Sprite Ribcase Gearbox Overhaul

Started by MiniDave, July 19, 2016, 02:37:27 PM

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MiniDave

#25
Wow, that looks fantastic!

I think we'll try it as it is, I should have sent you an extra new synchro to compare, I can get them easily up at Victoria British, just a few miles from my house. I think we did this repair exactly the right way....

Thanks you so much for taking this challenge on, you did a great job!
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

jeff10049

#26
Thanks Dave,

A extra new would not really help a good coated hub and new sync would be needed. I did measure the new one you sent on the hub before starting any work. It's about .005 more gap but i'm sure the old coating had some wear and of course the flaked off section so I think were good. I sure don't want to take off to much as i'd have to start all over.


I did not need to remove the bearing you may want to spray it out with brake cleaner just to be safe but I taped it off when removing the rest of the coating, and polishing the taper. I did not remove the nut either so if it was torqued it still is.

I'll ship it back  your way Monday.


jeff10049

Dropped off at ups on way home Pm'd tracking number you should see it this week.

MiniDave

Alrighty then, gear showed up today, so tomorrow I'll see about putting it all back together......
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

jeff10049

cool, Will the owner be putting it in the car right away? I'm interested to see how it all works out. I did quite a bit of math on area and friction coefficient to come up with the oil relief groove width and number on both the slots and circular grooves. A balance between getting the oil out fast and having enough contact area for friction. I noticed the old steel synchro you sent they were a softer metal had larger/wider  and more grooves than the newer harder synchro. Something that seems so simple yet has so much going on.


MiniDave

I don't think it will be right away, he bought an engine but got it home and found it had no compression, so I think he's still working on sorting that out - he only paid $800 for the car so he doesn't want to spend $5K rebuilding the motor. I'm staying under $500 on the trans build.

I'm trying to figure out how I could hook up an electric motor to turn the input shaft (slowly) so I could bench shift it, I also want to see how/if it works, but I have a very high degree of confidence in your work!

I should have it back together tonight.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

Ran into an issue....there are several different detents, balls, plungers, springs etc for the shift rods and since this gearbox has been apart I did not know what went where, so since I have two more gearboxes I thought I'd simply look at them. Some of the detents are held in place with threaded plugs so I removed both of them on one of the extra gearboxes and made note of what went where.

Then I did the same on the second gearbox - they were assembled completely different!

So, I emailed a friend in the UK who used to build these for a living and asked for some guidance. One thing's for sure, by the time I finish this one I'll be able to do them in my sleep!
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

jeff10049

Hooking up a motor would be kind of fun I know it will work how balanced compared to other shifts it is and will it ever give a crunch under certain conditions is what I'm wondering, of course even stock ones can do that if way mismatched shifts are forced.

Same material I used in my mini on second gear much more demanding  than fourth and it's perfect but a lot of engineering goes into stuff like this so a guy whipping out a weekend synchro is not a 100% sure thing.

How about a piece of heater hose between a 1750 rpm motor shaft and the input with some clamps?

Did you save the dc motor and speed controller out of that junk treadmill you built the engine stand out of? that could be a cool use for it trans tester motor.

Jeff


MiniDave

No, but I gave it to my neighbor across the street, he may still have it - that's a great idea!

I got it mostly assembled today but I'll need to take it apart again and re-shim the bearings, there's too much clearance between the main shaft and first motion shaft.....

My friend in England (who's the Sprite gearbox expert) contacted me back so I got all the detents and plungers sorted out, I sent him pics of what you did and he said he'd seen it done on other gearboxes in Germany and he thinks it will work just fine.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

jeff10049

wow that's cool, not that I thought I was the only one that ever did it but you sure can't find much info on the net about fixing/making  a synchro. Material choices are hard to find as well. I have a folder on the computer full of info about it but it took a lot of searching to find it.

I also bought several books but whats scary is some of the books that are considered the end all do all have bad info, they were not written by someone who has done it.
But by some technical person sitting at a desk with a part and measuring tools that interviewed some engineers on the subject and formed their own idea.
The encyclopedia of automotive engineering has some very incorrect info on the subject a $2000,00 book. If you were to try and build a synchronizer ring from info in that book you would fail.

