So I'm thinking of maybe putting together a new thread on how to do this job and synthesizing all the input members have offered in this thread. I'd like to cover thte 1.9, 2.3, 2.8, 3.0, S52, and S54 applications as well. Can anyone offer input on the differences between these various jobs, and also what parts (and part numbers) to use for each? I'll be sure to credit the sources (like The Randys) for the contributions. It just seems to me like there should be a clear resource to go to, as all of our cars are basically the same age, and all of those rubber hoses have been soaking in brake fluid for 17 to 14 years now, so this job will be needed more and more. Given the input I'veve recieved here, I'd hate for people to read my first OP in this thread and think that's the best way to do the job. Thoughts?
I'll defer to Terry and Ben on the best way to clean up and archive things.
/.randy
With the exception of individual part numbers, the 2.8s and S-54 will be just like your S-52, so all the same tricks will apply. I have never removed one of the "little" gearboxes (1.9, 2.3/2.5) but I doubt there'd be much, if any, difference in the steps required.
When Randy mentioned the plunger flying into the lounge, I was picturing your Oh $hit moment! While I always bench-bleed master-cylinders before installation (life is too short not to) I haven't tried doing the slave that way yet. I've never had any trouble using the BMW C-clamp/pressure bleeder method (I'm almost always alone, no shop-gorillas on hand) but I am always willing to try new ways to do something.
I would love to see a newer synthesis thread. The one from 2009 could probably be improved upon. If not in content, at least in organization.
The part numbers you're looking for and such can probably be found in that compilation thread I linked. Maybe you'll find it is good enough and doesn't need re-doing? I haven't actually read through it...
I had planned to do another one of my lists that shows all of the available options for replacing the hydraulic clutch line when I finally get around to doing my purchase research.
I'm also dragging my feet a bit, but this thread will get linked in a new clutch slave cylinder section of The Manifesto (it's been linked in the clutch line section for a while now).
Last edited by BenFenner; 09-12-2014 at 10:13 AM.
Ok, so here is a synthesis of the various posts and conversations on how to do this job:
Tools required:
- 3/8” drive 13mm swivel socket and extension (for the bolts attaching the slave cylinder to the transmission)
- 3/8” drive 11mm line crow’s foot and extension (for the top line nut on the metal clutch line coming from the master cylinder) and/or 11mm line wrench
- 14mm open end wrench (for the flat spots at the top of the rubber brake line you are replacing)
- 17mm wrench (for the bottom fitting of the rubber brake line where it attaches to the slave cylinder)
- 7mm combination wrench (for the bleeder screw)
- Assortment of vacuum caps and golf tees (to plug/stop the fitting at the end of the metal clutch line from leaking brake fluid once the rubber line is removed).
Optional tools:
- 3/8” drive 14mm (non-line) crow’s foot and extension (for the flat spots at the top of the rubber brake line you are replacing)
- Bench vise
- Bleeding drain-catch bottle and rubber hose (hose to fit over bleeder)
- BMW tool No. 90.88.6.215.030 (for compressing the slave plunger during on-car bleeding)
or
- Bavarian Autosport part No. CBT Tool (optional for compressing the slave plunger during on-car bleeding)
or
- Homemade retaining bracket: two 5" or so long bolts that will fit through the mounting holes in the slave cylinder flange, nuts to go on them, a flat metal plate with holes big enough for the two bolts to pass through--drilled approximately the same distance apart as the slave flange holes--and a 24mm or so 1/2" drive socket. Like so:
(You use the nuts to tighten the plate back and forth to compress the rod until the plate bottoms against the socket. The socket should hold the slave piston seal in without touching the slave housing--like when driving in a seal).
Materials/supplies:
- Large bottle brake fluid (I use DOT 4 synthetic)
- Rags and paper towels
- Cardboard (to lay out under the hose connection so the dripping fluid doesn’t drain onto the floor)
- Can of brake parts cleaner
- Nitrile or latex gloves
Parts:
- BMW 3.0 rubber clutch line part No. 21 52 1 159 714
or
- UUC Motorwerks stainless steel clutch line - E36 325i/is, E36 318i/iS/ti, all Z3, MZ3 (incl. S52 & S54) part No. SSCL-2
Procedure:
First remove the slave cylinder from the transmission by unbolting two 13mm nuts using a 13mm 3/8" drive swivel-socket and an extension. The slave is under pressure from the actuating rod, so remove each nut a little at a time so it pushes out evenly. Snake the slave cylinder out and away from the transmission and let it dangle.
