The cheapest way to upgrade the brakes.

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Re: The cheapest way to upgrade the brakes.

Postby Blue ass fly » Wed 04.09.2019, 18:58

What a great find
Definitely on my to-do list
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Re: The cheapest way to upgrade the brakes.

Postby johanvanboven » Wed 20.11.2019, 22:59

Thx.
After this mod, you will feel less difference in pedal feel between a 'modern' car and the 'old' Elan.
Now 6 yrs later, brakes are still feeling nice and pass MOT every yr.
A pity we can't fit ABS.
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Re: The cheapest way to upgrade the brakes.

Postby Rambo » Thu 21.11.2019, 15:10

I thought Dapinky was researching that or had even fitted it to his M100 ?

Maybe it was just another April Fools group buy to entice Dico and Monty :lol:
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Re: The cheapest way to upgrade the brakes.

Postby Fredjohn » Thu 21.11.2019, 15:57

Having just re-read this thread, I believe I may have found the problem with my brakes.

I have:

Wilwood 4 pot front, piston diam either 25.4mm OR 32mm (tbc)
PNM rear, piston diam 38mm.

As far as I am aware, I have the std BMC.

According to posts above (especially dapinky's early on), as you reduce the BMC diam, you increase the pedal travel. If you have larger pistons as I have, then the pedal travel MAY increase further and MAY go all the way to the floor.

Mine has very long travel, but not quite to the floor and is "soft" or spongy. They used to be fine, but don't inspire confidence any more. They have been bled several times and there is no air in the system. Also new fluid. Both rears have been pressure tested succesfully after fitting new seals and fronts are also OK, having fitted new pistons/seals in 2013.

I am aware several members have similar set-ups with a combination of Hi-spec or PNM all round and use std BMC.

I would like a much shorter travel and "harder" brakes if possible.

Is my BMC either knackered (technical term) or do I need to find a suitable larger bore BMC ie larger than the std 22.2mm??????

Advice help sought please.
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Re: The cheapest way to upgrade the brakes.

Postby lotusflasherman » Thu 21.11.2019, 23:41

Fredjohn wrote:Having just re-read this thread, I believe I may have found the problem with my brakes.

I have:

Wilwood 4 pot front, piston diam either 25.4mm OR 32mm (tbc)
PNM rear, piston diam 38mm.

As far as I am aware, I have the std BMC.

According to posts above (especially dapinky's early on), as you reduce the BMC diam, you increase the pedal travel. If you have larger pistons as I have, then the pedal travel MAY increase further and MAY go all the way to the floor.

Mine has very long travel, but not quite to the floor and is "soft" or spongy. They used to be fine, but don't inspire confidence any more. They have been bled several times and there is no air in the system. Also new fluid. Both rears have been pressure tested succesfully after fitting new seals and fronts are also OK, having fitted new pistons/seals in 2013.

I am aware several members have similar set-ups with a combination of Hi-spec or PNM all round and use std BMC.

I would like a much shorter travel and "harder" brakes if possible.

Is my BMC either knackered (technical term) or do I need to find a suitable larger bore BMC ie larger than the std 22.2mm??????

Advice help sought please.


Not advice really but just to say I run HiSpec with 4x 29mm pistons in front calipers, 2x 38.5mm in rear and the standard BMC. Pedal has slight mechanical movement and then starts hydraulic pressure quite high and can be pushed to about mid position for locking up... I think mine has more volume than yours if PNM rears are VW sliding calipers

My first SE did 100k miles in just over 3 years and I did change the clevis pin in the brake pedal to eliminate some mechanical movement and raise the operating point slightly. Steel braided hoses can reduce spongy feel, but if you've already got them .... I presume the caliper mounting bolts are tight and the brackets are not flexing ... wheel bearings correctly adjusted?

