Transmission overhaul, 5 speed

I'm reviving this thread to provide an update. As I stated earlier, I was stoked to have the car shifting properly again with no more grinding in third, but my happiness was short lived. After only about 2000 miles third gear started grinding again. So this past week I pulled the transmission apart and this is what I found:

It seems the third gear synchro ring is a poorly made after market part. The following is a picture of the original synchro (right) and the replacement synchro (left). The original part has machined top and bottom surfaces and the replacement does not. More importantly, and difficult to see in the picture, the replacement is not quite round and has high spots on the circumference.

001C.jpg


The following is a picture of one of the high spots on the replacement synchro:

005C.jpg


The next picture shows an original part with a much more uniform wear pattern:

006C.jpg



Another difference I noticed was the inside surface. The replacement part is smooth:

007C.jpg


The original part has machined grooves:

008C.jpg


I am pretty sure that what has happened is that the high spots on the outer surface of the replacement synchro quickly became polished after a short time and lost the ability to slow the gear while shifting. So now I am going shopping for better quality synchro rings.

I am not sure what the purpose of the grooves are on the inside surface. Suggestions???

Brian
 
Sorry to hear it happened again. I bet you are getting really good at trans overhauling. Please remind me what syncros you have tried and intend to try, for future reference.
 
Late to the party here. Its been a busy couple of months for me. In addition to other things I have built nearly a dozen X1/9 5 speeds since November. The replacement synchronizer you bought and installed is the new, aftermarket, replacement that most everybody sells. These are not OE specification. I have tried them and have not been happy with the results so I no longer use them. Also, the OE 3-4 sliders are hard to find and VERY expensive. Presently, I have exhausted all of the vendors I know of for both OE and aftermarket. Presently, I can't find any more anywhere.

As for the differences in the OE and aftermarket synchronizer; the grooves on the inside of the OE unit have no function. What is important with these is; the diameter, gap, thickness, outer axial radius, tension and material. The from my experience the replacements are of poor material quality and manufacturing specifications. Thus the primary radius isn't consistent, the tension is inadequate and the material is sub standard. They will not last very long and have likely pre-maturely worn your 3-4 slider.
 
Thanks for the reply Steve. The transmission is still in pieces on my workbench and I have ordered synchros from another supplier. Now that I know what to look for, I will see if they have the same issues.

Brian
 
Mr. Hoelscher,

From your expertise, do you have any thoughts on towing an X1/9 with rear wheels on ground? The Bertone Owner's Manual states on page 44:
verbatim:

General Towing Instructions:
Vehicle must not be towed at a speed exceeding 30 mph, or for more then a 30 miles.
- If the vehicle is to be towed over the specified distance or if the transmission or differential is damaged the vehicle must be towed with the rear driving wheels raised off the ground.

Reading all these ultra sensitive problems with the X1/9 transmission I would be very cautious.
 
I received new synchro rings from Eurosport UK this morning. These parts look much better made than the previous lower priced synchros I had purchased. The surface finish and radius looks to be much more uniform. I will try to post some pictures to show the difference.
 
Here a are a few pictures to show the differences between the various manufacturers synchro rings. The following picture shows the original part (bottom), the failed replacement part (center) and the new replacement from Eurosport (top). The polished high spots on the center ring are obvious, as well as the much "grainier" surface of the Eurosport supplied ring on top:

009C.jpg


Here is another picture with the rings in the same sequence showing the ends. Once again, the polished high spots on the failed replacement ring (center) are clearly visible:
012C.jpg


The following picture shows the difference in profiles. The Eurosport sourced ring (top) has a similar profile to the original ring (bottom). Note that the failed replacement ring does not have the top and bottom surfaces machined flat:
013C.jpg


Here is one last picture of the failed replacement ring showing the polished high spots:

015C.jpg


Once I get the transmission back together with the Eurosport sourced synchros and put a few kilometers on it Ill try to remember to post an update.

Brian
 
I have no desire to do any vendor bashing, but can you tell us how we could buy a part just like the replacement part that failed?
 
The supplier was Spider Roadster. I was a little reluctant to reveal the supplier of the bad part, as it is not his fault, and at the time I was not certain that the synchro was the root cause of my problem. When I contacted him he was genuinely concerned and offered a full credit on the price of the parts. Since then he has stopped supplying X1/9 transmission parts, and removed them from his website. This is sad because I had no issues with the other parts I bought from him. I was hoping he would take up the issue with the manufacturer and perhaps have the part improved.