Now comes the difficult part. You can see the 11mm line nut on top of a bracket, and the hard line leading from the master cylinder to the bracket good enough. What you can't see is any way to get a wrench on the rubber line--all you can see is a plastic shroud and a rubber grommet.
The plastic shroud terminates at the bracket into a metal fitting that is covered by the rubber grommet. This metal fitting does not have a six sided nut flange on it (the 3.0 and UUC replacement lines do). Instead, it is round with no obvious perch for a line wrench, as you might expect. However, if you pull the line down through the grommet (there is just enough play in the metal line to do this), push the grommet out of the bracket, and slip it up the line out of the way, you will see that there are two flat spots on the round surface that you can get an open end 14mm wrench over. These two flat spots do not allow you to use a 14mm line wrench, but only an open end.
Place the 11mm line crow’s foot (and extension) on the line nut, and, holding the 14mm open end against the bell housing to brace it, crack the line nut free with a ratchet set to “on” (because you are coming at from underneath/upside down).
Alternatively you can try using an 11mm line wrench, and, position the two wrenches ( 11mm line wrench & 14mm open end wrench) so that you can squeeze them together in one hand to brake the joint loose.
Fill the brake fluid reservoir all the way to the top. Have your vacuum caps and golf tees at hand (if using a golf tee be sure to shave the pointy end a little to make sure it will nicely plug the line—experiment on the new line).
Unscrew the slave cylinder and rubber line as a unit from the line nut and hand off to an assistant (or have something to set it on right at hand). Using a golf tee or vacuum cap, Immediately plug or stop the line on the car where the fluid is now pouring out.
Top off the brake fluid again.
Take the slave and line assembly over to a bench and line up the new hose to it to match angles of the bent metal portion of the lines. This is important because you don't get an opportunity to do this once the slave is mounter to the transmission. Then switch lines on the slave cylinder and tighten the line nut on the new line to the slave, making sure the mounting angle was just the same as on the old line with the bracket (no bracket on the new line).
Break the bleeder screw free with the 7mm box end wrench and tighten it again.
Bench bleed the slave cylinder line assembly as follows:
- Get a container of brake fluid. If the slave and line are brand new, you can "drink" directly from the bottle. Otherwise, fill something about the size of a Dixie cup.
- Standing at a bench, hold the slave cylinder with the push-rod pointed down in one hand, hold the hose end pointed up as the highest point in the other hand.
- Push the slave down against the bench, compressing the push-rod/piston.
- Stick the hose end into the fluid supply.
- Let the slave cylinder up, releasing the piston
- Pick the hose back up to the highest point
- Compress the piston
- Put the hose end in the fluid
- Release the piston
- Repeat
You only have to compress the piston until the is pure fluid in the hose, you don't have to shoot a stream across the shop each time. Repeat until there is no air in the hose at all. At this point you can either insert a plug in the hose end, or go directly to the car and hook it up.
Once the slave and line are bench bled and the line is full to the top, and holding the open end of the line as the highest point, take it over to the car and hold it up to the plugged line on the car. Moving very quickly (but surely), unplug the line and offer up the new line to the line nut and screw them together until the fluid stops running down your arms, then tighten them the same way you loosened them.
Now, if you think you got the line and slave on without introducing any air into the system, you’re basically done. If you think you should bleed the system, then, while the slave is dangling there, hook up the hose and bleed bottle to the bleeder screw and attach your clamping tool of choice to the slave and compress the rod. Top off the brake fluid. Have an assistance push down on the clutch pedal and open the bleeder until the pedal travels to the floor. Close the bleeder and have your assistant release the pedal. Top off the brake fluid and repeat a few times.
Using a small penlight and a mirror, look inside the hole for the slave cylinder in the bell housing and familiarize yourself with the clutch arm and how the actuator rod will contact it.
