Bad Syncro Ring?

On the way home from a car show this weekend, my Series 5 with Overdrive started grinding as I put it into 3rd gear. I am guessing it's the syncro ring... Thoughts?

Second question: I have what looks like a fully rebuilt Series 5 gearbox in the garage, Non Overdrive. Can I switch it with the one that's grinding and attach the OD to it?

 

Ash,

I assume the sound was just when going into 3rd? Was it everytime you changed up or down to 3rd?
If you matched revs did it still graunch?

If its each time you change into 3rd its likely a syncro ring. It could be a shift fork misalignment.

As for switching od unit over.. The answer is yes BUT ...

You would need to remove the mainshaft from the OD box and disassemble the standard box and install the OD units mainshaft.

It would probably be better to rebuild or repair the existing od box

 

Alp,

Yes, only going into 3rd gear, I can rev match, double clutch an get into 3rd without a crunch. Thanks on the info about gearbox switch. I had a feeling it wasn't going to be as easy as it sounded.

 

Did you check your oil level? Whenever someone says 'suddenly started happening' I begin to look for things that have changed... like oil loss, or something else. A bad syncro takes ages to develop and usually there's symptoms along the way, like crunching only on really fast shifts.

 

The first thing I did was change the trans oil, hoping it would help... It didn't. I'm not that lucky.

 

It's very odd that it came on suddenly. Was 3rd gear prone to crashing on fast shifts in the past?

 

No, it has always shifted very smoothly. I have only driven about 10 miles since the first grind, and that was to get me home, and a 3 mile drive to test it after I changed the trans oil. The first couple shifts into 3rd on the test drive with new oil, where fine, but then it started again.

 

I am batting around the idea of trying to rebuild the trans myself. I have watched youtube step by steps, but it might be outside my comfort zone.

 

Go on give it a go !!

You might get lucky if its just selector related, these you can remove/replace (fiddly) without too much internal dismantling.

If you`re unlucky then the pulling apart is pretty straightforward and, with the aid of utube footage, not too difficult to reassemble.

Things of importance are careful removal of the input shaft, so as not to lose any of the needle rollers - count them and store safely. If you don't get them all during disassembly be wary when you turn the box over as they`re likely to drop out and roll into the darkest corner of your workspace. Same story with the needle rollers, both ends of the lay (cluster gear) shaft, this comes out last so you are at least able to contain them if any drop out; again count them!!

The most irritating part of reassembly is the re insertion of the lay shaft, trying to line up the thrust washers and not disturbing the needle rollers as you thread the shaft through, don't force it, if it wont go smoothly stop and investigate, likely misplacement of thrust washers/needle rollers; same when you come to the input shaft, make sure the needle rollers stay in place.

Actually, if you are only doing the syncro ring, you wont need to extract the cluster gear, only remove the shaft and lower the cluster gear into the bottom of the casing, just be wary though if you have to upend the casing that it doesn't drop out.

 

For the layshaft you absolutely need to use a dummy shaft for reassembly. I used a 1/2" steel water tube cut to length with great success. Even though make sure that you use the heaviest grease you can find to keep the needle rollers in place. A gearbox rebuild is feadible but not an easy task...

 

Well of course yes, I'm assuming that anyone attempting this level of repair would have read the instructions and have the necessary tools, but since you brought it up you will also need suitable drifts/dummy shafts to remove the gear selector shafts.

 

Thanks for all the great info. One of the best things about having an Alpine is the support from this forum.

I am going to be as methodical with this as possible.

1. Bleed Clutch - easy option, and if it works I will do a dance of joy
2. Practice on my back up gearbox first and see if is something I can handle. Worst case, I will learn something, have lots of spare parts and not get too deep into my actual transmission and realize I made a huge mistake with no turning back.

I'll take lots of picks as I go and post them here

 

That sounds like the proper approach...

 

Ash, sorry to hear your problem. 1st, are you gonna make it to Channel Islands Show?
2nd, At 72, two jobs have intimidated me, and that's the transmission and the front suspension. But I've always been able to take something apart and put it together. But I've just never done them. Now though since I just finished the front suspension rebuild I'm thinking Transmission? Hell Yeah. Go for the trial on your spare.

 

Oops, I don't know, just watched that video and feel pretty intimidated by it. But since it would be my "spare" tranny. Might have to think about that a bit more. LOL

 

Jim,

I don't know if I'll make it to Channel Islands Show. It will depend on if I get this sorted in time.
Yeah, that video is a bit intimidating, but I will never use the transmission without overdrive, and I sort of bought it for parts anyway. I might as well strip it down, see how it ticks and see if I can put it back together, and if not use the parts to replace any worn ones on the OD box. I'm going to call it a learning experience... I foresee a lot of swearing in the next couple weeks.

 

The front suspension job is way more easier than the gearbox...

 

Well, Duhhhh.

 

Sorry, that's all that came to mind. Hope I didn't offend.