Bulkhead flex at clutch master cylinder

[KiwiPom]

Hi, after much fettling of the clutch linkage, resulting in a massive improvement to its operation I noticed the bulkhead flexes when the clutch pedal is depressed. Hopefully the video shows this clearly. Is this flexing normal?

It looks to me like the bulkhead would eventually crack from this movement.

There is a steel oval reinforcement on the inside of the bulkhead (visible from inside of the car), it is only a little larger than the oval flange of the master cylinder.

[Pete Boole]

Can't see the video. Can anyone else?

Pete

[pistolpete]

no cant see anything

[KiwiPom]

Not sure why video doesn’t show here is a youtube link instead, wait a few secs for me to get in the car and press the pedal a few times

https://youtu.be/4Wu70ZLSjT0

Simon

[rbgosling]

Hmm, yes, I see what you mean. Can't say I've ever had cause to look and see if mine does that!

[Alan_M]

The bulkheads can flex and crack in that area. I’ve had to repair the one in my SE as was starting to crack. In the prototype the bulkhead has split on three sides of the edges of the square shaped panel it’s mounted on. I have an article somewhere on how to build a reinforcing plate that attaches to the pedal box - I will dig it out.

[Alan_M]

Not sure why video doesn’t show

Simon

Because you can’t embed videos on this forum, only photos.

[KiwiPom]

The bulkheads can flex and crack in that area. I’ve had to repair the one in my SE as was starting to crack. In the prototype the bulkhead has split on three sides of the edges of the square shaped panel it’s mounted on. I have an article somewhere on how to build a reinforcing plate that attaches to the pedal box - I will dig it out.

Thanks Alan, I am interested in reinforcing the bulkhead, every time I use the clutch it crosses my mind whats going on under the bonnet

Another issue is the ignition lock lock moves slightly to the right when I press the clutch!

[KiwiPom]

This is my fix for the cracked firewall/bulkhead, I made the 8mm alloy plate plenty big enough in case I have to tie it back to the pedal box and/or A post in the future. The firewall still flexes very slightly when the clutch pedal is depressed, maybe thats “normal” (for Lotus)

Ideally there would be a (thinner) plate under the master cylinder on the other side of the firewall, but that would involve moving the brake balancer unit out of the way, and is quite a but of work, so that’s on the “to do” list.

I suspect the firewall was damaged by over tightening the master cylinder studs, or (more likely) the pipe union (which is currently far too tight to undo in situ, without risking further cracking).

[KiwiPom]

I also put some inner tube rubber on the plate back, thicker on one area to match the bulkhead shape (its not flat)