1963 Lotus Super Seven S2

[TEM]

I'm looking to rebuild the calipers on my Seven.  The calipers are marked "12MP".  I can find calipers and kits for the Girling 12SP but nothing for the 12MP.  My research shows that the 12SP has a 13mm piston but I'm measuring 12.8mm on my 12MP pistons.  My pistons are in good shape so I'm only looking for the seal kit.  Deos anyone know where I can get a 12MP seal kit or if the 12SP and 12Mp are the same.

 

Thanks,

Terry

[jbcollier]

Do you mean wheel cylinder kits?  12.8mm is 1/2 inch.  Do you have brake shoes and drums?  Or brake discs and pads?

 

Wheel cylinders from that era would all be in imperial, not metric.

[TEM]

Sorry for the confusion. These are the front brake calipers.  I meant that I have 42.8" diameter pistons on my 12MP caliper VS the 43mm referenced for the 12SP calipers.

The references I find on line for the 12SP show a piston diameter of 43mm (1 11/16").  43 mm is 1.693" where 1 11/16 is 1.688".  My 42.8mm measurement is 1.685".  My question is, can I use a 12SP seal kit on my 12MP calipers or is there a specific 12MP kit out there somewhere?

[SENC]

I've only paid attention to "type 12", "type 14", etc and not to the suffixes when considering calipers and rebuild parts on my Seven and Elan - so had to go look through old pictures to confirm what is on my 65 - 12SP.  

 

Mine were in good shape so I didn't have to rebuild my calipers, but I may have a set of pistons in my parts box.  It will be tomorrow or Tuesday, but I'll check.

 

 

[jbcollier]

The seal kit will work just fine.  Caliper dimensions are nominal not precise.

[TEM]

Thanks.

I don't know how different the SP is from the MP.  I agree that the pistons are probably similar enough but I can see that the two caliper castings look quite different.  I have included a picture of my S1 Elan project caliper (12SP) and my Seven caliper (12MP).  Perhaps it is only the physical size and possibly dimensions that are different and the hydraulic components are the same.  Just checking to see if others have used the SP seals in an MP casting so I don't waste time, really want to get this car back on the road soon.

 

[SENC]

It appears from the pictures that the MP version has ports on either side for attachment of the brake hose.  Total speculation, but could "SP" signify a single port and "MP" multiple ports?  Both being type 12s I'd suppose the guts are the same.

 

 

[TEM]

Senc, you may be on to something there.  The MP casting has provisions for a port on either side but only one is drilled.  The other caliper is drilled on the other side along with the bleeder.  But the two MP calipers are the same casting, just drilled differently.  The SP has two different castings for the left and right side.  From what I can tell, the MP predates the SP so not sure why they would do away with the single casting caliper, it seems like a more cost effective design.

 

Since I have not heard any direct experience with the MP/SP kits, I will go ahead to order an SP kit.  I'll report back any findings, good or bad.

[EdWills]

Hi Terry.

A number of years ago I required new brake piston seals for my 1969 Lotus Seven which is equipped with the later 14LF callipers from the Mk3 and 4 Spitfire (This information is according to Goodridge U.K.)  Girling U.K. has a web site contact option, and may be best to contact as they can go back into their library and advise which seal kit is best for your situation.  Goodridge U.K. were also very helpful, and supplied me with a photocopy of all the parts for my callipers.  They mostly sell brake hose kits for many U.K. and European cars and did include the Seven, but I couldn't find the Seven kit on their site anymore.  Burton U.K. were also very helpful with brake line kits and I obtained a 'vintage looking' set for my Seven from them.  

 

You probably know this already, but it is best that you do not attempt to split the calliper bodies undoing the bolts.  A new small rubber seal would be required (this can be obtained still as a spare part), but leaks may ensue if the halves are not bolted back together with the correct torque.  Lotus and Girling recommended that you should never separate the halves.  Good luck with your search and kit experience. EW

[TEM]

Thanks EW.  I purchased a 12Sp kit this morning but will reach out to Girling to confirm.  I can always use the SP kit on my Elan.  I'll report back what I find.

I never split my calipers.  Clean them up best I can, install new piston and seals, and put them back on.  No need to add drama.

[7Westfield]

YMMV, but I've split 14LF calipers several times over the years with no problems

 

when ordering kits, remember to order the rings for sealing the caliper halves---they are not included in rebuild kits

Edited April 24 by 7Westfield

[jbcollier]

If you split the calipers, please replace the square sealing ring between the two sides with the correct part.  Do not simply use an o-ring.  I have split the calipers and replaced the sealing ring, and I have rebuilt them without splitting.  Both methods work out just fine.

[IamScotticus]

If you must 

https://www.pegasusautoracing.com/productdetails.asp?RecID=6560

 

But put some new calipers on there. Save time, look better and ensure your safety. 

You might have a series one, or very early S2

 

https://rimmerbros.com/Item--i-210988R

 

https://britishclassicspareparts.com/product/brake-caliper-rh-girling-type-12-triumph-herald-1200-optional-spitfire-mk1-2-vitesse-1600-mk1-lotus-seven/

 

Look at it this way, put on new calipers, then take your time refurbishing the old.

 

 

 

 

Edited April 19 by IamScotticus

[jbcollier]

And, if you split the calipers...

 

https://www.pegasusautoracing.com/productdetails.asp?RecID=1144

 

https://rimmerbros.com/Item--i-17H7679