2016 -2019 tidy up

The J15 build must have been good as I have done very little since 2016. The one event of note was the concentric clutch slave cylinder. That was an engine out job and I have just stopped swearing at the untimely 2018 task  now I am safely into 2019.

I need to prepare for the 2019  hill climbs season so I decided a few tidy up jobs should be done to keep the car looking good. Perhaps I may take it to Stoneleigh this year or next.

1) Re-seal the aero screen with a black border at the bottom. The clear silicone is no longer clear so it looks very untidy. Masked off the bottom inch of the screen and had is sand blasted and painted black also used black silicone sealant this time.

2) More leg room needed around the steering column LHS, that was a flaw from the original build. Time to get the air saw out and lots of rubber edging and Silcoflex polyurethane glue.

3) New mats, the ones carved up from an Aldi door step mat does not look good, never did but they are cheap. Found some nice ribbed rubber matting on ebay. The drivers side has a metal plate glued on to reduce wear and tear on mats.

4) Replace various black domed cap head machine screws  that are rusty now rather than black. The latest ss jobs look much better.

5) Blackened the windscreen support/rear view mirror support, looks much nicer now.

Blackened mirror support metalwork 

Black border for Areoscreen

More leg room, Needs temp duct tape removed?

New floor matting

More oil cooling

I am still having some issues with the oil cooling and subsequent loss of oil pressure at tickover. The addition of the oil cooler + 6W fan has had an effect but not good enough. I have now uprated the fan to that of a 1300 GSR motorbike fan with ~2.5 x the power 15W. It gives a fair old draft so hopefully this will result in an improvement. I want to be able to stay out for more laps at Knockhill.

Uprated upper front wishbones

Over this summer I decided to try out a set of Toyo 195/55/15 888 SG (softs), they were quite difficult to get hold of as they are no longer listed under MSA 1b for 2016 as they are not E marked and the soft version of 888R's are not available yet.

I immediately noticed more grip on hill climbs but unfortunately my offside upper wishbone broke at Kames (in two places). I discussed this with Jeremy but we decided it could be a welding failure so I repaired the faulty bone. Unfortunately, the near side bone failed a few weeks later at Kames. Kames is a fairly primitive track with cobbled areas at the corners, great for sprints but hard on the car with it's tight turns.

Jeremy understands the demands of motorsport so he made me up a set of upper front sprint competition bones.

I have had these out at the 2015 XBC October sprint at Kames and got a time of 99.64s beating two Westfield's in the process with not a hint of cracking. If you are running medium compound tyre then you have nothing to worry about as that is what I ran last year with no problems. The problems uprating the bones is the next weak point may show it's self. I hope no time soon.

The two on the carpet have been uprated

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Oil cooler

Ever since I started tracking the J15 the Ford Sigma oil pressure would get very low after about 5 laps of Knockhill. This is caused mainly by the rear engine location and the lack of ventilation in the J15. The water temperature has never been a problem from day one. This issue was critical to such an extent that I had virtually no oil pressure ticking over at the pits after the 5 laps.  I started to use racing oil which is 10W-60, that has improved the situation somewhat in that the minimum oil pressure is now about 5psi now not zero.  The minimum oil pressure should be 14.5psi (ref John Baxter).

I decided to try an oil cooler. Rally Design have a 16 row with 125mm wide matrix. This makes the unit about 210mm overall wide and 124mm high. This oil cooler fits nicely just in front of the oil filter and in the air flow from the tunnel. This should be an adequate size for a 155bhp engine. The cooler has 2 x 1/2" BSP male threads. RD also sell a sandwich plate for the oil filter take off. RD don't supply DIY Mocal oil pipes, I had to get them from Ebay (Matt Lewis Racing). Mocal do a self assembly pipe and ends. I used 4 rt angle 1/2" BSP fittings (someone should tell RD). I backed up the self assembly fittings with crimp on 'O' Clips.

When the parts arrived The sandwich plate had no adapters to 1/2" BSP male, I ordered what I thought was the correct adapters from RD on line but then discovered the sandwich adapter is 3/4" UNF (female). Now as luck has it 1/2" BSP and 3/4" UNF are very close. The BSP thread is the same pitch but larger diameter. I have a 1/2" BSP tap bought for another project. Cooking with Gas now I think!

