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gear changing early
Posted: Sat Jul 17, 2021 9:40 pm
by badger
so today was a great day i drove the jag for 10 miles without fault...
WELL maybe not without fault but i got back to the workshop without phoning anyone and thats the first time in 6 years its done that.
so i have 2 new issues to look at
1 is an oil leak which needs investigating it wasn't like that 4 weeks ago but i have refreshed everything when doing the service
2 is the gearbox when i pull away it changes gear really quickly im in top before i get to 30 mph
and when i take my foot of the gas it judders as if its being held back.
if anyone has any ideas or pointers i'd really appriceate it as always
im still smiling from ear to ear that i was out in it ,everyone out there loves an old jag (the looks i got were amazing)
i'll be disapointed when i finally finish it and hand it back to its owner,
Re: gear changing early
Posted: Sun Jul 18, 2021 12:50 am
by Glyn Ruck
What year is this car? 99% of auto transmission issues are caused by incorrect fluid level. If it is a BW DG250

- Auto gear change..JPG (28.45 KiB) Viewed 2279 times

- Auto fluid level DG.JPG (54.98 KiB) Viewed 2279 times
Method for BW 35.

- Auto Fluid Level 35.JPG (88.55 KiB) Viewed 2278 times
Re: gear changing early
Posted: Sun Jul 18, 2021 10:59 am
by badger
the car is A 1965 but at some point in its life it has had an engine and gearbox change so n ot sure what its got
Re: gear changing early
Posted: Sun Jul 18, 2021 1:41 pm
by Glyn Ruck
If the transmission has an aluminium casing it's a BW 35. If cast iron it's a DG.
Re: gear changing early
Posted: Mon Jul 19, 2021 2:24 pm
by Orlando St.R
If it's a DG gearbox, I wouldn't be overly surprised if it was in direct drive (top/3rd) by 30 mph, if you were on a gentle throttle. If you want it to hold on to the gears, you'll need to use more throttle.
The judder when you take your foot off...gearbox mounts possibly? Or rear brakes binding?
What sort of oil is leaking? ATF? Engine oil?
Re: gear changing early
Posted: Mon Jul 19, 2021 8:21 pm
by badger
its defo engine oil leak it looks like around the front of the sump area but only started once i'd serviced it and put her back on the floor (mind you it was on axle stands so front was a lot higher)
could be a front seal or the sump gasket itself like a say its the first real run its had for 5 years
also tried being easy with trottle and keeping it planted (makes no difference )
the holding back isn't constant like brakes binding its hard to explain on here.
but i'll check fluid levels and go from there.
Re: gear changing early
Posted: Sat Jul 31, 2021 6:33 pm
by badger
hi all, while mucking about and sorting a few other things i found this under the car.
by what looks like the overdrive unit there are 3 wires (bottom of picture) and a wire from what i believe is the overdrive soloniod that goes to no where
can anyone show me where there meant to go at all.

- jag wires.jpg (744.61 KiB) Viewed 2127 times
Re: gear changing early
Posted: Sat Jul 31, 2021 8:16 pm
by cass3958
If you have an Auto box I doubt this is an overdrive solenoid. I am only guessing as I have a BW35 box not a DG250 but could this be the "speed hold". Not sure how it works or if I am even correct but it might jog someone else's memory.
The item on the left that has the dirty wires and blue connectors attached is the Anticreep devise.
Re: gear changing early
Posted: Sun Aug 01, 2021 1:44 pm
by NigelW
The gearbox looks like a DG and the solenoid is the intermediate speed hold, the item bolted to the floor is the anti creap device as Cass said so definitely not a manual overdrive.
Re: gear changing early
Posted: Sun Aug 01, 2021 2:03 pm
by NigelW
Looking at the wiring diagram on this site the yellow/purple and green go to the anti creap switch and the yellow /red goes to the solenoid. Unfortunately I can't verify this on my car as I put the DG box in the skip decade's ago.