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03-12-2015, 07:02 PM | #1 |
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Trans Synchro Ring Wear
We've noticed many posts that involve synchronizer ring questions. One issue that is hard to describe is the internal wear of the bronze ring itself, and the effects on shifting that result from excess wear.
The two synchro rings in the Ford transmissions from 1939 on are made of a bronze alloy. They are positioned in the transmission next to the hardened steel cones of second gear and the main drive gear. The gripping action against the cones when shifting is the force that equalizes the speed of those two gears with the speed of the mainshaft. Because the bronze material is softer then the hardened steel cones, the synchro rings wear out eventually. This is by design.....you want the inexpensive bronze part to wear before the expensive steel gear wears. Of course, this is really just a comparison of parts costs. The reality is that the overall labor and time to open up the trans, tear it completely down, replace the synchro rings, and put it back together is a major cost for the owner. However, a necessary cost when the shifting action no longer provides a smooth, quiet shift due to worn synchro rings. The following two photos show examples of a well worn ring and a brand new ring. Both are fitted to the cone on the same intermediate gear. Note the lack of a gap between the two parts on the worn example. This synchro will never do its job.....the trans will virtually always crunch when shifting into second gear. The second example shows the gap you want to see on a new synchro ring. When examining a used transmission, with the cover off, you can look at this fit on each ring. It is helpful to move the ring closer to the gear's cone to get the best look at any potential wear.
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03-12-2015, 07:13 PM | #2 |
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Re: Trans Synchro Ring Wear
Thanks for a great explanation and photos on this subject. It is very helpful in understanding the synchros.
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03-12-2015, 07:23 PM | #3 |
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Re: Trans Synchro Ring Wear
Great info/picture thread Mac, will print it off and keep in chapter 3 pg.24
I have a few Model A transmissions that I've been looking into, maybe an "In's and Out's" version in the future. Scott |
03-12-2015, 08:04 PM | #4 |
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Re: Trans Synchro Ring Wear
The "make it or break it" for my synchronization was the spacer ring, #7069 in the following diagram.
Even with new syncro rings I had no syncro action until I replaced the standard thickness spacer ring with a thicker one to get the clearance below 0.008" on the main shaft as illustrated and explained below. Once I put that thicker spacer in, my syncro worked great. Sure was a relief from having to double clutch every time I went from 3rd to 2nd. P.S. Got the thicker spacer from VanPelt as I do all of my transmission parts.
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Prof. Henry (The Roaming Gnome) "It is good to have an end to journey toward; but it is the journey that matters, in the end.” *Ursula K. Le Guin in The Left Hand of Darkness Last edited by Old Henry; 03-12-2015 at 08:10 PM. |
03-12-2015, 08:47 PM | #5 |
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Re: Trans Synchro Ring Wear
This is an invaluable thread, especially for those that plan on getting at the guts of their car's transmission. I just ordered a bunch of parts from Mac including new blocker rings and I'm sure glad I got a set because the ones that came in the transmission only provided about 0.015" of clearance between the gear face and the ring, far from the 0.060" to 0.080" required. A visual inspection of these components revealed no obvious flaws. This is not a job I want to do every other week so it's well worth spending a couple extra bucks on good parts that will last.
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03-12-2015, 08:47 PM | #6 |
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Re: Trans Synchro Ring Wear
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03-12-2015, 09:06 PM | #7 | |
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Re: Trans Synchro Ring Wear
Quote:
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03-12-2015, 09:45 PM | #8 |
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Re: Trans Synchro Ring Wear
Hi Everyone! I had to try to explain synchronizers to a class of students tonight. Hard stuff.
This video starts sorta slow but let it run... As good an explanation as any about how the synchros work. It doesn't address how they hook to the output shaft unfortunatel Somebody needs to get this guy a lozenge. This is not me talking. https://www.youtube.com/watch?v=vOo3TLgL0kM
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-Jeff H Have you thought about supporting the Early Ford V-8 Foundation Museum? Last edited by VeryTangled; 03-12-2015 at 09:51 PM. |
03-13-2015, 07:16 AM | #9 |
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Re: Trans Synchro Ring Wear
Oh yes, I made sure to order a thicker thrust washer as well. It was $6 well spent if I need it.
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03-13-2015, 09:59 AM | #10 |
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Re: Trans Synchro Ring Wear
Excellent information, Mac. I've got a '39 top-loader I need to go through one of these days and I will keep this information handy. Thanks.
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04-09-2015, 04:20 PM | #11 |
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Re: Trans Synchro Ring Wear
I have just rebuilt the transmission in my 1939 pickup and am ready to install it. I do not have the .060 to .090 gap between the syncronizer ring and the main drive or the second gear even though I replaced both bronze syncronizer rings. I have .006 gap between second gear and the thrust washer where the requirement is .004 to .008. I have replaced the 7069 washer and the front and rear cluster gear thrust washers as well as all of the bearings . Are my main drive gear and second gear worn bad enough that new syncronizer rings will not correct this situation?
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04-09-2015, 04:36 PM | #12 |
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Re: Trans Synchro Ring Wear
Don't ya love it, when you learn sumpin new every day.
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04-10-2015, 06:10 AM | #13 |
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Re: Trans Synchro Ring Wear
V12 Bill. In my 45+yrs working as a mechanic I've found that many times the "soft will wear out the hard" in situations like yours. A couple examples are the front cover seal wearing a groove in the crankshaft damper and the pinion seal wearing out the driveshaft yoke. Same holds true with blocking rings. When going thru a trans and running into a situation like yours we had to determine which part was worn. You always had a spare good ring laying around to ck which was worn. Customer usually got both pieces unless you could tell one part was really toasted. You didn't want the customer to comeback mad and lose 1/2 a day fixing it free.
