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ZF 5HP24 teardown

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#61 ·
Phil,

I have done a lot of troubleshooting the Air Test issues, and am now at this point;

Assuming the problem is that the rotary seals ("piston rings") do not seal with air flow, I pulled the intermediate and bell housing assembly again, and removed the rings and in their place temporarily put two of the O-rings removed in tear down that fit the grooves. However, they did not protrude enough to seal, so I put a strip of paper under each one to make them protrude slightly more. By introducing air into the intermediate plate for the B clutch, it now actuates solidly, with no leaks, so I have proven to myself that air testing will not seal the piston rings, and a LOT of air escapes. I could not test the A clutch this way because the pressure would just push the A/B clutch assembly off the stator shaft.

I put the transmission assembly back together, with the temporary O-rings still on the stator, and pressurizing Clutch B with the test plate works great, positive actuation, and NO leaks.

The A clutch is another matter though. When I pressurize the A port on the test plate, a lot of air leakage, and the surprising thing is that a fair amount of air is coming out of the cooler return port on the main housing! I think it has been all the time, I had assumed it was coming out in the bell housing area just from sound. I have been looking at what cut away drawings I have found on the forums, but do not see a flow path from the A port to the cooler return port. Any ideas here? I am going back downstairs and pull the front part of the transmission yet again, and go through all the parts trying to see how air is escaping. This is beating me up pretty badly.

With the O-rings temporarily replacing the sealing rings on the stator, all the clutches except A work as expected, B, D, E, and F solid actuation, no leaks. Some leakage on C, but expected since there is clearance on the bushings in the sun shaft.

"A" is my hurdle now, if I can ever find the leak path for this I will be ready to put the transmission back in the car.

Edit:
Now I see the path. The cooler return goes to the center of the A drum shaft, through the rear set of holes in the shaft, which are right in front of the stator bushing, so air passes through the bushing clearance between the A clutch pressure path and the cooler return path. I put in a new stator bushing, but it has more clearance than I expected it to have. The bearing surface on the new A drum measures 25.94 mm, the I. D. of the new bushing installed is 26.05. 0.11 mm clearance is a lot more than I would have expected.

Now I feel that air testing is fraught with leak paths that must work OK with oil, but pass a LOT of air. So much air passes through that with the "piston ring" seals on the stator, the B clutch would not even actuate at 60 PSI until I closed off the A hole in the test plate with my finger. It stays actuated when I remove my finger, then releases when the air flow stops. With O-rings temporarily replacing these rings, B has no leakage at all and works solidly.

I am really amazed that this thing works at all with such leak paths.
 
Discussion starter · #62 ·
I consistently measure shaft diameters of 25.97mm (occasionally 25.96mm) and the bush bore diameter is easy to remember as it’s generally bang on 26.00mm (occasionally 26.01mm, very rarely 26.02mm). So that’s nominally only 15 microns (half-a-thou.) radial clearance.

I know that all your bushings are new. Did you say that your A-clutch drum/input shaft was new too? I just wondered why you’d replaced it?

Phil
 
#63 ·
I replaced it with an upgraded one, as the original was the one that can fail. My transmission is an 021. I replaced it with this: http://www.cascadetransmissionparts.com/5hp24aclutchdrumheavyduty.aspx

I am disappointed with the new bushing, as it was supposed to be tighter than stock tolerance. I have some bronze stock and a good lathe, thinking about just making a new one myself to get it in the fit range you are stating. The new bushings in the sun shaft reduced the C clutch blow by considerably, but I think the stator bushing is worse than the one I pulled out.

You said in a post on one of the forums some time back that you were having a test plate made. How do your air tests come out on the A/B clutches? I get a LOT of air flow on mine. The temp O-rings proved that the "piston rings" do not hold air at all well.
 
