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> 914/LS vs 914/6
Cracker
post Nov 24 2015, 08:42 PM
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The first video shows a couple laps running behind the 914/6/3.0 (SixAddict) of a good friend. The longer part shows a little more solo action...man these cars are fun!


Second Day after changes (1 lap only) - amazing balance in the car!
https://youtu.be/NhHMaa0_R5o

https://www.youtube.com/watch?v=NhHMaa0_R5o


https://youtu.be/LfFdP8GnXiQ (12+ minutes)

https://www.youtube.com/watch?v=LfFdP8GnXiQ


https://youtu.be/9Te6GScwxek (3 minutes)

https://www.youtube.com/watch?v=9Te6GScwxek


The GT3 Cup is faster everywhere but still allot of fun to (try) keep up with. I might be a smidgen faster down the straights - barely at best.

Tony
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ThePaintedMan
post Nov 24 2015, 08:49 PM
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A lot of guys will run 1/16-1/8th toe in on the rear to keep the car from feeling so flighty when the hammer is down. Racer Chris will chime in and have the right direction for you though I'm sure.
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wndsrfr
post Nov 24 2015, 09:01 PM
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I'm not an expert but am thinking it's not only front but rear to pay attention to....
Do you have good hard trailing arm bushings? If they're the stock rubber ones, the tail may be wagging the dog.
Kermee is set up with a smidge of toe-in in the rear as well as front--like 1/16 each side.
Twitchy at high speed is helped with the air dam/splitter, and good rear spoiler but I think you've got that covered on the front anyway.
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Cracker
post Nov 24 2015, 09:06 PM
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John - I did fail to mention that the front and rear bushings are all new - poly. All very tight...thanks. I have thought about possibly bringing the toe in some in the rear too but the front is on the verge of scary - even at just 80-90! What Camber do you run?

It could be that I'm just rusty and being a wussy...but I don't believe so in this case.

Also. I'll be running Hoosier R7's, 650 lb rear springs and 23mm T bars up front.

T
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r_towle
post Nov 24 2015, 10:13 PM
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My opinion only.

Your tub has some fixed limits.
You want as much negative camber as you can get up front.
So, push both sides in and find th one that goes the least amount, pull the other one out to match.
If you want more there are camber boxes that provide more adjustment, and they bolt in.
Toe in or almost zero up front
Toe out for slow speed autox for faster turn in.

Rear,
1/8 in toe in with that motor for sure.
When you drop the power, the rears toe out under torque.
Rear camber is in my opinion very track specific....if there is a lot of elevation change, it matters.

Search in the paddock forum, this has been discussed in quite a bit of depth over the years.

Rich
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Dave_Darling
post Nov 24 2015, 11:13 PM
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How confident are you in your suspension pick-up points? In the suspension members themselves? Could anything be flexing overly?

--DD
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stownsen914
post Nov 25 2015, 05:52 AM
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I didn't see what tires you are running. Camber settings are very different for different tires (e.g. radials - slicks or DOT style - like more camber than bias ply tires). With that said, your settings seem in the ballpark, though you might want more camber for R compound radials.

What struck me is your toe settings. For a track car, I like toe out in front - about 1/16" total toe out. In the rear, for a 914 you need 1/4" total toe in as mentioned in the earlier post.

As for the dartiness you mention. you have 0 toe in the back. The rear is probably toeing out while you are driving, due to flex (and also the 914 rear suspension naturally toes out under compression). Rear toe-out will definitely make the car feel darty. You can also check for any looseness in your suspension, and make sure your rear suspension mounting point in particular are solid, since that is a weak area in 914s.

Scott
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Cracker
post Nov 25 2015, 06:37 AM
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Scott, Rich & Dave - Thanks to you all. I did "search" the paddock for info but didn't find anything "right on" with what I was experiencing.

The entire rear suspension has been reinforced (Chris Foley's) along with Patrick M. arms. All the bushings are poly (noisy!) and new. Very tight.

I added the "tire" and "springs" in my second post - Hoosier R7 but I'm sorting on the street right now with 5-year old Victoracers. It sounds like the the culprit might be the rear toe since I'm experiencing the WORST while under heavier acceleration. If I'm going down the highway
at 75, at static speed, its not nearly as bad.

From what I've gathered, do you'all agree with having 1/4 MORE camber in the rear's than the fronts? If so, I'm well short currently in the rear...how will increasing my rear camber .75 degrees affect toe out (under acceleration)? More sensitive or less?

Thanks!

Tony
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stownsen914
post Nov 25 2015, 07:37 AM
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QUOTE(Cracker @ Nov 25 2015, 07:37 AM) *

From what I've gathered, do you'all agree with having 1/4 MORE camber in the rear's than the fronts? If so, I'm well short currently in the rear...how will increasing my rear camber .75 degrees affect toe out (under acceleration)? More sensitive or less?



