Sprite Ribcase Gearbox Overhaul

[MiniDave]

I had issues with the shims on the bearings as they described in the instructions too, IIRC I reused the old shims.

I will find the link to the guide I used, but there are a number of detents and you do have to get them in the right places.....

I did find this.....

http://www.spridgetguru.com/TA0123.html

And some info on the shifter

http://www.spridgetguru.com/TA0128.html

[pbraun]

Looks good , thanks you!!!!!

Let you know how it works out.  Hope I don't shoot it first.  ;D

[MiniDave]

If I ever get well again I have another one in my shop to build, so we'll see how it goes. Good luck with yours!

[pbraun]

Just as a quick sanity check - when the main shaft bearing housing is correctly installed, it rests FLAT with the case, so the tail extension sits flat on top of it, correct?

That can be adjusted to some extent by the main shaft shims.  At least, for example, if the shim on the inside is too thick, the bearing housing will protrude from the case. That was one of my mistakes, anyway. Among others.

[pbraun]

Now, my next problem, other than getting over the flu, is I thought it was all set, but for installing the rear cover and shifter, but then when I put it in first, pop! and ping! and the three balls and springs in the slider fell out.

WIsh I knew what I done wrong. Maybe the slider was not oriented correctly. looked like too much room between it and third gear. could always see the synchro ring.

Anyway, I may be back at it in a week or so, if I feel ok.  Any suggestions as to where to look?

Thanks in advance!

[MiniDave]

I hear you on the flu......mine turned into pneumonia and I spent a week in hospital, I'm out two weeks now and I'm still under the weather.....

You did have the front cover on when you went to shift it,  right?

IIRC, if you used a screwdriver or whatever to move the shift fork, it can move too far and allow the balls to escape - not necessarily anything wrong in the trans, just that you moved it further than the fork would have been moved by the shift linkage itself, because the linkage is constrained by the detents and interlocks. The only way I know to put the balls and springs back is to take it back apart....it's possible that with enough hands and small screwdrivers you could coax them all back in in situ, but I doubt it.

Seems to me there was a lot of slop in the first gear/synchro, as much as I/8th inch but they tell me this is correct. The amount of play is controlled by the location of the front bearing, more shims between the bearing and first gear lessens the clearance.

When the rear housing is in place it does sit flat on the case, but you need shims between it and the rear bearing, and sometimes those come out of place when you're sliding the case over the rear mainshaft and cause it not to sit correctly, I put grease on the shims to hold them while I carefully slid the housing down into place.

Hope this helps,  but my brain is still fuzzy from the flu.......I'll be better next week too.....I hope!

[pbraun]

Humm, well, that does make sense about the first gear moving a bit too far and allowing the balls & springs to escape.   Tomorrow I am going to study and go over the manual and drawings to try and make sure I'm doing everything right before it gets messed up once more.

getting close to asking if I can ship the dern thing out to see you. Cheers, and feel better!

[MiniDave]

Clancy dropped off another Sprite gearbox for me to evaluate - but this one is just a bit different - can anyone spot why he was excited to find this one?  Hint -  it's for his race car......

Check out on page 3 the last Sprite gearbox I rebuilt for comparison to this one....

[Willie_B]

Straight cut gears?

[MiniDave]

AND.......

Close ratio gears! Perfect for a race box.....

It looks a little grungy inside but Clancy has a device driven by an electric motor that will run the gearbox and allow him to shift it thru the gears - so we're going to fill it with diesel and run it for an hour or more - then drain it and do it again. Since these gearboxes run 30 wt motor oil it won't hurt and should clean it up - that will let us know if it has noisy bearings and needs to be gone thru. This is a back up box so it's not critical to be done right away.

[pbraun]

Well, it's finally done!  Not as clean as yours on the outside, but everything not up to spec replaced on the inside!

Last nuts going on, then into the bug-i.

[MiniDave]

Cool, this has been quite the project for you, glad to see you mastered it......now, into the car and drive it!

