ABS update

[Cobra #3170]

I tried the system yesterday on a sealed asphalt road near my house. I got no error messages or warning lights so the installation passed. Normally I get about .54 G decel on cold tires on this surface because the brakes lock and tires slide. I tried two stops from about 50 mph one pulled .88 G and the other pulled .92 G. So far it looks like it was worth the effort and cost to put it in. The big advantage is that the car stops strait as an arrow. The pure manual set up used to stop with big yaw angles so that the car had to be steered and brakes released to keep it straight during the stop. We are entering the Pleasanton Goodguys event the first week in November. That will be the real test, if that goes well we will take the car to Scottsdale for the "Shoot Out In The Desert". Scott and I are taking it to the test course at Crows Landing tomorrow to do final set up and try different ABS levels using the dash switch.

[my427cobra]

Hi Cobra #3170. Always read your threads with great envy of your engineering skills, build skills and results.

For those wanabees like me, and if it's not too much trouble, could you list the top 5 or 10 steps/parts/$ involved in your ABS conversion.

I know - "Do not attempt this at home!" But I am curious.

Cheers
Greg

[Cobra #3170]

Originally Posted by my427cobra

Hi Cobra #3170. Always read your threads with great envy of your engineering skills, build skills and results.

For those wanabees like me, and if it's not too much trouble, could you list the top 5 or 10 steps/parts/$ involved in your ABS conversion.

I know - "Do not attempt this at home!" But I am curious.

Cheers
Greg

You are going to think I am crazy but if it makes the car faster I want it.

1. New cartridge bearing hub carrier and lower arm to my specs. because
the stock hub carrier would be difficult to incorporate a tone wheel. $12,100
2. Mark V Bosch Club Sport ABS with programming harness $8,000
3. All new brake fittings and tubing and having them formed by somebody
who knows how to bend and install tubing. $1,500
4. New rear tone wheels and sensor mounts (I designed them and had them fabricated by machine shops. $500
5. Adapters to mount Toyota Corolla tone rings to new front uprights $300
6. Mount for ABS pump and computer module $500
7. Misc. Hardware, straps and clips plus electrical fuses and wiring $100
8. About 80 hours of my time designing parts and installing wiring and
sensors Free

Could I do it cheaper now that I have done one? Yes, one could be done for about $10,000 plus install time now that I know how. You could probably use a BMW ABS and make your own wiring harness and save more but still not cheap.

[twobjshelbys]

Wow, that's a lot of work! The results are impressive and well worth it. This should remove the differences between the Cobra and the Corvettes. Eagerly await the results!

[my427cobra]

Thanks for the great detail Cobra#3170.

Always curious and love to learn these details. I often re-search this kind of stuff just to learn about it even if I never implement it myself.

So you hinted at a BMW ABS system. What year and model were you thinking?

A kind of donor car application?

Would that BMW donor ABS system provide all the other parts you detailed? the sensors, the speed tone rings, the pump solenoid, the pressure sensors and the yaw sensor?

Cheers
Greg

[olddog]

I would assume that increasing the G force in braking is putting all that force into suspension joints. Although it is likely not going to exceed what that monster FE is putting into the rear suspension, it is going to be new to the front suspension. Am I to assume that is why you changed out a lot of the parts?

[Cobra #3170]

Originally Posted by olddog

I would assume that increasing the G force in braking is putting all that force into suspension joints. Although it is likely not going to exceed what that monster FE is putting into the rear suspension, it is going to be new to the front suspension. Am I to assume that is why you changed out a lot of the parts?

No, the front upright change was for two reasons, number 1 was caliper knock back due to spindle flex. The bearings in an original Cobra were tiny to package inside the threaded hub. I went to a Kirkham style cartridge bearing like newer Corvettes use. This eliminates any flex in the system and resultant piston knockback. The new lower arm was required because the hub carrier would not package with my steel fabricated arm. The mounts are common to what I had before so load capability is the same. The second reason is that the cartridge bearing has a through bolt that is perfect for mounting a 48 tooth tone wheel on and it rotates with the hub. The original spindle would be a bear to mount a tone wheel and sensor, this was easy.
When I first saw the new hub carriers I thought ABS because they are perfect for it. At the rear I sandwiched the tone wheel between the drive shaft and drive hub and used the unused caliper mounts (hubs are common LH and RH and have ears on both front and rear) to hold my sensor bracket. Had to buy Witworth allen head bolts but it worked. These sensors have to be very solidly mounted because any vibration could send false signals to the ABS computer.

[Cobra #3170]

Originally Posted by my427cobra

Thanks for the great detail Cobra#3170.

Always curious and love to learn these details. I often re-search this kind of stuff just to learn about it even if I never implement it myself.

So you hinted at a BMW ABS system. What year and model were you thinking?

A kind of donor car application?

Would that BMW donor ABS system provide all the other parts you detailed? the sensors, the speed tone rings, the pump solenoid, the pressure sensors and the yaw sensor?

Cheers
Greg

This is a subject I know very little about, this is all I know. BMW has a model 3 series I think that has a stand alone Bosch ABS computer. There is a company that I am told has figured out how to hack the software in that computer to make it work in other cars. You would still need two pressure sensors, 4 tone wheels, a yaw sensor, 4 speed sensors and a wiring harness. I think they supply all that and the price is in the $3000 range. You should Google it and see what you can find. I understand some Corvette people use it to avoid the dreaded "ice mode".
The Bosch racing system is track only, has 11 settings for different conditions
and has better yaw control software so that is the direction I went. They use it on Porsche Cup cars so it has to be good or Porsche would not use it. There is an older Bosch system called the Mark 4 that is $1000 cheaper if you can find one but is not as good as the Mk5. This was so difficult to do I did not want to compromise anything.

[my427cobra]

Thanks Cobra#3170. Great info.

Will watch you progress with great interest.

Cheers
Greg

[Cobra #3170]

We ran at Crows landing today, first off we did a manual brake bleed then a system power brake bleed with my laptop connected to the Bosch unit. After doing that we turned the ABS off and adjusted the brake bias to get a simultaneous lock up. I had Scott turn on the ABS and try some stops in the 60 mph range. The car pulled 1.2 G which is better than we have ever gotten prior to ABS on 200 TW tires. We ran the test course to break in a new set of Bridgestone RE71's and the brakes worked flawlessly. Scott says it feels better and more controllable than the GT3! The unit has 11 settings from 1 to 11 with 11 being the most aggressive we had it set on 2. It will be fun to try the other settings as we learn the system. I think this takes the car to the next level but won't know till we run it in competition in November.

[Jdata]

That's awesome evolution!

[olddog]

If Carol Shelby was alive, I believe he would be reading this thread with great interest.

Well who knows. Maybe he is reading it.

[Cobra #3170]

Originally Posted by olddog

If Carol Shelby was alive, I believe he would be reading this thread with great interest.

Well who knows. Maybe he is reading it.

Thanks Olddog very nice of you to say. They called Carroll from the Optima event in 2009 and he loved the fact that the Cobra won overall.