Upgraded Engine Mounts

With the Southern Kit Car Club European road trip coming up it was time to give the car a check over and look for anything that might present reliability issues during the 1300+ miles.

One thing I've been keeping an eye on recently is the original Tiger engine mounts.  Other Avon owners have had issues with these failing and I suspected it was only a matter of time before mine gave me issues.  Upon closer inspection there did seem to be some metal fatigue setting in where the diagonal tubes meet horizontal plates.  I was not happy with this so decided now was the time to get on with fabricating a more robust replacement.

After jacking up the engine and resting it on some wooden joists I was able to remove the old engine mounts.  Straight away it was easy to see that in their natural rest position these had not been level with the top of the engine rubbers.  Instead they had been inclined and the tightening of the bolts had clamped them down onto the rubbers and had deformed the top of the rubbers over time.  This obviously meant that there was a constant force applied trying to tear the diagonal tubes from the horizontal plates, even before any twisting force is applied by an accelerating or decelerating engine.

With the original engine mounts fitted, the engine was not level.  So using the wood under the sump I raised the inlet side around 15mm to bring the bottom of the engine (sump) horizontal with the ground, when viewed from the front of the car.

Next I replicated the four flat plates.  This time out of 6mm steel instead of the previous 5mm.  For the diagonals I used 5mm thick 45mm box section.  This compares with the 1.5mm tube used previously.

Cutting these box sections to fit was a very difficult task.  Multiple compound angles and all work being undertaken with the engine in situ.  On the exhaust side I was having to work in between the small gaps between the exhaust headers - very difficult indeed.

In the end I got there.  Had them tack welded by Ashby Welding ready for a trial fit.  They fitted perfectly, with the horizontal plates resting on new rubbers, without any clamping and with absolutely no stress applied to the mounts or rubbers.  Back to the welders to have them fully welded up and here is the end result.  A very nice job done by the welder.

These have been painted up, fitted to the car and bungs inserted into the bolt holes to protect from water ingress.

Another long term to-do list job completed and hopefully another piece of reliability added to the car.

Engine Mount Strengthening

The offside engine mounting plate is fixed to the chassis spanning two chassis rails, where they come together in a vee shape.  This is strong enough to take the loads transmitted from the engine.  On the nearside however, it is a very different story.  The flat plate is welded on top of just one chassis rail.  Over time the loads from the engine cause this to droop and eventually this puts an abnormal loading on the engine mount itself, which then fails.

I'd kept an eye on my nearside mounting plate over the months and it had always been fine.  Recently though, I noticed that the non-welded side had drooped around 10mm.  It was on its way to causing the engine mount to fail.

So, I fabricated two triangular fillets from 6mm mild steel and got a local garage to weld these in place, after 'jacking' the plate back into its original horizontal position.  The welds are not the neatest in the world, but they seem to be good enough to be strong.

Raceline Wet Sump

I have never been entirely happy with my sump installation.  In particular, the fact that there is no baffling, with the consequent risk of oil surge when driving hard.  When building the car I had changed the standard Zetec oil pressure switch for a lower (15psi) version.  This at least should give some advance warning of oil pressure problems, but by the time it illuminates permanent damage to the engine may already have occurred.

In 2012 I did have one trip to Brands Hatch and one to Curborough Sprint Circuit.  While I had no oil pressure issues on these two occasions I started to think that I'd be pushing my luck with the three track sessions that I have booked this Spring.

So I decided to bite the bullet and upgrade to the Raceline wet sump.  This is very highly rated by those that use it.  It is even used on many race cars.  Most racers considering it to be good enough that at upgrade to a full dry sump installation is not even necessary.

The old sump was removed without any major problems.  Then it was time to start preparing the Raceline sump ready for installation.

Here is the main pan.  It is a very nice piece of engineering and you can see where the effort has been spent on the design, the casting and the machining.

Here is the Ford windage tray, Raceline windage tray and oil pick up pipe, etc.

First the oil pick up pipe is installed, with two rubber o-rings to make a seal into the main pan.  A metal filter gauze is inserted into this pipe from the outside of the sump.  This can be removed and cleaned at oil changes, if required.

Next the Raceline windage tray is bolted into place.  This windage tray is one of the methods used to control oil surge.

After that the Ford windage tray is bolted to the Raceline windage tray.  The Ford windage tray is designed to 'scrape' oil of the crank and con-rods.  Helping the oil to fall to the bottom of the sump and not be whipped up into the main engine block.

