The 1990 E34 B10 Bi-Turbo has a heavy clutch and a long pedal travel. Having researched, I decided to install a do-it-yourself (DIY) clutch stop in an effort to improve the driver's interface with the car and improve the enjoyment of the vehicle.
WHY DO I NEED A CLUTCH STOP?
Many cars with manual clutches are setup with long pedal travel from the factory. This is to cater to a wide variety of drivers who may or may not be sensitive to the clutch take off point or the engagement point. Another reason for the long pedal travel is to allow the engagement point of the clutch to change as the clutch wears down.
A clutch stop is a device which restricts the travel of the clutch pedal beyond what is necessary to to change gears smoothly. This results in faster gear shifts, a lighter clutch effort due to less pedal travel, less fatigue with your left foot in stop and go traffic, and an improved driver feel as there is less wasted time and effort in monitoring the clutch engagement point waiting when releasing the clutch.
Drivers of automatic gearboxes have no need for a clutch stop as there is no clutch pedal.
WHAT DOES A CLUTCH STOP LOOK LIKE?
A clutch stop normally consists of a bolt, washers and a couple of nuts. Specially made ones are available from different manufacturers. Just google "BMW clutch stop" and you will find a few.
You can also make one for a few dollars as a DIY project. It is a very cost effective modification. In my case, I made a clutch stop from a bolt that fit the hole in the car, 2 nuts and 2 washers. I also put on a small square of self-adhesive floor saver (small carpet-like fabric which you glue to the bottom of furniture to prevent damage to the floor). Approximate cost: $2 or less. I ended making my clutch stop with existing items in my toolbox.
Some people have used an elevator bolt with a nut very successfully. An elevator bolt is a of bolt with a large circular flat top. This is normally used on things like a fridge, stove, washer or dryer where you can raise and lower the height of the item by rotating the bolt and locking its position with a nut. Approximate cost: $5.
Picture 1
This is a general view of the pedal area with underdash completely removed, the side speaker unplugged, the Alpina VDO instrument sub-box removed (I replaced the aged double-sided tape mount with new velcro). The stock clutch stop is the small dot on the upper left of the clutch pedal. It looks like a white dot because I had just removed the tiny, tiny rubber factory clutch stop which allowed the pedal to almost hit the carpet. Note the tremendous amount of dirt hidden behind the dead pedal which has been removed in this picture.
Picture 2
Close up of empty clutch stop hole after removal of the tiny factory rubber clutch stop.
Picture 3
This is a general view of the DIY clutch stop. This was a prototype assembly ended up being too large and IS NOT the final one used. Unfortunately due to time restrictions, I did not photograph the actual one used in my car. However, this photo is sufficient to give you an idea of what its supposed to be.
The final version I used consists of a smaller, shorter bolt with washers and nuts on both sides of the clutch stop hole. The piece of pinkish carpet\fabric is a thick piece of floor saver with single sided adhesive available in hardware or dollar stores for very very cheap. The black rubber cap is actually a rubber tip intend for the bottom of chair legs. I ended up not finding and therefore not using a rubber cap. My clutch stop just has the floor saver piece stuck to the top of the bolt. Since the clutch stop is so small and high up on the floorboard, it is for normal intents and purposes invisible to most people.
Picture 4
This picture shows the clutch stop bolted and secured to its factory location before the application of the floor saver. As you can see, the bolt is not very long. I had to retract the carpet to get at the space behind the clutch stop hole in order to insert a washer and bolt behind it. You have to be very careful not to drop a bolt or washer down the carpet behind the mounting hole. One tip is to slip a piece of plastic bag or cloth to form a bib behind the clutch stop hole down to the floormat in case the washer and bolt behind the stop hole slips and falls. That way it won't end up behind the carpet but will rolls down to the floor mat.
TESTING THE CLUTCH ENGAGEMENT POINT
- Park the car on a flat ground
- Make sure no person or object is in front of the car. Safety first.
- Put the gear in neutal
- Start the car
- Depress the clutch. You should notice the clutch pedal travel stopping sooner than before.
- Engage first gear and keep your foot depressed. You should not feel the car moving forward at all. If the car starts moving forward, you have set the bolt too high so the clutch is already disengaging. Reduce the height of the clutch stop bolt.
If you have the clutch stop set right, the car will absolutely not move with the clutch pedal fully depressed even if you rev the car. If you have passed this stage, then let go of the clutch pedal slowly and feel the clutch take up point (friction) and proceed to drive normally.
Drive around to get used to the new feel. Then do some spirited driving to get used to the clutch pedal travel. Rev the engine and change gears at different rpms. If you feel the clutch not fully engaging and disengaging, adjust the clutch stop accordingly. You should be able to change gears (1st to 5th) at all rpms with no loss of smoothness - just reduced clutch pedal travel.
HOW IT FEELS AFTER THE CLUTCH STOP IS INSTALLED
The car shifts very smoothly and with less driver effort due to reduced clutch pedal travel. Since the shift takes less time, the driver's attention to the road is less distracted by the actions required to perform a gear change. Same for heel-and-toe downshifting and upshifting. The effort required is much less with no loss of enjoyment. We have just reduced the amount of redundant clutch pedal travel. Enjoy.
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