Gearbox rebuild (best possible shift).

[dcioccarelli]

I understand that this is a popular subject (even more popular than engines), but I'd like to try a new angle.

I have owned (as many of you have) several X1/9s. My 4 speed has always had a sweet gearbox (until I blew it up and snapped an axle) but then it was even perfect after the rebuild.

All 5 speed cars I have owned have been below par in my opinion. The problem is not so much the terminal issues that people concentrate on in these threads (dead synchros, slider gears and the like) but rather a lack in the precision of the shifting (in particular 3rd gear).

My suspicion lies with the shifter forks which many people fail to examine or replace. In fact, one "expert" has suggested that these should be welded and filed back in order to get the best possible shifting action. This would suggest that even the factory forks have tolerances which don't guarantee the best possible shift.

Other theories suggest using rose joints on the linkage....

I'd be interested in other people's opinions (e.g. Steve H) about how to achieve a switch like gearbox on an X.

Cheers,
Dom.

 

[Steve Hoelscher]

All 5 speed cars I have owned have been below par in my opinion. The problem is not so much the terminal issues that people concentrate on in these threads (dead synchros, slider gears and the like) but rather a lack in the precision of the shifting (in particular 3rd gear).
.

Yep. 4 speeds always feel better than 5 speeds. The cause has more to do with the shift lever than anything else.

My suspicion lies with the shifter forks which many people fail to examine or replace. In fact, one "expert" has suggested that these should be welded and filed back in order to get the best possible shifting action. This would suggest that even the factory forks have tolerances which don't guarantee the best possible shift.
.

Actually, the 5 speeds have beefier (larger/thicker) shift forks than the 4 speed. Welding up the shift forks to close up the tolerances wouldn't work for long. The forks have an anti-friction coating on them. Once you wear through the coating, the forks wear very quickly. You would have to recoat the forks after welding and even then I am not so sure that the tighter tolerances wouldn't result in the coating wearing out faster anyway. The biggest problem with 3rd gear is the use of a Porsche type synchro. They suck. As any old Porsche technician.

Other theories suggest using rose joints on the linkage....

I built a customer linkage that greatly improved shift feel and quality. I used a 4 speed shifter (which results in a 5th gear lockout) and a universal joint in place of the rubber lollipop. I also put a very stiff spring washer in the along side the shoulder washer (for preload) where the lollipop bolts to the transmission's shift rod.

The same can be done with the 5 speed shifter but it doesn't feel exactly the same. Pretty close though.

The problem with this is the hard linkage transmits a lot of vibration through the shifter.

Another big help was using a torque supressor mounted right beside the shift linkage. That really helps prevent binding.

The larger problem is; its a transverse mounted driveline that uses a linkage for the shifter. It is going to feel vague and sloppy compared to a 124 or a Miata. That doesn't mean it can't be effective. Shortening the throws can help. I also put a spacer under the shift lever and extended the lower half by an inch (equal to the height of the spacer) and that shortened up the throws considerably and that helped it feel more precise.

 

[LarryC]

What about the '79 ? It has no rubber on the linkage.

But still it can feel soft from time to time. Granted it wants to buzz and rattle when the engine is in one of its buzzy moods. Would the spring idea stiffen the linkage up? One has to wonder if Fiat noticed that and that was why the '79 went to the metal-on-metal approach, but then realized the transmission of high frequencies was too much.

 

[Steve Hoelscher]

But still it can feel soft from time to time. Granted it wants to buzz and rattle when the engine is in one of its buzzy moods. Would the spring idea stiffen the linkage up?

I tried a '79 linkage and found it no better than the '80+ linkage. If the rubber is in good condition, it has little effect on shift feel, other than reducing the buzzing.

If I had a '79, I would put an '80+ linkage in it and tighten up the top of the lollipop with a heavy spring washer.

 

[Dany]

question!