Here are  the installation pictures:

After a road test (a real test would be Knockhill) I added an air scoop in 0.8mm alloy sheet and Anti-kitty litter filter just in case of stone ingress.

After a track day at Knockhill (reverse) I saw no appreciable difference in oil pressure. I have now added a 120mm 12V fan to the equation. It appears to be an improvement but I will have to invest in another track day to find out. What an imposition.

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0-60 Time

In the absence of a rolling road it is nice to see if the performance of the car is dwindling in horses in any way.

There is an excellent on line 0-60 mph calculator http://www.060calculator.com/

For the J15 this gave 4.31s for 627kg and 155bhp. The weight was taken from the recent corner weight measurement and the bhp was taken at Sitech racing last year http://sylvabuild.blogspot.co.uk/2013/08/ecu-re-mapping.html

I set up a track on Race Chrono, using a safe bit of road where the terminal speed was less important and 60mph was obtainable in relative safety. You can see that the example gave a result of 4.8s which is about 0.5s pesimistic. However if you take into account that the test track was up a gradient then an error of 0.5s is not bad correlation. Also 0.3s is being lost in gear change time, something I may or may not be able to do something about, it is always going to be slower than a paddle shift in the Megabusa.

I have measured my wife's Mondaeo, Westfield Megabusa and a Westfield Zetec (*) and all gave results that were within 0.5s of prediction (* butterfly fault).


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Corner weights

 I have been concerned about the corner weights since a) running into the Kombi and b) Breaking a NS upper wishbone (on a speed bump I suspect). I have just done the Westfield Megabusa track car so it is now time for the J15.  There is a very good on line spread sheet and explanation of how to set up your car at: https://robrobinette.com/corner_weight_calc.htm

There is also a very good Excel spread sheet by Nick Warinner of ntw@360racing.com that I copied and modified to add the cross weight calculation information recommended in the above advisory site.

Cross weight = (Right Front + Left Rear)/Total weight.

I also purchased a set of Proform Bluetooth corner weight measuring pads from ebay tegiwaimports these are a budget product but works well and is easy to use.

Here are the results, you will have to open the image by double clicking it.
In summary I did the following.
1) Ensure the tyres are all the same pressure
2) The suspension height front and back are correct. In my case the lower front wishbones are horizontal and the front to back was 20mm
3) Adjust all the spring lengths FL = FR and RL = RR as a good starting point.

Before adjustment

After adjustment no driver

With driver

In summary I can see no issues with the suspension, the initial setup was done with a ruler and gives acceptable results only 1% out. The key issue is confidence the car is right.

Like the Busa I cannot see the advantage in my car of biasing it to handle with the driver only as it only makes a 0.3% difference. It means the handling is optimal with a passenger also depending on weight.

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Damaged rear tub

Bad day yesterday (16th April 2015), should have stayed in bed, the handbrake failed to grip on the hill and the J15 ploughed into my (new to me) VW Kombi. The damage to both vehicles was fairly extensive. The tailgate (large rear single door) on the Kombi needs the expertise of a body shop work. The damage to the bumper fixings and steps I managed to sort out myself. The J15 had at least 4 holes in the rear tub, bent  the hinge assembly and the fog light was ripped off. I have shown the GRP layer after removing the worst of the damage with a grinder so you can see the real extent of it.

GRP layers delaminated



More delamination near Fog light



damage extended from large hole



GRP repaired fairly quickly and the Gel coat applied by brush

First  gel  coat sanded down, GRP showing thru in a couple of places Not bad so far!



GRP showing thru on curved edge

Wax additive

I went to get some more gel coat from my friendly supplier in Rutherglen, he tells me there is a wax that you can add to the gel coat during the mixing process. I found this article on the matter: http://www.easycomposites.co.uk/products/polyester-resin/solution-mw-wax-gelcoat-additive.aspx

And it works......

 

The wax allows far better setting times without the use of packing tape or cling film to exclude the air.


Contents
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