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11-11-2016, 12:15 PM #1
- Join Date
- Jun 2013
- England, UK
ABS/Antilock brakes - possible to retrofit?
I had two alarming close calls with Dragon today. The first, on my drive to work, was the most serious. As I went to pull around a parked car on a blind bend, I realised the car was in the road, and of course a car came the other way at the same time, leaving me absolutely nowhere to go. Hitting the brakes, Dragon's front wheels locked - the road was wet, and must've been greasy, the front tyres are newer than the rears and have very good tread. I must've slid 10-15 feet going 'ohshitohshitohshitohshitohshitohshitohshitohshito hshitohshit'. How I didn't hit the oncoming car, I have no idea!!
I've long admitted that ABS is the only modern safety system I would like to have standard on every car. With Dragon's front wheels locked, I had no steering, and that was terrifying. Given the ability to retrofit just about every modern convenience can be retrofitted, is it at all possible to do so with ABS?
A while back someone linked to a company that made custom wheel sensors. I've searched, but I can't find that link. I know there's a lot of other parts necessary, but realistically, since an ABS system can be mostly self-contained, does anyone know if it can be done to the mk2? Has anyone done it?
If it's possible but we need the sensors custom-fabricated, would anyone else be interested in a group buy kit?
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11-11-2016, 01:33 PM #2
- Join Date
- Aug 2008
- St Louis MO
not a bad idea - i wonder if we could borrow all the parts from a FRS - its RWD and weighs about the same.
im guessing we would need sensor mounts and the computer - would you want it to link into the ECU as well ?
interesting tidbit i read - "If tire diameter varies more than 5 percent from that of the donor car, the traction control may get confused and engage at high speed"
that sounds fun!!--
11-11-2016, 02:32 PM #3
- Join Date
- Jun 2013
- England, UK
You're right about wanting a donor car of similar weight and RWD so the biases are set up correctly. Perhaps the mk3 would be a good place to start? Although we might need to account for the mk3 being a lot fatter!
There would also be a need to re-run all the brake lines, since the rear brakes are fed from a single line that's split at the rear axle. It's a lot of work, but for the better brake performance, I think it might be worth it.
11-11-2016, 07:34 PM #4
Did you flat spot the front tires,Rob?
Maybe not 'cause the road was wet.
I cheaper method of NOT allowing the front brake to lock up and lose your steering is an adjustable
Pressure device to limit front braking force.
For the stagger most of use,it's a good idea.
This is NOT for a Supra:
On a hard brake situation,the bias should be set to allow the REAR brakes to lock up B-4 the front.
On harder brake pedal application,all 4 brakes will lock up.
Better to test this on a wet road surface,by far.
Yes,my front brakes lock up B-4 the rears do,Rob.
I found out when driving in snow.I had to back off of the brake pedal to turn the car.
BTW: NICE DRIVING!
Accident avoidance technique: excellent!
Early VW's (Rabbits,Golfs)had a pressure regulator built into the rear brake lines that adjusted the pressure available to the rear brakes, based on ride height. It was a mechanical (that a )lever/arm was attached to the rear axel, controlling the amount of pressure to be applied.
IF the lever/arm was moved to the full UP(Trunk full of stuff) position,the rear brake pressure was increased,based on ride height.
When the car nose-dived,the pressure to the rear brakes was reduced,decreasing the rear lock up
The lever arm is adjustable and I'll bet that it would be a bolt on mod.
The road race guys already have figured this out.Right?Dave in Seattle. I keep LATE hours.Hidden Content
'84 type "L" ,Auto ,daily driver. Dk blue.
11-11-2016, 08:02 PM #5
Hardest part would be integrated 4 wheel speed sensors. The Mk3 system is really simplistic with only a single speed sensor in the transmission for the rear wheels. You can buy motorsports system so it can be tailored.
11-12-2016, 12:52 AM #6
I actually like not having ABS plus if all your suspension is working perfect and having new tires or good tires that stick to the ground most important than you should be in control even if they lock up let the pedal go some and you should be ok
New tires don't equal good grip so make sure the tires your using having great grip that's my biggest concern when buying tires
11-12-2016, 07:01 AM #7
following with interest, ive looked at the Bosch ABS setup, very nice, but the price.. finding a solution from another vehicle would be much cheaperIf in doubt, drift her out! Steer from the rear! less traction,more action! simple!
JZA61: 1JZ, GT35....That is all
11-12-2016, 08:00 AM #8
- Join Date
- Jun 2013
- England, UK
ABS is a polarising technology - I know others who'd rather rely on their own driving skills and not have a computer intervene. I've driven a car with abysmal ABS - the Rover 45 has ABS so sensitive that just pulling up to a junction can be enough to set it off.
What I think will show why I want to use it is this video - I pulled the footage off my dashcam. Try to remember when watching the video that I had no idea the Land Rover was there, and it's essentially a blind bend. When I saw its roof, as I was coming downhill, I assumed it was parked on the pavement (I drive this road every morning and though there are often cars parked on the pavement, I've not seen this before, so I wasn't expecting it) and was already preparing to swing around it when I realised it was parked in the road itself. That's when I saw the oncoming car. I hit the brakes at about 0:09. The wheels can be heard locking almost immediately, quickly followed by a very loud curse as I turned the wheel back trying to stay close to the Land Rover, and that's when I realised I had no steering. You can see from the GPS data burned into the video that I wasn't going very fast - this road has a limit of 30MPH or 50km/h, and I was doing 38km/h when I braked (annoyingly the dashcam is metric-only).
You can see how close this was. I didn't have time to apply threshold braking, I just had to hold the controls and trust that the wheels would find some purchase. As I noted to my colleague at work, it was probably pulling out past the truck that saved me, ironically, because if the wheels had locked pulling up behind it, I probably would have carried on into it. Smoke is visible coming from the front tyres when Dragon finally stops, so yes, I burned some rubber, but I don't know if I flat-spotted the wheels. They didn't feel any different when I pulled away, though.
Another colleague thinks the major reason was that the morning was very cold, so the rubber likely hardened overnight, and I hadn't driven far enough to warm the tyres up. And since I don't have the option of starting my mornings in a garage with tyre heaters, I'm turning to ABS. At the very least, it would give me more of a chance of steering out of the way.
11-12-2016, 03:57 PM #9
What tires are you running? Tires with an I by the way, none of the Y stuff :P
ABS would be cool but there is no way for it to be done cheaply. Would have to be an adjustable aftermarket setup to be tuned, and even then would take a ton of work to tweak and get right.
Your best bet honestly is to ditch the 14's and get some modern 16" or taller tires. 14's just don't get any new compounds anymore, while modern sport tires are almost as good as full on race tires were a decade ago. Same thing goes for motorcycle tires. You can get ones that look classic on smaller wheels, but they won't handle or stop as well as modern stuff for sure.
11-12-2016, 04:46 PM #10
Good tires and suspension like the others are saying is all very true.
I have no idea what brake system you're running, but if its stock and any one of the following is wrong: bad wheel bearings, warped rotors, pads that give you poor feel, moisture /air in the lines, or slide pins that even bind a little; your brakes will be sketchy at best.
ABS is possible, but it will be either expensive or it will be a challenging project.
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