thing
 

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Here's a way to think about it: let's say you lengthened the clutch slave rod by a lot, like an inch or something. With a rod that long, the clutch would be disengaged with the pedal at rest: the clutch lever arm would be in the same position it would be with a normal length rod and the pedal on the floor.

Again, longer rod moves the engagement point up, not down.
6 mm not an inch
 

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Remember that the rod throw is completely defined by the master cyl piston travel. Now, if the fork needs to take up some slack prior to getting into the sweet spot of beginning deflection of the spring arms, you are wasting some of the throw. Thats the idea here - by making the rod longer, it will take up some of the free slack == and it sure doesnt have to be much to have an effect
Yes, this is correct, the extra length takes up the free slack. So with the pedal & MC starting in the same place you don't need to push the pedal as far to disengage the clutch, so the pedal release point should move up.

Why'd it move down? Heck if I know. Maybe you changed something else when you did the job. Maybe air got into the system or the MC is bad or something. But if the clutch was releasing at the top of its travel before you did the mod then I don't think the slave travel was your issue: it seems like there's something else going on.

If you weren't getting enough throw in the clutch system (say, due to air in the system or something) the symptom of that is that the clutch pedal releases very low, if at all. Not high.
 

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you fix it, then it becomes more, complicated.... wonderful.... can you drive the car now? reverse and 2 nd gear is a systemic alfa romeo/zf gearbox problem,, always has, always well...there are some fixes for the second gear problem.. but leave that for a later day..have fun/ drive your car.. perhaps in the future, you will come across a extra tranny.. take your time and build that one with all the experince that is here, for your taking
 

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And a note: it can be a challenge to get all the air out of the clutch hydraulics on these cars. Most importantly, the slave bleeder needs to be rotated to the top while bleeding.

The other problem that can get you is if you measure you'll see that the MC likely slopes slightly up to the front of the car (and it definitely slopes up when you've got the front jacked up to do a bleed). Thus you can get a bubble of air in the front top of the cylinder that is difficult to get out.

What I do is bleed the clutch normally first at the slave. Then I lower the front, jack up the rear of the car really high, and jiggle the clutch pedal for a while. This moves the bubble to the rear of the MC where it can escape into the reservoir...you'll likely see some tiny bubbles when you do this.

Not sure if that's part of your problem (again, air in the hydraulics would cause low release) but figured I'd mention it.
 
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