The Ultimate 1983 Rabbit GTI - part 136 (Brake mods, Fuel Sender, Performance Testing)

Описание

The new 8168 Powermaster XsVolt alternator is working perfectly - my LiFePO4 battery appreciates it.

I ordered a VW mk3 non-ABS brake servo/booster because I had been using a leaky mk1 servo unit. I experimented with some shims between it and the master cylinder (which is a 22.2mm unit, also a mk3) and initially took up too much of the slack and had the car self braking! But with a single 12mm stainless washer as a shim it reduced pedal travel and now the brakes are feeling pretty good. I have the ability to electronically set the amount of vacuum assist so I have been trying out various settings.

One problem I still have with these much improved brakes (using Wilwood 4 piston calipers and 10.1" disks up front and mk3 disks on the back with a Wilwood proportioning valve) is that even with the valve on full minimum I still get rear lockup first. I am ordering fixed in-line pressure reduction valves to try out (I will leave the adjustable valve in the circuit) plus I am going to order a 25.4mm master cylinder which will reduce pedal travel another 30% (but also increase effort by the same ratio) - ideally I would like to heal and toe with minimal pedal travel and I can simply crank up the vacuum assist if I want a softer effort ....

My old fuel tank level sender unit was crapping out so I ordered a new VDO plastic replacement unit which worked out well but I had to modify the connector to create a right-angle version and now all is well.

It is full-on winter here now with snow and ice on the roads (and salt!) but I managed to get a full sunny dry afternoon this last weekend to do some performance testing. I had acquired a Gtech RR performance analyzer to measure 0-60, 60-0, power, cornering, etc. so I was excited to see what this GTI could do. Well, the Gtech unit had limited measurement accuracy as it seems to have a broken GPS antenna and couldn't get a fix on more than 6 satellites but it did give me basic 0-60mph info: with no off-the-line traction and short shifting into 2nd gear I saw repeated 6.0s times - this is with street tires, dirty conditions and almost freezing temperatures. With good conditions (the track!) I should be able to launch at a high enough RPM to get on the cams (I need 4,000rpm min) to get a high 4s time. The engine is pulling like crazy, putting out 0.6gs of acceleration at 60mph in 2nd gear (my old mustang with its 300hp engine only managed 0.42gs in 2nd gear at 45mph).

I also swapped out my Spal radiator fans for new units as I think I damaged them by running them at a 30% PWM duty cycle which seemed to have fried the brushes - current pulse arcing) - the fans were rattling and sounding horrible. I have now set the minimum duty cycle to 50% which is what Spal's own controller starts at.


You might want to check out the VW Vortex Thread on this project at:

http://forums.vwvortex.com/showthread...


You can also check out my web site on this project at:

http://derekspratt.com/HTML/Automotiv...