Insert the slave cylinder back into the bell housing, being careful to make sure the actuator rod contacts the clutch arm where it is supposed to (you have to compress the actuating rod to insert the slave cylinder to the point of being able to start the retaining nuts). Start and tighten the 13mm retaining nuts a little at a time, back and forth until the slave cylinder is mounted evenly and tightly. Don't forget the bleeder cap. Press the grommet back into the bracket, and push the new line back into it.
Check you fluid level one last time and adjust as required to the max line.
Clean everything with brake parts cleaner and a rag (don’t forget the gloves and safety glasses—that stuff is very nasty and absorbs through the skin).
Ralph and Contributors,
I greatly appreciate your dedication to the DIY's and love of the BMW marque. Kudos! This thread is very timely as I am starting to experience difficulty getting into first and second gears on hot days. I am going to replace the clutch line and slave. Correct me if I am wrong but given the "PITA" description of the job, one would be nuts to not replace an older slave while being down there? I enjoy working on cars but I don't like to just replace stuff because it may be failing. However, my time is valuable and I don't want to have to go back twice. The slave in question has 125K on it. Brake fluid gets changed regularly every 2 years. I am inclined to put a new one in while there.
Curt
99 M Coupe
99 996 Cabrio
86 Saleen Griggs Road Race Car
Very much appreciated!
Thanks, I'll pass this on to my mechanic.
'97 Z3 2.8 - Montreal Blue, Beige
Mods - RD Fr. strut brace; Short antenna; Hifi LCD+AUX; BMW soft-top; TMS RSM; K&N air; Bilstein struts; H&R Springs; Pedders camber/toe; extra padded M stitched 3 spoke steering wheel ...
To Do - Interior overhaul; rear window; lightweight rims ...
'98 M Coupe - Cosmos Black, Imola
----------
NOT with that company any more.
Uh, while I can agree with the "replace it while you're there", slave cylinders do not degrade in performance over time. They either function correctly, or they leak. The laws of physics do not change.
/.randy
I respectfully disagree. I've been doing this for quite some time and have seen the problems of a worn slave cylinder seal countless times. These are not "solid state" parts... any time there is a seal or rubber involved, there is wear and the potential for degraded functionality of the part. They can indeed be working but not working as well as possible.
Not looking for an argument here, just passing along irrefutable first-hand experience.
----------
NOT with that company any more.
Rob, I'm no spring chicken either. I'm trying to keep future searches from getting the wrong idea. Repalcing the slave cylinder will not fix anything except a leak.
The amount entering the slave cylinder is determined by external components. This volume of fluid will displace the slave piston by a given amount. It doesn't matter if the cylinder is brand new or several decades old. The fluid is doesn't compress. The cylinder doesn't swell (unlike the old hoses). Thus the fluid will either move the piston, or bypass it. Any fluid that bypasses will show up as an external leak. The cylinder will either work, or leak.
/.randy
Seals wear, pistons go a little cockeyed, and the part does not feel exactly right.
So at the point where a person is changing a clutch line, which means all the labor for a fluid bleed, it makes sense to replace the slave - even if someone tells them it doesn't need to be. It's a risk assessment issue of knowing that all parts are done and new and the big expense of labor is taken care of, versus the savings of the small cost of a slave and paying the same labor a second time.
I get feedback from a customer base using our flywheels and or clutch kits that numbers in the 5-figure quantity at this point. If something has happened with a clutch, flywheel, hydraulic system, or anything even peripherally related, I've seen it.
----------
NOT with that company any more.
FWIW I just installed the Rogue SS line (10 minutes to figure out the fittings even after reading all the threads), performed 'ye olde' two man pump a lot of fluid through the slave until firmed-up approach, and the difference is night and day. Two words... Do It!
FWIW, I just gave mine to my local mechanic with no instructions.
He just installed it, no problems... didn't even charge for the fluid, since so little was needed... said the only hitch was to not use the existing bracket because the line was bigger, but because the line was stiffer, no need for the bracket anyway.
It's made shifting into 1st and 2nd easier and doesn't seem to change when the car gets hot. Awesome sauce!
'97 Z3 2.8 - Montreal Blue, Beige
Mods - RD Fr. strut brace; Short antenna; Hifi LCD+AUX; BMW soft-top; TMS RSM; K&N air; Bilstein struts; H&R Springs; Pedders camber/toe; extra padded M stitched 3 spoke steering wheel ...
