18th October 2009
I took the car for the IVA test on the 1st October 2009, and to my horror it failed. I was hoping for a pass after the effort that had gone into the car, but as others have said, at least i know what must now be done to get it through.
Below are the results sheets from the test so that all can see and hopefully learn for my errors. The links above show the build stages, so this page shows what I did to hopefully solve the fails.
Starting from the first point,
Service Brake control/Mechanical components. Brake Master Cylinder retaining bolts not fitted with a locking device. I had not used Ny-lock nuts when fastening the master brake cylinder, a simple and silly mistake.
There must not be a feel of sponginess indicating air in the system! Well I must have bled the system about 4 or 5 times so if there is air in the system it was not for leaving the pipes. I had a think and read of the Sierra manual, one possibility was weeping of the master cylinder seals. So I decided the only safe course of action was a new master cylinder, the seals are no longer available on their own.
When I removed the old MC I did notice a very small amount of brake fluid around the push rod section, so perhaps not a bad idea to go for new.
I also thought about the pipe layout and particularly the brake light switch. This is elevated above the master cylinder and perhaps air was getting trapped in that section of pipe. So a new switch mounting has been made allowing the fitting of a bleed nipple, so that air could now be purged from that section as well as the wheel slave cylinders.
The braking ratio of the axles, for all values of brake force must be less then the frictional force ratio etc. Basically means that under braking when weight is transferred from the back axle to the front axle, the brake must be less that then friction on the tyres. The back wheels must not lock up before the front wheels under all loads.
Below is the results of the brake tests.
I was given a clue! Lose a bit from the rear brakes or get a bit more on the front. One section above that shows the brake efficiency at 53.78% front and 45.78% on the rear, means they are too close so that when weight transfer happens the rear would lock before the front and could lead to a spin.
One way to sort the problem would have been to use an adjustable regulator to the rear brakes. This is no longer allowed for IVA even if it is then locked when done. So another way has been sought.
It took a lot to figure the weight transfer, or weight distribution ratio as mentioned above, but the Internet came to the rescue and after some searching for answers, I was able to write a spreadsheet, enter the data from weights and braking forces and for it to work out the end results as above.
The next step is to solve the problem and after talking with a rep from Brake Engineering I have decided to reduce the rear slave cylinder size.
The standard Sierra cylinder has a bore of 22.22mm, but there are other cylinders that match the external dimensions but have bore sizes of 20.64 mm 19.05 mm and 17.46 mm. So the spread sheet was changed to allow me to work out the brake forces that would act on the back wheels, all else staying the same. This allowed me to make theoretical changes and watch the predicted brake distribution and weight distribution changes.
The spreadsheet is here for anyone to try: - braketest.xls
I have chosen to fit the 19.05 mm rear cylinders, which I hope will give me an approx 60/40 split on the front/rear brakes. This is work in progress.
Interior fittings. Side repeater body and N/S and O/S Int. These must also follow if above 3.2 mm from the bodywork have the 2.5 mm rule. These have now been covered by rubber hose to solve this issue, this is glued into position over foam on the body of the repeaters. The repeaters them selves give me another problem elsewhere!
More to follow!
19th October 2009
Picture of the new brake switch adapter that should allow air to be bled from the system.
Seat Strength For outboard seats the height of the top of the head restraint above the R point must be at least 700 mm. Now this equates to 753 mm from the seat area on a line parallel to the seat back! The problem arises in that my seats are designed to fold down flat and the headrest will go very low to achieve this. The fix is to sleeve the head restraint bars, so that the head rest will not go fully down into the seat. It means the head rest may have to be removed to fold the seat down, but so be it.
Exterior Projections All ‘hard’ parts contactable with a 100mm sphere, which form an external surface or protrude 5mm or more from the external surface must have a radius of curvature of at least 2.5mm. Headlight Mounts/Rear reflectors and Interior mirror.
This 100 mm sphere that represents a knee coming into impact with the car, can come in from any angle, no longer from just a forward direction, otherwise the headlight mounts would be covered by the front indicator lights.
The bar that holds the headlights has been redesigned. It is also wider to give more spacing between the front indicators as I am still loathe to mount them from the nose cone. A small amount of lathe work is still to be done in making two end caps, but that job is all but complete.
The two rear reflectors, the 60 mm red disks on the back of the rear arches are 6.2 mm thick and the rounded edge does not conform to 2.5 mm radius. It was suggested that I glue a large O ring on each of them, but I am looking to make two aluminium bezels. My reasoning is that any trim fitted to solve an issue will not be falling off after IVA.
The interior mirror has an edge of 1 mm plastic and the edge facing the driver needs to have a 2.5 mm radius, so I will either fit some form of edge trim or get another convex mirror that will pass.
Direction Indicators The front indicators are positioned more than 400 mm inboard widest part. & Angles of visibility on side repeaters not met.
I could have kicked myself over this! The rear wings are the widest part of the car and these are the second pair of wings the moulds for the first set were wrong. These new wings are an inch wider then original, so they add approx 50 mm to the width of the car. The indicators were over the 400 mm distance per side by 15 mm but would have been fine for the original wings. This has now been sorted by the new headlight bracket.
The side repeaters need to be seen from an angle of 5 degrees to 60 degrees rearward of the vehicle along a line formed by the extreme outer edge. This outer edge is made by the rear arches, and so the only way for the side repeaters to meet the requirements is for them to be mounted on the outside edge of the rear arches. But does that make the car wider still? This is still under review and I need to ask again of the inspection team for an answer.
