Hi,

Thanks for joining the conversation! I'm reaching out for help.

Procedure
I recently followed Atlantic British procedure to change out the automatic transmission fluid. Drained the pan, changed out the filter, replenish pan with Dexron III/IV fluid. (1) I start the car, (2) shift tranny through gears, (3) replenish fluid until it drips from the fill plug 1 drip per second, rinse and repeat steps 2-3, 4 times. By the 4th time, fill hole was dripping at the desired speed.

Symptoms
- Loud thud from driveline when coming to a stop, right around <10mph, tranny is changing gears from 2 to 1. This is the most notable and loudest thud/clink.
- You can feel the jerk in almost all gears, the car and transmission is responsive, no dragging noises, when accelerating with the throttle 50-100% it shifts like butter.
- I inspected the parked car from underneath, my assistant changed the gears while the car was running. The only thing I see the drum brake move around as a result of the transmission jerk.
- Loud thud/clunk when shifting from Drive to Reverse, or sometimes Park into Reverse.

Background / Thoughts
- Car shifted perfect prior to fluid change.
- A magnet in the pan had fine pieces of metal attached to it. Not a glob, but not a hefty amount.
- I noticed that the Drive Shaft Rubber Coupling is rather soft, pliable when I press it with my hand, I have a new on hand, and will replace it.
- I did not notice any play in the driveshafts, shaft and u joint are greased, no play in u joints.
- I don't own a nanocom to reset the transmission adaptations.
- I'm actively reviewing the ZF Automatic Transmissions Service Manual, hopefully it can point me in some direction.
- Air in the system? Did I over/under fill?

I'm leaving for Seattle tomorrow, if anyone is available for a quick chat, I'm happy to pay for beer/coffee, over a phone or w/e.

Thank you!

 

Check your diff and transfer case levels and really grease your drive shafts,not a little a lot, the clunk is not the transmission it is in the drive line.

 

Hi, Richard.

Done
- Transfer case level checked and level is adequate.

Todo (I'll report back)
- Grease the driveshaft after acquiring the tool/material.
- Check diff levels

 

Todays Observation:
- Video of the D2 driveline clunk when shifting between Reverse and Drive.
- I disconnected the battery overnight, which I think cleared the adaptations. On cold start, and first 10 minutes of driving, there's no clunking, smooth in all gears and various speeds. After full warm up and highway driving, the clunk is now only noticable when coming down to a stop. A jerk is felt while decelerating to 10mph and a change in gears occurs.

I'm leaving for Seattle today and none of the local shops had time to squeeze me in for an inspection.

 

Done
- Rear Propshaft Flexible Coupling Replaced, it was cracked in 10 places.
- Topped off both diffs with fluid.

Todo
- Grease the driveshaft after acquiring the tool/material.

Observation
- I no longer experience the clunking when downshifting (cold or hot). I am leaving for a 6 hour drive today, I'll report back if the fix is complete.

 

That clunk is pretty common. My D1 does it quite impressively , only after it's warmed up - suggesting something to do with the oils having thinned from being at the right temperature. It doesn't do it coming to a stop though.
It does it worst if I come to a stop, then select Reverse. However, if I slip the trans into neutral just before stopping, then select reverse, it doesn't do it - I guess the slack is gently wound the other way prior to stopping.

I've heard it said, it's the splines between the trans and transfer case being worn, plus the play in the driveshafts and diff.
It can also be the intermediate shaft in the transfer case - they wear the hoe oval and move.
I've also heard Techs same that some did it from new.
I've not sure - all the above can happen, and all making a little noise, could combine to make the big noise.

Was the clunk there before, when moving from D to R?

It could be the trans engaging more positively, because the fluid is working as it should, rather than the pressure being lower, or slurring into gear, rather than engaging firmly.

On a D2, it's important to check the double-u-joint - they have been known to fly apart and take out the trans casing.

 

@disco_rookie Yup that rubber donut can cause a lot of clunks,

 

Mid trip update:
- clunking is still there and very much noticeable, only when coming to a stop as the transmission shifts from 2nd to 1st around 10mph. It also doesn't happen every single time, some clunks are more intense then others.
- one way to circumvent the clunk is to shift into neautral before coming to a stop.
- it drives exceptionally well on the road, transmission is responsive.

Not sure what to do next.

Options
- Lubegard Instant Shudder Fix?
- Schedule driveline inspection for the future
- Recheck tranny fluid?

 

Option 4 = status quo, do nothing, live with it (it's an old truck). Might go on like that for years without a problem, or stop driving if it gets suddenly worse.
Option 5 = research land rover defender/discovery clunk repairs, watch several videos about it before deciding next move. Especially recommend Britannica Restorations (excellent technical content and funny stuff too), and Bearmach Trailfitter's Toolbox videos. Nearly all common problems are covered between the two, including how to adjust/repair transfer case gears/bearings and differential lash.

Maybe the slop in the drive train was there before, but only noticed now that the transmission is shifting better?

I notice in the video the driveshafts are moving when shifting gears. If the wheels are not moving, that indicates how much gear lash there is in the differentials. The differential gear lash could be the cause of the clunk. Gear lash is adjustable with a tear down of the differential. Good step by step videos online. Maybe get a spare diff from a scrap yard, set it up on the bench, then swap it in and repeat for the other end. Front and rear diffs are identical.

 

After 1500 miles last week, the clunking is completely gone, there is a minor jerk when changing from D to R fast (appears to be normal play in the driveline per other threads). But otherwise, happy to report no obvious jerking or clunking. Absolutely zero trouble on the trip besides the first 1-200 miles of driveline jerk when coming to a stop.