None of my cars had servos until I bought a Scimitar GTE after 7 years of driving so I'm quite used to pushing the brake pedal hard when I need to so never felt the M100 needed a smaller bore BMC to reduce pedal pressure and produce longer travel..
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Re: The cheapest way to upgrade the brakes.

Postby Fredjohn » Fri 22.11.2019, 11:38

Thanks Phil. Yes I do have steel braided hoses, callipers all correctly torqued and bearings all OK. Will check the clevis pin and replace if necessary, but I doubt it will make a major difference to how it all feels.

Rear callipers are indeed VW Golf Mk IV, sliding pin, 38mm diam pistons. Sliders all working well as just rebuilt them.

My pedal doesn't start working until about at least half way down, then it feels soft and spongy until wheels lock about 1-2" above the floor. Not inspiring.

My thoughts keep keep coming back to the BMC. Any other ideas folks? :smt102 :smt100
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Re: The cheapest way to upgrade the brakes.

Postby dapinky » Fri 22.11.2019, 11:47

It sounds like my maths lesson from many years ago isn't the cause of the issue (if Phils is good) - so I'd agree with his idea of checking the linkages.

Even a small amount of wear on a pivot pin will translate to a much larger movement at the end of the pedal (see - you get a Physics lesson now!!!).

Another thing to look at (but probably not so likely) is if you have got thicker carpets/mats than standard. If the mat has ridden up behind the bend in the brake pedal it will reduce the amount of travel avaiallable before hitting the floor. It can give the impression of insufficient pedal travel, but is still going to allow full brake pressure with enough pressure on the pedal.

If it comes back to the master cylinder, I would suggest that an OE version (22.2mm bore) would be the best replacement for a car with increased piston bore sizes.
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Re: The cheapest way to upgrade the brakes.

Postby lotusflasherman » Sat 23.11.2019, 13:40

Fredjohn wrote:Thanks Phil. Yes I do have steel braided hoses, callipers all correctly torqued and bearings all OK. Will check the clevis pin and replace if necessary, but I doubt it will make a major difference to how it all feels.

Rear callipers are indeed VW Golf Mk IV, sliding pin, 38mm diam pistons. Sliders all working well as just rebuilt them.

My pedal doesn't start working until about at least half way down, then it feels soft and spongy until wheels lock about 1-2" above the floor. Not inspiring.

My thoughts keep keep coming back to the BMC. Any other ideas folks? :smt102 :smt100


Might be an idea to consider the servo... not looked at M100 servo but on another car I had the internal diaphragm spring break and add pedal movement before anything happened.. (not spongy though). Still don't see how changing to different bore BMC will cure sponginess.. :smt017
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Re: The cheapest way to upgrade the brakes.

Postby peter canepa » Wed 27.11.2019, 01:42

Johan,
I've been reading your solution to better braking, really like the idea, and found the part on eBay. So now what's the deal with blocking off one of the ports? Left hand drive car here in California. Does that make it a single circuit system? If it does that's not good. Why would you not just re-route the brake lines to fit the new Master Cylinder?
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Re: The cheapest way to upgrade the brakes.

Postby Brit-Car-Nut » Wed 27.11.2019, 02:39

Re-routing the brake lines will be a task since they are combined in the middle of the system - thus the LHD cars have a 3 port Brake Master Cylinder.

Look for part number BS10514-10. It is a M12 x 1.0 bleeder for a truck. It fits fine.

I have a few extras if you can't find one.
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Re: The cheapest way to upgrade the brakes.

Postby peter canepa » Wed 27.11.2019, 20:41

John
Thx, Just to review. The new MS TRW PMF 172 which I found on Brit Ebay is a 4 port one, so we plug one hole. It does not effect the slit system whatsoever?
Sounds like I'll give it a try. Lots less work that replacing the calipers & rotors
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Re: The cheapest way to upgrade the brakes.

