Drum Brakes And Compensators...

[Anthony 1,000]

My 205 XS only just scrapped through it's MOT yesterday with a mere 53% efficiency on the rear brakes, so clearly something is amiss somewhere.

 

I was planning on replacing the rear beam with a 1.6 GTi one to get the thicker torsion and anti-roll bars (19/19mm vs 18.5/16mm), and figured that I might as well use the wider 1.6 GTi drum brakes as well seeing as the ones on my XS are clearly in need of some attention.

 

The only issue that I can foresee is that I'm assuming that the slave cylinders on the XS beam have compensators built into them, whereas on a 1.6 GTi the compensator is externally mounted in the engine bay. Thus if I use a 1.6 GTi beam on an XS without changing anything, I'll end up having no rear compensators at all. I know that running rear disk brakes (ie 1.9 and 309 GTi beams) without compensators and on standard front brakes results in the rear locking prematurely, but I've no experience of whether this is also true of rear drum brakes.

 

Has anyone tried this and can they confirm whether it gives excessive rear brake bias (ie rears locking up before fronts)?

 

I'm running standard 1.9 GTi calipers on the front in place of the original unvented Bendix junk

 

(I'm sure this was discussed a long while back, but I'm struggling to find the topic and related topics only seem to be about rear disk brake setups)

[Baz 421]

Would whacking in a single 1.9 in-line compensator work?

 

Easy enough surely!

[welshpug 1,627]

Would whacking in a single 1.9 in-line compensator work?

 

Easy enough surely!

 

or a single 1.6 compensator should work just fine with the 1.9 Fronts.

 

 

bias valve?

[Miles 331 1 Cars]

I'd stick with the 1.9 compensator's, The XS's use the same 4 line set up as the 1.9

[Anthony 1,000]

Oh, don't get me wrong - I know that I could easily retro-fit a compensator, it's just that if I can help it then I'd rather not do so as it's extra hassle having to remake some of the brake lines in order to fit a compenator or two (I'd probably just replumb the lot with a single front-rear line and a front-rear split on the MC if I had to, as that's how I normally do it on all 205/309's).

 

Assuming they're all running standard brakes, I know from experience that 205 1.9 GTi's lock prematurely with no compensators, 309 GTi's do but to a lesser extent, and 306 S16's are fantastic with no rear compensators thanks to the increased rear brake effort.

 

I'm sure that I'm not the first person by a long shot to fit a 1.6 GTi beam to an XS, hence the question of whether it locks up prematurely at the back or not? I'm happy for (and indeed would like some) increased rear bias over standard - just not so much that the rear locks first.

[welshpug 1,627]

how about using the XS wheel cylinders?

[Anthony 1,000]

how about using the XS wheel cylinders?

I'd considered that, but I need to check whether they physically fit or not - if they do then it's an easy solution to the problem.

[welshpug 1,627]

I believe that its only 2 different fitments, one type has a round section that pokes through the backplate, the other an oval shape.

[andychalmers 0]

I've just found out that Bendix (round hole in backplate not oval hole) 1600 GTI rear cylinders & 1400 Bendix cylinders are externally the same. However the 1600 cylinders use a M10 thread & 1400 uses a m12 thread. So easy option for you is too buy & fit 2 new or rob off your old beam 1400 rear cylinders & fit to 1600 beam. If you run 1600 cylinders without a brake compensator then your rear brakes will lock up very easily causing the back end to step out, not good on the road, mint if you can left foot brake & driving on gravel

 

Recap all road cars need a brake compensator for rear brakes.

1400's compensator is in the rear brake cylinders

1600 GTi's compensator in-line under bonnet.

1900 Gti's compensator in-line under car body

Rally cars ditch the standard compensator & fit a adjustable brake bias which is a adjustable brake compensator.

 

Hope this helps

[Anthony 1,000]

Ta - that's exactly what I wanted, words from someone who's done it and could confirm either way

 

Aren't most 1.6 GTi rear drums Girling though, atleast in my experience?

[humanz 3]

I've just found out that Bendix (round hole in backplate not oval hole) 1600 GTI rear cylinders & 1400 Bendix cylinders are externally the same.

 

Oddly enough, I got some Bendix wheel cylinders from a 309 (can't remember the trim level) which were very different. The round part was smaller, the actual wheel cylinder was smaller, and the holes for the cylinder to mount to the backplate were closer together.

 

Anthony, I'm in a very similar position, as I've converted my XS to a GTI, and I'm using a 1.6 GTI rear beam and rear drums. I could run the 1.6 brake lines including the compensator, but I'm hoping to eventually convert the rear to 1.9 discs, so Ive left the XS brake piping. If you do retrofit a single 1.9 compensator, let me know how effective as it is, as I've been considering it for sometime while the car's still by the mechanic.