TCS Rear Brake Slave Cylinders

[Dilkris]

Can someone please confirm correct slave cylinder size for TCS please. I measure the originals as 0.7" and note that I can buy from Triumph Spitfire specialists 3/4" (0.750") , 5/8" (0.625") and 11/16" (0.688") replacements - I guess the answer is the latter yes?     

[SilverBeast]

Do you mean the brake master cylinder? That's 0.7" on the UK single circuit system, with the servo still installed.

Edit: Sorry read the title properly now....

[Sparkrite]

I have recently bought  a pair of Borg and beck rear slave cylinders for my tcs at 17.8 mm which is .701 inch.

[Grumblebuns]

I believe that the TCS came with slightly larger wheel cylinders of 0.75" and the TC with 0.70" . The TCS also had slightly wider drums at 1.50" vs. 1.25" for the TC.

Tim Engle posted this a while back .

 http://lotus-europa.com/dbupdate/478/msg47864.htm

[jbcollier]

rear brake cylinders:

S1/2/TC = 0.75"

TCS = 0.70"

0.70" rear wheel cylinders were used on the Triumph GT6 Mk3 '71 - '72 and the Spitfire 1500 '76 - '80.

[Grumblebuns]

Yep, you're right, got them mixed up. Do you know of the reason why the TC got the larger cylinders, possibly due to the smaller sweep area for the slightly narrower drums?

[jbcollier]

The S1/2 and TC have the same 1.25" rear brakes (shoes, drums, cylinders) with manual adjusters.  The Special has 1.5" rear brakes with (sort-of) automatic adjusters.  They reduced the cylinder area to maintain the brake front/rear balance.

[Dilkris]

I have recently bought  a pair of Borg and beck rear slave cylinders for my tcs at 17.8 mm which is .701 inch.

Thankyou everyone for the feedback - "sparkrite" we are both on the same side of the pond - can you PM me where you bought these from?
JBC - Triumph specialist lists Triumph 1500 slave cylinders as 11/16" (0.688") - do you think 0.012" will make much difference? Problem in the UK is that once a part is sourced specifically for a Lotus, the price becomes (on average) 2 - 3 times more.  (Like diff bearings for example... )
Finally, TCS rear brake drums (1.5") are difficult to source here, and if you find them they are not cheap, but TC (1.25") not so. Is there a problem (sorry for the purists) in "converting" TCS brakes back to TC spec by changing drums, shoes and slaves cylinders? Notwithstanding the braking effect, are there any other parts that would be effected by this change? I am thinking I could at thesame time dump the "auto" brake adjusters (which don't seem to gain much favor) and replace with "manual" , but would I have to change the back plates?       

[Pfreen]

The 1.5" self adjusting brakes and drums for a TCS are from a late Triumph GT6 mk3.
Rimmer Bros and others carry the parts.  https://rimmerbros.com/Item--i-GRID008074

[GavinT]

Moss Motors have the TCS 0.70" type wheel cylinders for $18.99  - DELPHI/LOCKHEED branded, which I thought was pretty reasonable.

https://mossmotors.com/wheel-cylinder-rear-70-bore?assoc=70777

Here they are at Anglo Parts with no brand info.:

https://www.angloparts.com/en/catalogues/part/184411/053.027

There seems to be plenty of the correct 0.70" type around on eBay etc. too.
I can't see a lot of point going back to the smaller TC/S2 brakes.

[jbcollier]

11/16" and 0.70 are the same cylinder.

I'm not a fan of the 1.5", self-adjusting brakes.  But, with a little fettling, they do work.  It's always simpler to stay with stock.

Just a heads up, the new brake drums are not balanced.  No big deal on a Triumph, a huge deal on a Lotus.  Get any new drum balanced first.

[Pfreen]

The rear brakes on a tcs are "self adjusting" via the handbrake.  The late  GT6 mk3 rear brakes are standard "stock" on a tcs.

The new brake drums I installed last year were balanced.  The original brake drums were not balanced.

[surfguitar58]

rear brake cylinders:

S1/2/TC = 0.75"

TCS = 0.70"

0.70" rear wheel cylinders were used on the Triumph GT6 Mk3 '71 - '72 and the Spitfire 1500 '76 - '80.

Would the .75” slave cylinder fit the 1.5” TCS drums? As in a way to get a little more braking force in a servoless TCS?
t

[Pfreen]

It may or may not fit.  If it does, I doubt the adjuster will work since the adjusting ratchet fits in the back of the cylinder.  A good idea though.

Maybe the .75" can be machined in the back for the adjuster?

[FourLoti]

Reviving an old thread, which still is relevant and was helpful to me.

Also wanted to add an update for future readers. It is mentioned that both Moss Motors and Rimmer have the correct self-adjusting cylinders. Going down that path, I learned that Moss does NOT carry the late GT6 MKIII type. The units they show as fitting a '73 GT6 are the non-adjusting type -same as earlier GT's and most Spitfires. I corresponded with them and they confirmed they don't have the later part.

In addition, while Rimmer does appear to show the correct type with elongated barrel, it seems a bit "iffy" as they only list 0.625 inch? 

Doing a bit more shopping, I found this DFC part at PartsGeek.  https://www.partsgeek.com/catalog/1973/triumph/gt6/brake/wheel_cylinder.html?brand=dynamic_friction Just finished putting them in without any hassle whatsoever.

Regards,

Ron