944 Spec Shake Down - Could have been better - Help Needed

[loftygoals]

This weekend I hauled my 944 Spec car to Houston to do some testing before the NASA TX race next weekend. I had made changes to the front spring rates, new 28mm Welt front bar, and 19mm Lindsey Racing rear car. The motor was completely overhauled as well.

 

Day 1

First Session

Spent the session watching the gauges making sure the new motor was ok. Motor seemed to be running pretty well, but it was only 32 degrees and I had never driven the track before so I didn't push it. Even at an easy pace, the car felt very loose. On my cool down lap, I managed to spin the car. I don't know how. The car died in the spin and it wouldn't refire. I had to be towed back to the paddock.

 

Turns out the starter trigger wire had come unhooked. While I was fixing things, I also stiffened the front bar to try and remove some of the oversteer.

 

Sessions 2 & 3

Lost a session working on my car and drove my students car the 3rd session.

 

Session 4

Had a good session playing with a SM. Actually I thought it was a Spec Miata, but it was prepared beyond SM. I was very pleased with how my 944 would run away from it in the straits. Before the rebuild, SM's would run away from me on the straits. I was loosing a lot of time toi the Miata on corner entry, because my 944 would get sideways with the smallest amount of trail braking.

 

The car also had a miss at higher RPMs. This turned out to be a loose signal wire to the coil.

 

Day 2

First Session

I noticed just before I left grid that my voltage was only 11 Volts. I hopped out and checked the wiring and belt for the alternator. Everything looked good. I was gridded in a line of a bunch of cars, so I went out. Just as I completed my first lap, the voltage gauge was pegged at over 18 Volts. I had already passed pit in, so I had to go around again. I made 2 more corners before I smelled something burning. Then smoke started pouring out of the hood.

 

I killed the master, pulled off track, jumped out of the car, and high tailed it to the nearest corner station. If the car was going to burn, it wasn't going to do it with me in it.

 

Once safety confirmed the car wasn't on fire, I was again towed back to the paddock.

 

Session 2

I missed the next session working on my student's car and my own 944.

 

Turns out the alternator shot craps. If over-volted, overheated, and then stopped spinning. When it froze, it burned up the belt. When the belt broke, it snapped with such force that it dented the hood.

 

All the wiring checked out fine, so I put the battery on a charger. I was determined to get a good session in, so I planned on running the car just on the battery.

 

Session 3

The car was running great, despite not having an alternator. It was sticking well in the corners, but was a mess under braking. I still can't get the car to brake in anything but a strait line. The smallest amount of steering will cause the rear to come around. A bump in the pavement under braking will cause the back end to come around.

 

Session 4

Packed up. The braking issue was keeping the car from being much fun.

 

 

 

What I need help with...

I can't figure this braking issue. It has existed since the car was built in 2007-2008. The car is corner balanced and aligned properly. I am running Hawk HT-10's front and rear and fresh Brembo 600 fluid. The problem has existed through caliper rebuilds, rotor changes, and pad compound changes. There just seems to be tons of rear brake bias.

 

In 2008, the only way I could get the car to be drivable was to raise the front ride height by a full inch and mix compounds-- F:Hawk Blue/R:Autozone streets or F:Hawk HT-10/R:Hawk Blue. I don't mind throwing Hawk Blues on the rear axle, but raising the front an inch is really not a solution.

 

I just can't figure out what is going on. The only things in the entire system that hasn't been replaced are the hard lines and the brake master. The brake pedal feels firm.

 

Any ideas or suggestions would be greatly appreciated!

 

Thanks,

-bj

[Sterling Doc]

BJ, you are the king of weird problems, too

These cars don't like to sit for long periods of time...

 

A lot of us have issue with too much rear bias. Several of us in the Midwest have gone to running a pretty dramatic split friction pad F/R - like a Hawk Blue Front, and HP+ rear.

 

Stick some HP+'s in the rear, and it should help a bunch. They're cheap, too.

[loftygoals]

BJ, you are the king of weird problems, too

These cars don't like to sit for long periods of time...

