here's hoping it all works out properly and fun!
My Baby is BACK and better than ever, with a new heart (aka engine) and 5 speed. I am in love!
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Hey guys, just wanted to give a quick update. I made it from Palm Desert to Phoenix over 250 miles without incident (averaging 20 mpg btw), and somewhere along the drive I think I finally figured out what has been causing the bizarre intermittent problem I described earlier. With help from @HB Chris and a few mechanics here at the event, the issue now appears much more likely to be clutch-hydraulic related rather than anything catastrophic in the gearbox or driveline.
On one occasion during the drive, I noticed the clutch pedal had dropped much farther than normal and was not fully returning on its own. I was able to hook my foot behind the pedal and pull it back up a few inches, after which the pedal feel returned to normal. That seems to fit a leaking slave cylinder allowing air into the system, or possibly another issue somewhere in the clutch hydraulics or release mechanism. In other words, the working theory now is an intermittent clutch slave / hydraulic problem, not a transmission failure.
The good news is that the car is otherwise running great. It made the drive here without incident, is pulling strongly, and generally feels excellent. The current plan, if the mechanic here has time, is to inspect the slave cylinder for leakage, bleed the clutch system thoroughly, and take a quick look at the master cylinder, hose, pedal return, and related clutch release hardware just to make sure nothing else is contributing.
At this point I think I’m probably fine for the rally, but I wanted to close the loop and share what now seems to be the real culprit. Thanks again for all the input here. I really do appreciate it. If anyone has anything else to add, I’m all ears, but for now I think I’m in reasonably good shape.
On one occasion during the drive, I noticed the clutch pedal had dropped much farther than normal and was not fully returning on its own. I was able to hook my foot behind the pedal and pull it back up a few inches, after which the pedal feel returned to normal. That seems to fit a leaking slave cylinder allowing air into the system, or possibly another issue somewhere in the clutch hydraulics or release mechanism. In other words, the working theory now is an intermittent clutch slave / hydraulic problem, not a transmission failure.
The good news is that the car is otherwise running great. It made the drive here without incident, is pulling strongly, and generally feels excellent. The current plan, if the mechanic here has time, is to inspect the slave cylinder for leakage, bleed the clutch system thoroughly, and take a quick look at the master cylinder, hose, pedal return, and related clutch release hardware just to make sure nothing else is contributing.
At this point I think I’m probably fine for the rally, but I wanted to close the loop and share what now seems to be the real culprit. Thanks again for all the input here. I really do appreciate it. If anyone has anything else to add, I’m all ears, but for now I think I’m in reasonably good shape.
Glad to hear all worked out. Perhaps relevant - just had a discussion with Don yesterday and since I am running an entirely new clutch, slave/master cylinder, lines, etc, he was cautioning me that when bleeding it, one should be careful with the slave cylinder. The bluebook walks through the technique, but essentially because you can’t easily reach the bleed screw, the slave should be dropped down off the bell housing and then he suggested pumping the piston by hand while having a hose attached to the bleed screw with the other end in a vat of brake fluid. He cautioned against using a pressure bleed on the slave since it could drive the piston out. So yes seems like improper bleeding could be the issue. He also told me that I should expect to have to bleed my brake/clutch system likely three times in the first month or so of driving just as the air bubbles that are inevitably there coalesce into larger air bubbles which can then actually be bled out.
That is extremely helpful. Hopefully the Mechanic servicing the rally can do that for me.
Made it through first full day of rally with no issues, although did consume some clutch fluid. Watching carefully. Car ran great!
No drips on the garage floor?
Another 212 miles and no clutch fluid used and no Drips. I think all is well. Car is running really well keeping up with all the fast Ferrari, Lamborghinis Porsche’s, etc..
Guys, I wanted to report back after completing the Copperstate 1000 in my 3.0 CS.
Overall, the car was excellent. Other than the transmission/clutch shakeout issue I dealt with right before the event, the BMW performed extremely well for the entire rally. Once underway, it gave me no real trouble at all. No overheating, no fuel delivery issues, no altitude-related carburetor drama, and notably, it did not use a single drop of oil over the trip. That alone made me very happy.