#64 ·
ds003 said:
---------------snipped-------------------------
I am disappointed with the new bushing, as it was supposed to be tighter than stock tolerance. I have some bronze stock and a good lathe, thinking about just making a new one myself to get it in the fit range you are stating. The new bushings in the sun shaft reduced the C clutch blow by considerably, but I think the stator bushing is worse than the one I pulled out.
Click to expand...
Well, I did it this morning. Made a new bushing, MUCH better fit than the one in the bushing kit I purchased. Now I have 0.001" clearance instead of 0.0045". Can't put it back together yet as I damaged one of the little "piston" rings on the A drum shaft. Ordered new ones.

By the way, here in the USA, Eriksson Industries has proven to be the best ZF parts supplier to me by far. Great on the phone, seem to have just about everything, and ship fast. They also have exchange on the valve body housing with the Sonnax oversize pressure regulator valve installed, $125 + $50 core charge.
 
#66 ·
#67 ·
ds003 said:
Well, I did it this morning. Made a new bushing, MUCH better fit than the one in the bushing kit I purchased. Now I have 0.001" clearance instead of 0.0045". Can't put it back together yet as I damaged one of the little "piston" rings on the A drum shaft. Ordered new ones.
Click to expand...
I air tested again this morning, and the new bushing I made completely stopped air escaping on the A clutch test! (that is with the temporary O-rings instead of the seal rings on the stator still in place).

Hopefully will have the transmission back in the car this weekend. Fingers crossed.
 
#70 ·
I have a 5hp24 that had the A-drum problem,reverse workd fine at the time. I replaced the A-drum,seals and frictions.Now all forward forward gears work great and it down shifts great,when you put it in reverse it clicks in and will idle back but add resistence or gas and will slip.Any ideas. Thanks, Bryan
 
#72 ·
Dear Phil

I have been reading your various posts with great interest. I have a RR 4.4 with 5HP24 box that appears to have a fault. It is fine going up through the gears (need to check this again at motorway speeds though) but when at motorway speeds (in 5th I assume) if I press hard to get kickdown I sometimes get a heavy thump (feels like someone has hit you up the rear) when it changes down to 4th.

I've tried driving in sport mode (no 5th used) and seems fine. Recently at motorway speeds and tried switching into sport - big thump as changed down to 4th.

I'd like to get this fixed before the box lets me down. The local specialist says that most of these faults are due to valve block cracks causing over pressure but admits they only usually get them in when damage has resulted.

Web searches support this view so I'm considering getting this changed now to prevent damage.

I'd be interested to hear what you think about this?

Many thanks in advance

Paul

(used to work as a mechanic, done manuals but never autos).
 
#73 ·
Hi all....first post for me and this is the best teardown I've seen for the 5HP24A. I don't have a Range Rover but an Audi RS6, with this same trans. I have a guy working on mine and he is having a hard time fixing one leak in the tailshaft transfer case. Trans fluid is leaking out of the weep hole just below the blue vents on the left side. He's done 3 seals and it keeps leaking. Any help would be greatly appreciated!! Thanks!
 
#74 ·
Broke 5HP24A said:
Hi all....first post for me and this is the best teardown I've seen for the 5HP24A. I don't have a Range Rover but an Audi RS6, with this same trans. I have a guy working on mine and he is having a hard time fixing one leak in the tailshaft transfer case. Trans fluid is leaking out of the weep hole just below the blue vents on the left side. He's done 3 seals and it keeps leaking. Any help would be greatly appreciated!! Thanks!
View attachment 17619 View attachment 17620
Click to expand...
Guy fixed it....thanks!
 
#80 ·
Hi, no problem! ;-)


I now have which can build the small with the size of 75-90.
It's okay, but a bit larger would not hurt

The gearbox (BMW) has a mileage of 395.000 km.

The a wave is easily broken. The F piston looks good. The fins
A clutch look very well.
Image

Image

Image

The replacement wave is of KÜHLE will cost ~ ca. €90
The B clutch is broken, they had small chips of A wave...




Here are my rings, and the special tool for the transmission output.
Image


Thank you, greetings. Christoph.


ps:
I'm sorry about the translator, but it's better this way :p
 
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