Hi i’ve got a mk2 coupe which doesn’t have a brake booster (i think i saw someone say because it’s a right hand drive and they couldn’t fit one in) and i want to improve the responsiveness/safety of the brakes. would it be possible to fit a brake booster and have it work reliably. and if so how difficult/expensive would it be to do

thanks

nothing bolts straight on or even close

 

what has been done is graft in some mk2f bulkhead panel and then it fits , or use a mk1 golf style corss linkage to place the servo over the gearbox 

Don't worry about it, just get used to giving them some force. In the 80's, these cars were the car of choice for most people's grannys. A booster won't make it any more safe, it'll just change the feel. Personally, I always found the feel on the later servo'd cars to be a bit vague. 

Helpful advice from Yeti. I suspect that most of the concern I have about my 1988 Polo CL's brakes relates to comparison with modern car braking performance. However, before owning my recently acquired 1988 Polo, I had a 1963 Mini, a 1973 MG Midget, and a 1980 MGB GT - all of which had better brakes! So, short of adding a servo, does anyone have any recommendations for improving my Polo's braking performance? Different discs? New pads? Adjustments to the rear drums? Any suggestions would be welcome - in the meantime I will follow the advice about force on the brake pedal!!

Check the tyre pressures? Needs to be sufficient to not roll on the sidewalls, but not so much the contact patch becomes elongated.

 

New Dot4.1 brake fluid ? and bleed with a pressure or vacuum bleeder.

if the fluid's dark, it has absorbed moisture and boils under hard braking.

New rear drums and shoes will reduce the brake pedal travel if the Xmas tree shaped wear-adjuster has reached its greatest drop.

 

If a rear cylinder has any seepage it should be changed (may as well if changing the shoes and bleeding) otherwise you have half brake circuit capability and brake fluid level will have dropped. 

 

But rear drums don't do much work as the most weight and spinning flywheel inertia is at the front.

 

Unless the car's lowered lots and the balance valve in front of rear nearside wheel is sending too much force to the back as it thinks the car is heavily laden, so check that is correctly attached to the rear beam. 

Only tweak it a little to compensate then try brakes on a quiet road (or you'll pirouette the car).

 

I have a left hand drive 75hp with a factory brake servo. It used to have the VW1 postage stamp pads and solid discs and they worked fine, but would suffer brake fade when lorries kept pulling out on 2 lane Autobahns at 140+kmh.

 

I upgraded to VWII carriers and mounts, vented 239mm discs and OEM quality pads (Pagid?) like Polo G40 uses.

 

I've also used EBC Greenstuff pads with grooved discs that were marginally better after 500miles bedding in, though along with a change to better tyres.

 

I've heard Ferodo DS2000 or DS2500 pads for VWII calipers suggested for track days with BremboMax rotors.

 

Or Wilwood Midilite calipers.

 

 

I will check the points raised by dvderim. However, tyre pressures are fine, and I do not suspect any issues with the brake fluid - the brake pedal does not feel spongy.

My car is not used for any sort of high speed driving, has not been lowered or "improved" in any other way. I am just looking for more responsive braking in normal conditions and a shorter stopping distance in an emergency!

When I used to drive a UK right hand drive mk2 Polo (no servo, 4speed) I recall using more engine braking.

Approaching roundabouts, say, change down a gear, raising clutch and pressing brake at the same time, to raise the revs about 1000rpm (usually without blipping accelerator to match road speed in dry weather).

 

Can't do that in emergency of course. Then it's just how fast you react and how hard you press without locking the wheels.

 

Do you have roller brake test measurements from a recent MOT?

 

 

Feels firm not spongy. Good. 

 

While you may not suspect the brake fluid it really needs changing every 2 years. It's time not miles based guidance.

 

Another thought. Does the brake pedal have significant travel from rest to biting point? Just wondering if it's worn at the pedal box.

Using engine breaking is second nature to me as I have been driving for a long time.

The last MoT was passed without advisories in September last year and the car has only done 400 miles since then. I don't have the brake test results.

I do not have a record of when the brake fluid was last changed, but if there was air in the fluid it would surely result in a spongy pedal?

There is not excessive travel on the brake pedal, nor does the travel vary.

I have come to the conclusion that the brakes on my Polo are probably normal for the model and year, but I will check over all the points raised over the next few months.

Proof of the pudding will be in six months time when the MoT is due.

Thanks for your advice.

 

That looks lovely. Old school driving.

 

Good, it doesn't sound like you've got brake fluid loss, or a single circuit brake fault.

 

It's not air in the brake fluid but water. This boils under the high pressure of braking and changes to compressible gas, then reverts to liquid (Boyle's law PV=RT).

At 3% water content -the wet boiling point- can become noticeable as degraded braking. 

 

In extreme cases the moisture can also rust the master cylinder (or brake cylinders), so the seal slips on the piston and lets fluid past, like a worn bike pump, so exerting less pressure on the friction parts. At the master cylinder it stays in the reservoir.

 

(At the rear drums it can even seep onto the drum wall and reach shoes' friction liners as drum rotates ruining them, but this would be noticeable as puddle/moisture for a car stood for a long time.)

 

You could buy a brake fluid moisture tester and dip it in the brake fluid reservoir.

 

This one is very cheap, probably won't last, but good enough for peace of mind.

https://www.ebay.co.uk/itm/314806823681

 

Thanks again for your very comprehensive response. Clearly it is important to check the quality of the brake fluid. However, using a tester that costs £2.49, including postage, is unlikely to give me confidence in the result! How can anyone make money out of selling what appears to be a complicated bit of electronic wizardry for such a low price. Postage alone will eat up half that, then there’s the manufacture in China, shipping to UK, packaging, etc. where’s the profit for the UK seller? You’d be hard pressed to buy a biro for that money!

Nevertheless, I am tempted to buy one and try it out on all three of my cars, just for the fun of it!

On the subject of leaks, amazingly the car does not leak anything at all - oil, coolant, brake fluid, etc - judging by the cardboard on the garage floor!

Of course, it is possible that there is a small seep into the rear drums, causing loss of friction. To be investigated.

As for Boyles law, I thought that applied to gases. As I understand it, the problem with water in the brake fluid comes when it gets very hot and boils. I doubt that this will ever be the case with my exploits in the Polo, and certainly not for the leisurely short journeys it is currently used for!

Rust is a different issue, so testing is a sensible precaution.

Thanks again for your thoughts on this subject.

c