D1 automatic hard shifts & lag

[outono]

Took the Rover on a 1,000 mile trip this past week and ran into some annoying transmission issues:

• The truck holds 2nd and 3rd gear for far too long before hard shifting into the next gear. I can usually trigger the shift by letting the throttle off. If I keep the throttle depressed, i've been able to rev up to 4,000 RPM before a shift occurs.
  
  
• Sometimes, during a lagging shift, it will shift hard into the next gear and then shift again and again right after one another, as if trying to catch up or something?
  
  
• When downshifting, it seems to do it too early so the revs jump 500 to 1,000 RPM
  
  
• I also feel coming off the line from a stop seems slow, as if I have the wrong stall speed on the torque converter (obviously not the case here). Truck otherwise drives great.

The fluid is at the correct level. Previous owner says they changed the fluid and filter, which would have been about 8,000 miles ago or so. Nobody knows if this is the original transmission so if it is, it's got 261,000 miles on it. I do have a new Ashcroft LT230 installed, but I don't think that is having any effect here.

I have noticed, prior to installing the new LT230, that my speedo would go to 0 sporadically (my ScanGuage would also show speed as 0). It recovers fairly quickly. I know this is a VSS issue, but I have not seen the problem occur ever since the T-Case was installed.

There are no codes, but that's because my ECU won't complete its cycle. I plan on resetting the adaptive values next week and trying again to see if it'll throw any codes.

 

[1of40]

My 97 NAS 90 trans has 200k on it and I was getting the sales signs of delayed shifting. This has been my daily for 20 years so I know her pretty well, but with that said in my best day I’m a shade tree mechanic with limited experience. What I did that resulted in improved performance was to drain and replace a two quarts of fluid at during three consecutive engine oil change intervals. I was concerned replacing all the fluid at once could be a shock to the internals. Some folks have speculated this was not necessary, but I’d still recommend doing it this way on any trans this old. I feel like this is a cheap experiment.

 

[terryjm1]

I’m not very knowledgeable about auto boxes. Most of my experience with them is removing them for manual conversion. But, I have a 96 D1 (155,000 miles) that the trans was shifting a little late and sometimes a little hard. I changed the fluid drained from the pan, about 6 quarts if I remember correctly. I was told in most cases that is all that is needed, not a full flush. It definitely helped. I changed the filter as well but from my assessment I don’t think there was anything wrong with the old one. It was surprisingly clean. If I did it again I would just check and clean the old filter.

On that particular D1 I do not think the the fluid had been changed previously, at least not for a very long time. The pan gasket was dried out and broke into pieces upon removal. As I get more miles on it I may drain and fill again, maybe at 10,000 I will do it again. I used a Castrol “high mileage” fluid. Supposedly it has additives that somehow help tired transmissions shift more smoothly. .

I also was told a full flush on a high mile transmission can make things worse and the drain and fill is not only all that is needed but is a safer bet. I don’t really know how accurate that is but all things considered I will take that advice.

At 8000 miles maybe another drain and fill is in order? I’d be surprised if it makes a great difference based on what you describe but, at any rate, it’s a low cost and easy try it and see option. It sounds to me like it is more likely an electronic / electrical issue of some sort.

Also, any chance the downshift cable (I’m guessing not the correct terminology.) got out of adjustment somehow as a result of the t-case replacement. I know that can cause late / hard shifts.

Also, I was told there is some module that can get clogged that causes the same symptoms.

 

[luckyjoe]

It has been many years since I dealt with the ZF on a D1, but nearly identical symptoms pointed to the clutch packs. For me at the time, this resulted in swapping the trans for known low-mile unit. No amount of flushing would cure the issue.

I tend to go all in so bear with me. Given your position, and current faults, I would do multiple fluid changes with some driving in between. Ultimately I would change the filter first and if unknown to you, and you plan to keep the vehicle, I would also replace the trans cooler lines. You have now effectively flushed the ZF. If this has not resolved the issues, the problem lies within the box and you’ll have to either repair or replace it.

 

[kris812]

I did the worst thing ever and sunk my Rover in a river. Gas tank vent was cracked and filled the tank full of water. Got it running after 30-40 mins in the river dead and back home.