 

Or short periods. Even after first building the car I had lots of issues. I've yet to have a weekend where something hasn't broken on the car. I've been through 3 transaxles, had coolant hoses pop, shift linkage fall off, valve springs break, lifters explode, bent valves, crap clogging the intake snorkel, failed injectors, failed alternator, 4 wheels (not tires) stop holding air, clutch failure, 2 clutch slaves fail, and 1 rotor crack in half. Considering the piles of money I have invested in this car, I can't believe I haven't torched it yet. I guess I figure it will burn itself to the ground soon enough.

 

Despite all that, I still love this car and think I'll get through all the teething issues soon enough.

 

 

A lot of us have issue with too much rear bias. Several of us in the Midwest have gone to running a pretty dramatic split friction pad F/R - like a Hawk Blue Front, and HP+ rear.

 

Stick some HP+'s in the rear, and it should help a bunch. They're cheap, too.

 

Thanks. I'm glad to hear that others have experienced rear brake bias issues, too. It's comforting to have someone else sharing my pain. I don't understand why there would be so much rear brake bias on these cars. Is it an issue that all cars experience or just some of them?

 

-bj

[944-Spec#94]

I have never had any abnormal issues with rear braking stability. I have been in my car since 2000 and I have always run the same pads front and rear. Most of these runs have been with an open diff as well.

 

So lets go over a few things first.

What are your spring rates?

Alignment settings?

 

 

This is what I have on my car.

Brakes = Hawk blue front and rear

 

Springs - 350lbs front and 30 mm rear t- bars. 400 lbs springs could work too, but I have never tried them.

 

Sway bars - Weltmeister 28 mm front and 22 mm rear. Front is probably in the middle of the range and rear is middle to full soft. - A stiffer rear bar = less stablity on braking and full soft is really too soft and much too soft with an LSD.

 

Alignment.

Ride height - roughly 4" at the rocker all around. The key is the car is level front to rear. Rear end high produces oversteer

 

camber = roughly 3.5 front and 2.5 rear. For now I can remember the exact settings, but these work good 95% of the time.

 

Toe--- This is real key

Front toe = 0. Zero toe for minimal scrub down the straights.

Rear toe = -1/16 per side. I use strings to set the rear toe and measuring to the rim outside edge I have 1/16 toe in at each rear wheel. This toe setting is key as if it zero or possibly less than this it is easy for the rear to deflect out under brakes creating oversteer at corner entry. It will not create rear lock-up, but make trail braking hard. This the ideal setting for an open diff car. For an LSD car you might get away with zero toe.

 

Shock settings - 1/2 to full stiff front and rear. Shocks don't really play a role unless you making tightish S bends were you toss the car side to side. Otherwise they don't play that much of role.

 

 

Anyway by using the above as baseline I have been able to control rear grip during trail braking pretty easily. Moving the front sway bar by 5 mm can have big impact on rear stability, but also impacts the car all over the track. So that may not be the best solution.

 

The other thing to remember is braking technique can also play role in rear end stabiity. I tend to like just a bit of oversteer at turn in so that I can corner faster by using that momentum to my advantage. However I try to make the car stable in straight line braking and use trail braking to create the oversteer.

 

 

So if you have too little rear toe in you can have braking issues. If the front springs (actual springs not sway bar) are too soft you make have rear end instability. If you have a rear end high rake you may have issues.

 

Note from what you descibe it is not rear braking problem. The reason is that you say that you can brake in a straight line just fine. It sounds like a either chassis issue or driver confidence/technique issue. The driver issue can be resolved by swapping cars with another driver.

 

The chassis issues I have attempted to cover here and my first look would be at rear toe. There have been a couple times my rear toe has shifted a bit and caused more instabilty. Do you have the same issues turing left as right? If it is different left turns vs right turns it could be one wheel toe-out or blown out shock on one side. It could also be a loose suspension part like a wheel bearing or bad bushing in a rear trailing arm.

[Sterling Doc]

Joe makes very good points about making sure the basics are covered - be sure to check those things. The added grip that our cars have vs. street cars may increase load transfer (away from the rear), and the stiffer suspension increases the speed at which this weight transfer happens vs. a street car. I worked around rear lockup issues for a long time, but after having a Dave Royce (pro & suspension engineer) drive my car a couple of years ago, have changed to a split friction setup.

