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pops out of second gear on acceleration

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windrose

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My BN7 side shift is frequently popping (jumping) out of second gear upon acceleration. What are the most likely reasons?

Thanks
 
Aloha Windrose,

Doesn't look like you're getting much satisfaction on your transmission issue. I tend to agree with steveg that it might be time for a teardown. At a minimum you might want to drain your transmission oil, and check for bits of metal, which may at least point to/confirm a larger problem. Years ago, when I took my BT7 transmission apart I found that one of the gear selector forks had a missing "ear". It still shifted OK but wasn't entirely smooth. I'm not suggesting that this is your problem, but from the sound of things, one of the gears is not fully engaged. If memory serves me, the selector forks are pinned/bolted to the selector shaft. Perhaps this bolt or the selector shaft itself is the culprit. Again, try checking the oil first......

Maybe this will inspire someone with a stronger technical background to chime in.....sorry I can't be more helpful.

DB
 
Normally, when popping out of gear on acceleration,it's a sign of worn gears & or slider hub. If box has been apart recently, I've seen end-play or shims(spacers) missing. Either way i'll have to come out & tear it down.cheers
 
Thanks David

I drained oil (it was too heavy - 80W?) and replaced with 30W. It was harder to get it to pop out but it still did. It also has a "tick" sound in 1st along with the usual whine so I suspect a chipped gear there. I guess I will have to open it up and see what I find. I have a spare non-O/D trans. as a back up for parts if there are major problems.

Tony

davidb said:
Aloha Windrose,

Doesn't look like you're getting much satisfaction on your transmission issue. I tend to agree with steveg that it might be time for a teardown. At a minimum you might want to drain your transmission oil, and check for bits of metal, which may at least point to/confirm a larger problem. Years ago, when I took my BT7 transmission apart I found that one of the gear selector forks had a missing "ear". It still shifted OK but wasn't entirely smooth. I'm not suggesting that this is your problem, but from the sound of things, one of the gears is not fully engaged. If memory serves me, the selector forks are pinned/bolted to the selector shaft. Perhaps this bolt or the selector shaft itself is the culprit. Again, try checking the oil first......

Maybe this will inspire someone with a stronger technical background to chime in.....sorry I can't be more helpful.

DB
Click to expand...
 
Windrose,

A chipped gear wouldn't surprise me - the older transmissions like yours (and mine) had no syncromesh on first gear, so there may have been some crunching by previous owners to get it into gear. Not sure that's the problem in your case, but it's certainly worth a look. I'm still using Castrol 20/50 in my transmission, with no problems, although there a number of BCForum threads that you can explore for alternatives, such as Redline, and other synthetics. If you suspect your oil was as heavy as an 80 weight, I'm surprised you could shift at all! That's differential weight. That spare non overdrive transmission is fairly rare for a Healey....

Cheers
Dave
 
davidb said:
If you suspect your oil was as heavy as an 80 weight, I'm surprised you could shift at all! That's differential weight.
Click to expand...

Actually, gear and motor oil ratings are quite different so 80wt gear oil is approximately equivalent to 20wt engine oil by viscosity

75W-90 gear oil would be roughly equivalent to a 10W-40 engine oil
80W-90 gear oil would be roughly equivalent to a 20W-40 engine oil
80W gear oil would be roughly equivalent to a straight 20 engine oil
https://www.gasgasrider.org/html/gear_oil_evaluation.html

Andy.
 
Thank you Andy. I didn't know that. It always seemed quite a bit thicker to me. So can gear oil be used in transmissions as well as differentials?

Dave
 
The term "diff oil" usually refers to the API GL5 category of gear oils which have Extreme Pressure additives for hypoid gears. GL5 oil has that stinky sulphur smell and will not allow the synchromesh to work properly if used in a gearbox. Best to use GL4 (or engine oil) in the gearbox and GL5 in the diff.

Interesting information on gear oils here

Andy.
 
Andy is correct, in fact many re builders will void warranty's if Gl-5 is used because it attacks the synchros. Brass doesn't like GL-5.

Geno
 
Genos2 said:
Brass doesn't like GL-5.
Click to expand...

Interestingly, I recently discovered that this is an urban myth.

Pretty much all modern GL5 oils have no effect on yellow metals according to these tests.

The incompatibility is because the additives intended to lubricate the sliding hypoid gears also lubricate the sliding synchromesh cones and prevent them from working properly.

Andy.
 
"Interestingly, I recently discovered that this is an urban myth." To each there own, myself, I don't see the point when a manufacturer specifically says no warranty if this type fluid is used, why I would go against it & void my warranty. I guess it's only $ & if you got burn it. I like doing a task properly One time & not redoing it. Yes there are many "urban myths" on the internet, also many studies-ask any politician. cheers Geno
 
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