There is way more incorrect/bad info on the net about synchronizers than good. Some of the u tube videos about how they work are painful to watch they are so full of bs.

I should create a page about the ones I have repaired materials used and the end result that the search engines can find. Also with links to the info I have found that is good and correct about the operation.

A video of a transmission driven by a motor with the top off and just using a fork to shit would be cool wish I had a high speed camera to show the operation of the ring.

For those reading that may not know what a synchro does it's just a cone clutch. When the slider starts to move the dogs in it contact the synchro first and push it onto the cone of the next gear at this point in time the ramp portion of the teeth in the slider and synchro should be touching and the gears are traveling at different speeds.

This speed differential keeps the synchro loaded against the slider teeth the harder you push the more force you put on the cone clutch to either speed up or slow down the input shaft to match the road speed. This also puts more force on the ramp areas of the teeth that are in contact to keep you from pushing past and grinding the gears. since they are ramps they try and force apart.

Sometimes they are called blocker rings instead of synchros because they block the
shift. Once the the input and output speeds are synchronized their is no force against the ring and it allows the teeth to slide past and on to the mating gear with out a crunch. The closer the driver matches the road speed to engine speed the easier life will be on the synchro. The reason why tapping the throttle on a downshift makes it quicker you're helping the synchro get the input up to matched speed.

they're are many different types 2 piece up to 6 piece synchronizers but they all work the same sometimes they move the gear hub instead of having a ring and the friction material is on the gear like the gear dave got on ebay that style uses the least moving parts.

Hears a link to some pictures of how the teeth meet up if anybody cares. They're a little full of themselves as we are a shop that has been doing what they do for years we used to have to adjust the timing of synchros on the mitsu 5 speed truck trannys in d50 pick ups back when I was starting out at 16 years old they had a problem where the teeth points would meet up and lock you out of a shift. But they're right in that you don't hear about it. Most shops just fix stuff and the owner hears blah blah blah here's your bill. They do sound like they know their stuff though.

http://www.jackstransmissions.com/pages/synchro-blueprinting


Jeff

MiniDave

#35
Interesting article.....so it looks like what they do is narrow the teeth slightly so as to sharpen the engagement points and make it easier for the teeth to slide past each other into engagement?

The other synchro type I'm familiar with are the Porsche style...they work almost like a centrifugal clutch. Two small bands and a couple of bits, as you move the slider towards the gears it engages the bits which force the bands against the hub, causing the speeds to match and allowing the slider to engage.

Here's what they look like....



We used to replace these by the box load as truck drivers would ruin them getting them on and off the transporters....I don't know how.

Great stuff Jeff, and thanks for you close attention to my project, I appreciate it!
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

jeff10049

Those porsche ones work really good I wonder how the heck they were ruining them maybe a bad batch and that was the excuse?

I had a car that the synchros had no blocking action they were just a synchro the preload dogs was all it had so you had to shift it gently the cone would come up and start to synchronize but if you pushed past the tension of the dogs too soon it would just grind. Thats how it was made you just had to know how to drive it and it worked fine sort of a feel thing come up against it and wait until it felt like no more tension and follow through. 1968 lloyd wagon maybe, or it was the 1960 model 96 bull nose two stroke three cylinder saab I can't remember but it was one of those cars.  The 2 stroke saab was fun I'd be poring a quart of oil in the gas tank at the station and get looks like WTF I'd just say it's a quart low they would shake their heads and walk off muttering dumb ass kid LOL. That car had some power when you wound it up.

MiniDave

#37
Probably the Lloyd, I owned a few of those 2 stroke Saab stories and I remember being able to shift as fast as you wanted.....

I think I have all the mysteries sorted finally, know where all the detents go, and had the main and first motion shafts installed but took it back out again. There was what I considered way too much play in the 3-4 shift sleeve (even tho my contact in England said it was fine that way) so I shimmed behind the bearing on the first motion shaft, doing so moved the gear into better alignment with the layshaft gear too....so now I'm putting it back together again, hopefully for the last time.

