No 5th gear diagnosis...pics

Oh Haha · 10-21-2006, 02:45 PM

Well, we have the trans out. Further inspection revealed not a whole he!! of a lot to me. The gears are in good shape as well as the synchros. The are still pointy with not a lot of wear.
The gear picture is 5th.

What we(wcc and I ) found is that the 5th gear slider assembly is not engaging the synchros enough to meet. The "cone" doesn't compress enough to let the gears mesh. Are they supposed to mesh that way? Would we be able to compress it by hand with enough force on the bench? We only took the front cover off as the other gears work great. What do you guys think?

Jim Sims · 10-21-2006, 03:01 PM

The teeth on the inside of the slider engage the dogteeth (synchro hub) on the gear. For this to happen the synchro ring must collapse (shrink in diameter) to allow the slider to move over it. Inside the synchro ring are brake bands (under the big retaining ring holding the synchro ring onto the dogteeth) which push outward against the inside of the synchro ring keeping it from collapsing until the slider and gear/synchro hub/synchro ring are turning at the same speed. Then the brake bands release, allow the synchro ring to collapse and the slider to move over it and engage the synchro hub or dogteeth. Something may be wrong with the brake bands or the pieces that operate them - the anchor block and energizer block.

Oh Haha · 10-21-2006, 03:03 PM

These should give as better idea as to what I mean. The "brake band" doesn't compress enough to let the slider assembly mate with the other gear.

Oh Haha · 10-21-2006, 03:06 PM

Yes, that's exactly what we think is the problem, Jim. You can see it get to that point and then it won;t move any further. Do the teeth on the gears and synchros look to be good? Are the brake bands and blocks easily replaced?

Oh, you rock, Jim!!

Jim Sims · 10-21-2006, 03:07 PM

The part that won't collapse is the synchro ring; the brake band(s) are inside it.

Jim Sims · 03:16 PM

"Are the brake bands and blocks easily replaced?'

Yes. Just spread the retaining ring with retaining ring pliers and pry it off. I would look at things first and then decide what to replace but I usually replace brake band(s) and the synchro ring as a matter of course. I have reused the anchor block and energizer block. If the brake bands are jamming there may be other damage inside.

Oh Haha · 10-21-2006, 03:14 PM

oops

Jim Sims · 10-21-2006, 03:15 PM

Given what I can see in the posted images the slider teeth and synchro hub teeth (dogteeth) look reasonable and reusable.

Oh Haha · 10-21-2006, 03:17 PM

Thanks Jim. The wife will be glad to know this will be inexpensive.
Now, the big quesion is why did this happen?

Jim Sims · 10-21-2006, 03:22 PM

Don't relax yet; what does the inside of the synchro hub look like?

Cause? I can only speculate: wear of parts or too abrupt a shift into 5th or debris inside.

Oh Haha · 10-21-2006, 03:35 PM

Hmmm... I need to remove the large nut on the R/5th operating hub to remove the 5th gear synchro, right? I don't have a tool to lock the input shaft yet so this mught have to wait for now. I am leaving the car off the road for winter so I am not in a big hurry. I would like to get the trans fixed soon so it is done, though.

Jim Sims · 10-21-2006, 03:46 PM

Yes, the nut must come off. I lock up the transmission by selecting two gears at once usually 5th and one other and then remove said nut holding the guide sleeve (sometimes called the spider) on. You will need to do this to get to the synchro hub/synchro ring. Since 5th gear doesn't work you will need to lock using a combination of two other gears besides 5th or use the factory tool (or a substitute) that locks the input shaft.

Jim Sims · 10-21-2006, 03:50 PM

Are there any notches or significant burrs that on the guide sleeve or the sliding sleeve at their interfaces that may be impeding their relative movement?

Oh Haha · 10-21-2006, 03:55 PM

No, no interference at all on the guide sleeve. All parts slide nicely until it gets to the synchro band.
I would guess the distance between the dog's teeth mating is around 2mm. I didn't measure it but it very close, just not enough.

Oh Haha · 10-21-2006, 07:36 PM

Well, I couldn't wait so I removed the synchro hub. Strange cause I didn't even have to lock the trans in two gears. I used my impact to break the large nut free and removed it by hand.

Here's some pics of the hub itself. It looks good to me. On the bench I could actually get the two sets of dogteeth to mate with the band collapsing as intended. I reinstalled the setup on the trans and it was the same problem as before. Stupid car!!!

Oh Haha · 10-22-2006, 12:48 PM

I disassembled the synchro hub today. In the process of removing the large circlip, the lip that retains it cracked. I can"t believe I was trying THAT hard.