Transmission vent tube was melted closed and it sucked up Full of river water, I flushed and flushed by swapping pan fluid 10+ times to get rid of the strawberry milkshake that came out. Even changed the filter the last time. And all was well, for 1000 miles!

As I'd drive down the freeway it would Neutralize, aka go into neutral while in drive. Took to a tranny shop and they suggested a full system flush and new filter for 400$.

Yup, that was a total waste of money! Lost reverse and still Neutralizing.

What happened was the water does NOT mix well with the clutch plates, the clutch material was flaking off and clogging the filter thus Neutralizing. Master tech said even a shot glass of water will do this to auto transmissions.

I found the shop guys drinking beers working on a border patrol vehicle and Lost my shit on the owner; as my pan was leaking after this, and I said no shit your guys were drunk.

The owner decided to rebuild my transmission for another 500$. So 900$ for rebuild I got a great deal! However 10k miles later it leaks, power stall test is only 1600rpm, shifts low RPM even with kick down cable so tight it clicks the intent. But it does shift smoothly.

Last thing to note, I was shifting at 3000 RPM WOT and bogging on hills till I changed my fuel filter again for 4th time in 30k miles. I shifted once at ~3800 for the first time in a long time and was so happy I haven't been WOT since. The fuel filter was the Last thing on my mind as it was already new and gas tank has been flushed twice.

 

[outono]

Thanks everyone for the replies.

I've been driving it a bit more this week and it doesn't feel consistent enough to be clutch packs, though perhaps it just means im in the early days of failure. As I mentioned above, I really only began noticing this more around the time the T-Case was installed so its possible it has something to do with a mechanical item needing adjustment.

I have not looked at the Detente (kickdown) cable yet. On previous vehicles (non-Land Rover), i've run into several out of adjustment cables that were the cause of my transmission woes. This would be the ideal outcome...

I got a backup VSS, but since I haven't seen my speedo fail with the new T-Case, im thinking perhaps it was more a problem with the old T-Case and how the sensor was fitted to it.

I think i'll do what y'all say and start with a flush and perhaps a filter replacement. The fluid, when first checked, was red but appeared to have quite a bit of soot. After several pulls on the dipstick, the soot was really no longer there so my guess is that the dip was just dirty.

Of course, as with any Rover, one problem usually isn't all you have. The truck sat for nearly 5 days and when I fired it up, the oil pressure light took a good minute to go out. Im sure it's just lost prime, but that is extremely annoying since the top end and oil pump were rebuilt less than a year ago.

 

[kris812]

Thanks everyone for the replies.

I've been driving it a bit more this week and it doesn't feel consistent enough to be clutch packs, though perhaps it just means im in the early days of failure. As I mentioned above, I really only began noticing this more around the time the T-Case was installed so its possible it has something to do with a mechanical item needing adjustment.

I have not looked at the Detente (kickdown) cable yet. On previous vehicles (non-Land Rover), i've run into several out of adjustment cables that were the cause of my transmission woes. This would be the ideal outcome...

I got a backup VSS, but since I haven't seen my speedo fail with the new T-Case, im thinking perhaps it was more a problem with the old T-Case and how the sensor was fitted to it.

I think i'll do what y'all say and start with a flush and perhaps a filter replacement. The fluid, when first checked, was red but appeared to have quite a bit of soot. After several pulls on the dipstick, the soot was really no longer there so my guess is that the dip was just dirty.

Of course, as with any Rover, one problem usually isn't all you have. The truck sat for nearly 5 days and when I fired it up, the oil pressure light took a good minute to go out. Im sure it's just lost prime, but that is extremely annoying since the top end and oil pump were rebuilt less than a year ago.

I personally would pass on the filter unless you need a pan gasket. It's a real PITA to change (Y pipe & cross member) and unless you're neutralizing it's not clogged.

6qt pan flush is the best idea IMO. Also check or play with the kick-down cable some and see what happens. As per RAV I'm adjusted WAY too tight (but big tires don't help my case)

As for your oil pressure issue, stay away from synthetic oils. I had something similar happen as I only start it once a month. Also some Lucas/STP additive helps keep oil tacky as all I can get easily is synthetic blend now.