Gearbox locked

[Steve Hoelscher]

Bjorn, forgot to mention, the broken synchro crescent spring pad is not common. Most likely the result of a badly missed shift, or the transmission popping out of gear.

It would have been interesting to see how that broken pad could have jammed the slider in place. Thinking through how it works if the parts were still captive inside the synchro ring I don't see how it could have done that.

Usually, such things are accompanied by a bent shift fork or a blown up synhcro ring.

 

[Bjorn Nilson]

It would have been interesting to see how that broken pad could have jammed the slider in place. Thinking through how it works if the parts were still captive inside the synchro ring I don't see how it could have done that.

It looks like the pad was worn as well. It was shiny and much flatter than to my replacement part. I think a part of it slipped in through the gap under the synchronizer ring and got squeezed there. My theory is that in such case it would have caused a heavy pressure on the sleeve, so heavy that it got stuck in gear. This in combination with the missing interlock plunger on the selector shaft caused the gearbox to lock when shifting to another gear.

I find the work with the gearbox extremely interesting and I am eager to learn more. So today I removed the sealing cover on the donator box (that now has become my sand box) to find out more about preloading the diff. The cover and shim came out w/o problems but I had to use the hydraulic press to remove the bearing. That can't be normal? I expected this bearing to be removed by hand/little force just like the others? There is no way to shim it correctly if a hydraulic press is needed to put the bearing in place? I am going to build a simple tool similar to FIAT A95655 to be able to shim the bearing correctly when time comes.

 

[Steve Hoelscher]

I find the work with the gearbox extremely interesting and I am eager to learn more. So today I removed the sealing cover on the donator box (that now has become my sand box) to find out more about preloading the diff. The cover and shim came out w/o problems but I had to use the hydraulic press to remove the bearing. That can't be normal? I expected this bearing to be removed by hand/little force just like the others? There is no way to shim it correctly if a hydraulic press is needed to put the bearing in place? I am going to build a simple tool similar to FIAT A95655 to be able to shim the bearing correctly when time comes.
View attachment 54818

One of the things I was thinking was; if the pad had jammed up and over the spring it could bind up the slider.

As for the differential bearing preload; welcome to my world. Most bearing failures are from people ignoring bearing preload but many are caused when people try to set the preload but get it wrong. Its far easier to mess it up than get it right.

 

[Bjorn Nilson]

One of the things I was thinking was; if the pad had jammed up and over the spring it could bind up the slider.

As for the differential bearing preload; welcome to my world. Most bearing failures are from people ignoring bearing preload but many are caused when people try to set the preload but get it wrong. Its far easier to mess it up than get it right.

It looked like the broken and worn pad jammed under the spring, at the spring gap/opening.

Yes, I realize the importance of correct bearing preload and somewhat understandable that some people are ignoring it and hoping for the best. However, a quick and dirty job is not my style, and I would like to do this job as well as I can.
But I assume the bearing must be able to move (with a little bit friction) in the gearbox case? And then the shim should keep it in position with correct preload. If a hydraulic press or a hammer is needed to install it something must be wrong?

 

[Steve Hoelscher]

It looked like the broken and worn pad jammed under the spring, at the spring gap/opening.

Yes, I realize the importance of correct bearing preload and somewhat understandable that some people are ignoring it and hoping for the best. However, a quick and dirty job is not my style, and I would like to do this job as well as I can.
But I assume the bearing must be able to move (with a little bit friction) in the gearbox case? And then the shim should keep it in position with correct preload. If a hydraulic press or a hammer is needed to install it something must be wrong?

I could see it happening that way too. Either way would expand the synchro and lock it in the groove. Odd to see that failure though. It takes a lot to break one and they are stronger than the spring or synchro. I assume it must have been previously damaged, or perhaps installed incorrectly, which caused the break.

The bearing race is a light press fit in the case. If a hand fit it will spin in the case and that's a major problem. You will have to fit the race and seat it against the bearing to determine preload.

 

[Bjorn Nilson]

I finally got the gearbox reassembled and everything seems to be well. As I wrote, some parts were broken and missing which probably caused the gearbox to jam. As I don't trust the previous rebuild, and I use a paper gasket between gearbox halves, I would like to adjust the differential bearing preload. Currently, I have a big play in the bearing so it must be settled. I have a 20-ton press, but its gauge is starting at 500 kg so it is far too heavy to settle the bearing at 350 kg (770 lbs). I've been in contact with workshops in the neighborhood to get some help, but none of them have a press small enough to do this job. I do not trust the "feeler gauge method" so are there alternative ways to solve this issue?

 

[Dr.Jeff]

I wonder if it can be accurately measured by the rotational torque needed to turn it? That's how some similar applications are checked but I do not know if it would be appropriate here.

 

[Jefco]

I remember seeing Edd China set pinion preload with a spring scale and leverage arm (like 10" long, for ease of calculation) on an assembly.
Don't remember exactly what the preload was, though; something like 20 in/lbs.
'Settling' didn't seem to be part of it, though. Where does the 350kg come in?
Is your bearing not seating in the housing?

 

[Bjorn Nilson]

I remember seeing Edd China set pinion preload with a spring scale and leverage arm (like 10" long, for ease of calculation) on an assembly.
Don't remember exactly what the preload was, though; something like 20 in/lbs.
'Settling' didn't seem to be part of it, though. Where does the 350kg come in?
Is your bearing not seating in the housing?

350 kg is the preload that should be set according the service manual. The bearing and its cone is mounted in the housing, but the cone is approx 1mm away from the bearing rollers.
I think using some kind of clamp to press in the cone would be possible (350 kg is not very much) but how to measure the pressure?

