DAX40 Return to the Road

Dave Bilyk · 04-13-08, 02:35 PM

Last week saw my DAX through MOT and back on the road after a 3 year absence. Now I did not build the car, I bought the finished car on the road in 2002. Since I have now spent many hours and done plenty of hard work improving the car, I feel that I should make a continuous thread instead of just posting in seperate technical threads. Not really a build thread, but a development thread.
Today I went for my first real drive since it was a really nice sunny day, I got a call from a friend who was at Knockhill circuit, he said 'listen to this', and said that what I had heard on the phone was an original. So the wife and I got in the 40 and away to knockhill, unfortunately he did a demonstration run and then left, so I didn't get the pleasure, the GT race was interesting though.
Anyway, I had a good drive, and apart from the fast idle not wanting to release, it was a perfect run, amazing how a run in one of these cars is an adrenaline soaked wet dream.
So on to the thread and what changes I have made so far.

Dave Bilyk · 04-13-08, 02:56 PM

The first change I made to the car was promoted by the soggy suspension and tendency to scrape the nose at any opportunity.
The springs turned out to be 200lb/in front 250 lb/in rear, so I replaced them with 300 front and 350 rear which seem much better, but I think I could easily go stiffer than these and I know that some of you are using considerably stiffer. I am open to suggestions as to what rates to use, which I will do when I install anti roll bars, as I am sure that they would be of great benefit, nay essential, to adjustment of handling.

Dave Bilyk · 04-13-08, 03:29 PM

On to the brakes, the Granada front brakes were ok, but forget trying to get any decent balance from the rear Scorpio brakes, as the pads just tended to craze and crack with heat. Checking the piston and pad sizes gave me the impression that they are not capable of providing decent front/rear balance.
The other issue was the servos, which tended to stick on, although I checked and cleaned / polished the air valve, and bought refurbish kits for them, they still seemed to do it. After a spin at Knockhill where the back brakes stuck, and a stop on the motorway on the way to Goodwood when the fronts stuck on big time, enough was enough, and the servos came out.
After balance calculations, and checks on what would fit inside the 15" rims, I decided on Wiwood Narrow Superlite fronts, and Hispec Billet handbrake calipers rear, both with 310mm Wilwood discs, a package which seemed to give a good theoretical balance and leverage.
The rears were the most difficult to fit in since the hubs are designed for sliding calipers and so there is very little space available. but the combination of Wilwood discs and Hispec Billet calipers did the trick. Caliper brackets for the rear were Hispec with my requested offset, and my own design for the fronts. See threads
Wilwood Front Brakes
and
Rear brake upgrade for DAX40

Thanks to all you guys for your help in this.

Dave Bilyk · 04-13-08, 03:56 PM

Other fixes, the clutch was so heavy I could not hold it for more than a few seconds, to the rescue came Bernard who sent me a 7/8" master to replace my 1". Now I can live with it. Hope to see you at the Le Mans Classic Bernard?

Also now fitted is a Mallory Unilite distributor to replace the Prestolite marine distributor.

Hazard warning Light switch from a VW Camper Van, a monstrosity, but I thought it looked period anyway.

Since the car had no means of locking the doors, I fitted a remote locking system, I have not covered that in a technical thread, but did ask about flexible conduit for the wiring.
Flexible conduit for door lock wiring.

Dave Bilyk · 04-13-08, 04:11 PM

In the last few weeks, while I prepared the car for the road, I fitted traditional style wing mirrors over the wheel arches, and replaced the front body mesh with alloy mesh, the effect of this on cooling is very significant, since the old steel mesh was very tight, and the new alloy mesh is much more open, there is a lot maore airflow through the rad, she now runs at 75degC instead of 90degC and only heats up when stationary.
My 'number plate' was painted on the old grille, but in the interests of moving a little further towards legality, I have put a stick on plate on the top of the nose. While not legal, it is the only real option, and since it has the correct white reflective background and black letter size, and is easily visible I believe it to be legal in the spirit of the law anyway. Any comments?
A dose of Tcut and a good polish, and I am quite pleased with the result of the front end makeover.
p.s should I continue the black stripe down the grille by painting it on ? mmmm

JackW · 04-13-08, 08:46 PM

Nice posts Dave. As a future GT40 owner (this is what I think is commonly referred to as "the power of positive thinking"), I always love reading about the various issues owners have had and also the things they have done to overcome them. Sweet car too.

regards

Jack

Ian Anderson · 04-14-08, 03:12 AM

Dave

From one "DAX" to another

Looking good and glad she's back on the road

Ian

Dave Bilyk · 04-14-08, 01:38 PM

Thanks guys, here is one of my next jobs, already purchased alloy radiator from Dockings, I will fit it in the next few weeks. My current radiator was repaired, but the repairer was concerned about its poor condition. Sure enough it is running on Radweld at the moment, so I had to get a reliable solution for Classic LeMans. Using the advice from this forum I will mount it using rubber mounts to protect it from electrolitic corrosion and mechanical shock.

