Lotus Elan

Master cylinders access : modifying Pedal box cover

PostPost by: TonyA » Fri Sep 02, 2022 12:47 pm

The Workshop manual says replacing either brake or clutch master cylinder entails dismantling the pedal box and unbolting and disconnecting BOTH the master cylinders, even if only one is being changed ! All this because access to the clevis pins and in particular their securing split pins are difficult.

Various past writers on this subject suggest this can be avoided either cutting a big square out of the top of the pedal box , and then replacing with a lid with screws, or more interestingly, drilling suitable round holes, to be filled with grommets.

Questions: 1. Is it practical to get at the clevis pins from the footwell and any tips (aside from removing the steering wheel and front seat).
2. can anyone provide a drawing or sketch of the position and size of the access holes need in the pedal box cover..?

Thx..TonyA
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PostPost by: alaric » Fri Sep 02, 2022 1:58 pm

The whole of the top of the closed part of the pedal box on my +2 lifts off. It's actually held in place with silicon sealant. Very easy to get the brake mc out. No need to reach into the foot well. I can upload a pic later when I get home.

Regards.

Sean.
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PostPost by: prezoom » Fri Sep 02, 2022 3:00 pm

I left about a 1/2" lip around the top of the box. Cut a new top from a fresh piece of metal, and used self tapping screws to hold it in place. Access is now very easy to what was a difficult area. A gasket was used to seal the top plate to the box, keeping unwanted fumes from entering the passenger compartment.
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PostPost by: mbell » Fri Sep 02, 2022 5:59 pm

prezoom wrote:I left about a 1/2" lip around the top of the box. Cut a new top from a fresh piece of metal, and used self tapping screws to hold it in place.


This is also how i did it. I used a thin sheet of ali for the lid and formed over the edges of the pedal box to avoid water ingress.

Recently swapped to dual circuit master and it made my life a lot easier being having access.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: TonyA » Fri Sep 02, 2022 8:43 pm

Did those of you who cut an access square in the top of the pedal box lid, , did you do this in situ, or after the removal to avoid doing it again..?

Anyone managed to get the clevis pin out of the m/c plunger from the footwell without dismantling or cutting into the pedal box lid..? Tips..?

Anyone cut two round access holes instead a big square..?

Sean, how did your lid become detachable from the lower oedal box/bulkhead..? Your pic would be most helpful.
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PostPost by: Steve Brooks » Fri Sep 02, 2022 9:04 pm

Hello chaps, like most I fitted a plate and gasket ( leave 1/2 inch lip all around) for easier access to the master cylinders. I did mine a couple of years ago as I had to replace the shaft and dismantled the pedal box so it was out of the car.
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PostPost by: mbell » Fri Sep 02, 2022 9:39 pm

TonyA wrote:Did those of you who cut an access square in the top of the pedal box lid, , did you do this in situ, or after the removal to avoid doing it again..?


I did it some years back, so not 100% sure. Believe I did it with pedal box removed while giving it a once over. (Can also re-enforce the underside mounting while your doing it.)

For the square i just measured the four corners of the square, drilled them and cut between the drill holes. I cut down the center line of holes, so I could bend a small lip over. To add strength and remove a sharp edge.

It maybe specific to my pedal box but one of the brake master fasteners (lower?) is a bolt not a stud, so requires a spanner inside and outside the pedal box to remove the master. That is a not fun two person job without the mod.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: Hawksfield » Sat Sep 03, 2022 9:44 am

Hi

I did it insitu with a Dremel and small cutting disc, after drilling four holes 1/2" from edges.
ensure that you cover underneath and around top to prevent grindings getting everywhere. drilled and fixed with self tappers.

Used it early this year to re seal brake MC. spot on. :P
John

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PostPost by: SENC » Sat Sep 03, 2022 12:03 pm

I was able to remove and install MCs, clevis pins and clips without the mod or removing the box... but I said words I didn't think I even knew and promised myself I'd do the mod at the next convenient opportunity - and only my obscene stubbornnesskept me from doing so mid-stream. If you have double-jointed shoulders, elbows, and wrists, give it a go, but know that some operations are effectively blind so you're working by feel. Bottom line, don't fret about the modification, just do it.
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PostPost by: Foxie » Sat Sep 03, 2022 1:16 pm

I did this mod many years ago.

The main reason was to minimise the free travel in the pedals using adjustable pushrods.

:)
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PostPost by: Robbie693 » Sat Sep 03, 2022 3:50 pm

Last time I did this, removing the pedal box, I wondered after I'd put it back together if it would be possible to disconnect the circlip holding the pushrods in and extracting the master cylinder that way. In my mind it seems like it would be easier than fiddling one handed with a clevis pin at a moving target. I have not tried it yet but it might just work...
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PostPost by: TonyA » Sat Sep 03, 2022 9:15 pm

Thx everyone.. I cut the lid in situ making 8mm holes at each corner, as suggested in mbell' post to retain strength, then used a Makita multi tool and Fein semicircular metal cutting blade (very effective method for careful cutting out of sheet steel and without sparks)

Access to the clevis pins and split pins is now a cinch !

To minimise the size of the cut out but still leave enough room to get at the clevis pins, leave half inch on the two sides and lower edge but you can leave an inch on the upper edge where the mounting bolts are. See the photo in Foxie's post

I made the lid with 1cm fold over sides hopefully for better water protection.
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