So a new hub is in order but I think I found the real cause of my problem:
In the second picture you can clearly see a crack in the dogteeth gear. It wasn't visible to me when the retaining clip was in place.

I looked at the Pelican catalog but I am unsure what exactly to order. Can I just get the entire hub assembly ready to go?( Sorry for what may seem like silly questions but the transmission is not my strong area on these cars.) Thanks,

Oh Haha · 10-22-2006, 02:00 PM

Alright, I have it figured out now. I just need a synchro hub. Part # 10-1550-315-M184

As it already cracked in half I don't need to worry about removing it so much. How is it installed, though? WOuld this be better left to a local trans shop? That snap ring was a bi!@# to remove. I have the correct tool but it was still very difficult to even get it to spread apart.

Would one of you more experienced guys let me know if I am on the right track with this repair? Thanks......again.

Motorhead-45 · 02:19 PM

Quote:

Originally posted by Oh Haha
How is it installed, though? WOuld this be better left to a local trans shop?

The dog teeth are normally pressed on. You can take it to a shop with a press and they can do it for you in about 5 minutes or less or you can place the gear in the freezer and the dog teeth in the oven for about 30 minutes or less and you should be able to tap the dog teeth on the gear if you don't waste a lot of time letting the two parts come back to room temp.

With regards to the snap ring...if you are using a good set of snap ring pliers you should try and work just one end of the ring over the lip first and then slowly work the rest of the ring off. Getting the snap ring back on is even more fun than taking it off. Use the same technique of getting one end over the lip and seated first and then slowly work the rest of the ring over the lip until it's all seated.

Grady Clay · 10-22-2006, 02:39 PM

Wayne,

There could be a bunch of issues here.

Do I understand you correctly … ?
” Well, I couldn't wait so I removed the synchro hub.
Strange cause I didn't even have to lock the trans in two
gears. I used my impact to break the large nut free and
removed it by hand.”

You are saying that the pinion nut was appropriately tight
and you first broke it loose with your air wrench and then
it spun off by hand?

Then;

” On the bench I could actually get the two sets of
dogteeth to mate with the band collapsing as intended. I
reinstalled the setup on the trans and it was the same
problem as before.”

You are saying that when the free gear II was on the bench
the sliding sleeve was able to slide over the syncro and
engage yet when the gear is in place, the sliding sleeve on
the hub it wouldn’t engage the gear?

What I’m trying to picture here is exactly how the crack in
the circlip groove prevented engagement.

I have never seen this part fail in this way. Has anyone else?

What do you know about the history of the transmission?
Has that set of dogs been replaced prior or are they original?
If a replacement part, are there any manufacturer’s codes,
trademarks, etc?

Other issues to look at are the fit and condition of the hub
and parts of the sliding sleeve that contact the hub. Is
there anything there that would prevent engagement?

Would it not engage when operated with the shift fork or
when the fork wasn’t in place and operated by fingers?

In this image:

What is this (red arrow)? Why is the distance between the
(purple) dogs different from the distance between the (green)
dogs?

In fixing this problem, you must be very careful to inspect the
new parts. I think there are some less-than-proper parts
that have found their way into the system. You want to
make sure that someone doesn’t unintentionally supply you
any.

When you are ready to reassemble, use the old pinion nut
and torque it on the pinion shaft. With a dial indicator on
the end of the pinion, pry & push the pinion axially. Record
the movement. We don’t want you to reassemble with a
bad 4-point bearing.

For final assembly, use a new nut and don’t forget to peen
it in place.

Best,
Grady

BTW for all; cleaning the transmission parts and not having
any oil on them allows for better images. Pay careful
attention to bright lighting from a slightly oblique angle.
There is a real art to being able to get images of gears that
allow good on-line diagnosis.
G.

Oh Haha · 10-22-2006, 03:04 PM

Grady,
I 'll answer as best I can:
1. Exactly. I guess I thought the nut would have been a bear to remove. I only "touched" with the impact enough to break it loose.
2. COrrct. I could engage the synchro to the gear on the bench. When installed on the trans, it would not engage.
3. The sliding sleeve and all of the other parts look good. No burrs or strange markings.
4. The trans was rebuilt to fix a second gear synchro aboiut three years ago. I don't believe 5th or reverse was touched so these may be original parts. I need to dig out my bill.
5. Could I have cracked the synchro in any way.

The trans worked excellent with no grinding ever in 5th. It just knid of stopped going in on my last ride. I wasn;t even getting into when it happened. I was just casually going into 5th.

thanks for the tip on picture taking.