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04-10-2015, 11:01 AM | #14 |
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Re: Trans Synchro Ring Wear
Is there a place on this site where this type of information is available/cataloged for easy reference including measurement and fit for transmissions, carburetors, brakes etc.? If there is I've not found it. If not, would that be possible? Sure would save some of us a lot time looking and asking the same questions over and over. I'm aware of Van Pelts site and that information is helpful but, sometimes a more detailed description is given here by very knowledgeable folks which clears things up faster for some of us.
Just my $0.02 worth. |
04-10-2015, 12:16 PM | #15 |
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Re: Trans Synchro Ring Wear
As far as transmissions, Mac VanPelt's book is the best reference. To put all that info on this site would take too long and rob too much band width. You just can't beat MVP's book. They are available from a lot of parts vendors as well as from Mr VanPelt's web site.
For the other items, you need the specific manuals for the vehicle being worked on. |
04-10-2015, 03:25 PM | #16 |
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Re: Trans Synchro Ring Wear
I just got off the phone with Mac Van Pelt about my problem with the blocker rings in my transmission. It seems that the repo blocker rings are made way off shore and are not up to specs. Surprise, surprise. Mac has the correct size blocker rings that will give you the correct space of .060 to .090 between the blocker rings and their corresponding mating cone. He also stated that it is very rare to have wear on the mating cone/gear as the steel is VERY hard. I just ordered a set of rings from Mac and will get back to my PU when they arrive. Thanks for the suggestions from others.
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04-10-2015, 06:00 PM | #17 |
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Re: Trans Synchro Ring Wear
A few years ago I reconditioned one of my V8 Gearboxes replacing several parts and fitting new synchro rings and changing gears was alright for awhile, and then it was getting harder and harder to change into 2nd and top gear and someone suggested worn synchro rings, which I could not believe, so I removed the gear gearbox and dismantled it, and I found that the new synchro rings were worn out after 200 miles, the bronze in them was too soft, I admit I changed gears quite often, changing the grade of oil etc, trying to find the fault in the gearbox. I then fitted a good set of synchro rings out of another gearbox and now I can change gears easily, problem solved.
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04-11-2015, 07:11 AM | #18 |
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Re: Trans Synchro Ring Wear
In that diagram I think there is a ring that is missing , slides on the end of the main shaft snout before bearing 7118 goes on ?
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04-11-2015, 09:09 AM | #19 |
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Re: Trans Synchro Ring Wear
I think you are right. Its is more of a spacer ring than a retaining ring. A cross section of the ring would be round instead of square. It goes on the snout of the output shaft just behind the 7118 bearing.
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10-12-2016, 10:27 AM | #20 |
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Re: Trans Synchro Ring Wear
Amen on Mac's transmission book, it's awesome.
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10-12-2016, 11:01 AM | #21 |
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Re: Trans Synchro Ring Wear
Mac, have you ever considered a how to rebuild book for the banjo rear ends? Your transmission book is excellent and I can imagine what a help banjo rear end book would be.
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10-12-2016, 11:27 AM | #22 |
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Re: Trans Synchro Ring Wear
Vern Tardel has a book on banjos.
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10-12-2016, 12:05 PM | #23 |
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Re: Trans Synchro Ring Wear
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10-12-2016, 02:48 PM | #24 |
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Re: Trans Synchro Ring Wear
Ther is another aspect of wear that many people do not consider when attempting to fix a problem gearbox that causes jumping out of gear.
If you go back to Macs pictures there is a ring of matching teeth below the bronze syncro cone (balk ring) These are part of the gear. These lock into the syncro hub (the ring that the selector fork runs in) These teeth are pentagon shaped (5 sides sort of) there are two flats that point to the top (as Mac's picture sits) There is the bottom face(it never wears) and then there are the two important faces which are the drive and over run faces. These two are important. When they are new, straight edges laid against them are going away from each other at the top. (Think about the pentagon) These faces wear and the angles eventually go the other way so that the straight edges would eventually meet. ( the load side wears more than the over run side) Anyhow this is the important bit. These teeth "hook into the syncro hub (explain later) and under load, hold it in gear. When these teeth wear, the angle is reversed, and they "walk" out of mesh. So, on a long climb up hill (or during descent) your car jumps out of gear. You can hold the gear lever and help it, but it fights you to jump out. If you look inside the syncro hub there are the big grooves across the inside, but each end of the grooves is angle cut "back" on both sides. This is the complimentary angle that holds the pentagon shaped teeth in gear. All of the above is not really anything to do with "syncronising" to achieve a smooth gear change. It is just about keeping it in gear. Problems here are exacerbated, by other issues (excessive end float is one) Many people think it is the springs and detent balls on the selector shafts, that hold this type of gearbox in gear. That is not the case. I hope this helps to enlighten someone. It might mean that someone has to spend more money, but that their gearbox rebuild is a successful one time effort. |
10-12-2016, 03:57 PM | #25 |
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Re: Trans Synchro Ring Wear
Here's another link, this one from Richard Lacy's son Dennis, on transmission rebuilding.
http://www.jalopyjournal.com/forum/t...970252/page-18
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10-12-2016, 06:02 PM | #26 |
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Re: Trans Synchro Ring Wear
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Some of the repro ones have bad slot dimensions and the conical seats are not right. You have to have one in hand to compare to a good one to see what's wrong. |
10-12-2016, 08:52 PM | #27 |
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Re: Trans Synchro Ring Wear
If I remember a quick reference to see if you have problems with syncros you can see one with the filler plug missing.. probably see if you have a gap.
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