snatching in and out of gear

rockdemon

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Staff member
A couple of weeks ago i was forced by a flat battery on the saab to take sleipnir on a 200 mile jaunt at very short notice - so where normally before a long journey i'd have checked levels etc, i didnt have chance. On the journey there it seemed to have issues when going over 70 - i though electrical or something at the time. However on arrival in rural areas the gearbox seemed to be having trouble holding on to first, even when put their with the gear lever. A check later that evening showed that the level of gearbox fluid was off the bottom of the stick. The next morning i procured some gearbox fluid of the correct sort (bit of a miracle considering where we were) however the gearbox now seems to have a tendency to slam in and out of gear (3rd and 1st - not 2nd if i'm reading it right!)

Those who remember the saga i had getting this gearbox sorted in the first place will know that i had to drive about 35 miles without a gearbox cable to get it home. However i then fitted the cable and it's been OK since.

Question is, what could this issue be? Is it something i should be able to adjust out with the cable tension or is it back to square one? Really want to get the car to the v8 engine 50th celebration at the beginning of august, so happy to put the engine on hold to get it drivable if that's what it takes...

Thanks in advance...
 
I think if the fluid level is correct I'd have a look at the cable to see if it's got snagged up somehow, so raising the pressures. Easy things first! After that if there's no problem with the cable we can move on. The cable adjustment shouldn't have changed, and even if the locknut was loose the cable would back off and lower the pressures, not the other way around.
 
Cool - I'll take a look at that over the weekend. I have this nagging feeling it buggered if im honest. I do have an lt77 sitting in my shed but i wasnt quite ready for that yet... You think the cable is too tight if anything - so I should be looking to back it off a turn or two to see if it improves matters?
 
You think the cable is too tight if anything - so I should be looking to back it off a turn or two to see if it improves matters?

"Snatching" would imply harsh engagement to me, and that would be pressures too high, but I wouldn't randomly adjust the cable to try to fix it as I may have misinterpreted your use of the word.
If you are in a position to do a more comprehensive roadtest we can move forward with the results of that.
 
When I say snatch it feels like it loses drive with the motor temporarily gaining revs then slams in again. Eg. First gear then revs jump with the car losing drive then slam into second. In third gear like a slipping out of gear then back in.
 
Those can be symptoms of a low fluid level, but if you've checked the level correctly, then the increase in revs can be "flare", and in this case as it's all in forward drive, it's probably a front clutch fault, which in the end will result in a total loss of drive. Chances are as it slips you hear that happening and lift off the throttle, and at the moment that's enough for the clutches to get a grip again. I wouldn't advise a stall test as although that might prove the point, it could also finish off the clutch for good.
 
One other question, since this started happening, have the shift speeds changed at the same time? If so is it upshifting earlier than it was?
 
Upshifting seems more inconsistent if that makes sense...?

Something has changed then. The problem is that if it is the front clutch failing then to fix that the box has to come out and be dismantled, and it would be nice to avoid that, so I'm trying to think of other possiblities.
 
I'll have a careful look for cable issues and I'll check the fluid one last time. I wonder if the low fluid caused clutch wear and it's damaged it.
 
Slip will always cause clutch wear and eventually damage. All you can hope is things haven't gone too far.
 
Yup. Prove I'm a plonker once again I guess... Oh well. Sun is out. Beach tomorrow I reckon.
 
Havent looked at the car this weekend - had a break, aside from removing a couple of pistons from the original engine.

I did think having a look round on ebay of Ron and his upgraded BW35 - I note the aussies sell rebuild kits for bw35 and the upgraded 40 as interchangeable which if they have upgraded plates and clutches could be a worthwhile investment? Assuming it's not available in the UK of course...

AUTOMATIC TRANSMISSION REBUILD KIT BORG WARNER BW 35 VALIANT CORTINA ESCORT LTD
 
They are the same plates as the 35, check the 35 page, the part numbers are the same. Rear frictions used to be heavier duty, they were grooved, and you could fit those in the front clutch to uprate that, but the grooved plates are NLA.
 
OK - so today i was carless (Sven had to be lent to the father in law!) so I had to drive the p6. Given what you'd said about low fluid I dumped some more fluid in. It gave a rather large burp up the filler tube and the fluid level dropped down as soon as I ran it. So i think (fingers crossed!) that we were dealing with an air lock of some kind. Does that ring true as a possibility? It then drove 25 miles without any issue...
 
If you fill before running and the level is up the tube it could trap some air, which needs to vent out, but the underlying problem would be the low fluid level in the first place. I'd be inclined to check the level again now it's had a run.
 
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