Brake pedal travel

[Austrianvespaguy]

So, I'm not loving the brake feel on the E30, and I can't for the life of me seem to improve it. Redid rotors, pads, guide pins, and SS flexible lines on all four corners and thoroughly bled the whole system. The brakes do work OK, but there is a significant amount of pedal travel before they really start to bite. It also doesn't feel like air in the lines, as that tends to give a more linear build up of pressure over a longer length of travel. This feels much more like mechanical 'slop' prior to engaging the hydraulic system. Anyway, I did some research and found recommendations to adjust the booster clevis length. I messed with that some today but to me it appears that all this does in move the pedal height around, but beyond that doesn't actually help take up any slack in the system. Am I missing something here, or is this just kind of the way the E30 brake pedal geometry is?

Hmm, slight update. Realized that after extending the booster clevis just a little (maybe a turn), all of a sudden the brake lights wouldn't turn off, as the pedal wasn't closing the switch. So I extended it a bit more (maybe another 4-5 turns) so that it properly rests up against the switch. So now the brake likes work properly again (although now I have no idea why they also worked before I touched anything), and the dead travel does indeed seem a bit improved, but now the brake pedal seems to sit stupidly high compared to the clutch and throttle pedals. What is normal for these cars?!? Is the brake light switch position adjustable independent of the pedal/booster adjustment?

[Austrianvespaguy]

Brake pedal now sits a good inch above the plane that both the clutch and throttle pedals lie in. . . see attached.
EDIT: Per Bentley 1998-1990 models' brake light switch is non-adjustable, so I guess it must be right now this way, but still leaves me wondering why it worked before I adjusted it and why the pedal is so high, but I guess I'll just drive it around for a while and see how it goes. . .

[JimmyP]

You are on the right track, but the adjustment I think you seek is not the booster clevis.
An e30 has and adjustment in the brake pedal pushrod which adjusts the brake pedal free play. A vary small amount can / does make a huge difference in pedal travel and brake feel.

When I got the E30M3 that became my race car the brake pedal felt like crap.
My street car on the other hand felt amazing.
Both cars 1988s, about 100 cars apart in serial numbers.
At that time, all the brake hardware was identical. I couldnt figure it out.

Like you I changed lots of brake parts on the "to be" race car, with very little change.

I was guided to adjust the free play and afterwards a couple very minute adjustments got that silver one to the same pedal feel as my red one.
Probably the differnce to one being built on a wed. vs a fri.

You will need a couple 13mm (I think, its been a while) wrenches and a small one, maybe 5-7 mm (or a small adjustable).

The pushrod is threaded that comes off he brake pedal with a lock nut and a flat sided pushrod that goes forward to the booster.

Make VERY small adjustments. If your pedal travel is too long, lengthen it (a little).
When I say a little, I mean 1/4 turn adjustment at a time.
Adjust, drive it with the brakes warm and see. Then adjust more. Literally no more than 1/4 to 1/2 turn of the rod at a time.
You must do it with the brakes warm though. It will be possible to get a great feel cold, then when warm they will drag.

I rode around in my car for a while with the wrenches in the passenger seat pulling over in parking lots making adjustments until I felt just the slightest drag, then I backed it off a bit and the pedal was fantastic. Easily the equal of my street car.

Hope this helps.
Cheers
jimmy p

[AndrewBird]

It might just be late models, but the piston of the brake light switch pulls out and then will auto adjust the first time you press the brake pedal.