What is the cost to Convert to ABS?

[Tom F&L GoR]

Whoa! On any other car you might be correct, DrDJ. But the OEM calipers on a non-ABS Viper are too front-biased, so heavy braking is limited by the performance of only the front brakes. Or you may find the fronts too easy to lock up and flat spot the tires. The rears do not do enough work.

Stoptech has a front-only kit that provides a caliper with four smaller pistons, effectively required an unnoticeable amount of harder brake pedal application, but shifting more of the total work to the rear.

Stoptech also has, as does any other 4-wheel kit, excessively large calipers for the rear which you dial down using the proportioning valve to get proper front-rear braking. Same for Dave's SRT conversion - large rear caliper that looks great and is used at about 25% of capacity.

The OEM caliper can be enlarged from 36mm piston diameter to a 40mm piston to also get proper front to rear braking. This simple change (and the ones above would be similar) resulted in a stock '94 improving from ~0.8 G's to over 1.0 G's braking using street tires.

Once you have a four tires doing as much work as they can (which won't be equal, the fronts still do more) then the heat capacity of the brake pad comes into play.

 

[KepRght]

Tom, what would be (in your opinion) the ultimate brake setup for 0-100-0. lets say you already had ABS, and you wanted the brakes to fit under 18" stock wheels. lets also say that you have 15k budget. your goal = not to be bested in 100-0 breaking. no touching suspension, tires, etc. just brakes. anyones comments on the ultimate setup would be welcome

 

[Tom F&L GoR]

ummm.... OEM fronts and 40mm rears? (had to say this.)

You've put quite a limit on the tweaks. Looking forward to all the other ideas people have out there.

Pedal feel to get to threshold braking is achieved through master cylinder diameter and caliper piston volume. Having a directionally smaller MC and/or larger piston volumes will increase pedal travel, but help you find that "best" pedal modulation. Some will suggest stainless brake lines, and with your budget I would go ahead. I put mine on after a rear brake change, and honestly couldn't tell you it made a difference.

I don't know how agressive the ABS will be and it may prevent threshold braking. For the simple 100-0 in a straight line, you might add a switch to disable ABS, add a manual proportioning valve, and practice to find the best prop valve setting. Or you may find full stomp and letting ABS apply brakes is better. Certainly ABS can ****** with each caliper independently, unlike your foot.

Next would be weight - how much do the calipers and rotors weigh? On an uneven surface, less unspring weight will keep contact with the road better, so get lighter wheels, lighter calipers and lighter tires. (Interestingly, those OEM cast rear calipers are only slightly heavier than the front calipers. When you put four-piston calipers on the rear and have to add a parking brake, your total is probably heavier than the ugly duckling caliper that already includes the parkign brake.)

Brakes generate and dissipate heat, so whatever caliper has the largest brake pad would probably do better. I think there are many complicating factors (such as each brake pad material has a best operating temperature) so maybe instead of saying large pads, the better answer comes from finding pads that work best at the temperature you will do the 100-0 event. The answer will be a lot different if you do this event once or 20 times. And larger pads add weight.

If it's 20 times, look into a brake fluid recirculation system. Parts cost is ~$300, labor adds more. But it will virtually eliminate any risk of fluid boiling since the fluid isn't captive in the caliper anymore. I've used one for years and it's a rarely seen, significant advantage.

You said no suspension changes, but corner weighting the car is not really a change, it's tuning. So many posts here talk about right front tires skidding. With driver and battery on the left, the right front can be over 100 pounds light. It sounds almost trivial, but don't you let off the pedal when that one tire skids? Yet you haven't approached maximum braking because there were three tires that were still rolling. It's another underplayed advantage - just do it with weight in the car simulating the passenger load you want to optimize it with.

I don't know much about the different brands (Brembo, Stoptech, Wilwood, etc) because I'm cheap, have 17" wheels, and can already run up the ********** of ABS cars at track events. The only issue I deal with that the OEM rear pad size is relatively small and so for every two pair of fronts, I go through a set of rears. That totals about three track hours per set of rear Brakeman #3 pads, and something a little harder becomes too hard (no brakes) for the street.

Your budget could allow you two or three tries at different setups. Maybe you could purchase an in-car decellerometer and 40mm calipers and measure the braking, then Dave's kit and measure again, and then a full-zoot Brembo race brake system and measure again. I'm sure you could line up people before hand to take the used parts from you so it's not all lost.

 

[Matthew Howell 97 GTS]

An exact parts list would be a great start for those looking to start this project. It could help others doing the conversion from making the same mistakes along the way.

Some specific questions are:

What ABS controller is used?
Where to mount the controller?
How to communicate with the controller?
Wiring to the controller?

This would also make a great Tech Tip article.
Too bad Mopar Parts doesn't make a conversoin kit, they have all the parts.

 

[REDSLED]

Ineteresting discussion here and I will throw my $.02 in as I don't have a product to promote (no offense to Tom and his rear brake upgrade) For a car that is not really going to see heavy track usuage, the brakes are sufficient. I ran the Viper Days series for several years on the stock set up and was just as quick and more times than not quicker than guys who spent big bucks upgrading their brakes. I've used the Stop Tech 4 Wheel kit and it did perform, but the performance was not Earth shattering. The system itself is pricey and the pads are not cheap either. With this system I did go through pads at a faster rate than other systems, as did several of my friends with the same system but the quality is good and the customer support is Top Notch. For the posers, the "Bling" factor is an A+ as the big calipers look great. They can also be ordered in multiple color options to add more "Bling" I currently run a Wilwood 6 Piston Front caliper(same used on Nextel Cup cars) on my race GTS and have the stock front Viper calipers mounted on the rear. Although the calpers don't match and the bling factor is not as high as the Stop Tech, the performance is better. Brake pads are also cheaper as they are mass produced and there are more compounds available. I will be trying out Daves Big Brake Kit in the next month so see how the SRT 10 calipers do on the track. A fellow GTS owner currently runs that set up on his racing GTS and he says the breaking is very comparable to that of the Comp Coupe (and as he ran a CC in World Challenge last year, I would say he's qualified to make that claim)
I will report back after some track day testing. For a street car I think adding ABS is a waste of money as ABS is not going to save you from rear ending the car in front of you if you are too close. On the race track I would say ABS is an advantage but on the street it is not.
God luck to all.

 

[97 Viper GTS]

Here is an ABS conversion parts list (as requested- these are all '01 Viper parts):

Teves Mark 20 ABS integrated electronic control module/hydraulic control unit (part # 5017905AA)

2 front ABS wheel sensors (4854412AA)

2 rear ABS wheel sensors (4854414AA)

R and L front steering knuckles (5264874AA and 5264871AA)

R and L rear steering knuckles (5086712AA and 5086713AA)

Rear hub and bearing (2- 4848716)

Front hub and bearing (2- 4763182AB)

You also need the ABS wiring harness, but I don't have that part handy (and it is about $700 anyway). Tone rings are included with the hubs on '01. Also, don't forget you will need new calipers/rotors/hats.

Shawn