xcarguy

. . . . . .

Okay, Jim's new forum name . . . . . . . Rocket Man. :jester:

Don, You're basically breaking new ground (in the Stalker realm) with your car by introducing a combination that’s yet to be tried. At the very least, install the pro valve on the front (I'm with Dave on this). If it doesn’t produce the desired results, then you’ve discovered what doesn’t work and you take a different approach. If it does work, then great! Either way, you’ve got valuable information to share with others who may be considering one of these cars. Although we're talking different venues, FWIW, I’m dialed in to 22psi on the front of my car also. Even though I’m running a 16x10 combo on the front, 22 psi illuminated the graining I was getting on the inside edge of the tread at 19 psi, produced an even wear pattern and resulted in the best overall grip. I run a 16x12 combo on the rear and 20 psi; 19 psi was also producing graining in the inside edge of the tread, so 1 single psi in the rear and 3 psi in the front made a huge difference in tire wear and grip. I say this because 16-24 psi is a large psi margin and I feel pretty confident that you’ll find a psi within that range which works well for your application. If you try the front pro valve, I’d experiment with tire pressures and see what it yields. As for pads, I run Wilwood BP-20 pads on front and stock 95’ Grand Am GT pads on the rear. The BP-20’s are Wilwood’s middle-of-the-road pad; better stopping power than the BP-10’s, but not as frictionally aggressive as the BP-30’s which also tend to eat rotors . . . or so I’ve been told. Several owners on this forum run Hawk pads and have had good results with them, however they very well may be better suited for the occasional track day rather than E Mod. Don’t write off trying various combinations of brake pads down the road. Again, you’re breaking new ground with your car. You also mentioned possibly using a 22” tire in place of the 20”. Last year, I was running a 15x10 square setup and getting around 1.2G’s sustained. I moved to the staggered pattern I’m now running and am now gettting 1.5G’s sustained per my data logger. The reason I say this is that by going to a larger tire with a larger contact patch, grip increased significantly. A larger tire on front (this is just a thought for consideration) with a larger contact patch may provide you with additional grip during hard braking. Anyway, the best of luck with getting your car setup. This time next year I’ve no doubt that you’ll have lots to good advice and valuable information to share with others. :cheers:

Dave and Don, My apologies for my last post; sounds like you guys already worked that out.

Dave, Under hard braking, the front tires are locking up while the rears are not. While I agree that the bias is favoring the front wheels, I wouldn't necessarily call that being in the ballpark without some hands-on experience behind the wheel. I also agree that a driver has to learn a new car and that the new car has to be dialed in. However, I don’t think that’s the issue here as Don’s experience, and posts, would suggest he’s fully aware of a necessary learning curve as well as a need to get the car dialed in . . . . Hence one reason for this thread. What I'm getting from Don in his posts is that, based on his level (years) of driving experience, the car simply feels unbalanced in the area of aggressive braking. And it may very well be unbalanced; the car is running a radically staggered wheel/tire setup with the contact patch between the tire and the track definitely favoring the rear tire, and, power assisted brakes are being used to stop a car that weighs less than half of what the power assist was originally designed to stop. I think Don is looking for ideas, suggestions, etc. for getting the rear brakes a bit more engaged in braking. One of the problems he’s up against is that the proportioning valve for the rear brakes is ‘full open’ with no more room for adjustment, thus the reason for tossing the idea on the table of using a proportioning valve on the front brakes in his opening post. Don, Having said all this, what type of brake pads are you running on the front and rear? And tire pressures?

degoetz, I think the issue may very well lay with the different size front and rear tires (that's a stab at best). What tire pressures are you running fron and rear?

John hit 173mph at VIR: QUOTE=midgetracr;58656]The calculation used the following data: 6791 RPM from datalogger, 3.23 rear axle ratio, 0.82 5th gear ratio in the TREMEC TKO 600 5 speed trans, 71.3" actual measured tire circumference from Goodyear 22.5x10.0x13 slicks, 60 minutes per hour and 5280 feet per mile. This yields 6791/(.82*3.23)*(71.3" /12) *(60 /5280) = 173.12 MPH The RPM data was from my AIM EVO3 data logger on the quickest lap during timed session #1, measuring the tire with a tape measure, specs from TREMEC on the trans and counting teeth when I installed the differential gears. The above neglects both tire slip (which I think is minimal because of the downforce at that speed) and tire growth because of centrifical force which I have no way of estimating. Using the above formula it would require 7060 RPM or a larger tire to go 180 MPH if my math is correct. Because the soft rev limiter begins to retard timing at 7000 the engine will actually rev that high even if the limiter was not changed. I think the valve train would be OK to around 7500 but have never tried it. 200 MPH would require a narrower 80" tire to fit inside the fenders.

Looking good! :cheers:

degoetz, Can you post a close up photo of your MC?

I"m assuming the proportioning valve is full open (max rear brake). On the brake pedal assembly itself, do you have separate front and rear master cylinders. If so, do you have an adjustment (similar to this: http://www471.pair.com/stalkerv/gallery2/main.php?g2_itemId=6813)? If so, can you adjust the 'bias only' to your liking and then use the proportioning valve to fine tune?

Can you dial more bias to the rear with the current setup? Also, is one front tire locking up before the other?

jevs, Ran Speedhut in my Birkin; nice gauges. I've had my relatively small 346 cid LS6 powered car near the limit of my 160 speedo with a little room to spare. If I had a choice, I'd opt for the 180 . . . . or the 200 if your a complicated man. :jester: This may very well be something you have already considered, but on a more serious note, if you plan on running your car well into triple digit speeds (as I know you are ), you will need to address the issue of adding down force to the car. M-Spec or not, the inherent design of these cars transfers weight to the rear wheels at speed. John Meyer, who hit 170+ at VIR running the UTCC, ran with a large wing up high and just forward of the roll cage (about mid chassis). Without down force at such speeds, your front end will have a weight deficient.

Perhaps you guys purchased the all new Next Gen SX . . . . who has 54? :jester:

An older video, but worth a revisit. Heikki's locost spin at 2:18.

The horn wouldn't work if he relay was bad. Ditto on a bad switch.

Congrats!! Buyer wasn't Sharkey was it? :cheers:

That particular type of switch mounts to the column. If you're not set on having that type of switch, you could opt for a simple three-way toggle switch (ON-OFF-ON): http://www.skycraftsurplus.com/heavydutytoggleswitchdpdton-off-on.aspx

Allen, Would Brooklands be a consideration?

Dave, Sent you a pm. Shane

I thought you said I trashed your paint job. :jester:

The annual Stalker Ambush will be happening in a couple of weeks in that area. Part of the activity is to head over on Sept 14 to either spectate or participate in Chasing the Dragon hill climb.

Not yet. Did NJMP in July with no issues. Next planned event is COTA.

Tommy Ivo was doing some pretty radical stuff back in the 60's with multi engined AWD dragsters. Here's a few photos and a link to the article (food for thought): http://www.speedhunters.com/2009/07/guest_blog_tony_thacker_nhra_museum_gt_gt/

Nonsense! . . . . . Drive it like you stole it! :jester:

Not sure if the cutoff needs to be reachable by the driver. On my Birkin, the cutoff switch was located on the side of the scuttle (driver's side).