'85 x with new (rebuilt) tranny purchased at Midwest ( so you rebuilt it ). New clutch kit, lollipop, master and slave clutch cylinders...shorthened stick (matt's little adapter) 2" off

Shifting is way better than with the old transmission, BUT i still have issues:
1st gear is not alsway easy to find after complete stop from neutral. workaround: I have to put it in 2nd, friction the clutch and then it will go into 1st.
2nd sometimes wants to crunch while cornering (weird)
3rd and 4th are sometimes hard
reverse from neutral is also fleeting... (see 1st gear for workaround...)
Oil levels are fine (checked twice while adjusting link)

Damn it seems all my gears are not easy to find !
i've adjusted the links (lollipop sandwich) twice now but it doesn't fix the issues.

Any thoughts? I have roughly 2 months on this NEW tranny...

thanks!

 

[Steve Hoelscher]

Shifting is way better than with the old transmission, BUT i still have issues:
1st gear is not alsway easy to find after complete stop from neutral. workaround: I have to put it in 2nd, friction the clutch and then it will go into 1st.
2nd sometimes wants to crunch while cornering (weird)
3rd and 4th are sometimes hard
reverse from neutral is also fleeting... (see 1st gear for workaround...)
Oil levels are fine (checked twice while adjusting link)!

Well, what you are describing is a dragging clutch. If the clutch isn't fully releasing then it turns the input shaft slightly and will cause most of the issues you are describing. You said you have a new clutch. It may need adjustment or bleeding, or both.

Did you check to ensure that the top of the lollipop is tight? That's the point that causes most of the shifting problems. The bolt can be tight but the linkage still wobble at the joint. If it wobbles, that's a problem. You will need to have someone move the shifter left/right while you look directly at the joint.

 

[Dany]

thanks for the quick reply

What is involved in the "adjustment" of the clutch? are we talking taking things appart again?

As for the lollipop, I am still unsure as its use, because it does seem pointless to have a solid round piece instead of a flexible one.
I haven't really check its tightness because I don't understand its mechanics so may not be able to interpret what i'm seeing.
What I did do was check for bolt tightness at the sandwich and the other end, and that seemed ok.

It makes sense that the clutch be involved because when the second gear crunches, it's the same feeling as if the clutch was not properly disengaged, like my foot was not at the bottom of the pedal course.
I can try and bleed the clutch (both master and slave?) again, though that I haven't tried.

thanks again

 

[EricH]

Clutch adjustment

What is involved in the "adjustment" of the clutch? are we talking taking things apart again?

No.:dance:

It's all outside the transmission. With the slave cylinder spring disconnected, and your foot OFF the clutch you want the slave rod to be almost but not quite pushing on the release arm... just a teeny skosh, a millimeter or so of free play. And then when you push the clutch pedal in, you should get a full stroke that fully releases the clutch. If it doesn't, then you need to bleed the system (air will compress instead of extending the rod) and/or check the free play at the pedal to ensure that a full stroke of the pedal is giving you a full stroke into the master cylinder.

As for the lollipop, I am still unsure as its use, because it does seem pointless to have a solid round piece instead of a flexible one.
I haven't really check its tightness because I don't understand its mechanics so may not be able to interpret what i'm seeing.
What I did do was check for bolt tightness at the sandwich and the other end, and that seemed ok.

Like SteveH says, check for free play at the tranny end. But I'd bet long odds that the clutch adjustment will take care of the problem, as what you are describing is classic dragging clutch behavior.

It's described as a "flexible" coupling, but "solid, vibration-isolating" would be more accurate. The hard rubber layer doesn't have a lot of give, so you can generally think of it like you would an engine mount - rigid despite the rubber.

 

[Dany]

hey thanks

Makes a lot of sense.
not sure about the term "full stroke", but i remember adjusting the slave rod because the brand new setup was crazy. A millimeter off the floor with the clutch pedal and I was launched forward. It was WAAAAAY too low. Maybe i screwed it worse, but now the clutch response height is acceptable. Although everyone trying my car for the first time will stall because they get surprised from the clutch...

i'll work on that tomorrow! and let you know.

Again thank you