For those who have followed the project, this is Carl Nelson’s 3.5-liter high-compression carbureted build with the performance cam and 5-speed, and on this event the combination really showed itself well. The car pulled strongly everywhere. We saw major elevation changes, from essentially sea level to roughly 7,000 feet, and the carburetors behaved far better than I would have expected without any adjustment. No obvious loading up, no major flat spots, and no meaningful sense that the engine was down on power at altitude. It would pull uphill in fifth gear at speeds where I would normally expect more complaint from a vintage carbureted setup.
On the faster sections, the car felt genuinely strong. There were long stretches where we were running well over 100 mph, and at 100 mph the engine was turning about 4,200 rpm in fifth gear. That seemed to be a very comfortable place for the drivetrain. The engine felt relaxed, responsive, and very much in its element. Sound-wise, the car was exceptional. A number of people commented on how strong and how good it sounded, and in a rally filled with serious machinery from the 1960s and early 1970s, including some very special Ferraris, Porsches, and Maseratis, the BMW did not feel outgunned.
Fuel economy was also better than I expected given how the car was driven. On the all-highway portions, the car averaged almost 20 mpg. With highly spirited driving, that dropped to roughly 13.5 mpg, and for much of the balance of the trip it was in the 16 to 18 mpg range, with several legs right around 17 mpg. For a 3.5-liter high-compression carbureted E9 being driven properly, I thought that was more than respectable.
The one clear limitation I noticed was aerodynamics. Compared with my Alfa Romeo 1750, which feels much slipperier at speed, the BMW feels like it is pushing a lot more air. At one point a strong crosswind hit the car at speed and moved it around enough to get my full attention. That was a useful reminder that however composed the chassis may be, this is still a relatively upright early-’70s coupe with the aerodynamic properties of a handsome brick.
Still, the biggest takeaway is that I came away from the event far more impressed with the total package than I expected. The car felt fast, stable, charismatic, and surprisingly versatile across a wide range of conditions. I genuinely fell back in love with it on this trip, and at the moment it may be my favorite car in the garage.
So overall, I’m quite pleased with Carl Nelson’s build, even allowing for the transmission-related shakeout issues. Thanks again to everyone here who has offered advice, input, and encouragement throughout this project. I really do appreciate it. I thought the forum would enjoy the report, and I’ll attach the video clip below.
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Overall, the car was excellent. Other than the transmission/clutch shakeout issue I dealt with right before the event, the BMW performed extremely well for the entire rally. Once underway, it gave me no real trouble at all. No overheating, no fuel delivery issues, no altitude-related carburetor drama, and notably, it did not use a single drop of oil over the trip. That alone made me very happy.
For those who have followed the project, this is Carl Nelson’s 3.5-liter high-compression carbureted build with the performance cam and 5-speed, and on this event the combination really showed itself well. The car pulled strongly everywhere. We saw major elevation changes, from essentially sea level to roughly 7,000 feet, and the carburetors behaved far better than I would have expected without any adjustment. No obvious loading up, no major flat spots, and no meaningful sense that the engine was down on power at altitude. It would pull uphill in fifth gear at speeds where I would normally expect more complaint from a vintage carbureted setup.
On the faster sections, the car felt genuinely strong. There were long stretches where we were running well over 100 mph, and at 100 mph the engine was turning about 4,200 rpm in fifth gear. That seemed to be a very comfortable place for the drivetrain. The engine felt relaxed, responsive, and very much in its element. Sound-wise, the car was exceptional. A number of people commented on how strong and how good it sounded, and in a rally filled with serious machinery from the 1960s and early 1970s, including some very special Ferraris, Porsches, and Maseratis, the BMW did not feel outgunned.
Fuel economy was also better than I expected given how the car was driven. On the all-highway portions, the car averaged almost 20 mpg. With highly spirited driving, that dropped to roughly 13.5 mpg, and for much of the balance of the trip it was in the 16 to 18 mpg range, with several legs right around 17 mpg. For a 3.5-liter high-compression carbureted E9 being driven properly, I thought that was more than respectable.