 

Dave's point was that in any reasonable circumstances, the fronts should always lock first. They do most of the braking, and being able to keep them at threshold is more important than the rears, and it is safer this way as well. Of course, you want the bias close, but erring on the side of front lockup first is safer, and allows you to explore trail braking more confidently, which is critical to transferring high corner entry speeds into mid corner speed safely.

 

I also like that the initial bite of the HP+'s are a bit less, which avoids lock up with the initial weight transfer. They've also held up well in the rear (NOT in the front), and again, they're very cost effective.

[loftygoals]

Joe, thanks for taking the time for such great response. I have replied below with my setup and thoughts. I think we are on the right track.

 

So lets go over a few things first....

 

My Suspension:

• 400# Front Springs (switched from 350# to reduce dive under braking)
  
• 30mm Rear Torsion Bars
  
• Front Koni's set 1/4 off Full Stiff
  
• Rear Koni's Full Stiff
  
• Front Welt 28mm Sway Bar 3/4 stiff
  
• Rear Lindsay Racing 19mm Sway Bar (5 adjustment holes) 1/2 stiff
  
• Ride height 5" front an rear (Min to keep the car legal for SCCA ITS), Corner balanced

 

Alignment

• Font Camber: -3.5
  
• Front Caster: 2.9
  
• Front Toe: 1/8" Total Out (I like the toe out for turn in)
  
• Rear Camber: -2.5
  
• Rear Toe: 0 (Semi-trailing arm suspensions gain toe in on both compression and extension)

 

 

 

If the front springs (actual springs not sway bar) are too soft you make have rear end instability. If you have a rear end high rake you may have issues.

 

Being that I stiffened the front springs and have the car level, I don't think this is the issue. BTW, I stiffened the front bar to reduce mid-corner oversteer, not under braking. Under long sweepers, the rear would step out too quickly at the limit. With the stiffer front bar setting the car is much more neutral.

 

So if you have too little rear toe in you can have braking issues.

 

The chassis issues I have attempted to cover here and my first look would be at rear toe. There have been a couple times my rear toe has shifted a bit and caused more instabilty. Do you have the same issues turing left as right? If it is different left turns vs right turns it could be one wheel toe-out or blown out shock on one side. It could also be a loose suspension part like a wheel bearing or bad bushing in a rear trailing arm.

 

I will try adding some rear toe. The car is solid in the rear. All the bushings and wheel bearings only have a few races on them.

 

The other thing to remember is braking technique can also play role in rear end stabiity. I tend to like just a bit of oversteer at turn in so that I can corner faster by using that momentum to my advantage. However I try to make the car stable in straight line braking and use trail braking to create the oversteer.

 

Not to sound too full of my self, but I have pretty good braking technique. I have a handful of other track/race car and I've been in lots of race cars from GTS3 BMWs to American Iron Mustangs to IT7s. I've never experience braking instability like this.

 

The BMW M Coupe in known for being a rotation happy car, but I've never had an issue controlling it even under heavy trail braking.

 

As a side note, the IT7 was the most entertaining because it was falling apart during my stint. I lost the clutch and had to shift without the pedal, the rear shoes fell out of their tracks and stopped working all together, the motor kept over heating, and the hood latch broke.

 

Note from what you describe it is not rear braking problem. The reason is that you say that you can brake in a straight line just fine.

 

I wouldn't say I can brake in a straight line "just fine." It's the only way I could brake. In a strait line, the rear brakes will lock before the fronts.

 

 

Dave's point was that in any reasonable circumstances, the fronts should always lock first. They do most of the braking, and being able to keep them at threshold is more important than the rears, and it is safer this way as well. Of course, you want the bias close, but erring on the side of front lockup first is safer, and allows you to explore trail braking more confidently, which is critical to transferring high corner entry speeds into mid corner speed safely.

 

As I mentioned above the rears will lock long before the front. It has been this way since the spec suspension installed,SS brake lines installed, and calipers rebuilt. I don't remember it being a problem when I tracked the car on stock pads, stock suspension, and street tires.

