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Discussion Starter #1
Was wondering if it is possible to remove the F Clutch Brake without full disassembly of everything else? It seems like everybody removes the F clutch from the opposite side of the transmission as everything else. I would think if this is possible it would make fixing the F clutch allot easier.

Thank You
Chris
 

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Unfortunately not. The F brake drum bolts onto a flange at the very rear of the casing i.e. the casing isn’t open at the rear.







All of the running gear has to be removed from the maincase first, before the F brake/sprag assembly can be extracted. It’s the very last thing to come out.





Always slacken off the 12 countersunk (Torx TX40 head) screws holding the drum to the flange before you remove the running gear. The screws seize on their tapers and you need the weight in the transmission to prevent it moving while you’re slackening them off. If you don’t have pneumatic tools, strike the heads first with a hammer and drift to release the friction in the taper.





Phil
 

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Discussion Starter #3
Thank you Phil. I seen your write up but was unclear on that 1 thing. I tried to PM you but did not seem to find the button to do that so was hoping i would get your attention with this post. :) Looks like i have some work a head of me.

The problem i am having is when the vehicle is cold i can go forward and in reverse just fine. When the vehicle is up to operating temp i can go forward in all gears just fine but reverse will start to move then it is like it pops out of gear and free revs. I can go back into park and then reverse again and the car will start to backup and once again pop out and free rev. If i let the vehicle cool back down i then can go in reverse again just fine.

Does that sound like the F clutch?

Thank you Phil!
Chris
 

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Both the C clutch and F brake are used for Reverse, so it could also be the C clutch causing the problem. The C clutch is used exclusively for Reverse and isn’t activated in any other gears.



It may be either of the hydraulic supply circuits for these clutches which is at fault (seals leaking), rather than the clutches themselves e.g. support bush O-rings for C clutch feed.





You will read a lot on-line about the F brake piston problem with the 5HP24. The issue was that the inner and outer piston seals are actually bonded to the metal piston and the ‘rubber’ material would wear, allowing the circuit to leak.





ZF fixed this in August 2001 when piston 0501 208 317 was replaced by 0501 212 967, which used an improved ‘rubber’ material. I’ve never seen one of these later pistons fail.





As the F brake is also used in Manual 1st gear, you could also test whether you’re getting engine braking in Manual 1st when the fluid is hot. If the car just freewheels when you lift the accelerator (i.e. the sprag overruns) then this would certainly indicate an issue with the F brake.

How convinced are you that this isn’t just a gear selection issue i.e. the selector lever on the transmission is moving back into Neutral or Park, and it’s therefore a cable adjustment issue rather than an internal transmission problem?

Phil
 

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Discussion Starter #5
I was reasonably convinced it was the F brake until you mentioned the updated F brake piston in 2001. I will try the manual 1st gear today and see if i get engine braking. I have also been talking with Gary Ferraro "makes really informational Youtube videos on transmissions" about the problem and his experiences. He basically has the same thing to say as you with 1 extra possibility that he has ran into with having problems in reverse when up to operating temp and working when cooled down. This is what he had to say...

"Chris, very well could be the F clutch piston, very common issue with the bonding coming off. In reverse also the C clutch is on, what also happens are the 2 bushings in the hollow shaft wear out causing C clutch apply oil to escape and you will loose reverse when hot, I have a video on that problem as well, if your going to get into this trans I would address both areas, if you need parts, there is a ZF distributor in CT that sells what you will need. The hollow shaft, there will be a core charge so they will want your old one. Gary"

Have you ever ran into that problem Phil? Thank you again for everything the RR community are really amazing!

Chris
 

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I certainly check the clearances of the sun gear shaft bushes on every transmission that I remanufacture.



The internal shaft invariably measures ø31.96mm and the bush bores generally come in at ø32.01-32.03, so around 25-35μm radial clearance is what you should expect. This is typical for a transmission with around 100,000 to 150,000 miles.







I very rarely see anything different to this. Occasionally you see one where the lubrication supply has failed, for whatever reason, and the bushes have overheated and worn (or even seized) as a result, but that’s pretty unusual.

Nevertheless, it’s a possibility.

Phil
 

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Discussion Starter #7
Today i tested the Manual 1st gear engine braking test and the it worked perfectly. So i am guessing this proves the F clutch is working..?.. Phil you mentioned a possible gear select position problem could be causing the problem. Is there a way to test this or a way to make the adjustments that may be needed? I have a IID tool and monitor some transmission values today. Pressures seemed to be around 750 and when it would shift drop down to the 200-250 then back up to 750 after the shift. But i did notice when i tried to log shift solenoids and gear selection all values were NA and never changed. It did not matter what gear i was in it never registered within IID tool. The problem i have with this is i am not sure that the IID tool can log those values in a 03 and maybe they are options for newer vehicles.

Any advice where to go from here?

Chris
 
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