Brake pad material

T

tommy

New member
I was reading an old article by Peter Garnier about his experiences with a lotus cortina while working for Autocar. In it he mentions that the car originally had very soft (DA4) material which wore out in 3000 miles which he replaced with DS11 pads, but that Colin Chapman reckoned this would upset the brake balance enough to possibly cause a spin. Did all P14 brake type loti use these soft pads originally? The reason I ask is my car has always had a brake balance problem, with too much rear brakes and I never sorted it, despite replacing everthing, until I fitted a G valve into the rear circuit. It would be interesting if these soft pads would have sorted it, so is there an equivalent available today?
Also has anybody else had similar balance trouble with a P14/rear manual adjusting brake lotus. So far anyone I have spoken to has never had this problem, but with a standard system with all new parts, what could be the problem, if everyone elses cars are ok?
Tommy
 
I have tried DS11 and I wouldn´t recommend them for road use. They need heating up before they are able to stop a car. Really it doesn´t matter, DS11 is not available any more.
For the balance problem I have never noticed that the car tend to spinn at hard braking. But, I have never driven a LC that hard, only a early GT and that car was fitted with Mintex 171 compound at both front and rear.

Tommy, check the sizes of the pistons in the rear wheel cylinders so they are correct to the spec of your car. If they are replaced they might very well be the wrong size. That can cause the rear brakes to me more efficient than they should be.
 
Rear brakes are the correct 0.7 inch lotus rear wheel cylinders. One of the pieces of advice I got was from Brian Moorcroft who told me to try the 0.75 gt ones. One trip up the road and pant soiling slide later, I reverted back to the 0.7 cylinders. Also tried VG95 rear linings with no improvement. If I tried an emergency stop type braking manouver at 30 to 40 mph I was seeing the road ahead through the side window and there were two thick black rear skid marks.
Tommy
PS it was not the availability of hard DS11 I was interested in but the soft
DA4 material or its equivalent.
Tommy
 
Hi Tommy,
Just an idea, have you had thoughts on trying a smaller sized rear wheel cylinder? It should do the opposite thing, ie make the rear brakes not quite as good?
Matthew
 
What pads do you have in your car? The rear linings tend to last much longer than the front pads, maybe your linigs are good old stuff and the front pads are modern crap? Have you tried to skim off the discs and fit a new set of good quality pads?
 
0.7 is the smallest size wheel cylinder available for that brake type. New old stock Girling gdb520 pads were what I was using in the P14 calipers and I then upgaded to brand new P16 calipers,discs and EBC greenstuff pads but still the same. Tried various makes of pad both new and n.o.s. for these and still the same. Got fed up with stripping and bleeding brakes so finally fitted a Girling G valve (from a Morris 1800) to the rear circuit and now brakes great but I would still like to know how it seems only my car is like this.
Tommy
 
Not entirely relevant...but I've found Ferodo DS2500 the best all purpose pad for my mk2, Good from cold on the road but still able to cope well with a full day's track action.
 
Tommy,
Are you sure your front brakes are up to scratch?
The fronts being disc in my opinion are more prone to siezure than the inboard rears?

I found this on GJK (mk2) and rebuilt the front calipers as I had to much rear brake . This sorted it.

If you could get on a MOT brake tester they could tell you if the fronts are up to spec.

Wet weather can also make a difference and thats why bias boxes are fitted to many modifed cars.

Graham
 
Fronts all brand new P16, calipers, discs and pads to see if this made any improvement over the P14 calipers which had been rebuilt and new discs fitted and also appeared in perfect working order on mot brake test. P16s made no improvement at all. The only comment mot testers made about the brakes was that they could not believe how powerful the rear brakes were as nothing that they normally test had such powerful rear brakes. With G valve (anti lockup valve) fitted to the rear circuit car pulls up straight and true without drama and will lock the front if you stand on them so I think nothing wrong at the front.
Will someone else out there take their P14/manual adjusting rear brake lotus out and do an emergency stop at 40 miles an hour to see what happens? Just to see if mines the only one with this problem or whether they are all like it. I must admit this really drove me to distraction and made me not want to drive the car as I regarded it as unsafe, so I was glad to find the G valve solution but I still would like an answer to the cause of the problem.
Tommy
P.S. PROBLEM THERE WHEN ROADS WET OR DRY
 
Lotus Limited (U.S. Lotus club) gave out a Girling part number listing for all of the 1960's Lotus produced cars with a membership when I join in the early 90's. It lists the Rear wheel cylinders for the Lotus Cortina as

To -- Z74C065789 as 64673675 repair kit: SP2171
from Z74C065790 as 64674138 repair kit: SP2210
--------6/65 - 9/65 as 64674138 repair kit: SP2210
--------9/65 - 9/67 as 64675534 repair kit: SP2296

hope this helps
 
Hi Tommy,
I had similar troubles with AJT, which has P14's. I used Girling pads at first and found the front brakes worked, but wern't inspiring.
I spoke to Mintex, who put me intouch with Questmeade of Rochdale.
01706 860088. Speak to a guy called Alan. He reccomended a set of pads made by pro-friction @ £46 + vat & post. There are 2 sizes which fit P14's,
PF520, which fit straight in, or get the PF519-F-16.D which need a bit ground off the pads to fit. However, they give 20% more surface area than the standard ones. AJT will stand on its nose!
Basically, improve the pad material at the front and the drums at the rear won't show the rest of the braking system up anymore!
Hope this helps.
Scott 8)
 
