V2Rocket

Would it even be possible to install such a system on a car that didn't come with ABS at all, nor has any provision for it from factory? Swapping the suspension stuff shouldn't be too bad, but what about wiring/hydraulics?

TonyG

Yes.

You'd need late offset rear trailing arms with the ABS holes and the ABS stub axles in the rear.

And in the front you'd need the late offset spindles with the ABS holes in them, and the late offset ABS hubs with the ABS rings.

You'd have to make a wiring harness and use the correct pump. I can give you the guy's email that has the pumps and makes the harnesses if you don't want to do it yourself.

And them you'd have to plumb it up which is not difficult. Out from your master cylinders to the ABS pump. From the ABS pump to your wheels . Basically you intercept the lines coming out of your master cylinders and insert the ABS pump.

TonyG

333pg333

Wonder how much more difficult this would be with Tilton pedal (no stock mc, slave or booster) setup? Guess pressure is pressure, plumbing is plumbing.

car_slave

FYI - at the bottom of this post there is nice wiring diagram for the updated ABS 5.3 unit.

http://www.renntech.org/forums/topic...t-wheel-speed/

Here are a few items I learned from doing this:
You need to connect the the brake light switch wire to get it the function properly. This is signal which is sent to the unit when you press the brake pedal. Also, you'll need to run the engine to get a signal so you can locate the brake light wire with a volt meter.
Another thing I found is that it might not be a good idea on a 968 because the speedometer signal comes off the original ABS computer via the wheel speed sensors.
Hope this helps.
If you are looking for 5.3 pump with wiring connector shoot me a PM. I have one ready to go with a modded mounting bracket.

TonyG

No different.

The stock master cylinder is a dual master. The Tilton is the same thing just with the master cylinders separated.

You would still plumb the same way... both master cylinders into the ABS.

Honestly, the Tilton thing really isn't worth the money, especially if you have a good ABS.

I did it because I wanted all of the braking components out of the engine bay. The fact that it has a balance bar is somewhat trivial with the ABS unit.

TonyG

Eric_k

I have a 996 ABS working in my 968. I was intending to add a post once I took out to the track for a real test. I've only done a few street tests so far. I plumbed and wired it so it would be reversible - in case it ends up sucking. But, so far so good.

The speedo signal is not an issue. Pin 23 on the ABS units outputs a speedometer signal. That should go to pin 17 of the 968 ABS connector. The brake light signal is pin 25 on the 968 ABS connector and should go to pin 14 of the ABS. I used a gutted 968 ABS computer to make a jumper from the 968 ABS connector to the 996 ABS plug.

car_slave

Thanks for the info Eric. I might try it again later this year or next. I ended up putting my original unit back in because I was running out of time. I Need to get a tech inspection done next week. Let me know how it works for you. What wheel/tire size are running? I'm working with stock size stuff, which also makes me wonder if that will be compatible with a 996 unit.
Looking around the web I've seen that a lot of people have switched over to Bosch 5.3 units.

333pg333

^^^SPAM ALERT^^^

333pg333

I did it to remove the stock booster (avoid lockups) and the rest of the hardware. Can still run as it is and for the brief time I used it, it felt great but that was with smaller brakes and less power. Cars I will be up against will have all the mod cons inc Sequential gearboxes. ABS would help me close the gap a little.

Definitely keep us in the loop Eric. You should do a thread on this. How much 4 do you have into this conversion so far if you don't mind me asking?

Eric_k

Less than $300. The pump with connector was found cheap on ebay plus some brake line and fittings.

Eric_k

I'm currently running 275/40-17 on all 4.

Eric_k

I finally had a chance to use the ABS in anger this weekend. I changed a few things on the car over the winter so it is hard to quantitatively say how much improvement is the ABS itself but the lap times definitely went down. I improved my personal best by 1.7 seconds on a relatively short Portland track. I got down to a 1:14.4 without the chicane. I can say the ABS felt much improved. My sense was that I could use more brake before ABS engaged and when it was engaged it was less intrusive and not as "chunky". It's certainly not the ultimate in ABS but a nice bang for the buck improvement. Here is video of my best qualifying lap:

I used an ABS unit from a earlier 996 (996.355.755.03). It is just ABS, no traction control, PSM or anything else on the unit. In order not to cut into the car's wiring harness, I used a spare 968 ABS brain and gutted it. I then mapped the pins from the 968 connector to the 996 connector. Everything you need is already going to the 968 connector or the connector at the stock pump. My car is a 968 so there are likely some subtle wiring differences but it should be similar to the 951 wiring. Now the zombie 968 brain is the jumper between the stock wiring and the 996 pump. I also made jumpers in the brake lines to go from stock line to the relocated ports on the 996 unit. I also wired up a ODBII connector but I haven't tested it yet. For reference, the car has big reds on the front and the stock rears with a tilton adjustable bias valve.


Thanks to Tony for blazing the path.

333pg333

Great work Eric and you look like you've stepped up a gear on the track. Fast and controlled. Looks awesome!

btw, what axles and CVs are you using? Have you had any issues with them?

Eric_k

Stock axles. I haven't had any issues with them - yet.

Peedster

Q about the ABS cables running from fender to the ABS pump.

My car is an 87 without ABS. I looked today and what is needed from the ABS sensor to the ABS pump?
My brake pad warning cables look exactly the same as the ABS cables? Do i need something more here?

Also, is it possible and fairly easy to drill and tap the spindles and rear traling arm for the sensors?
This way i only need new hubs front and rear.

What about upgrading to the boxster sensors? Are these supposed to be any better than the 20 year old 944/968?

/P