Rear Fog Lights RS3, RS4 & RS6 are all due to the wiring loom as supplied, compliant for the SVA, but not IVA. The fog lights could be switched on from the side light position and not just the headlights. The RS10 & RS11 relate to the tell tale light. It had one but the wrong light, the switch would light up, but you could only notice it in the dark so not good enough. This has been partly fixed by an earth return from the headlight position of the indicator stalks, this will feed a relay through the fog light switch to only switch the rear light on correctly. I have ordered a tell tale light that has the correct symbol and can be seen under daylight conditions.
General Construction. Rear suspension ball joints not fitted with lock nuts. OK, so other builders of the Roadster will know there are no ball joints on the rear suspension, but it means the rear camber adjusters. These are 20 mm threaded bars that fit into the top wishbone, they can not rotate and become loose, but fitting lock nuts will stop any wear happening to the threads. A valid point, I have now got the lock nuts and will fit when the rear axle come off to fit the new brake cylinders.
RS7 wiring under dash / Protect battery terminals / wiring passing through un-grommeted holes at headlight mountings/front cone.
Wiring under dash now sorted, more insulation tape around wires as in a normal car loom and a few more tie raps used. The un-grommeted holes I have sorted with the new headlight mount. Still to find battery terminal covers or a complete cover for the battery.
23rd October 2009
Fitted the new brake switch adapter today, also the switch, relay and lamp for the fog light. Took a trip down to a few breakers yards to get some battery terminal covers and also swapped the offside rear brake cylinder for the smaller size and fitted the lock nut to the top wishbone. If the weather holds tomorrow I will do the near side.
Here is a picture of the modufied headlight bracket showing how I solved the sharp edge problem, still to make the end cap and come up with a tidier way to hold the cable to the indicator, it could run internal I guess.
The silver nut at the bottom will have a 12 mm nut cover fitted.
24th October 2009
Finished the rear brake cylinders and lock-nuts on the wishbones. Filled and bled the brake lines, the Easybleed make life easy when doing it on your own. Car is still on the trailer so no chance to try the brakes yet.
Made the aluminium bezels for the rear reflectors, not sure if I will use them! They look fine, but have seen some nice chrome finished reflectors from SVC, so if I get chance to see a few I may pick them up. Managed to scrounge some rubber sheet for the battery top so that is now covered
6th November 2009
OK so a little while since last update, but I have been busy honest!
Now I hope to have all the points covered, but only time and retest will tell me if it is enough. The secondary side repeaters have been fitted to the wings, small lamps in the outer edge.
Not sure if you will notice it or not in the next picture?
The headrests have the tubing fitted and glued to stop them retracting in too far. The battery cover with terminal covers. Then there is the rubber piece over the internal body of the normal side repeaters. The wires have also been rapped and tie rapped to the frame.
The centre mirror was edged with grommet strip and then a cable cover glued over the top to finish. Another close up of the headlight bracket, now with it's end plug. Lastly the locknut on the rear camber adjuster.
I did buy some different rear reflectors, but to be honest prefer my own. Will take the car to a garage Saturday to test the brakes, it will not be a comprehensive test as with the IVA, but hope to get figures from it all the same.
11th November 2009
The brake tests on standard MOT rollers gave indications of back breaks locking at around 100 Kg and front around 130 Kg, unfortunately no way of indicating balance and the point at which they lock up is dependent on the weight of the axle. So having a re-think on this and trying to figure a way of measuring brake pedal force easily.
To that end I came up with this!
A clutch slave cylinder from a Honda motorbike and a pressure gauge. Due to the cylinder size, 2 bar indicated is approx 23 Kg pressure on the pedal. This needs to be a higher figure so an addition of a spring should help. The idea is to strap the cylinder to the base of the foot and read the pedal pressure on the gauge. It does not need to be accurate just repeatable so the same effort can be applied at various stages to test both axles.
Changed my idea for the new side repeaters. At an auto jumble I spotted another variety of small amber lamp holders, and bulbs for them arrived in the post today. They are a lot brighter and give a better viewing angle as you can see from this simple 12 volt battery test.
I should have them fitted tomorrow night. These have removable lenses so makes it a lot easier when you need to fit replacement bulbs. Silicone sealant will be used on the inside of the wing and the smaller size will give more clearance from the tyre.
16th November 2009
Completed fitting the lamps over the weekend, once again I bled the brakes to ensure no air came out of the system, there was none but needed to be sure. I managed to book my IVA retest for the 23rd. So now it is just a matter of waiting, and keeping my fingers crossed.
Thought I would post a picture of the lights fitted, would like comments as to suitability if possible.
So here we have the new light fitted, not as sleek granted.
The second view is looking under the wing, you can see one of the clips that holds the plastic tube with the wire s running internally and the end of the lamp holder covered in silicone, plenty of clearance from the tyre.
When I last took the car out on the trailer, the tarp I used caused a lot of scratches on the rear arches and bonnet. So I treated the car to a small car cover, it is not tailor fitted but a standard small car size costing about £19. I will used elasticated straps under the car to pull it tight so should provide better protection?
23rd November 2009
The car has passed retest. All the time now seems to be worth it and I can look forward to getting the registration number, taxing the car to finally drive it on the road. Bit out of season, but hope to get some good days.
Just a couple of pictures to close the pages off, two of the car at the centre, wet!
Next the main one, a copy of a copy of the IVA test certificate with a few bits blanked out. The main one is now with DVLA.