The one clear limitation I noticed was aerodynamics. Compared with my Alfa Romeo 1750, which feels much slipperier at speed, the BMW feels like it is pushing a lot more air. At one point a strong crosswind hit the car at speed and moved it around enough to get my full attention. That was a useful reminder that however composed the chassis may be, this is still a relatively upright early-’70s coupe with the aerodynamic properties of a handsome brick.
Still, the biggest takeaway is that I came away from the event far more impressed with the total package than I expected. The car felt fast, stable, charismatic, and surprisingly versatile across a wide range of conditions. I genuinely fell back in love with it on this trip, and at the moment it may be my favorite car in the garage.
So overall, I’m quite pleased with Carl Nelson’s build, even allowing for the transmission-related shakeout issues. Thanks again to everyone here who has offered advice, input, and encouragement throughout this project. I really do appreciate it. I thought the forum would enjoy the report, and I’ll attach the video clip below.
The Copperstate 1000 was an absolute riot. Great roads, great people, great cars, and my 74' BMW 3.0 CS E9 came to play. In a field full of Ferraris, Porsches, Lamborghinis, Maseratis, Jaguars, and plenty of other rolling jewelry, the old BMW more
The Copperstate 1000 was an absolute riot. Great roads, great people, great cars, and my 74' BMW 3.0 CS E9 came to play. In a field full of Ferraris, Porsches, Lamborghinis, Maseratis, Jaguars, and...
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FYI
Hey guys — looking for a little advice on three separate items on my 1974 3.0 CS.
First, I lost one of my BBS center caps on a recent drive. I’ve attached photos of the wheel and the remaining cap setup. If anyone can tell me best source for a replacement, I’d appreciate it.
Second, I’m debating whether to install a live wideband AFR gauge. The car is running dual Webers and I’ve been doing a lot of driving across major elevation changes, from desert elevations up to Ketchum and beyond. I have already done some dyno work and jet changes, but I’m still trying to sort out whether the next step should be 120 mains, 115 mains, or just leave it alone for now. For those of you running carbureted E9s, do you think a permanent wideband is worth it, and if so, what setup do you recommend?
Third, I’m considering adding an anti-sway bar setup. The car is running really well overall, but I’d like it to feel a little flatter and more confidence-inspiring in corners. I’m looking at the Ireland Engineering kit,
www.iemotorsport.com
but before I order anything I’d love to hear from people who have actually done this on an E9. Would you recommend a full front/rear kit, a rear bar only, or something milder? My steering does not really have slop — it just feels a little too light and over-assisted for my taste — so I’m trying to improve handling feel without making the car worse.
Any advice on any of the three items would be appreciated. Thanks very much.
First, I lost one of my BBS center caps on a recent drive. I’ve attached photos of the wheel and the remaining cap setup. If anyone can tell me best source for a replacement, I’d appreciate it.
Second, I’m debating whether to install a live wideband AFR gauge. The car is running dual Webers and I’ve been doing a lot of driving across major elevation changes, from desert elevations up to Ketchum and beyond. I have already done some dyno work and jet changes, but I’m still trying to sort out whether the next step should be 120 mains, 115 mains, or just leave it alone for now. For those of you running carbureted E9s, do you think a permanent wideband is worth it, and if so, what setup do you recommend?
Third, I’m considering adding an anti-sway bar setup. The car is running really well overall, but I’d like it to feel a little flatter and more confidence-inspiring in corners. I’m looking at the Ireland Engineering kit,
Sway Bar Kit 28.5mm Front / 22mm Rear – E3/E9/E12/Early E24
www.iemotorsport.com
but before I order anything I’d love to hear from people who have actually done this on an E9. Would you recommend a full front/rear kit, a rear bar only, or something milder? My steering does not really have slop — it just feels a little too light and over-assisted for my taste — so I’m trying to improve handling feel without making the car worse.
Any advice on any of the three items would be appreciated. Thanks very much.
