RolexNJ

I will comment from my personal experience on the 33/5. First and foremost, it gets down to the application of the car. If it is street car, do you need it? No. A DE or track car, for me, I would say yes. We all know it shifts some of the pressure to the back. That's suppose to help with not only reducing front brake wear, but also for compressing a bit of the back suspension, hence, giving better stabilization. In a straight line, that won't help that much, but in a trail braking turn, on a dry flat surface, this will cause the outer rear suspension to squat some, hence, create a better contact patch. This is the "old school" thinking of why we do trail braking. Under dry conditions, if we know a track how many turns that would ideal for alot of trail braking, we will adjust while driving the brake bias to accomodate trail braking. I'm not going to go into trail-braking here, because anyone who is anyone in racing knows that some of the fastest ways around a track is this method. Al Holbert, when I ran in the same series with him, was a master of doing this with his Porsche 962, as was Geoff Brabham in the Nissan too.

The bad news. If you are on a track and the braking zones and/or the turn in points are choppy or bumpy, yeah, you could get some wheel hop, and get lock up in the back. All of which would not only unsettle the car, but worse, could actually induce the back end to whip around. If you have ABS, you may be saved. If not, get ready for the back to whip baby, it's drifting time like the ricers do! And oh, I didn't even mention too what it's like in wet conditions.

Hope that helps from the "real world" racing experience.

333pg333

Yes I'm going to try the car with all the new suspension and the stock valve first and see if I think I still need it. As I'm going to much stiffer rates and valving I may not need it with a lot less nose dive under brakes?

RolexNJ

P: What that question for me, sorry? Or Brian? And which part? I tired tonight. And I sent you back an email too. Im sure you got it by now?

Chris White

I am with Rob – on the street there are no real gains and it is safer to lock up the front first in slippery conditions.
On the track I have found that the 33/5 is not the hot ticket for some 951s. I was instructing a student last year with a modified 951 that always locked up the rear under hard braking – especially in the areas that are not very smooth at the Glen.
I drove his car for a couple of laps and could not get anywhere near the potential out of the brakes as the rear would lock up. He was running matched pads, stiffer springs and the 33/5.
I also found that running the 33/5 with the big reds up front gave me very high rear rotor temps – over 250 higher in the rear than in the front.
So it depends on the set up and I would really not recommend it for anything that might be driven in the street in the wet…

Chris White

333pg333

Thanks for the advice guys. I'll leave it off for now.
By the way, can anyone give a brief description of 'Trail braking'? My idea is that it is to do with momentum cornering or braking in that rather than fly up to the corner leaving the braking to the absolute last second and hitting the anchors really hard, probably unsettling the car on a less than very smooth track, you come off the gas a little earlier and brake with less pressure and into the turn. Keeping a more even speed up and the car is much more settled allowing you to apply the power earlier through and out of the corner.
A bit long winded but you get what I mean?

theedge

Hmmmm interesting... I might swap it out then. Ill try driving and see. This is why I keep stock parts Probably wont do TOO much rain driving, but this is BC so avoiding rain is like trying to avoid smog in LA.

Chris White

Ummmm…nope.
Traditional (some folks call it European) braking is to only apply the brakes while traveling in a straight line – We were all told that this was the only safe way to brake (remember drivers ed in high school?) Trail Braking or trailing brake is when you do the majority of the braking in a straight line but continue to brake as you turn in. The purpose is two fold – it allows you to start barking just a tad later but the main benefit is to use the brakes to rotate the car. No, not like fast and furious, it’s a controlled action that helps the car to turn into the apex.
From a technical stand point not only is this used to rotate the car but it also fills out the friction circle. That’s a whole other thread….

Chris White

RolexNJ

I dont want this thread to go OT for Brian and his excitment with his early Christmas toy/s. Your understanding of it is off for the most part, sorry. We could go on and on about this and I don't want to here. I "highly" suggest you go out and buy the video I suggest over the Internet. But for now if you want, you could start a new thread and ask all the racing "experts" here on the theory behind it too?



The video was made by the Skip Barber Racing School when we used to drive Forumla Fords. It is the basic principles of going faster and faster. They teach you all of these things in their 3 day Driving School. I am a graduate of this school so long ago I cant remember, ouch. Either way, the principles hold true whether you drive a 951 or a Ferrari F1. Buy the video and make it your bible, review it again and again. It is about overall driving skills, not just trail braking. Trail braking is a very advanced technique. Most people can't get the basics down for years, let alone this! You should focus more on learning that then just one element. Put it this way, usually only pro-level drivers utilize trail-braking "properly" (key word). Just buy the DVD video with the link I gave you or search somewhere else. The best advice I can give any aspiring driver is to start here with that video, or go to a very good driving school. Either way, trail-braking is an advanced art form, not for any rookie. If done wrong, you will do nothing but constantly spin out and maybe flip the car; and I'm not kidding too!

http://sbi-2000.stores.yahoo.net/goingfaster.html

RolexNJ

Brian:

When are you going to be done with this 2.7L of yours? Is this an entire winter project? Who did the bore, someone near you?

Chris White

RolexNJ

Great, another frickin guy that you are doing and is ahead of me. I am soooo on the back of the line it's a joke. What can I do go get bumped up here?

theedge

Damn straight back of the line!

Probably gonna send it down later this winter. Im still unemployed (waiting to hear about a shot at being network admin at the PNE/Playland which is a monsterous amusement park here) then ive gotta make sure ive got enough money to pay Chris.... Unless he wants to work pro bono and I can return the favor by doing advanced testing to make sure the engine stands up to the rigors of Canada

Thom

Not trying to compare apples with oranges but ...

What would experienced 951 owners here go for between a DTA with GT30** turbo and a VR kit ?

I suspect the latter would require less work, but would it offer as much "refinement" as the former ?

RolexNJ

I cant speak about the first one, for I dont know it. But Vitesse's turbos are a direct bolt-on, unless you tell him otherwise. And as far as performance, ha! As far as I'm concerned for 951s, and I've tried 3 different other turbo configurations, his are best on the market without a doubt!!

Brian, maybe you know about that DTA? I don't?

theedge

Brian as in me, or the other Brian?

I think the general consensus is that almost any standalone can be made to have great drivability, cold starts, etc etc but the big factor is how many hours of tuning it takes and how **** the owner is

Theres also features like Acceleration Enrichments, Decel Fuel Cuts, how the injectors are fired (bank, batch, squirts per cycle, etc) and all sorts of other stuff that can contribute to the overall "experience".

The only standalone I have any real experience with is my MegaSquirt, and I think its great so im keeping it. In fact its running right now next to me, with my freshly assembled MegaView hooked to it.