4AD Gearbox - Stuck in 1st gear

[Paul Bouchard]

Being somewhat new to the 4AD we found ourselves in a bit of a pickle... The gearbox, mainly a carry-over of the 4A, would unceremoniously stick in 1st gear! A sharp tap back on the shifter lever would get things back, but 1st was always a problem.

Luckily, Phillip remembered an article or discussion with Bill Haverly and/or Ashley Crossland about this very same issue. Seems that in the 4AD (later ones anyway) there is a pin that was added to the 1st-2nd synchro. Well a complete disassembly of the gearbox was needed to investigate. There is no outward indication of a pin, so the bearings were removed and the gears taken out.

Being ever so careful to keep everything organized (for later reassembly) the synchro was removed and the pin located!

With the synchro removed, you can see the wear that the pin has made in the shaft and what (we hope) is the cause for the "stickyness".

the pin itself simply drops from the synchro and was left out for the rebuild. Once the selector and shift lever is assembled to the gearbox we will update the thread to let you know how it all worked out.


Keep your fingers (and toes) crossed!

[kabu]

Hi Paul,

Interesting information. I had the gearbox almost totally disassembled but I cannot remember that pin (anymore). Since my car is still not drivable I cannot tell how well the gearbox functions in practise, we'll see.

Are you planning to leave the pin out or just rotate the gear so that the pin goes into different spline on the axle?

BR/
Pekka

[Paul Bouchard]

Kabu,

The plan is to leave the pin out. There was thought of, as you suggested, rotating the gear so that it went to another position on the shaft, but as this "feature" was added later and not all had it the decision was to leave it out. It is possible that your gearbox did not have the pin as it was added on later cars. Which year or car number I can not say as I am not fully knowledgeable in the 4AD and all of its "peculiarities". Once the top of the gearbox is back in place I can report on the success (or failure) of the theory. But given that the pin was not in all years I would suspect that things should be ok. One theory that I am considering (for the pin) is that it helped hold the selector (synchro) in 1st gear. Perhaps reports of cars popping out of 1st? I can not say for sure.

I will say that this rebuild has been eye opening! Being an A and 4A guy, this car is quite different while at the same time being quite the same. Confusing? Welcome to the club!!!

We also just finished rebuilding the front suspension bushes. Luckily we had a pair of lower suspension pins (at the end of the lower "A" arm) as the original ones were quite worn... along with bushings that were non-existant! A new set of bushes helped there, although they needed a bit of reaming for a perfect fit.

Anyhow, brakes are next!

[mikeyr]

My 4AD had the sticking problem for 40,000 miles over 30 years, it was easy to ignore once I knew how to drive the car. Take off in 1st. and shift as quickly as possible into 2nd. Although one time I did have to drive 20+ miles home in 1st gear because of rush hour traffic making me stay in 1st longer than I should have. Just let the gearbox cool down and shifts back out easily implying to me a heat issue.

I was told it was a shifter issue with some mal-adjusted shifter and I was told it was easily adjusted but I never tried. Being what I assume is a heat issue, it makes more sense that its a pin than a bad adjustment.

GOOD LUCK I know one 4AD owner that can use this info.

[Paul Bouchard]

Thanks Mike... and I am glad to report that it was a SUCCESS!!

Well, so far. The gearbox now shifts effortlessly through all gears. thanks to Ashley & Bill for their info and suggestion on the pin. I can only speculate that this pin helped keep the car in 1st gear (?). I know that with my 4A gearbox (on the A) 1st can pop out. 1st is a straight vs meshed gear so possibly more likely to do so. At any rate, the pin is stored in a little baggy should the next owner choose to put it back on.

This 4AD went from a cosmetic restoration to a fairly extensive one. The race is now on to get it ready for Stowe!

Paul

[Paul Bouchard]

CAUTION - Photo not for sensitive or younger viewers... car with body off!!

The 4ADT 2 weekends ago...

[mikeyr]

Ok, there are rules about porn on this site, one more like this and I will have to say Thank You! You should know better than to post naked cars !!!

[Paul Bouchard]

Mike and all who may have been offended...

I am truly sorry about that. Mike is right that the rules should be followed.

In order to comply, I am re-posting the photo with the "offensive" areas censored.

Paul