I have the stiffer 28mm sway bar on my E9 and like the handling. I hadn't been the one to install it so unfortunately can't speak to its feel vs the stock but it does feel fairly "grounded". I just replaced its bushings and used the Ireland Engineering ones which worked out well.
I installed a wideband AFR gauge on my MGA in order to help finetune the carb setup at my engine rebuilder's suggestion. In that case I hooked it up to a digital gauge which I placed in a hidden location under the dash. It's installed with a magnetic mount so if I actively needed to be looking at it while accelerating/driving I could easily reach down and pull it into view. Since I'm a bit more of a novice at engine tuning (or should say complete newbie) I do find this number helpful as an actual valid data point from which to make comparisons or tweaks. I have an injected CS so don't need it in the E9 but if I had carbs I probably still would do it the same with a gauge that I can access when needed rather than having it on my console in permanent view. Most of them out there have some digital component and so don't quite look as period. I am planning to add a three-gauge row below my radio with water temp, voltmeter and oil pressure, so I guess could/would add it there if I needed it, but not sure that it's as valuable always in view as some of the others. Actually attaching it is fairly easy - I drilled a hole in the exhaust just past the exhaust manifold and welded in a bung and then just screwed in the sensor and ran it to the gauge.
Thinking about it, any benefit to adding an engine strut brace? Again, something my car has that I didn't add and so can't speak to the handling without it, but my understanding is that that will also tighten up a bit of the handling.
I installed a wideband AFR gauge on my MGA in order to help finetune the carb setup at my engine rebuilder's suggestion. In that case I hooked it up to a digital gauge which I placed in a hidden location under the dash. It's installed with a magnetic mount so if I actively needed to be looking at it while accelerating/driving I could easily reach down and pull it into view. Since I'm a bit more of a novice at engine tuning (or should say complete newbie) I do find this number helpful as an actual valid data point from which to make comparisons or tweaks. I have an injected CS so don't need it in the E9 but if I had carbs I probably still would do it the same with a gauge that I can access when needed rather than having it on my console in permanent view. Most of them out there have some digital component and so don't quite look as period. I am planning to add a three-gauge row below my radio with water temp, voltmeter and oil pressure, so I guess could/would add it there if I needed it, but not sure that it's as valuable always in view as some of the others. Actually attaching it is fairly easy - I drilled a hole in the exhaust just past the exhaust manifold and welded in a bung and then just screwed in the sensor and ran it to the gauge.
Thinking about it, any benefit to adding an engine strut brace? Again, something my car has that I didn't add and so can't speak to the handling without it, but my understanding is that that will also tighten up a bit of the handling.
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Hey guys — unfortunately I have a more definitive update on the clutch issue, and it looks like the car is getting towed back to the shop.
After completing the rally and driving roughly 1,300+ miles, the BMW had actually been doing fine overall. The clutch issue had been intermittent, and the working theory was that it was probably hydraulic, most likely the slave cylinder or something related in the clutch release system.
This morning, though, the clutch pedal was fully down on the floor when I went to drive the car. I could manually pull the pedal all the way back up to its normal position, but the moment I pushed it even slightly, it dropped straight back to the floor. For the first time, I also had to add clutch fluid, and I noticed a small amount of fluid on the garage floor. At this point, I do not see any realistic option other than towing it to the shop, because I do not think it is safe to drive.
In hindsight, this likely explains the earlier bizarre incident I posted about, where I heard a thud/clunk from underneath, pulled over, and then the car briefly seemed bound up or would not move properly before later acting normal again. It now looks like that may have been the early warning sign of a clutch hydraulic failure that has finally become a full failure.
So the working diagnosis now seems to be:
I do have a video showing exactly what the pedal is doing and can post that as well if it is helpful.
At this point I assume the right move is:
Thanks again to everyone who helped think through this. This one is frustrating, but at least it finally seems to be declaring itself.
After completing the rally and driving roughly 1,300+ miles, the BMW had actually been doing fine overall. The clutch issue had been intermittent, and the working theory was that it was probably hydraulic, most likely the slave cylinder or something related in the clutch release system.