 

I almost wonder if when I was doing the spec build, I left the master dry too long and damaged the seals on the secondary piston. I have a brand new ATE master sitting on the shelf. Do you think it would be worth swapping in?

 

Speaking of the master cylinder, how much pedal travel do you guys get before the brakes start to engage? The first 1/4 to 1/3 of the travel does nothing. After that it feels solid.

 

Thanks guys!!!!

-bj

[Sterling Doc]

BJ - good info.

 

I would try softening the rear Koni's to 1/2 stiff - this won't change the steady state balance that you're happy with mid corner, but it will let the rear end be a bit softer in transition - i.e. when first hitting the brakes, and first rolling into the corner. Remeber, Konis adjust rebound damping (droop). Make this very stiff, and you "pick up" the rear tires under braking. Softening the rear Konis should help the issues you're having quite a bit. Over stiff damping in the rear makes that end more skittish. Combine this with front toe out, and you've got a handfull, especially under braking. I'm not a fan of front toe out outside of autocross, but this is a personal preference. Before you're done, I suspect you'll also need to soften the rear bar slightly, but one change at a time.

[loftygoals]

BJ - good info.

 

I would try softening the rear Koni's to 1/2 stiff - this won't change the steady state balance that you're happy with mid corner, but it will let the rear end be a bit softer in transition - i.e. when first hitting the brakes, and first rolling into the corner.

 

This is a really great suggestion. I might be transferring weight to the front faster than the rear shocks can extend causing the rear to get too light.

 

...Combine this with front toe out, and you've got a handfull, especially under braking. I'm not a fan of front toe out outside of autocross, but this is a personal preference.

 

This is a battle... turn in vs. straight line drag. I typically like a little front toe out to get the front to turn quickly. This helps get a little rotation on turn in. Usually this is a great setup for me. With my current issue, I'm not sold.

 

Before you're done, I suspect you'll also need to soften the rear bar slightly, but one change at a time.

 

Really? I thought many guys were running the Welt 28mm front and 22mm rear. On full soft the Welt rear should still be equivalent to a 19-20mm bar. I thought that might be too much bar, thus why I opted for the 19mm Lindsay bar. With the adjustments, it should range approximately equivalent to 17mm-21mm. In the middle setting, it should be about the same as a Welt on full soft.

 

Again, this is why I love the series despite my unreliable car--the other racers. I appropriate the time, help, and support.

 

-bj

[Sterling Doc]

BJ - you're right, I was thinking you had a WM bar. It'd help if I read your post better!

 

The support and openness in this class is great, and I think it's one of our defining differences. Tim, Chuck, and Joe really set the example when I was starting out, so it's good to pass it forward.

[944-Spec#94]

I think you need to change the rear toe settings.

 

Do you have an LSD? If not I would get my tail wagging around if I had one side shift torward zero toe. With an LSD you can run less rear toe.

 

 

Remember the 944 rear end will move to toe out due to braking loads. This effect is much greater than any change from ride height and I have seen it over and over again. Rear toe is one of the most critical settings on a 944 racer, especially so with the semi-stiff bushings we run. Even with metal solid bushings the arms flex some. No that much, but I learned all this from Chris Cervelli who raced a 450 hp 944 Turbo back in the late 90's. He in fact recommended 3/16 total toe in on the rear to counter not having METAL bushings. Rear end stepping out at speed can also be due to rear toe (or lack of toe in to be specific).

 

 

Now If the onyl thing you have not changed in the brakes is the master cylinder then it might be a good idea. I don't believe locking rear brakes is a normal thing. Back in 2003 I remember going into one turn at Arizona Motorsports Park trail braking hard from 100 mph and due to slick and fresh asphalt hear each tire locking slightly as I modulated the brakes. I always felt if I could feel and here that 4 tire intermittent locking I was right on the edge of adhesion. I have gotten the inside rear to lock up in a unloaded situation, but not very often.

