Plus 2 Braking No Servo

[Galwaylotus]

I did a lot of investigation and found a suitable tandem m/c in a AP Racing CP5615-2CD. AP produces these specially for Caterham.

Check out the Caterham site as this m/c was a bolt-in job with just a minor modification to the push-rod. There's a picture on my earlier post (page 3 of this thread).

[gerrym]

Galway, presume you have a RHD car. Was there sufficient clearance between bodywork and outlet connections. Did you need to use banjo connections or just flared tubing. Is this on an S3? I guess the Plus 2 setup is quite different in terms of clearance.

Regards

[alaric]

Hi Galway, I'd love to find that master cylinder of yours, but I've failed miserably to locate it. Is it on a website somewhere or should I be phoning for price etc.

I have found these:

This looks closest to what you have and is on https://www.caterhamparts.co.uk/product ... 57e28aae65

There's not spec at all though so I'm not sure if this is the right one or not.

This looks like the one in the post by Galway, but there's no infor re bore etc.

If you could let me have any more info that'd be appreciated.

All the best.

Sean.

[gerrym]

Sean, one of the reasons why I went for the Triumph Spitfire 1500 unit, it that is much easier to refer to, buy spare parts for and even replace in the future should that be required, compared to a low volume special.

I did speak to the appointed distributor for AP, they told me the unit was a "big secret" and they couldn't deal with me etc etc.

Anyway, job done with the GMC226 part number. I bought mine from James Paddock and it arrived within a day of ordering, no dramas. It's made in Japan in the Girling/Lucas/TRW factory there, to modern QA/QC standards

Regards
Gerry

[alaric]

Ok. Thanks for that. As I've probably moaned about before I'm not happy with my servo as it died on the shelf after being refurbished at cost of ?190. So, if the pedal load is ok and the feel of the brakes is better without the servo, and I can get an off the shelf unit to give me a split system, then I'm sold. I should be concentrating on getting the car on the road for now though. It was going to be May but work has ground to a halt again. Need motivation; dashboard is next job.

Thanks again for the details.

Sean.

[alaric]

Hi. I've just been in contact with elanfactory in Aus, and been advised that switching to the non servo tandem master cylinder with 0.7" bore is not recommended. Here's what the email said:

"I suggest you should talk to your insurance company before removing the remote brake servo. The only approved way to install a tandem system on an Elan +2 is with two remote servos (per the Federal spec Elan +2). I would suggest any substantial modification away from the original brake system design needs engineering certification either by Lotus or a consulting engineer approved by the UK road authorities."

Fair enough response from a responsible supplier, and I do agree any mods to brakes should be to some recognised solution. I didn't think removing the servo was that big a deal though, from other posts that I've seen.

I had emailed asking for a price for the master cylinder and postage back to the uk. How many of you have engineering certification? I was planning on getting the whole car checked out anyway (by the likes of Matty), since I've rebuilt it from scratch, but certification to offer to the insurance company I'm not sure I wanted to get into.

All the best.

Sean.

[Galwaylotus]

Galway, presume you have a RHD car. Was there sufficient clearance between bodywork and outlet connections. Did you need to use banjo connections or just flared tubing. Is this on an S3? I guess the Plus 2 setup is quite different in terms of clearance.

Regards

I do indeed have a RHD S3. The outlet ports are on the left of the m/c as you sit iin the driver's seat so there are no bodywork interference issues. We did use banjo fittings just because it made a neater installation but didn't need to.

[gerrym]

Alaric, this reply may be well intended but I don't think it reflects reality in the UK.

Can't imagine Lotus getting involved in recertifying (to what standard) a car which they last remanufactured in 1975. Get real!!

However the bit about insurance companies has been discussed and that is valid. So too is the overall design of the system which has been discussed in the context of correct pad compounds, reinforcement of the body around the bulkhead, pedal box assembly, etc.

The deletion of the servo has been verified by feedback on this forum as being a practicable solution in terms of pedal force. Several contributors have commented that with Greenstuff pads, pedal forces are fine. The change to a tandem m/c everything else being equal should increase the safety of the system because the hydraulics are no longer at the mercy of a single failure point (eg rear driveshaft failures which are well documented for the rotoflex original design). Getting rid of the insidious failure modes of a remote servo has to be a major safety improvement in a critical system such as the brakes. Putting two of those evil devices in beyond the pale. (Gee, even remember all the hassles my Dad had with his Rover which had the same Girling remote servo).

So for me, I'm quite happy to document, model and test the system to the satisfaction of a competent motor engineer, as may be demanded by an insurance company specialising in classic cars, many of which will have been modified for modern road conditions.

In any case, for me it's a matter of installing thought through modifications. Every time I choose to drive a classic it's a matter of faith that the car's active safety is in good a condition as it can be, because by comparison to my modern with 8 airbags, brake assist, NCAP 5 stars, pre-tensioners, etc, etc I don't stand a chance on the passive side of things.