[pbraun]

Yeah, and I didn't share about troubles getting the rear extension on........but all ok now - Into the car and out for driving!
Thanks for your help!

[MiniDave]

Quite a while ago (wow! March!) I posted some pics of a sprite Gearbox Clancy brought by for me to teardown and inspect and today I finally managed to get into it. Most of it looks salvageable, although I need to clean some parts up so I can inspect them thoroughly before I can say for sure. The one part that has me concerned is the laygear, if the inner bearing surfaces are damaged it may not be worthwhile to rebuild it....a new laygear is mucho dinero.....

It was a bitch kitty to get apart, things were rusted badly like it lay in water for a while, but only the reverse gear seems pitted and damaged, maybe it was laying over on its side? One of the screws that hold the shift forks in place, the head had completely rusted off, I had to weld a nut onto the end of the screw to get it out - and it was the one on the bottom of the reverse gear - but I knew a trick. I'll show Howie Didit later....

[MiniDave]

Well, bad news.....there is little to nothing left inside that is any good, so we're talking about where we're going from here. I found a set of close ratio gears that I could build from for a reasonable amount......I also sent a note off to MED as in watching a vid (Jemal from Mania) he mentioned that they sell dog shifters, gears, aluminum forks and other bits so I asked for a quote on those too.

[MiniDave]

Found a source for both the straight cut gearsets and the dog gearsets in the UK, now I just need Clancy to decide what he wants to spend on the box for his racecar.

[MiniDave]

Meanwhile, another Sprite gearbox has found its way into my shop - actually this is the second one he brought me, the first one was so torn up it would have taken a major amount of parts replacement to make it work again - this one out of a Lotus 7. He later confessed he thought his nephew might have done the damage trying to shift it into 1st while moving fairly quickly....there are no synchros on first in these gearboxes.

Anyway, after looking at all the needed parts for this one he's decided to build a straight cut gearset much like I'm going to do for Clancy.

The laygear on this one shows considerable wear too, hence the need to go all in and do the straight cut gears - the cost of the helical laygear is half that of the complete set of straight cuts, which include a new laygear too.

I've got most of the case and gears and shafts I'll be reusing all cleaned up, still have to clean the tailhousing and shifter box yet.

When I get parts in it will be a total rebuild instead of a freshening like he hoped to do.....all new gears and first motion shaft, new laygear, new bearings thru out, new tail shaft bushing and seal and of course all new gaskets and seals. We're also going with a modified front cover that uses a replaceable lip seal instead of the original, which used a reverse screw thread to keep the oil in the box - no seal of any kind.

I'm hoping Clancy will sell one of his project cars, if he does we're going to build a dog box for his Sprite - that will be a first for me.

[MiniDave]

OK, I got everything cleaned and ready for re-assembly, just waiting to hear from the owner on what gears he wants to use. He sent a note off to a company in England, haven't heard back from them yet.

[MPlayle]

The way most smaller companies in Europe tend to operate during the holidays, it may not be until next week before you hear back.  (Lots tend to be closed for the two weeks covering Christmas to New Year.)

[MiniDave]

WillieB fired up his little lathe and made me a tool to pull the rear bushing out of the tail housing on the Sprite gearbox. It arrived in the mail today so I went straight down to the shop to try it....it worked perfectly!

I used the pusher tool to shove the old bushing in and then set up the acme thread and socket and pulled it right out again! Perfect!

Thanks WillieB!

A few pics to show how it works. First I used the pusher part to shove the old bushing back in the tail housing, then a pic showing it pressed fully in - the shoulder of the tool allows me to set the bushing at exactly the right height.

[MiniDave]

Then I assembled the tool with the acme thread rod and special nuts ($5 each!) and a large socket to receive the bushing and inserted it in the housing. I stopped part way so I could see if it was pushing it out straight - which it did beautifully.

Result!

My 6" Wilton vise sure makes these jobs easier as it holds big stuff like this securely.

[Willie_B]

Just what you had in mind. Looks like it works a treat. Now that I see the pics I really get how you are using it.

