Hi to alls
This a question for BorgWarner gurus ...
The symptom regarding gear shifting is as follows : Clunking noise when shifting from intermediate drive to direct drive only
Everything else works perfectly : neutral to intermediate is flawless
No slipping, no skidding, the kickdown works very well. During the kickdown, the shift from direct to intermediate happens almost without a clunk.
The clunk only occurs when progressively pressing the accelerator, triggering the shift to the higher gear
The oil level is correct
Could it be a matter of adjustment (bands in the gearbox) ?
Should the different pressures in the box be checked, especially the Direct Drive Clutch which is involved when changing frim intermediate to direct drive ?

My best regards
Gérard

 

I would check the universal joints in the driveshaft first.

 

https://www.studebaker-info.org/Tech/Diagrams/stx.html

The link might help.

 

This is what I found about Clunking noise when shifting from intermediate drive to direct drive only.
Your comments are welcome.If the cracking noise occurs only when shifting from Intermediate (2nd) to Direct Drive (3rd) on a BorgWarner DG 250, here are the possible causes:

1. Worn or faulty direct clutch

• When shifting into Direct Drive (3rd), the direct clutch engages.
• A worn, burnt, or poorly pressurized clutch can cause harsh engagement and a cracking noise.

2. Issue with the intermediate brake band application

• The intermediate brake band (which holds the intermediate drum in 2nd gear) must release properly to allow the shift to Direct Drive.
• Incorrect adjustment or band wear can cause a delay or abrupt release, leading to a cracking noise.

3. Hydraulic pressure issue in the gear shift circuit

• Low or unstable hydraulic pressure in the passages can cause harsh engagement of the direct clutch.
• Possible causes:
  1. Clogged oil filter
  2. Worn-out oil pump
  3. Stuck or worn valves in the hydraulic control unit

4. Excessive play or wear in gears and components

• If internal components (gears, clutches, planetary gears) are excessively worn, they can cause harsh engagement and abnormal noises.

✅ Check the ATF level and condition (replace if necessary).
✅ Measure hydraulic pressure by connecting a gauge to the system.
✅ Inspect and adjust the intermediate brake band (servo adjustment may be needed).
✅ Check the direct clutch for wear or burning.
✅ Clean the hydraulic control unit to prevent sticky valves.

If the problem persists, a full transmission overhaul may be required.
My best regards
Gérard

 

I have a BW35 in my S Type so can't comment specifically on the DG250 but I used to have a clunky change when stationary from Park to Reverse. Car would try to launch itself if I did not have my foot on the brake. This was also around the same time I had difficulty pulling away from a junction up hill when cold.
Problem sorted after checking the oil level correctly.
I had been checking the oil when the engine was off as you would with the engine oil but I took the car back to my Transmission shop, to the guy who had rebuilt it for me a couple of years previously. He showed me the correct way to check the oil in the gearbox.
Engine running with someone in the drivers seat with their foot on the brake and the car in gear. I found I was over a quart low on oil and once topped up no more clunks and she pulls away up hills when cold now.
I now use the recommended Jaguar Churchill tool "Wife" when checking the oil and not had a problem since. He explained that if you check the oil when cold or with the engine not running the Torque converter can drain oil back into the gear box giving you a false reading of your true level. I would assume this is the same for the DG250, BW35 and any Auto gearbox.

 

Cass is absolutely correct in the way to check the oil in the DG250 box.ie engine running, in gear with the brakes applied
I was shown this by an automatic specialist back in the 1980s.
I have had several automatic MK1s and Mk2s and invariably all had low automatic oil when I first acquired them.

 

Thanks to Cass and Bill
I have understood that oil level in the DG is key for the proper functioning of the gearbox.
What is the Churchill tool, so called "Wife" ? Is it the JD 677 ?

Below the Jaguar practice :
With the car on a level floor, set the handbrake firmly. Set the selector lever in the P position and start the engine.. With the footbrake applied move the selector to L and raise the transmission fluid temperature by running the engine at 800 rpm for 2 or 3 minutes. With foot still on the brake and selector lever at L run the engine at its normal speed and check the fluid level. Add sufficient fluid to bring the level up to the « Full »mark on the dipstick. DO NOT OVERFILL.Is this practice good for ensuring the proper oil level ?
What is the added value of the Churchill JD 677 tool ?

My best regards
Gérard

 

Sorry Gerard this has obviously been lost in translation. Others whose first language is English are no doubt laughing but not at my joke. "Wife" in French is Épouse. She who is in control of everything and but when asked nicely will sit in the drivers seat and put her foot on the brake pedal for me so I can check the oil level. "Wife" can also be used for removing the bonnet, bleeding the brakes, passing spanners when you are lying under the car and holding torches. "Wife" should not be used for cleaning the car or asked to make coffee.
Hope this helps to explain.

 

Hi Cass
I searched for a long time for the Churchill tool so-called "Wife" without any success and finally came across JD 667.
I'm too serious in my questions !
Someone has to press the brake pedal when the gear is engaged in Low : your wife or a friend or somebody anyway ..
I tried it alone with the handbrake fully engaged, selector lever to L and measured the gearbox oil level.
I didn’t take too long, fearing that the car might move on its own
My best regards
Gérard