Regards

Gerry

[alaric]

Hi. Totally agree Gerry. I think they must be concerned about liability. I have the solid drive shaft conversion, have changed the gearbox to a T9, and have re-routed the fuel line and replaced the rubber caliper pipes with stainless braided ones. Noone has checked the flares on my copper pipework or that I haven't used too tight a bend radius in places. So it's a bit of a minefield. I doubt I'd get a certification from the likes of Matty. All I can do is declare the mods to the insurance company at the outset and make sure I'm accurate and declare that it was me that carried out the work. That's my approach anyway. Elanfactory did say if it was for track use no problem, so perhaps I have to say that when ordering to keep them happy that they are not liable.

All the best.

Sean.

[kstrutt11]

Alaric,

Removing the servo and changing master cylinders etc only affects the brake pedal effort, if you can still lock the wheels (without breaking something in the pedal box etc) it will be fine, Where you have to be carefull is when you change the brake balance by modifying the brakes, generally modderately improving the fronts is not a problem but you need to be very carefull with the rears (hence why it is only recommended to use improved pads on the front).

If you are looking for someone to check the workmanship on your vehicle there are many vehicle inspectors out there or even a good MOT tester. (I am a chartered engineeer but you need liability insurance to carry out inspections so I would not do it for others).

p.s your's sounds very much like mine type 9, solid shafts, no servo. (mine also has no roof and MX5 seats!).

Kevin

[alaric]

Hi. I'm surprised the pedal box would need to be beefed up. Looks very strong to me. I've beefed up the bulkhead that it screws into with more fibreglass matting, and it's secured in place with a plate that screws on from the underside, sandwiching the fibreglass. The box itself now has a thicker and stainless shaft and new bushes, but is very solid. I haven't cut the top off or made an access hole like some have, as I felt that'd weaken it - a few tiddly screws in place of a continuous joint stopping it flexing - not for me. Mine's the last design on the production line as the car was made in Oct '72, so perhaps the earlier ones are more flimsy. I bet when they rust too they can collapse on the unwary. I'm going to leave mine alone for now and crack on with getting the car on the road. I'll get the servo rebuilt.

All the best.

Sean.

[gerrym]

Sean, a few points:-

1/ My comments about the pedal box were intended to mean that it should be in good condition. My car when bought with 12months MOT had a seized and corroded pedal shaft. The holes in the sides of the pedal box supporting the pedal shaft were severly ovalised and over-sized. Not the best for operation with a servo but even worse with higher loads in a non servo situation. As well as a risk of the whole thing jamming against the throttle, there must have been a lot of mechanical losses in transmitting the pedal force into the master cylinder. (Note car was bought from a well known Lotus dealer who must have known at least a little about this)

2/ Top access holes. Most of the modifications I have seen involved making small access holes in the top to ease installation of the bushing pin and the split pin connecting pushrod to pedal. If the holes are small, say 1.5" square they will have minimal effect on the stiffness of the pedal box. The ability to check the top of the pedal and pushrod is a useful maintenance aid. The cover is just there to stop weather entering into the cabin. Conversely your description, cutting off the top would lose the bracing effect of the top and yes would make the pedal box that little bit more flexible.

3/ Pedal loads without Servo. The reply came from the Australian supplier and was along the lines of certification etc. Just for interest, and thinking that maybe the Australian requirements were/are very demanding, I checked the Australian Design Rules (ADR 2nd Edition Part 31) and reviewed their criteria. These were valid from early 70s . Basically they required a deceleration around 0.6G with a pedal input less than about 670N. There was also a requirement to pass a less stringent test with the Servo disabled. These are not stringent criteria for braking systems. Both of the criteria should be easy to satisfy with the Plus 2 without servo (assuming everthing in good working order). Mike has already said pretty much the same thing (in the UK context).

So I should sleep pretty easy knowing that what is proposed in the context of historical standards (Ie no ECUs, ABS etc) is sensible from both a reliability, practicality and legislative perspective.

Regards

[Galwaylotus]

2/ Top access holes. Most of the modifications I have seen involved making small access holes in the top to ease installation of the bushing pin and the split pin connecting pushrod to pedal. If the holes are small, say 1.5" square they will have minimal effect on the stiffness of the pedal box.

Is that 1.5 inches square (2.25 square inches) or 1.5 square inches?

[gerrym]

Galway, we should post a questionnaire to Plus 2 owners to find a) most popular size measured in square inches of their pedal box top access holes b) the ideal size of top access holes measured in inches squared. Rules of the questionnaire exclude all baby Elan owners from commenting, anyone with a headless pedal box must first build a finite element model of their box to prove it confirms to Norwegian design rules and all those with round holes must use alternative obsolete units of measurement -square ell?

[Galwaylotus]

Sounds good to me. Off you go and I await the results with bated breath!!