Rchowchu · Dec 29, 2019

Hi all

looking for abit of help before I buy a new gearbox . Was out at a pay and play site the other day and just lost drive Turned out to be a half shaft so changed that after that lost drive.

I topped up the gear box oil as it was rather low but can only seem to get 1st gear when it’s selected and same with reverse.

anyone got any ideas what I could do to fix it or new box ?

Sorry it’s a discovery 300tdi auto

cheers
Rob

ifloochies · Dec 29, 2019

ATF is a detergent oil, and the new oil you put in has inadvertently loosened up crud in the box that have found their way into the mechanical governor at the back of the box.
That governor is what is responsible for adjusting line pressure to change gears based on rotational speed, so by not operating properly, you're stuck in one gear and there's very little you can do from outside the box.
You may be fortunate enough for it to clear up by itself with use, but if it doesn't, you would have to drop the transfer case to access the back of the box.

Rchowchu · Dec 29, 2019

ifloochies said:
ATF is a detergent oil, and the new oil you put in has inadvertently loosened up crud in the box that have found their way into the mechanical governor at the back of the box.
That governor is what is responsible for adjusting line pressure to change gears based on rotational speed, so by not operating properly, you're stuck in one gear and there's very little you can do from outside the box.
You may be fortunate enough for it to clear up by itself with use, but if it doesn't, you would have to drop the transfer case to access the back of the box.

Would it still be the governor even tho I can only get 1st in 1st not in D ?

discool · Dec 29, 2019

“can only seem to get 1st gear when it’s selected and same with reverse” So as it should be.
So what are you expecting? something other than first ratio when selecting 1 and reverse when selecting R.
What happens when you select positions 2 or 3 or D ?

ifloochies · Dec 29, 2019

Rchowchu said:
Would it still be the grovernor even tho I can only get 1st in 1st not in D ?

Yup, still is....
The ZF box in the discovery 1 is an all mechanical unit, no electrical solenoids to go wrong.
You only have said governor to regulate the functions of the box.

Rchowchu · Dec 30, 2019

discool said:
“can only seem to get 1st gear when it’s selected and same with reverse” So as it should be.
So what are you expecting? something other than first ratio when selecting 1 and reverse when selecting R.
What happens when you select positions 2 or 3 or D ?

I get nothing in D and nothing when I select 2nd gear and 3rd gear.

discool · Dec 30, 2019

Rchowchu said:
I get nothing in D and nothing when I select 2nd gear and 3rd gear.

Okay, Ashcroft Transmission’s Q&A has nothing to say that applicable to your issue other than what’s below.

Also as stated in a post above, it has been known for selecting issues after a fluid change on gearboxes that have a high mileage and had infrequent or never had a fluid changes, but then some have been lucky and every thing is back to normal with a second fluid change, it’s nothing new as the early RR autos had the same problem.
You can call Ashcroft’s whom I understand are very helpful, so no guessing and will diagnose the fault/s.

Q
I have a 4sp ZF, when I select "D" the vehicle won't move, when I select "1" the vehicle moves off. I can then select "D" and continue to drive normally. If I stop I have to start in first again. Why?
A
A sprag clutch has "inverted" and will need replacing. No further damage will occur if you continue to drive but you will need to select "1" every time to start moving. A rebuild is required to correct this.

dieseldog69 · Dec 30, 2019

Rchowchu said:
Hi all

looking for abit of help before I buy a new gearbox . Was out at a pay and play site the other day and just lost drive Turned out to be a half shaft so changed that after that lost drive.

I topped up the gear box oil as it was rather low but can only seem to get 1st gear when it’s selected and same with reverse.

anyone got any ideas what I could do to fix it or new box ?

Sorry it’s a discovery 300tdi auto

cheers
Rob

Go see the fellas over at Safari engineering and see if he has a good used box he can sell you.

Rchowchu

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ifloochies

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Rchowchu

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discool

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ifloochies

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Rchowchu

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discool

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dieseldog69

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