Postby Brit-Car-Nut » Wed 27.11.2019, 21:44

peter canepa wrote:John
Thx, Just to review. The new MS TRW PMF 172 which I found on Brit Ebay is a 4 port one, so we plug one hole. It does not effect the slit system whatsoever?
Sounds like I'll give it a try. Lots less work that replacing the calipers & rotors

You got it in one try!

The cylinders are basically the same except for the FED car they had to re-work the plumbing to get around some physical blockages in the path. You still have two brake systems so (theoretically) if one chamber or cylinder fails, the other one is supposed to be enough to slow the car and stop it.

The TRW PMF 172 does show up on eBay US every now and then...
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Re: The cheapest way to upgrade the brakes.

Postby johanvanboven » Thu 28.11.2019, 00:26

Hi Peter,
On LHD models, they could not fit the 4th pipe, the distance between BMC and body is to small.
It can only make a difference in an emergency stop because the fluid for Lh F and Rh R has to pass through 1 pipe.
Maybe someone can make such short bended 180° brake pipe?
Some picture's to show how it is on LHD.
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Re: The cheapest way to upgrade the brakes.

Postby peter canepa » Sat 30.11.2019, 22:05

Guys,
OK thanks. Johan thanks for the photos. I'll order parts and get started as soon as the weather here gives us a break. :bowdown:
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Re: The cheapest way to upgrade the brakes.

Postby peter canepa » Mon 09.03.2020, 19:55

After finally finding a master cylinder from England, and having the supplier CANCEL the order because I could not supply the vin #, I said I had a Opel Kadet. Because there is no listing for a Lotus. I threw in the towel. Besides its winter, even in California. Now while surfing Bring A Trailer, I see a BRG in Texas, that's my exact car with these PNM Brake upgrade kits on it. Has anybody else used these? There pricey, but seems like a real top notch way to improve the brakes, and keep the original wheels.
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Re: The cheapest way to upgrade the brakes.

Postby Rambo » Mon 09.03.2020, 20:29

Quite a few of us are running about with the PNM brake upgrades Peter. The front PNM calipers are basically Hi Spec 4 pots with the PNM logo on them and the rear PNM upgrades are essentially VW mk IV calipers with different brackets.

Both front and rear upgrades give better braking and appear to require less frequent maintenance

NB there have been a few problems with the rear kits from memory. I'm fairly sure JohnW had a few brake fluid leak problems ?? Assume now sorted ??
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Re: The cheapest way to upgrade the brakes.

Postby Rice crispy » Mon 09.03.2020, 22:44

I've had issues with the rear calipers from pnm. They were the early ones they did and I believe they use a different caliper now. I had a leak shortly after installing them which was replaced foc then the same caliper failed again after about a year and 4000 miles, Peter replaced foc again ( I believe it was the original one rebuilt again). The replacement lasted 2 years any maybe 5000 miles and failed again and I had to buy the replacement, cant remember how long ago that was ( a search for the post will tell you) but all been ok since.
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Re: The cheapest way to upgrade the brakes.

Postby Rambo » Tue 10.03.2020, 08:55

Lotus Elan Central • View topic - PNM engineering rear brake calipers
viewtopic.php?f=41&t=22242#p280604
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Re: The cheapest way to upgrade the brakes.

Postby peter canepa » Tue 10.03.2020, 22:16

Guys,
Thanks for pointing the PNM Upgrade out on our site. A lot of discussion and for a California car, I can't be taking calipers off and sending in for repairs in England.
I've never heard of a caliper leaking. So I'm now going to go back to the idea of changing the Mstr Cylinder, and see what happens. These kinds of parts have to be sourced here, and talking to my mechanic I think we can.
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Re: The cheapest way to upgrade the brakes.

Postby Fredjohn » Tue 10.03.2020, 22:50

Peter, you can source improved brakes your side of the pond. Go to wikiLEC at the top of the page, then click on brake upgrades.
You will find there a Wilwood conversion.
Only problem with this is sourcing the caliper mounting bracket.
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