3sec. delay switching from Drive to Reverse

[Madmiel]

Hi Guys,

I'm new here! I own a X5 4.8 for about two months and I really enjoy driving it. It drives nicely and also shifts smooth but there's only one problem when I put it in reverse. When the engine (Automatic) is cold it engages right away when putting it in reverse. But when the engine is at operating temperature it takes about 2 -3 sec before it engages....

I've changed the fluid, filter, magnets, sealing and Mechatronic sleeve (it was leaking a little bit). My first thought was a low ATF level was causing it, but after the fluid change the issue still exists. (Oil change done with OEM products and Safeguard 6 fluid and topping of at 40" Celsius). I've not done a reset of the adaptation values: should I try?

My second thought was a faulty / sticky reverse solenoid?

Anybody got an idea?

[upallnight]

Hope you put aside a little cash when you brought the BMW. Sounds like it's time for a tranny rebuild. Perhaps that is why the previous owner sold the money pit.

Loss of reverse in this ZF manufactured transmission is, unfortunately, not an uncommon occurrence. The typical fault is failure of the F-Clutch actuating piston. More specifically, the inner and outer sealing rings that are molded to the inside and the outside edges of the piston. As the piston’s seals fail, the clutch pack is not compressed fully and starts to slip. This slippage causes wear to the clutch material. Eventually, the clutch pack does not have enough clamping force and friction to move the vehicle. This shows as a partial or full loss of reverse.

The “fix” is to perform a full rebuild using a master overhaul kit that includes not only the clutch plates, but the intermediate steel plates that go between each clutch plate. The reason the kit with the steel plates is recommended is due to the F-clutch being fully worn out. The original steel plates will have more wear than typical for a normal rebuild. Obviously, the F-clutch piston must be replaced as well, due to the worn-out and/or damaged seals.

Here's a link to a rebuild on the Ranger Rover forum which uses the same ZF trans.

ZF 5HP24 teardown

[crystalworks]

Upallnight... that is most worrisome as our truck does the same thing. Put it in reverse, wait 2 or 3 seconds and then it engages. Just thought it was the way this trans was...

So you're saying I should keep my eyes out for a decently priced used trans? Not loving that. Any idea on how long it takes for the reverse gear to just give up the ghost? I'm guessing not due to variables, but I thought I would ask anyway.

[upallnight]

Originally Posted by crystalworks

Upallnight... that is most worrisome as our truck does the same thing. Put it in reverse, wait 2 or 3 seconds and then it engages. Just thought it was the way this trans was...

So you're saying I should keep my eyes out for a decently priced used trans? Not loving that. Any idea on how long it takes for the reverse gear to just give up the ghost? I'm guessing not due to variables, but I thought I would ask anyway.

I would just find a decent trans shop that is knowledgeable in ZF transmissions. Buying a use transmission is just a crap shoot. You can roll the dice but chances are you can come up with snake eyes.

Here's a link to a thread in which a X5 owner bought a use trans and after the installation he had no reverse. Lucky for him he is doing all the work himself and not paying a mechanic $100+/hours to do the work.

http://www.xoutpost.com/1094103-post24.html

His no reverse was the F clutch piston, like in my post above. Don't have money for a tranny rebuild, "Dump the X" while it is still running.

[fmugur]

Originally Posted by upallnight

Hope you put aside a little cash when you brought the BMW. Sounds like it's time for a tranny rebuild. Perhaps that is why the previous owner sold the money pit.

Loss of reverse in this ZF manufactured transmission is, unfortunately, not an uncommon occurrence. The typical fault is failure of the F-Clutch actuating piston. More specifically, the inner and outer sealing rings that are molded to the inside and the outside edges of the piston. As the piston’s seals fail, the clutch pack is not compressed fully and starts to slip. This slippage causes wear to the clutch material. Eventually, the clutch pack does not have enough clamping force and friction to move the vehicle. This shows as a partial or full loss of reverse.

The “fix” is to perform a full rebuild using a master overhaul kit that includes not only the clutch plates, but the intermediate steel plates that go between each clutch plate. The reason the kit with the steel plates is recommended is due to the F-clutch being fully worn out. The original steel plates will have more wear than typical for a normal rebuild. Obviously, the F-clutch piston must be replaced as well, due to the worn-out and/or damaged seals.

Here's a link to a rebuild on the Ranger Rover forum which uses the same ZF trans.

ZF 5HP24 teardown

This is a common problem on the 5hp24. You are right. But I haven't seen an 6hp26 rebuilt for the same reason yet. His is a 4.8is with a 6hp26. Do these have the same weak point?

[Madmiel]

@upallnight the reverse works perfect, no slip at all. It only takes the transmission 2 - 3 seconds to engage the reverse but only when the oil is at operating temp. When in reverse it doesn't have any slip at all. Could it be a faulty solenoid? I've read similar issues with this type (6HP26X) that was caused by a sticky solenoid but only those symptoms where with cold temp. instead of operating temp like in my case!

[crystalworks]

Originally Posted by Madmiel

@upallnight the reverse works perfect, no slip at all. It only takes the transmission 2 - 3 seconds to engage the reverse but only when the oil is at operating temp. When in reverse it doesn't have any slip at all. Could it be a faulty solenoid? I've read similar issues with this type (6HP26X) that was caused by a sticky solenoid but only those symptoms where with cold temp. instead of operating temp like in my case!

Mine is the same (shows identical symptoms)... does the 4.4 use a different trans?

[bcredliner]

I suggest taking your X5s to a well recommended transmission shop that is familiar with BMW transmissions for a diagnosis. You could need an overhaul but it could be something much less costly to fix. The key is not to wait until it gets worse. Find out what is going on now. If you let it go it is likely you will damage more parts and perhaps assure you will need a rebuild.

FYI-the dealer does not fix transmissions.

[fmugur]

Most of the 6hp26 issues seemed to be related to solenoids.You might have one that needs to be replaced.

[Madmiel]

@bcredliner I found out BMW dealers don't fix transmissions, they don't even do a fluid change. I ordered the parts at my local BMW dealer and it took them 1,5 month to deliver the parts. It had to be ordered from ZF (manu.) shipped to München (Main storage EU) to the Netherlands....