[MiniDave]

Ran into a snag with our little puller, turns out it works fine on a used bushing, not so much on a new one! Like trailing arm bushings on a Mini, they have to be reamed to size once in place, so I'll be sending the new bushing along with the tool back to Georgia to have WilieB work some more magic on it.

In the meantime the owner brought me another tail housing to use with a good rear bushing in it - we checked it with a driveshaft yoke to be sure - so I'll clean it all up and put a new rear seal in it and call it good. We also didn't like the looks of the shifter ball in the shift housing so he brought me another one of those too.

Today I assemble all the gears and bearings onto the shaft, dropped the laygear in and checked the shims then installed the reverse gear. Next in was the input shaft (or first motion shaft to some of you) and then the cluster. Once in place the first motion shaft slides back into place and then you raise up the laygear and slide the shaft in.

That's as far as I've gotten tonight, I'll probably have to take the whole shebang back out as I can't seem to thread the nut on the first motion shaft even tho it's new and the threads should be perfect.....so I may have to clean them up and I can't do that in the gearbox. It's always sumthin......

[MiniDave]

Finished up this gearbox today, as far as I could go. We have a new front cover coming - the original covers don't have a seal in them for the input shaft, rather a reverse thread on the inside of the cover which is supposed to redirect the oil back along the shaft into the gearbox. They leak.

The new cover has a machined boss and an actual seal in it - should work much better - but we don't have it yet, so I put the old cover on and he can run it like this till the new cover comes in then just swap them out.

I had mounted it up in my engine stand, but that really doesn't work so well, it's too low and makes me bend over, plus you can't reach the input shaft if you need to spin it or hold it in place.

I made some little temp brackets to hold bearings and detent springs in place while I checked the fit of all the parts inside and made sure it would shift easily, they worked well, but when I stood the trans on it's nose to install the tail housing the layshaft slid right out the front!  ::)  So I installed the front cover to hold it, then turned it up and put the tailhousing on. The gasket that goes on this end was not cut quite right, I had to enlarge or move the holes so that it would fit correctly, there is a locating pin on the rear bearing housing that dictates where all these pieces go, you can't just fake it!   ;D

So it's mostly there, he didn't bring the rest of the parts that hold the shift lever in so I can't shift it much, the lever jumps up or binds without the top parts but I found a nice JPS shift knob (this trans is going in a 62 Lotus Super 7 - a real one, not a Caterham version) in my stuff that I got somewhere - brandy new - so I put it on for him. I have no idea where I get this stuff, it just shows up somehow!

[MiniDave]

Finally got all the parts in for the second gearbox - this one for Clancy's racecar.

He brought me this box last fall with a "no hurry" instruction, I finally took it apart in January and it was a mess. He swears it was dry inside but I could clearly see it had been at least 1/3 full of water, and things were not good. He had hoped it was just surface rust but when I got it apart - it was clear it was simply no good. 2nd and 3rd gears were "welded" to their shaft by rusted needle bearings - I had to drive the 3rd gear off with a 3 lb hammer and big drift - I tried pressing it off in my 20 ton press - wouldn't move a lick! - so the three pounder was pressed into service.

The pic of the two shafts tells the story.

Fortunately the owner of the silver box had a spare mainshaft Clancy could have and that's what I'll put in it this week as I get going on the build.

We also found a place that sells a front cover with an actual seal in it instead of the reverse thread that always leaks.

So all parts are here, I've already cleaned and painted the cases, still have some cleanup to do on some of the internal parts and all of the nuts, bolts and studs, plus I'll run a tap in all the holes to make sure all the threads are good.

Clancy's on his way to Phoenix today to deliver a racecar and will be back Friday - I should have it ready to go for him by then. He had taken all the gearbox cases and some other parts down to a blast place in North KC to have them dry ice blasted - they were NOT clean, so the guy didn't charge him for the job (which was expensive!) and I spent a lot of time cleaning the parts that they didn't........