No Gears

[GARRICK.CLARK]

Hi guys.
I'm trying to solve a gearbox issue on a mates bug.
Bug is a 65.
He bought a GT box for it. When he bought the box the diff wasn't fitted, so he refitted it, along with the short shafts from his old box. I wasn't present while this work was being done, Bought a New late standard clutch to go with the GT box, old clutch was an early one so wouldn't do. I helped refit the engine, all went well. Started the engine, cant get gears without it grinding. turned engine off, selected any gear, started engine with clutch pressed and its trying to either jump forward or grind a gear, like the clutch isn't even pressed. So what's going on. Is it clutch related or box related. Engines now back on the floor.

Were 1st looking at the clutch side of things. I measured how far forward the throw out bearing travels along the steel guide tube with the clutch pedal pressed to the floor. Its 10mm from pedal up to pedal down. Is this enough.

Should the release bearing without the engine fitted and with the cable adjusted properly be all the way back on release bearing guide tube. How much guide tube should be showing in front of the fitted release bearing.

With the wing nut tightened down so there is no threads left on the cable and with me holding the release bearing to stop it moving on the guide tube there is about an inch and a half of play. The Bowden tube does have a bow in it, but looks to straighten out a bit as the cable is adjusted up to try get rid of the free play in the pedal.
Any ideas would be appreciated.

[GARRICK.CLARK]

Also I can put it in 2nd gear with the engine off and with the shift rod coupling cover under the rear seat removed I can see the end of the hockey stick. I attempt to start the engine with the gear stick in 2nd positon and I can see the end of the hockey stick/shift rod coupling jump back out of gear.

[Marc]

...I attempt to start the engine with the gear stick in 2nd position and I can see the end of the hockey stick/shift rod coupling jump back out of gear.

That's disturbing. Are you certain that the front mount is sound & tight?

Spec for clutch pedal freeplay is ⅜" to ¾". Personally (particularly with a diaphragm-spring cover) I'll run a bit more, provided there's no grinding going into Reverse, but 1½" is probably too much. Bowden tube "sag" is supposed to be 25 to 45mm (1 to 1-13/16") - add washers at the bracket until you have more preload, that should make the effective length of the cable shorter so you can adjust it tighter. While you're at it, clean out the Bowden tube and inspect it before repacking w/grease - if the internal spring is broken it can telescope when the pedal's depressed.

Other causes of "clutch drag" symptoms include dirty splines on the input shaft which don't allow the disc to "float" to & fro, high friction between input shaft & glandnut needle bearings, clutch disc hub dragging on a glandnut that's standing too proud of the flywheel (several causes, thicker-than-stock washer's #1 on the list), clutch cover diaphragm rubbing on disc springs when depressed...sounds as though you have the correct cover for the late TOB arrangement (no center thrust ring) but you may want to check that the ends of the "fingers" of the diaphragm aren't contacting the guide tube when they flatten out under compression (look for marks on the tube).

[GARRICK.CLARK]

Hy Marc, Very good advice there about the clutch. i'll check those tips out in the morning.

This box is supposed to be a good unit. If when all the above has been checked its going to be a case of sending the box away to be stripped , checked and put right. There's nothing else it can be is there.
The front mount is a new one.

[Marc]

Does the mainshaft have any endplay? Radial movement is normal, but it shouldn't move for & aft no matter how hard you tug/push on it.

If the mainshaft snapring (under the nosecone) popped free it could cause the trans to jump out of gear. That's something that can usually be put right without major surgery, I'd check it before having the trans rebuilt.

[GARRICK.CLARK]

Progress was made. The clutch disc was not sliding on the input shaft. cleaned up the splines on the shaft.
refitted the engine. Got gears now. Had to fit a standard gear stick as it selects the gears better. Bush in tunnel is worn along with the shift rod block under rear seat. BUT.
3RD gear is squealing its nut off.
So its going to need a strip down . Why would 3rd squeal .
I need to understand what's gone wrong before I ring the local gearbox guy on Monday.
Cheers Marc.

[Marc]

...Why would 3rd squeal? ...

Haven't seen that one. Perhaps there's a problem with the needle bearings inside it. I'm assuming the lube is good/full. Any unusual noises from 4th?

There's one classic noise that I'd describe as more of a "turkey-gobble" than a squeal, caused by the thrust washer between 4th and the mainshaft bearing having too large of an I.D. causing it to sling around on the shaft - that one's usually most prevalent when the trans is cold and quiets as it warms up. The factory started making tighter-fitting washers (a light press-fit on the shaft) to cure that.

[GARRICK.CLARK]

well Cause the back of the bug was jacked up we only put 2 ltr of oil in as that's all it would take because of the angle of the box. Bugs not been driven just pushed out of garage onto level ground. I don't think 0.5 ltr of oil is gunna stop the noise.

[Bruce2]

You need to drive it in 3rd gear. Right now 3rd gear needle bearing is dry. It will not get any oil ever while you idle the engine. You have to drive it to get it lubed up. Then the noise will be gone. Same applies to a noisy 4th.

[GARRICK.CLARK]

ok ill give that a try, just using 1st and 2nd.
Went out for a little spin.
found 3rd.
The strange thing with it is , with the car on flat ground, clutch pressed to floor, I can find all gears now.
on a slope, the box squeals its nuts off. We will take box out this week and send it to the box guy.
I will let you no what the problem is once stripped .

[GARRICK.CLARK]

Hi guys.
The box is stripped now and it seams the bearings a worn and the 3rd and 4th shift fork are worn also. Can someone tell me what other gear box codes have the same shift forks as the AS code box that we are trying to fix.
Thanks G.

[Marc]

We never got the AS in the USA, but I believe that's the swingaxle variant of the IRS 3.875:1 AT trans produced from 8/72 (`73-up model years).
So far as I know the change to the .190" thick, steel, 3/4 fork was across-the-board so any trans made after that should have the same internals.
The codeletter alone doesn't give enough information on most transmissions since it usually spans several years and internal variations.
Fortunately, at the same time a new numbering system was adopted which gives the production date in DD-MM-Y format, e.g. AT 02 03 6 was built on March 2 1976.

You'll probably want to limit your search to swingaxle cores in order to score the correct extra differential parts (the late swingaxle side gears are super-rare on this side of the pond and it's quite likely you could sell them to defray most of the cost of the core), but if all you're after is the gears/forks/etc. any single-sideplate (or late double-sideplate) IRS core should do.

[GARRICK.CLARK]

Thanks Marc, I should be able to find 1 pretty easy.
To be continued.