This morning, though, the clutch pedal was fully down on the floor when I went to drive the car. I could manually pull the pedal all the way back up to its normal position, but the moment I pushed it even slightly, it dropped straight back to the floor. For the first time, I also had to add clutch fluid, and I noticed a small amount of fluid on the garage floor. At this point, I do not see any realistic option other than towing it to the shop, because I do not think it is safe to drive.
In hindsight, this likely explains the earlier bizarre incident I posted about, where I heard a thud/clunk from underneath, pulled over, and then the car briefly seemed bound up or would not move properly before later acting normal again. It now looks like that may have been the early warning sign of a clutch hydraulic failure that has finally become a full failure.
So the working diagnosis now seems to be:
- failed or failing clutch slave cylinder
- or possibly another clutch hydraulic issue such as the line or master cylinder
- but much more likely hydraulic than anything catastrophic inside the gearbox itself
I do have a video showing exactly what the pedal is doing and can post that as well if it is helpful.
At this point I assume the right move is:
- tow it
- inspect for slave cylinder failure / leak
- inspect the line and master cylinder
- repair and bleed the system fully
Thanks again to everyone who helped think through this. This one is frustrating, but at least it finally seems to be declaring itself.
I am by no means an expert, but having just assembled this this past weekend, if the slave was failing but the master was fine I would imagine that the pedal wouldn’t fall to the floor since the master would be holding pressure. The fact that the pedal falls would suggest that there isn’t any pressure in the system or that the master has failed. The brake and clutch use the same reservoir - is that still full?
restart
Well-Known Member
I’m with Chris in post 11…
linkage?
Something just slipping in and Out of position at the wrong time.
Hopefully minor!
It’s great that you haven’t forced it to drive when it doesn’t want to,
That’s when the big things break!
Good luck!
linkage?
Something just slipping in and Out of position at the wrong time.
Hopefully minor!
It’s great that you haven’t forced it to drive when it doesn’t want to,
That’s when the big things break!
Good luck!
Fluid was not full, but not completely empty either. Really glad I did not have a problem on the rally. Hope you can get enough fluid in there to hold so I don’t have to tow it to the shop.
Your brake fluid reservoir has likely gone below the clutch nipple level.
Meaning your brakes will still work but you have a loss of fluid on the clutch side.
Don't forget to check for fluid inside the car below the clutch master,
Meaning your brakes will still work but you have a loss of fluid on the clutch side.
Don't forget to check for fluid inside the car below the clutch master,
Thank you — that helps. I checked inside the driver’s footwell and around the clutch pedal/master area and could not find any sign of fluid there. The reservoir had dropped below the clutch pickup for the first time, but after topping it off the level is still holding. The pedal, however, is still fully depressed. There is also a clear/slightly yellow oily fluid underneath the car running down the center and extending far back, which makes me think the leak is more likely at the slave cylinder, hose, or line near the transmission, with the fluid then spreading rearward underneath the car. At this point I think it is pretty clear the car needs to be towed rather than driven. I feel very lucky this happened overnight in the garage and not while I was out driving.
Not trying to dissuade the towing, but if you have a way to jack up the car at least the slave cylinder is relatively easy to access since it’s in the middle of the car on the driver side of the transmission. If the leak is coming from there then a little tightening might solve the issue.
If the pedal is engaged with the master cylinder, and it is floppy, then either the MC is leaking, or the slave is leaking, or the line between them is leaking.
It is possible for the MC or the slave to "leak" internally, without drooling fluid all over the ground. But in any case unless there is a broken or disconnected mechanical linkage, the issue sounds hydraulic.
It is not a hard fix. Just jack up the car and pull the slave out. My guess is that it will be slimy with fluid at the business end. Rebuild or replace it, bleed the system and it should be fine.
It is possible for the MC or the slave to "leak" internally, without drooling fluid all over the ground. But in any case unless there is a broken or disconnected mechanical linkage, the issue sounds hydraulic.
It is not a hard fix. Just jack up the car and pull the slave out. My guess is that it will be slimy with fluid at the business end. Rebuild or replace it, bleed the system and it should be fine.