Brian
 
beezee said:
Since then he has stopped supplying X1/9 transmission parts, and removed them from his website.
Click to expand...
Perhaps he had greater issues with his supplier for all things transmission related, hard to say. But it sounds like he took care of you properly and professionally...glad to see there are still some decent business people out there.

Regarding the "original" syncro vs the latest one. I don't recall, did you state if the original item was a Fiat original part or original to you and your trans tear-down (as in no idea what brand it was)? Also, in the pictures the latest item seems to have a slightly different profile - less of a crown - compared to the original (and worn) one. Or is that just the angle of the picture?

Mike, well stated.
 
beezee said:
The supplier was Spider Roadster. I was a little reluctant to reveal the supplier of the bad part, as it is not his fault, and at the time I was not certain that the synchro was the root cause of my problem. When I contacted him he was genuinely concerned and offered a full credit on the price of the parts. Since then he has stopped supplying X1/9 transmission parts, and removed them from his website. This is sad because I had no issues with the other parts I bought from him. I was hoping he would take up the issue with the manufacturer and perhaps have the part improved.

Brian
Click to expand...
Thank you. I understand your concern and I, for one, don't think anyone has been bashed. Just the facts.
 
Dr.Jeff said:
Perhaps he had greater issues with his supplier for all things transmission related, hard to say. But it sounds like he took care of you properly and professionally...glad to see there are still some decent business people out there.

Regarding the "original" syncro vs the latest one. I don't recall, did you state if the original item was a Fiat original part or original to you and your trans tear-down (as in no idea what brand it was)? Also, in the pictures the latest item seems to have a slightly different profile - less of a crown - compared to the original (and worn) one. Or is that just the angle of the picture?

Mike, well stated.
Click to expand...

I am pretty certain the original synchro is a Fiat original part. I did not see evidence that the transmission had been taken apart previously. In addition, all three synchro surfaces looked the same.

You are right, the latest part does not have as much of a crown as the other two rings, but it is not as pronounced as it appears in the picture. The end of the top synchro is a little out of focus.

Brian
 
You can't compare the outer axial radius of a used synchronizer to a new one. That's where they wear. The bottom one is a worn OE. Note the narrower gap of the middle unit. That's one of their problems. The top unit does not appear to be an OE unit either but likely a better aftermarket part. I don't blame vendors for crappy synchronizers. The parts are getting hard to find and a crappy part is better than nothing.
 
Steve Hoelscher said:
You can't compare the outer axial radius of a used synchronizer to a new one. That's where they wear. The bottom one is a worn OE.
Click to expand...
That was my point, even the worn old ring has more of a crown than the latest new one. But the new one appears better than the prior aftermarket ring, so hopefully it will work better. Perhaps see if the vendor for this new ring can offer more info about it; the maker, country of origin, boxed part number, ???
 
Dr.Jeff said:
That was my point, even the worn old ring has more of a crown than the latest new one. But the new one appears better than the prior aftermarket ring, so hopefully it will work better. Perhaps see if the vendor for this new ring can offer more info about it; the maker, country of origin, boxed part number, ???
Click to expand...

You don't understand, the synchro ring doesn't wear flat. The wear is tapered. So a worn out synchronizer ring will still have a significant crown.
 
Ahh, I get what you are saying now. Does it wear evenly (symmetrically) on both sides of the taper? Thanks.
 
"No, the wear is asymmetrical."
Humm, then that does not seen to correspond with what is seen in the examples above. Regardless, I was only commenting on the comparison between the three samples and how their seem to profiles differ, regardless of wear.
 
I think what Steve is saying is that the rings wear more where they engage with the slider. That is why they can sometimes be flipped over to get more life out of them. They also seem to wear more towards the end gaps.

Thanks everyone for your comments. This has been a great learning experience for me. I have overhauled many motorcycle transmissions over the year, but this is only my third car transmission, the last one being my wife's '84 Nissan Pulsar which I had to rebuild twice as well, once when the linkage failed and another time when a bearing failed. Now that I think of it, it was kind of reminiscent of the X with angular lines and pop up headlights. I guess that explains why she likes the X.

24046340012_large.jpg



Brian
 
Yes, if you look at how the slider engages the synchro ring before the engagement teeth mesh, you will see that the wear has to be from the center to the edge on the side toward the slider. And because the synchro ring has to compress as the slider engages the gear the change in circumference causes the pressure points to be at the ends.

By the way, I took these photos in my garage Sunday afternoon:

0219181248.jpg


0219181248b.jpg
 
You must log in or register to reply here.
Back
Top