Dave Bilyk · 05-10-08, 02:42 PM

Today I returned to the track for the first time in 3 years at the Scottish Motorshow at Knockhill.
Now with upgraded brakes that were working well, and new tyres that gripped, the experience was very enjoyable. The only fly in the ointment was a misfire which came in at 4000rpm at full throttle, if I backed off the throttle, it would go to 5500 which is as much as this engine ever wanted to go to before tailing off.
When back on the road, the engine revved freely so I havent figured this out yet. I will check the distributor, the last time this happened it was a broken rotor arm contact, but this is a different distributor.
There was an Ultima there too which was pulling about 50mph more than me with exhaust flames on the overrun, awesome.
Now I have the brakes to stop it I will have a look at the engine soon, booked on a rolling road in two weeks, but my guess is not very many hp. The joy is in improvement though so we will see where we go from here.

regards
Dave

SteveB · 05-10-08, 03:24 PM

That nice new rad should give miles of stress free motoring.

It could be worth checking the fuel system for partial blockage or filters etc. A good blow out may do the job. Simple stuff first.

Regards

Steve

Ian Anderson · 05-10-08, 04:05 PM

Dave

Good to hear our Dax is having it's legs stretched and seeing some fast work - bummer about the mosfire.

Tomorrow I'm working on mine all day just checking things over as I have done over 400 miles in the last 2 weeks - ran really well but got hot in traffic. (Need to restrict flow through my non functional (looped) heater system - people suggest with the loop it means a substantial flow is removed from the radiator circuit.

I'm interested in your comments on the tyres as I'm on the brick hard 18 year old Goodrich ones!

Then it's start of plumbing in some forced cockpoit ventilation - I'm going for duct from the 2 Naca openings into a box on top of the pedal cover - fan into cockpit and air vents -be able to install the drivers window at last.

I'm also going to fit 2 fans - 1 either side inside the front of the rear clip to nove hot air as much as possible when stationary - like waiting for track at Le Mans (2x 120mm computer fans rated a 50cfm should assist)

I look forward to having 2 of the Rarest Gt40's next to eash other for a photoshoot (For those not in the know Dax produced low 30's of this kit and recon that only about half have been completed.)

Ian

Dave Bilyk · 05-10-08, 05:55 PM

Thanks Steve, will do. I have installed a pair of glass tube filters in the suction lines, so I will check those and the carb filter. Your build progress is great to see btw, rear clip is awesome, love it.

Ian, same sort of mileage as mine, hoping to make sure everything is sorted for the big trip.
As well as the water flow, I found the air flow was just as important, having replaced my tight mesh grille with a more open mesh, running temp is down from 85 - 90 to 75, and it only reaches 95 in a jam.

Tyres I am really chuffed with, the set of 4 Kumho for less than the price of an Avon, great value and quality, recommended for less than 250 quid. When I got them, I ran my finger on the tread rubber, by comparison the 17 year old Goodrich felt like fibreboard, well oxidised rubber.

Good idea with the naca ducts, I noticed my ventilation only recycles the internal cockpit air, so only works with the air conditioning system on, which isnt working at the mo.

Likewise with the rear fans, will remove significant heat.

Dave

Dave Bilyk · 05-11-08, 01:50 PM

The misfire occurs only under moderate to wot acceleration so you can only test on the road. If you just rev the engine at a standstill, its fine, (secondaries dont open). Today I have checked the distributor, adjusted timing (2 deg out) and checked cleaned and gapped the plugs. Still does it.
Now, I can take it to 4000 and accel gently through to 6000, but if I give it wot, it bogs down at 4000 and makes that fluffing noise. What I now believe to be the reason is that the vacuum operated secondaries start to open at that point, but arent supplying fuel, so the mixture goes too weak to run.
Under low acceleration, the secondaries dont open until 5500 to 6000 hence it runs normally at low throttle. Next I will have a look at the float level in the secondary chamber and adjust.
Any advice from Holley experts welcome.

Dave

SteveB · 05-11-08, 03:07 PM

Dave

A thorough clean out may help, blow through all the jets and make sure ther is no crap in the needle valves. It may be worth getting a manual for the carb and a set of new gaskets.
I think there are various types of gasket and some can be installed upsidedown affecting the fuel / air flow in the galleries on the carb

Steve

Paul W · 05-11-08, 03:49 PM

I had a similar problem a few years back on an old 4 banger I had - turned out to just be a bad plug lead - swapping out 1 at a time might be worth a try.

SteveB · 05-11-08, 03:54 PM

Hi Dave

There is a rebuild guide for the Holley here

Rebuild a Holley Carburetor

Steve

Dave Bilyk · 05-11-08, 05:52 PM

Thanks guys, I already ordered a gasket set, inc secondary diaphragm so that rebuild guide will be handy.
I checked the float chamber levels today, and found that the secondary adjuster was down so far that it had disengaged from the adjuster nut, so I followed the wet adjustment procedure. I could blip the throttle by opening the secondaries by hand, so there is fuel getting through now, tomorrow, I will take another test run.

Dave

Dave Bilyk · 05-12-08, 04:41 PM

Sorted. It was the float level in the secondary chamber, now she pulls up to 6000rpm, sounds good, not that powerful, but pulls well. I have it booked on the rolling road in a couple of weeks, so we will see. Must admit I am tempted to get a power box, but thought I would go with the rolling road for now.
I received the carb overhaul kit today, so can do that at my leisure now.

Dave