 

 

The other thing is that I think your front end could be too stiff. 3/4 stiff on the weltsway bar is quite alot. I run 350s and never run over 1/2 stiff on the sway bar. Any more and my front end washes out. I am not really sure what that is doing, but it just does not seem right. It should cause the fronts to lock up very easily, but it is not. Hmm I wonder if your front brakes are too weak and that is causing the rears to seem so much stronger? Not really sure. The rear shocks should not be doing much underbraking even at full stiff. I run mine like that.

 

Also front toe out... I wonder if when turn the front is wandering and make it feel like the rear end is moving? I don't know it is very hard to judge without driving the car.

 

 

If I were you I would swap the master cylinder and reduce the toe on both ends. Then see where it goes. The think I keep thinking about is the toe both front and rear is making the car very twitchy. You seem to be going really stiff in front to compenstate. So make the toe more neutral and let the spring rates due the work.

 

My thory on suspension.

Toe should be zero for minimum straight line drag. If you need to adjust it fine, but try not to. For the 944 rear the toe in is a band aid for the rear suspensions design.

 

Camber = set camber by tire temps. You should set the camber by what makes the tire temps the best.

 

Spring rates = Set to create good steady state balance from front to rear and hold up the car to keep it from flopping around.

 

Sways used to fine tune the chassis to optimized balance. If you need to go full stiff or full soft to achieve balance you are covering up something else that is wrong. Fix that and you can get balance and a faster car over all.

 

Shocks - At least for our cars have minimal impact. These are really fine adjustments in the transitions and the Koni's we use are not that adjustable to have much impact. Some guys feel them, but alot don't.

[loftygoals]

I think you need to change the rear toe settings.

 

I agree. Looks like it is time to try out the new alignment machine I bought. I don't have the alignment lift yet, so I'll have to measure on the ground, but at least I don't have to use strings and tape measures anymore.

 

Do you have an LSD?

Nope. It's the only thing the car is lacking to be 100% maximized to the rules. Saving my pennies for a torsen or a Gaurds clutch LSD. I've always been a fan of clutch pack LSDs for road racing, but after driving some cars with torsen diffs, I must say I love them on corner entry.

 

Remember the 944 rear end will move to toe out due to braking loads. This effect is much greater than any change from ride height and I have seen it over and over again. Rear toe is one of the most critical settings on a 944 racer, especially so with the semi-stiff bushings we run. Even with metal solid bushings the arms flex some. No that much, but I learned all this from Chris Cervelli who raced a 450 hp 944 Turbo back in the late 90's. He in fact recommended 3/16 total toe in on the rear to counter not having METAL bushings. Rear end stepping out at speed can also be due to rear toe (or lack of toe in to be specific).

 

Wow, great information! I had no idea that a 944 would deflect so much under braking. I figures with the low 11 degree trailing arm and derlin bushings, that things would stay in check better than that. Most of may chassis tuning has been done on BMWs. The E30's are know for lots of deflection, but I would have never guessed a 944 would be so bad.

 

The other thing is that I think your front end could be too stiff. 3/4 stiff on the weltsway bar is quite alot. I run 350s and never run over 1/2 stiff on the sway bar. Any more and my front end washes out. I am not really sure what that is doing, but it just does not seem right. It should cause the fronts to lock up very easily, but it is not. Hmm I wonder if your front brakes are too weak and that is causing the rears to seem so much stronger? Not really sure. The rear shocks should not be doing much underbraking even at full stiff. I run mine like that.

 

I never experienced any push over the weekend with the front end set to 3/4 stiff. Swaybars should not effect braking in a straight line. If both sides are compressing evenly, there should be no additional spring rate added by the sway. Besides, 3/4 stiff should be around the same effective rate as a 30mm front bar. The rear is set at 19mm effective. That is exactly the same as the MO30 package that seems to be highly regarded.

 

I like Eric's suggestion to soften the rear. Not only might it help keep the rears on the ground under braking, but since rebound and compression adjust together the car may squat quicker under acceleration. I need that weight transfer with my open diff.

 

Also front toe out... I wonder if when turn the front is wandering and make it feel like the rear end is moving? I don't know it is very hard to judge without driving the car.

 

I don't think that is the case. I like lots of front tow out and I'm very accustom to the wondering it produces. I'll have to do some testing with front toe settings and see what feels the best vs. laptimes, though.