 

[Jefco]

I've looked at the procedure; I see your question more clearly now; apparently, rotational torque can't be measured easily here.
So Bjorn, you have tool A.95655?
Even without, if you can arrange to measure it accurately with the dial gauge, simply stop when the readings stop changing and use that for the calculation (-0.1mm[+- 0.02] for interference fit, as required). This assumes the measurement will stabilize before 350kg (or thereabouts) is reached.
If I were doing it, I'd use both methods (dial and feeler) and see if they agree (they should).

 

[Dr.Jeff]

I just reviewed the procedure in the manual.

First, it says you can do EITHER the "feeler gauge" OR the "dial indicator" method, so I'm sure using a feeler gauge is more than sufficient. And it does not require the special tools that you would have to rig together.

Second, with the dial indicator method, the "pressure" that is noted isn't to adjust the preload, but only to make sure the bearing is fully seated in the bore before measuring with the dial. The reason the "feeler" method does not need this step is because the "retaining flange" is installed with the method, so it will fully seat the bearing. Therefore if you wanted to do the dial indicator method but cannot measure pressure, I imagine you could install the bearing with the retaining flange torqued to fully seat it, then remove the retaining flange and use the dial indicator.

However I'd just do the feeler gauge method personally.

 

[Bjorn Nilson]

So Bjorn, you have tool A.95655?

I will attach a dial gauge to a plate that I've made. It will work more or less same as the A.95655 tool. My only problem is applying correct pressure on the bearing cone.

 

[Janis]

I finally got the gearbox reassembled and everything seems to be well. As I wrote, some parts were broken and missing which probably caused the gearbox to jam. As I don't trust the previous rebuild, and I use a paper gasket between gearbox halves, I would like to adjust the differential bearing preload. Currently, I have a big play in the bearing so it must be settled. I have a 20-ton press, but its gauge is starting at 500 kg so it is far too heavy to settle the bearing at 350 kg (770 lbs). I've been in contact with workshops in the neighborhood to get some help, but none of them have a press small enough to do this job. I do not trust the "feeler gauge method" so are there alternative ways to solve this issue?

I added a thin stripe of this silicone on both sides of gasket, it sealed perfectly.

 

[Jefco]

applying correct pressure on the bearing cone.

The 350kg should be considered a pressure limit; if the measurement stabilizes with less pressure, you're done. A simple arbor press may be enough.

 

[Dr.Jeff]

For that matter you could just gently drive it in with a soft hammer/sleeve until it seats fully. You'll feel when it hits the bottom of its recess. Then use the dial gauge to measure the depth.

 

[Bjorn Nilson]

For that matter you could just gently drive it in with a soft hammer/sleeve until it seats fully. You'll feel when it hits the bottom of its recess. Then use the dial gauge to measure the depth.

Though about that as well. But the horrifying stories from Steve H scares me .

I added a thin stripe of this silicone on both sides of gasket, it sealed perfectly.

I dressed the gasket with Hylomar Blue on spray can. Very handy.

 

[Jefco]

gently drive it in with a soft hammer/sleeve until it seats fully

The problem with this is that it only works if the shims are perfectly flat; driving it home doesn't guarantee it stays fully seated to be measured accurately, but I don't think you necessarily need have 350kg to be rid of any 'ripples'. The manual doesn't say, but the pressure is probably meant to be applied during the measurement, not released first.
In the feeler guage method, you reach shim flatness before you reach torque on the flange bolts. Is that 350kg? doubtful, or the space would never close at torque, as it is supposed to, and that value is low.

 

[Dr.Jeff]

The problem with this is that it only works if the shims are perfectly flat; driving it home doesn't guarantee it stays fully seated to be measured accurately, but I don't think you necessarily need have 350kg to be rid of any 'ripples'. The manual doesn't say, but the pressure is probably meant to be applied during the measurement, not released first.
In the feeler guage method, you reach shim flatness before you reach torque on the flange bolts. Is that 350kg? doubtful, or the space would never close at torque, as it is supposed to, and that value is low.

As I understood the manual the shims go on top of the bearing, between it and the "retaining flange". Therefore they are not involved in seating the bearing into its place in the case. So seating the bearing will be flat. Although as I say that it kind of doesn't make sense as far as preload goes. However that was what the illustration looked like.

Also I understood the pressure is only to install the bearing, not for measurement. So the actual amount of pressure does not seem all that critical. However I may be understanding all of this wrong; to me the manual is not very clear and the illustrations not extremely accurate in a lot of places.

 

[Jefco]

I've been looking at it wrong, too - I'm used to having a stack of thin shims, not a thicker, single shim, which seems to be the ideal here.
And I was conflating the pressing and the measurement, which is just plain wrong.
The 350kg is indeed just to seat the bearing in the case, and not involved in the measurement (or the preload itself), so it's an upper limit, and doesn't involve shims.
The shims are included in the measurement with the feeler gauges, so I can see why Bjorn doesn't want to do it that way.
I'll look at it again tomorrow, and see if it looks different again.

 

[ng_randolph]

I have never opened up an X1/9 transmission, but this is what I gather:

The right side outer race for the differential is "seated" in the case; pressed in until it bottoms out in the case. When you get there, you'll see that the gauge on the press starts moving up quickly.

The left side outer race is not seated the same way. Have a look at the pictures in this post by @rizthewiz and this post by @Steve Hoelscher (6th photo from the top).

So as I see it: With the full stack of shims and the bearing cover in place, apply a load of 350 kg to settle the bearings (without the shims, you might be just pressing the cover against the case). Then remove the load, take measurements as described in the FSM (either method). Assemble with the correct shims etc.

Perhaps if Steve sees this he can set us all straight.