In the first pic you can see the misalignment - although the angle of the photo makes it look worse than it was, it's the gear on the right end -  in the second pic the gear fits nicely into the layshaft gear. You can also see the increased gap between the gear and the bearing - I used every shim I had hoping it would be enough and I think it was just right. This should take out a lot of the play too, but if you take out too much the cones won't release and it won't shift. All the other gears line up with the layshaft perfectly so I decided not to change the shims on the rear bearing. When I measured one of the other gearboxes the play was about 1/8", this one was more like 1/4"....this is what you get when someone who doesn't know their way around the shop starts "tinkering".....by the time I'm done with this one I'll be able to rebuild them in my sleep!   ;D

After all this I sure hope it works, although it may be a bit before I get to find out - the engine he bought that went with this transmission had no compression - we don't know if somethings wrong or if the PO was tinkering with it too. By the time I'm done I think he'll have that sorted too but I may wind up going thru the motor also - just enough to make it run. I'm hoping the PO got the valve adjustment wrong or something simple like that, I don't think anyone's been inside the motor based on the oil/dirt on it.

The car he bought is a 68 Sprite Mk II, and it's hard to believe but it has no rust - none! He paid $800 for it so he's not looking to spend $5K on a motor and trans for it....I'm bound to a $500 max on the gearbox build and it will take all of it....but thanks to Jeff10049 at least I'll be able to save it.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

When I look at gears it might as well be Chinese.  Glad you know what you're doing!

MiniDave

No one ever said I know what I'm doing!   ;D ;D ;D ;D
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

Well, it's coming together......there are some shims that go on the rear bearing and they look like wave washers instead of being nice and flat.....consequently I couldn't get them to hold still so I could install the back housing.  So I sprayed some high tack on them and weighed them down with a big impact socket. If they flatten out all I have to do is put the rear housing on and install the shift housing and shifter and it's ready to go.

It took a while to get back on top of all the little bits and bobs, but I have it all sorted now. Ken Evans at Klassic Transmissions in England was a great help, we must have emailed back and forth 4 times........
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

jeff10049

cool,

I would of moved the input in as well, and I keep forgetting to say that I use walnut shells in my blast cabinet for stuff like this way easier to clean and more forgiving if you miss some. Baking soda works well also just wash it away great for old electrical contacts too. glass bead is a bitch to clean out as you know.




MiniDave

I have a walnut shell pressure blaster that I built to clean the carbon off the intake ports and valves on my MINI, direct injected cars are afflicted with carbon buildup - I will use it next time, for sure!

Glass bead might give a beautiful finish, but man what a PITA to clean up afterwards!
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#43
Allrighty then.......tonight I buttoned up the gearbox, all the gears engage and shift smoothly, and the shafts turn easily as they should. Of course it looked better before all my oily pawprints were all over it......oh well.......

I managed to get the second gearbox out of the two gears - it was locked in 4th and reverse and it feels pretty good now. I think it could easily be rebuilt. The third gearbox has noisy bearings but I think it can be saved too......
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

#44
Customer came and picked up the first gearbox today.......and dropped off yet another one for me! I'm also going to pick up the no-compression engine and see if I can figure out what's bothering it too.

He also has a Bugeye gearbox (smooth case) he wants me to fix, as it grunches pretty good into second.....but it's still in the car..... tomorrow when I pick up the engine he wants me to drive the Bugeye to see what it does before he pulls it out.

By now I think I pretty much have the hang of these!

The one I finished is going to be a spare for his Bugeye so I may never know if the work Jeff did on the synchro works unless he decides to use it while I have the smooth case out for overhaul. I doubt he'll do that tho as it's quite a lot of work to get these in and out. The second one will go in the 68 Sprite (assuming we get an engine that runs) and the other two - who knows, maybe he'll sell them. The main thing is his money is good and he's bringing me more work.  4.gif
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

Next thing you know you're buying a shop in Ramona and building engines and gearboxes full time  ;D

Willie_B

It is an engine and trans out to get the trans out of a bugeye. Enclosed under it so no other way.

MiniDave

Yep, that's why I don't think he'll want to install this one then change it back to the smooth case once it's rebuilt.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

Quote from: 94touring on August 20, 2016, 01:17:06 PM
Next thing you know you're buying a shop in Ramona and building engines and gearboxes full time  ;D

Yeah, what do you think the chances are of me finding a cool little shop like yours, for affordable money?

Second, what do you think the chances are that my bride will want to live there?
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

jeff10049

bummer seems like a lot of work for a spare I hope he uses it I want to know how well it all worked out.

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