S1 Original brake performance

[Granthar]

Deal all

I have just acquired a set of S1 front calipers and pistons from a fellow member. My 1965 ots came with cooperkraft front calipers. I am considering going back to stock and would appreciate your experiences.

I have just finished reconditioning the rears with new discs, girling pads and seal kit, as well as the handbrake.

I am keen to achieve good front rear proportioning to make the most of the braking performance. I drive fast on the road but no track time for this car planned.

I would appreciate your experience or redirection to previous threads

Ps what color are the pistons and Calipers originally?

Many thanks

[DWW]

Hi, what was wrong with the Cooperkrafts apart from not looking the part. I personally upgraded mine to 4 pot calipers and vented discs from Fosseway Performance and find the braking and balance excellent, a great improvement from stock.




But if originality is what you are after....

[dlgis]

I personally upgraded mine to 4 pot calipers and vented discs from Fosseway Performance and find the braking and balance excellent, a great improvement from stock.

Danny did you upgrade all round or just the fronts? I have brakes on my to do list

[christopher storey]

If you revert to standard after having had Coopercraft front brakes you will find a definite deterioration in braking performance . It is not that the front brakes were not up to standard at the time : it is just that the performance of modern disc brakes is now in a different league. The most noticeable occasions when this is apparent is in what I call the "rejected takeoff" scenario : one starts to accelerate hard to overtake another vehicle, and then decides for whatever reason to abandon the manouevre . With the originals, there is then a noticeable hesitation before deceleration starts, whereas with moderns such as Coopercraft, there is no feeling of inadequacy at all

[DWW]

"Danny did you upgrade all round or just the fronts?"

Just the fronts.

[caveman]

Nothing wrong with my Coopercraft front callipers after 22yrs and 6k miles use so far.

[Granthar]

Hi, what was wrong with the Cooperkrafts apart from not looking the part. I personally upgraded mine to 4 pot calipers and vented discs from Fosseway Performance and find the braking and balance excellent, a great improvement from stock.




But if originality is what you are after....

Hi, thanks for your reply

I live in Switzerland where modifications are only allowed with certification so I anticipate problems when I next have inspection. I have noticed severe front bias to braking, causing the fronts to lock very easily. I have reconditioned the rears to ensure they are not the problem, I also notice uneven wear on one front tyre so need to set the alignment before I can test the bias. Does anyone have braking effort measurements for f/r?

Finally of course I would like originality as long as this doesn’t strongly compromise driving experience, I will always drive like a 20 year old.

Rob

[Granthar]

If you revert to standard after having had Coopercraft front brakes you will find a definite deterioration in braking performance . It is not that the front brakes were not up to standard at the time : it is just that the performance of modern disc brakes is now in a different league. The most noticeable occasions when this is apparent is in what I call the "rejected takeoff" scenario : one starts to accelerate hard to overtake another vehicle, and then decides for whatever reason to abandon the manouevre . With the originals, there is then a noticeable hesitation before deceleration starts, whereas with moderns such as Coopercraft, there is no feeling of inadequacy at all

Thanks for the opinion, I guess I should try to drive an original set up. A friend has an original s2 which is not the same setup but closer to mine than Coopercraft

[DWW]

Didn’t realize that you still have to have inspection on classic cars, here in the UK they are exempt. There is also a different attitude to modifications here they are not covered by the MOT.

[Granthar]

Thanks for the replies. I am however surprised that with my rebuilt original 1 3/4 rear calipers the rear locks before the Coopercraft fronts. If the Coopercraft provide greater breaking than stock wouldn’t I expect them to lock first? As it stands the balance of the car is not good I prefer the fronts to lock just before the rears.

Anyone had similar experience?

[abowie]

my rebuilt original 1 3/4 rear calipers the rear locks before the Coopercraft fronts

If this is the case you need to fix it as it is dangerous. If you brake hard while turning and your rears lock you will spin.

The stock brake bias on the E type is pretty close to 2/3 front 1/3 rear.

I don't know what it is with the aftermarket brakes you have fitted, but you can work it out it by calculating the piston area of front and rear calipers.

Personally I would just fit the original front calipers, assuming they are in serviceable condition.

[Granthar]

Based on areas of the pistons the ratio is 45:30 f:r or 3:2. Based on 2 1/8 f and 1 3/4 rears

My plan is to fit the originals and see

Thanks

[DWW]

Will definitely be interesting to see if that improves the balance or indeed make it worse.

[bitsobrits]

Based on areas of the pistons the ratio is 45:30 f:r or 3:2. Based on 2 1/8 f and 1 3/4 rears

My plan is to fit the originals and see

Thanks

When determining a basic force ratio, wouldn't you also need to take into account the area of the brake pads?

Something like comparing (pressureXarea) for both front and rear.

[Jeremy]

"Danny did you upgrade all round or just the fronts?"

Just the fronts.

I upgraded my brakes with Zeus - a moderate and unobtrusive upgrade with cast iron twin front calipers and new rear cylinders (no vented discs or sharp-edged alloy calipers). The man at Zeus emphasised the importance to me of keeping front and rear braking effort in the correct ratio for safe and effective braking. He specifically said, if you upgrade the fronts, you must also do the rears.

[1954Etype]

How are the brakes plumbed into your servo. On the early 4.2 cars, the rears came on before the fronts. Check your plumbing.

[Granthar]

Based on areas of the pistons the ratio is 45:30 f:r or 3:2. Based on 2 1/8 f and 1 3/4 rears

My plan is to fit the originals and see

Thanks

When determining a basic force ratio, wouldn't you also need to take into account the area of the brake pads?

Something like comparing (pressureXarea) for both front and rear.

The brake clamping force is the product of the piston area multiplied by the hydraulic line pressure. As the friction force is the product of the clamping force multiplied by the coefficient of friction of the pad/disc combination I would expect the pad area would affect the coefficient of friction (bigger pads bigger coefficient), and hence the braking force. I have the same brand of pads; Bendix f and r.

[Granthar]

If you revert to standard after having had Coopercraft front brakes you will find a definite deterioration in braking performance . It is not that the front brakes were not up to standard at the time : it is just that the performance of modern disc brakes is now in a different league. The most noticeable occasions when this is apparent is in what I call the "rejected takeoff" scenario : one starts to accelerate hard to overtake another vehicle, and then decides for whatever reason to abandon the manouevre . With the originals, there is then a noticeable hesitation before deceleration starts, whereas with moderns such as Coopercraft, there is no feeling of inadequacy at all

Thanks for the opinion, I guess I should try to drive an original set up. A friend has an original s2 which is not the same setup but closer to mine than Coopercraft

I have installed the original setup as I do notice an initial bite compared to the Coopercrafts. I am definitely locking the rears before the front which is both dangerous and suggests another problem. Could the slave or master cylinder be at fault?

[Andyp_67E]

How old are your tyres? Old tyres that have gone hard but with lots of tread will give the impression of brakes easily locking up as they are frequently the overlooked part of braking performance on an E Type.
Andy

[Granthar]

Just replace all 4 tyres with a new alignment and bleeding. I’ll see what affect this has.

Looking in the service manual there are 2 ways to connect the servo; for “early “ S1 4.2 cars the rears connect to the first circuit connection with “later” cars connecting first the front circuit. I have currently the early setup, but have had advice to switch to the later setup as per the diagram below

Anyone have experience with this?

Many thanks