 

Thanks!

-bj

[Sterling Doc]

BJ, one more suggestion. When you're working on dialing in the car from scratch, make big changes, to get the feel for what happens. It may be too far, but then you've found out what *that* adjustment does/feels like. Once you have experience, and a good baseline setup, you can make small changes as needed, for a particular situation.

 

I'd try setting the rear shock to full soft for one session, and see what that feels like, then fine tune it from there. If the situation does not improve with the shocks on full soft, you can rule that out as part of the problem.

[jaje]

I would have trouble locking up brakes trying to trail brake into certain turns. I was running DTC 70 front / DTC 60 rear and it seems to be too aggressive a rear compound so next season I'm running DTC 70s up front and Hawk Blues in the rear hoping that will cure the tail happiness. I can't do a comparison yet as I've yet to drive the car with the setup and I'm also going from an open to an LSD transmission (which also helps with preventing lockup from braking).

[944-Spec#94]

 

... I've always been a fan of clutch pack LSDs for road racing, but after driving some cars with torsen diffs, I must say I love them on corner entry...

 

.... Most of may chassis tuning has been done on BMWs. The E30's are know for lots of deflection, but I would have never guessed a 944 would be so bad.

 

... Besides, 3/4 stiff should be around the same effective rate as a 30mm front bar. The rear is set at 19mm effective. That is exactly the same as the MO30 package that seems to be highly regarded....

 

-bj

 

Couple things.

Torsen diffs have no lock-up on decel so give you no benefit vs open at corner entry. They do help getting power down on corner exit. The clutch type diffs make a difference since they lock the rear wheels somewhat preventing swapping ends. You can get to the same feel at corner entry with an open diff, but the car will be compromised elsewhere. The clutch plate LSD will also limit inside rear wheel locking when trail braking.

 

The E-30 rear suspension is of a very similar design so suffer the same type of issues.

 

Also the 30mm M030 bar is hollow. Plus the design is different from the weltmeister bar. So the 28 mm weltmeister is in fact MUCH stiffer than a M030 30mm hollow sway bar.

[loftygoals]

Couple things.

Torsen diffs have no lock-up on decel so give you no benefit vs open at corner entry.

 

Exactly! Many cars with clutch pack LSDs push on entry. The open nature on decel is awesome!

 

 

The E-30 rear suspension is of a very similar design so suffer the same type of issues.

 

The E30 has a much larger sweep angle and the subframe bushings that the trailing arms attach to allow for tons of movement. The 944 geometry is much better. Plus the E30 has no factory adjustment for camber or toe in the rear. The add on E30 kits are difficult to set and increase the sweep angle even more. The 944 of course has both adjustment using just eccentrics..

 

 

Also the 30mm M030 bar is hollow. Plus the design is different from the weltmeister bar. So the 28 mm weltmeister is in fact MUCH stiffer than a M030 30mm hollow sway bar.

 

That huge Welt bar isn't hollow? I wondered why it weighed so much. I went with it because I like the mounting so much better on an early car than the stock style mounts on the control arms.

 

Again, thanks for the education!

 

-bj

[Sterling Doc]

We don't need much lock up at our power levels, so the push doesn't seem to be much of an issue. The OEM 40% LSD has a breakaway torque spec in the single digits, yet controls wheelspin pretty well. There is a rare OEM 80% LSD that Nick at Bennington has, but I feel it's overkill in our cars. I do like the pseudo anti-lock function of the clutch type LSD.

 

An LSD hasn't made me much (if any) faster, but it has made the car easier to drive, and easier on tires!

[loftygoals]

An LSD hasn't made me much (if any) faster, but it has made the car easier to drive, and easier on tires!

 

That's I haven't ever had a much of a problem putting power down, so I have left an LSD as the last item in my build.

 

-bj

[944-Spec#94]

I got a factory clutch pack LSD mostly for the stability under braking. It does add understeer at corner entry, but you counter that with sway bar adjustment front and rear.

