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Farmyard exotics ABS deletions - Page 7 - Suspension/Brakes/Wheels/Hubs/Steering/Geo - The Lotus Forums Jump to content
Barrykearley

Farmyard exotics ABS deletions

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Vacuum was measured late last night under the dash off one of the small tees. Just under 20” at that point. 

I will see if I can squeeze some time in this morning once I’ve dropped my eldest at work


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All done.

so I drop the car off the ramp - start her up. Double check vacuum - magic.

let her warm up in the garage and tidy up. Go to open the door - nope - it’s locked itself. Thankfully the bonnet was open. 

So after some swearing - she’s now sat on the mot ramp. I’m now awaiting my eldest to finish having her eyelashes done and I can go back and collect the car. Which has once again locked itself on the mot ramp - window wound down to make sure it didn’t do it again - which it did.

i must say - brakes are great. DDAD86F1-73BC-4503-8610-C431CE836B1E.thumb.jpeg.ed0836010207e4223fe66195dc986bca.jpeg

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Whilst my DM is working properly at the moment, when it dies I know what I'll be doing instead. Top job, or rather jobs.

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DanR

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Thanks chap. This ones actually far nicer and simpler in many ways as it uses the existing mechanical vacuum pump which is on the non power steering cars. 

Vacuum level out of the pump is exactly the same as my S4s is set on assistance. So no need to add any extra weight to the car - and makes it cheaper for the owner of the vehicle as well.

first time I’ve ever driven a carb turbo - other than I need a lesson in starting them when warm - it’s an absolutely beautiful car to drive. Not as quick - but  really nice all round drive. Funny thing - just reversing the car it seems so much smaller. The lack of power steering is a real throw back to my old Esprit S.

 


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Well it’s been over a year now since I’ve done the S4s - and it hasn’t been without it’s issues. A whole lot better than the Delco - but some issues none the less over the last 3000miles or so.

some facts worth considering. 

Lotus fitted a small vac pump to run the flaps - either they considered the vacuum from the inlet not to be reliable enough or not to be enough full stop. I’m sure they didn’t add the pump to add weight and cost unnecessarily.

on earlier cars Lotus used a mechanical pump again disregarding the inlet vacuum.

the servo as fitted requires a vacuum range of 0.4-0.8 to effectively operate. The turbo engines on the S4 and S4s in both of my cars measures at 0.2 at the inlet manifold. If it wasn’t considered good enough to run flaps by lotus then I’d consider it unsuitable in any way for braking use.

the pump has the habit of chattering - this is due to the electrical config and specifically the pvl switch. I’ve been in contact with PVL whom supply the vacuum switch as fitted. They confirm that this is not suitable for application. The chattering of the pump if ignored for a long period of time causes carbonisation on the relay contacts and premature failure. I’ve had one relay fail (closed) which luckily wasn’t a problem. It did however allow the pump to become so hot as to allow the vac pipe to melt off.

so stopping the chatter is the biggest issue. It’s not in anyway connected to any vacuum leak whatsoever. And swapping the vac switch it’s exactly the same. In fact swapping out for a preset switch or the application from a kitcar supplier the chatter is even worse. Relays used are diode protected ones. It’s could be to do with the servo and the bleed off of vacuum - but swapping to another servo and it’s still identical.

This very issue has been spotted by another forum member as well on a similar setup

Today I’ve been playing again with this setup - replacing the relay, again, and adding an adjustable time delay relay into the circuit. Chatter completely stopped. 

Next task is to relocate to the front of the car, swap to the preset switch which is designed for the job and use the PVL switch set a wee bit lower to flag up as a warning light for low vacuum along with the addition of a small vacuum reservoir. Refit the lotus vac pump for the flaps in the boot and see if @Steve V8 car supply me with a new bit of carpet for the melted piece which covered the pump.

Let’s see if it’s better over the next 3000miles as frankly that’s the real test

 


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4 hours ago, Barrykearley said:

and see if @Steve V8 car supply me with a new bit of carpet for the melted piece which covered the pump.

Are we talking about the little carpet cover attached to the left wheelarch with velcro?

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Barry I had severe chattering when I fit the kit to my S4.  The reason ended up being I did not have the one way valves installed correctly and far enough away from the pump.

If I remember the most important was to have a one way valve between the booster and the pump,  The fluctuations from the booster caused the sensor switch to trip.  I was not following Ian's instructions closely - because i knew better 🙂

Double check those 1 way valves.

 

 

 

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Valves checked and about 4 different brands and makes used. I’ve even mocked it up off the car with multiple different lengths of hose. The chatter occurs as soon as the servo is actuated - once the chatter has stopped - then it doesn’t occur again until the servo is actuated again. Tried different pumps, servos, valves, switches, a reservoir etc. 

Tracy from my local mot place has been up - he builds cars for racing - he’s adamant that the servo is used to running on a high vacuum manifold system that would not worry about leakage at actuation like the switch setup does. The Esprit manifold vacuum is simply too low to run this servo. Either way it has now been overcome.

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