Rear wheel cylinders '74 T/C special

[kram350kram]

Are the rear wheel cylinders Triumph Spitfire?  Any recommendations on increasing piston size over stock ? Thanks in advance?   

[Pfreen]

The brakes on a tc with 1.5" shoes comes from a 1973 Triumph gt6 mk3.  These brakes are self adjusting (sort of).
I assume you want to go bigger with the pistons to improve the brake balance.  That seems like a good idea.  However, I don't know the next size up Girling cylinder that will fit.

Let us know if you find out a bigger size.

[rjbaren]

I read in one of the posts somewhere on converting the Europa to a race car and that the rear brakes can be converted to a twin leading shoe system to improve the rear brakes.  I just can't remember where the document is regarding the conversion by Jensen.

[Grumblebuns]

If you're referring to the "Lotus Europa Twin Cam Competition Manual" by Jensen Motors, it's located on the Home page side bar under Articles on Repairs and Modifications. Details on braking are pretty sparse in the manual. I believe the Specials came with 0.75" wheel cylinders, a bit bigger than the regular TCs.

[jbcollier]

A number of British cars use the same style of rear cylinder.  They are available in sizes ranging from 5/8 to 3/4 (maybe 7/8).  RD sells them by application.  British Parts NW by size as well.

Please be careful about changing from the stock size.  Regardless of the fact that the Europa is mid-engined, most of the braking is done by the front wheels, especially at the limit.  Changing the rear cylinder to a different size may result in the rear brakes locking first at the limit.  This results in the rear end spinning around.

The stock Europa brakes, properly maintained and adjusted, work very well indeed.  Road testers were astounded back in the day.  As with any mid or rear engined car, and all motorcycles, you have to squeeze the brakes progressively harder to make sure to weight transfers first before applying full pressure.  OEM pads are also prone to fade in heavy use.  Upgrading the pads is important for high speed driving on the track or mountains.

[Pfreen]

My front brakes lock up way before the rear brakes.  I personally would like to get the rear brakes to lock up before the fronts.  Then, I would install a brake bias valve in the rear hydraulic line and adjust the brakes so that the fronts just lock up before the rears.
It is manageable as is, but they are not up to modern brake standards. 

Going with two master cylinders and a balance bar is the best, but not easy to do.

As it is, I have no adjustment, except changing front pads and their coefficient of friction.  There is not much choice available for the rear shoes lining.

Has anyone ever tried changing the rear booster for one with more boost.  I know lockheed has a number of different models.  I have two of the lockheed boosters.  I think they are both 1.9:1, 7" diameter units.  Lockheed does offer a 2.3:1 , 7" diameter booster. 

I think the problem with finding a larger diameter brake cylinder is finding one that will accommodate the shoe adjustment star wheel.  You may be able to bore it out and fit a larger piston and seal.

[SwiftDB4]

Fit disc brakes at the rear. Even better use at least a 2 piston caliper. I converted my S1 to 4 pot Wilwoods front and rear. Can lock up all 4 wheels now. Huge difference at track days, but probably not necessary for street use.

[BDA]

 

Disc brakes are more efficient and don't require adjustment (in case the adjusters don't work), and are much simpler. There are lots of ways people have done it. Some are described here ( http://lotus-europa.com/manuals/#brakes) and here (https://drive.google.com/drive/folders/13bJcEUU9KWMnbB8FJ95qiq_rk6qD-uf4), and Lotus-supplies sells kits (https://www.lotus-supplies.com/part-category/brakes/disk-kits/).

[EuropaTC]

Out of interest I plugged in 22& 25mm dia rear cylinder pistons into the spreadsheet and I'll admit I was surprised at how much difference it made (in theory of course). 

Standard Europa TC comes in at F/R 75/25 split, which frankly is awful. Great on dry roads, lousy on wet ones. 

Going from 19mm dia rear piston (TC/75/25) to 22mm it's 69/31 & at 25mm it's F/R 63/37, a significant improvement and in theory both F/R lock about the same time. Front slightly ahead of Rear, but it's a close run.

I don't know if there is a rear wheel cylinder with a 25mm piston that will fit, but if you can find one it should make a difference in terms of the F/R percentages.

Personally I'd just save up the pennies and go for rear discs, it's a well worn path to follow. 

Brian