 

At my home track it took me 3-4 events before I got the LSD dialed in. Frist run with it I could trail brake like mat, but the pushed on. Corner exit full throttle. I made a few driving style adjustments and it helped, but it did not get fixed until I adjusted the sway bars and reset the rear toe. Then it made difference. Got me .2 to .3 second and most importantly gave me little extra margin at turn 2 at PIR that allowed me to stay in contact with the leaders for a race distance rather that being strong for 2 or 3 laps then fading because I could not balance the car to the very limit every single lap.

[Al F.]

Wow, excellent information in this thread!!

 

BJ...you better be there this weekend!!!

[loftygoals]

I thought I would post the results of my changes...

 

After all the suggestions in this thread, here's what I did:

 

• Switched to very non-agressive compound in the rear - PBR Metal Masters
  
• Softened the rear shocks to the medium setting (early rear adjustables have 3 settings or clicks: soft, medium, and full)

 

And that's it. I really wanted to adjust the rear toe settings, but didn't have time to get it to my buddy's alignment rack. I don't have an alignment lift for my shop, yet, but I have purchased the computer alignment machine. I tried just using the machine with the car on the floor of my shop, but the machine needed calibration. I didn't have time to figure that out.

 

Alignment

Because of all the discussion about rear toe, I thought I'd share where my toe settings are really at. I went for 0 toe in the rear. I had originally decided to do 0 rear toe because of development I've done with my BMW M Coupe. My M Coupe has an E30 semi-trailing arm rear suspension that is similar to the 944 setup. Conventional wisdom is to run a little toe in on that suspension. After some testing, I found my M Coupe is faster and feels better with 0 toe. I thought I'd try the same on the 944.

 

When I scheduled my alignment with Pro-Tuning Performance I asked if they had done a 944 alignment. They said yes, so I didn't think there'd be an issue. (Until I get my rack setup, I like to use these guys because they are good mechanics and they have an amazing alignment rack. It's a brand new high dollar Hunter rack that is capable of doing some really trick stuff.) Although, they had done 944 alignments before they didn't have the rear toe adjustment tool. They were able to get one side to 0 and but the other side was stuck at 1/4" toe out!

 

Like I said, I was unable to change this before the race. It will be adjusted before the next race, though. I'm going to run 1/16" to an 1/8" of total toe in for the rear.

 

Swaybars

There was also some discussion about sway bar settings. I left my front 28mm Welt set to 3/4 full stiff. The rear, a Lindsay Racing 5 position 19mm adjustable, I had set at one hole stiff past the medium setting. I know this sounds like a ton of bar, but the car felt amazing. One of my big complaints with the car when I ran it in 2008 was that it took forever to settle down and take a set. There was way to much body roll with the turbo bars I was running. So I went big with the settings on the new bars.

 

The result was an awesome car! The car had grip in the rain where other cars just didn't have any. I know it seems counter-intuitive for a stiffer car to get more grip in the wet, but that is just how it worked. I was able to make some passes in places even the crazy Spec Miata drivers wouldn't go.

 

I think this is going to be a great dry setup. In the future, I think I'll soften the rear bar in the rain. I was having a lot of problems getting the rear to hook up under acceleration. The other 944 Spec cars were driving away from me out of the corners. Part of this was probably that Al and Dave are used to running AI/CMC cars that are light in the rear and have tons of wheel spin in the rain. Part of it was definitely the stiff rear sway bar setting.

 

Brakes

For this past weekend I ran Hawk HT-10s up front and PBR Metal Master's in the rear. This adjusted the brake bias WAY to the front. This setup was freaking amazing for the rain. The rears would always lock before the rears. In fact, I never got the rears to lock. This would allow me to brake much later in the rain than I could in the past. I could also trail brake deep into the corner in the rain. If the front locked, the car would push out a bit, but I'd back off the pedal and the grip would come right back. Metal Master's only run about $35 for the rear. I'd highly recommend picking up a set to try in the rain.

 

For the dry, the metal masters will be too little in the rear. I also picked up a set of Hawk HP+s that I plan to use in the dry. If that's still not enough, I have a set of Hawk Blues that I can try.

 

So that's my setup summary. Thanks to all for the discussion and the help. I'm very pleased with results!

 

-bj