Standard Zetec Silvertop sump gasket fitted along with oil drain plug and gauze filter plug.  There is a double top hat spacer with rubber o-rings fitted that makes the oil seal between the sump pan and the engine oil pump.

The sump itself fits very well.  The main issue, and one which consumed a lot of time, was getting access to all the sump bolts.  Many are hidden by things like the starter motor, engine mounts, etc.

The old Tiger ERA sump was higher than the gearbox bellhousing.  The Raceline sump is level with the bellhousing.  The previous sump had around 100mm of ground clearance, but unfortutately the Raceline sump only has about 65mm.  This is too little, especially as the car is used a lot on country lanes, where there is often a raised centre to the road.  So the springs on the front dampers were wound up by 20mm.  Due to the geometry of the wishbones this translates to an increase in ride height of about 35mm, i.e. back to around  100mm under the sump.  Result.  I will take a look at the rear ride height as soon as I can and get the car leveled again.

Before running the engine for the first time I removed the plugs and rotated the engine by hand (socket set on crankshaft pulley).  I wanted to make sure that the Ford windage tray was not fouling the crankshaft or con-rods.  Next, I took the spark plugs out and cranked over the engine until the oil pressure light went out.  Once this was done it was time to fire up the engine and go for a test drive.  I'm happy to report that so far all appears to be working fine and there are no leaks.  Roll on the good weather and some track time!

Raising the Height of the Engine

Tried to fit the air filters on to the throttle bodies.  The rear filter fits, but the front filter fouls on the upper chassis rail.

A 5mm space plate was inserted between the engine mount rubber and the chassis.  There is now 2 or 3mm clearance.  Should be enough as the engine shouldn't rock much with the firmer rubbers.

Engine and Gearbox Fitted

Engine and gearbox being fitted.  Wooden blocks used in place of the engine rubbers to find the right position for drilling the holes.  Despite checking and re-checking the engine and gearbox did end up a little further back than planned.  Possibly due to the fact that one of the Tiger engine mounts does not sit flat with the plate on the chassis.  When the engine rubber is in place this is squashed on one side to take up the difference.

Final result seems okay, there is some small amount of the propshaft splined tube showing outside of the rear of the gearbox, just not as much as expected.  In a way this might be helpful.  It will mean that the Rally Design gear lever remote ends up just that little bit futher towards the rear of the car - every bit counts here as the gear lever gets very close to the dashboard when this particular remote is used in the Avon.

Drilling the bolt holes for the gearbox mount was a bit of a challenge - getting the drill down inside the transmission tunnel, especially as I had already fixed one side to the chassis.  The solution was to use an oversize hole at the top and then drill a correct size hole at the bottom, by drilling down at an angle.

 Thanks to Pete for loan of the engine crane and Gary for help with the fitting, including use of his Avon as a reference for measurements.

Tiger ERA Sump

Time to replace the tall original Focus sump with the shorter ERA sump from Tiger.  On the later Black Top Zetec engine both the steel sump pan and the alloy lower crank case need to be removed.  Here is the engine with just the sump pan removed.  Visible is the plastic oil pick-up pipe.  This cannot be shortened so will be replaced by a earlier steel pick-up pipe that has been modified by Tiger (chopped, shortened and welded).

 The lower crank case removed.

Four bolts in two of the main bearing end caps are replaced with Silver Top Zetec bolts that have a threaded stud on the top.  Tubular steel spacers are added to allow the windage tray to be at the right height.

The windage tray, again from an earlier Silver Top Zetec, is bolted on to the four studs using thread-locked M8 nuts.  The modified pick-up pipe is bolted on using a new gasket.  This pipe is attached to one of the studs via a mounting bracket.  Washers were used as spacers to get the right height (8-10mm from bottom of new sump).  This was checked using a ball of Plasticine.

 

On trial fitting the ERA sump fouls with the oil pump housing.  This means the sump bolt holes do not line up.  A curved recess is present on the original lower crank case (seen lower left).

A similar recess was made on the ERA sump using a round file.

Sump mounted using a new gasket and the original bolts tightened to the specified torque.

Once the car is on the road I'll think about adding some baffles to the sump to prevent oil starvation when driven hard, e.g. on the track.

The next problem is one of the engine mountings.  I had previously trimmed this to make if fit around the water pump housing.  Now with the new sump on the engine mount hits the sump edge before being flush with the mounting holes cast in the engine block.  If tightened in this state the engine mounts will 'push' the sump sideways and the large engine loads will be transmitted through the sump - not good.  Next job then is to trim a little of the lower edge of the engine mount.