Thanks Scott, it is good to know that I am not alone with these problems, as I have not been able to find anyone with similar experiences until now. I just got funny looks when I tried to explain it to people and my Uncle ,who has been a Ford mechanic from the 1950s and an mot tester had never seen or heard of such a problem.
What symptoms were you experiencing with AJT? My car did not even dip the nose before the back was locked and sliding. Heavy braking at more than about 30 mph was damn scarey. I would like to go back to P14 brakes as I am having arch clearance problems with the wider track of the P16s so thanks for the brake pad contact. How much do you have to modify the 519 pads to fit?
 
Hi Tommy,
With AJT, when I applied the brakes, they just felt wooden. As if the pads were made of timber. If you've ever used a car on a race track and experienced brake fade, this feels the same, the front brakes aren't reacting to the pedal pressure.
I had to remove a fair bit of the 519 pad to make them fit. The shape is the same, but the 519's have a larger silhouet. I just put an original pad back to back with the pro-friction and scribed around it. Then set about it with my bench grinder (wear a mask, otherwise you'll choke!).
The extra pad surface area you get is around 20% and your brakes will be as good as any of the FIA racecars who're using P14 calipers.
It sounds like your rear brakes are in fine condition!
Some people suggested that the disc's wear rapidly, with these pads fitted, but I've not seen any wear at all on AJT's (original Ford), in the 1500 miles I've covered so far. I had quite a bit of squeal and screech at first, but that dissapeared after fitting a set of anti-squeal shims.
Let us know how you get on Tommy.
Scott 8)
 
Hi Scott is it just the steel backing you had to grind down or both it and the friction material. Also did you have to grind down all round the pad or just the top and bottom where it slides in the caliper.
Tommy
 
You'll have to grind a bit off from 3 of the four sides and yes it's a bit of pad material, as well as the backing.
I think it's worth trying the smaller pads, judging by what you've mentioned about your brakes, I'd say they'd be a real improvement.
Good luck mate.
Scott
 
Tommy,
One other thought on this after working on my rear brakes today after spotting what I tought was a brake fluid leak.

It's that back in the 60's seals weren't of such good quality as they are now. Ingress of oil from the differential may have rendered the rear brakes less effective. My pads were "oiled". (incidentaly had a unipart number on them)

If you have rebuilt yours and theres no il leakage, along with new shoes, modern brake fluid and possibly new cylinders, which combined with 9" drums on modern tyres give exceptional rear braking?

Incidentally does anyone know how easy the rear seal is to replace and where you get them. Any special tools needed? I was able to pull the 1/2 shaft out ok but the seal was tight.

Graham
 
Tommy,
One other thought on this after working on my rear brakes today after spotting what I tought was a brake fluid leak.

It's that back in the 60's seals weren't of such good quality as they are now. Ingress of oil from the differential may have rendered the rear brakes less effective. My pads were "oiled". (incidentaly had a unipart number on them)

If you have rebuilt yours and theres no il leakage, along with new shoes, modern brake fluid and possibly new cylinders, which combined with 9" drums on modern tyres give exceptional rear braking?

Incidentally does anyone know how easy the rear seal is to replace and where you get them. Any special tools needed? I was able to pull the 1/2 shaft out ok but the seal was tight.

Graham
 
Tommy,
One other thought on this after working on my rear brakes today after spotting what I tought was a brake fluid leak.

It's that back in the 60's seals weren't of such good quality as they are now. Ingress of oil from the differential may have rendered the rear brakes less effective. My pads were "oiled". (incidentaly had a unipart number on them)

If you have rebuilt yours and theres no il leakage, along with new shoes, modern brake fluid and possibly new cylinders, which combined with 9" drums on modern tyres give exceptional rear braking?

Incidentally does anyone know how easy the rear seal is to replace and where you get them. Any special tools needed? I was able to pull the 1/2 shaft out ok but the seal was tight.

Graham
 
Hi Graham,
Big Marky Ibbott (QB maestro) came up with an excellent solution to removing those stubborn half shaft seals, which involved screwing hefty 2" woodscrews through either side of the metal part of the seal and then using a claw hammer to wrench the seal out. Plus, if that fails, you can turn the hammer round and take out your pent up frustration on the rest of the car!! There's a solution to all problems, isn't that right Bertil?!
When you refit the new seals, don't forget to soak them in oil, at least overnight, as they are made of leather and will burn up when you first drive the car. Then you'll be back to square one, with axle oil pissing over your new brake shoes! Also have a good look at the new seals before fitting them. Most are now very old stock and become hard, then the gaiter spring won't be strong enough to pull the leather lip tight around the half shaft and create the neccessary seal.
Hope this all makes sense!
Scott 8)
 
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