To Do - Interior overhaul; rear window; lightweight rims ...
'98 M Coupe - Cosmos Black, Imola
On my '98 Z3 M Roadster S52 I used the stock rubber flex hose from the 2001 - BMW - Z3 Roadster - M54 - L6 - 3.0L – GAS Z3 2.5l, 3.0L
CLUTCH HOSE #21526753766 from Tomkinson. It was a single rubber "CDV delete" hose and fit perfectly. The hose fit up to the mounting bracket correctly and all the hose fittings threads at the slave and the master end matched up. Perhaps good choice for those that may want the stock look. I was able to bleed the slave without removing it. (yes that surprised me too!)
I've read all the threads I can about this and I am scared shitless to dive into it! But, nothing ventured, nothing gained and I appreciate this comprehensive write-up. I think I'm going for the rogue engineering stainless clutch line (I guess I think if I spend more $$ I'll get something superior!) and a replacement slave cylinder while I'm messing with this anyway. I need to order a set of crows foot wrenches but I think I'll improvise and skip the slave bleeding tool and mash the rod against the transmission housing or whatever...
I'm did the Rogue + new slave a couple weeks ago. LOVE it! So much better. Although I did have my Indy do it.
-Scott
Current BMWs: 2000 M-Coupe, 2016 528i
M-Coupe Build and Maintenance Log
Past BMWs:
2014 X1 sDrive28i, 2000 740iL, 2002 325i, 1999 M-Coupe, 2000 323Ci, 1979 323i, 1983 320i
Follow Randy's advice about bench bleeding the slave/hose assembly and installing it full, and you shouldn't need to worry about bleeding it on the car. Otherwise just be sure not to have someone step on the pedal with the slave dangling without the retaining bracket (slave bleeding tool). The tool btw was very easy to fab up.
Ralph- thanks for clarifying further. I'm gathering my wits (and tools/supplies) to give this a go. I'm pretty sure since I'm old, probably slow, can't see, will be on my back under the car on ramps AND will likely have no eager assistants in my household except maybe to push a clutch pedal in for me - that I will want to do the bench bleed followed by an under-car bleed just to be thorough. Appreciate your patience with a couple of probably dumb questions:
1. Please clarify your instruction above- it says slave is dangling, but should the slave be positioned in any way to ensure any trapped air escapes? Pressing the clutch pedal while the slave is not installed won't risk blowing anything out? - (come to think of it- I guess if I'm supporting the pushrod against the transmission housing that would be unlikely)
2. Also, on the bench bleed- nothing is being done with the bleeder screw, correct? Just the new line that is used to suck and expel fluid?
Thanks again
Oh, and along with the recommended tools, I thought I would drag this faucet wrench under the car with me- this thing has helped me more than once on a non-plumbing challenge!
wrench.jpg
Last edited by mreloc; 01-26-2015 at 07:40 PM.
If you're going to bleed the slave on the car, you want it dangling down--in situ air gets trapped and won't come out. However, I highly recommend making a retaining bracket like I picture in the instructions above, or else it will blow apart--pushing the rod against the transmission won't keep the piston from blowing out of the slave. As to bench bleeding, the instructions are Randy's (RF900kfw) not mine, as it was his contribution earlier in this thread. Read the thread through from the start to get the full idea. That being said, yes I believe the bench procedure does not involve the bleeder screw. Ugh, I don't envy you doing this job on your back, brake fluid running down your arm and all over you. This is a job for a lift if ever there was one.
Mine came without the hardline part, too. Haven't been under the car to inspect how to reuse the original one, but I'm hoping it will be obvious- however the pic above makes it appear that the rogue fitting won't have anything to screw into on the hard line, does it?
My understanding is with the Rogue line you reuse the hard line and all the bracketry. With the UUC, you go straight to the slave without the pretzel hard line.I actually prefer the UUC way, but you have to get it clocked right.
The pictures above are misleading. Our stock line does not have the hard line extension built into the flex line like the later cars. It's a separate piece that can be reused.
Last edited by rf900rkw; 02-20-2015 at 12:17 PM.
/.randy
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