Personally I run less camber in the rear since my rear tires are wider. This is a pretty typical setup from what I understand. What tires are you running?

Definitely fix the rear toe though. And for the front you could probably go with 0 toe rather than toe out if you're driving on the street.
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r_towle
post Nov 25 2015, 08:38 AM
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QUOTE(Cracker @ Nov 25 2015, 07:37 AM) *

Scott, Rich & Dave - Thanks to you all. I did "search" the paddock for info but didn't find anything "right on" with what I was experiencing.

The entire rear suspension has been reinforced (Chris Foley's) along with Patrick M. arms. All the bushings are poly (noisy!) and new. Very tight.

I added the "tire" and "springs" in my second post - Hoosier R7 but I'm sorting on the street right now with 5-year old Victoracers. It sounds like the the culprit might be the rear toe since I'm experiencing the WORST while under heavier acceleration. If I'm going down the highway
at 75, at static speed, its not nearly as bad.

From what I've gathered, do you'all agree with having 1/4 MORE camber in the rear's than the fronts? If so, I'm well short currently in the rear...how will increasing my rear camber .75 degrees affect toe out (under acceleration)? More sensitive or less?

Thanks!

Tony

Contact Chris.
He did a lot of great analysis on the rear trailing arm physics throughout the full range of motion.
The chassis has limits, so you will rub inside or outside depending on your camber in th rear, and your tire width.

Adding and removing shims is not too hard, Chris has those for sale.
Paint the inner edge of the rear tire with white shoe polish and check as you add more negative camber by removing shims.
Once it starts rubbing, add one shim back.
That will be the physical limitation of your tub, and mine will be different than yours.

Then make sure to match both sides.
Also, when you think you have as much negative as possible, take ten lbs of air out of the tires and go beat on it around all sorts of corners and up and over elevation changes...
Then check the shoe polish on the inside to make sure you are right.
The lower air pressure will allow the tire to flex more....to make it rub.

In the front, again, the tub will dictate what you can do with the stock setup.
If you don't car about stock, and the racing body won't add points for mods, using a die grinder you can oval out the three upper mounting holes and get more negative camber, but go slowly, once again the car will rub up front at the limit.

So, once again, get polish on the inner tire and look for rubbing at the rear.
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ThePaintedMan
post Nov 25 2015, 09:01 AM
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Tony, good tips from Rich and the other folks here. As I said in my first post, and as Stowsen pointed out, rear toe out has a big tendency to make the ass end of the car point in random directions, especially under acceleration. Some folks (drifters), autocrossers, ralleyers and cars with inherent understeer may actually use rear toe out to help point the car, or free it up. But it comes with the trade off of being really, really touchy, bordering on unpredictable.

As said previously, your settings aren't far off, but the main difference is the rear toe. I would start there before making huge camber changes. Toe has the most immediate, noticeable effect on the way the car drives and turns into a corner. As Rich said, camber is *typically* adjusted based on tire temps/wear and eventually driver input on how the car feels at the center of the corner. Yes, some cars run more toe at the rear, depending on spring rates, tire loads and generally how the car is being driven.

I too like either a neutral front toe, or maybe a little toe out a the front (I HATE understeer). But the rear is always toe-in.
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andys
post Nov 25 2015, 10:50 AM
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IMHO, There are street settings, and there are track settings. I don't believe in one size fits all. Aggressive camber and toe out (front) works well for the track, but will prematurely wear the tires on the street. If you plan on doing a track day, set it up accordingly, then re-set everything back to more street friendly settings.

As for the track, record all the data you can each time you pit; tire temp profiles, hot and cold tire pressures, shock settings, sway bar(s), springs, and what effect changes have on balance, etc. Without a tire temp probe and pressure gauge, you'll be shooting in the dark, though since you run a DSR, I suspect you already know this. Do you have a rear sway bar? 650# springs in the rear seems pretty stiff.

Andys
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JamesM
post Nov 25 2015, 11:34 AM
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QUOTE(Cracker @ Nov 24 2015, 08:06 PM) *

John - I did fail to mention that the front and rear bushings are all new - poly. All very tight...thanks. I have thought about possibly bringing the toe in some in the rear too but the front is on the verge of scary - even at just 80-90! What Camber do you run?

It could be that I'm just rusty and being a wussy...but I don't believe so in this case.

Also. I'll be running Hoosier R7's, 650 lb rear springs and 23mm T bars up front.

T


What sort of poly, Elephants multi piece poly bronze or are you talking a single piece of plastic? Single piece poly bushings, especially in the front, will bind and severely impact handling and ride quality. They can also wind up damaging your chassis and control arms. I have a thread somewhere on here with pictures of the damage caused by poly bushings. The harder ones can be made to work ok in the rear but absolutely must be machined to exact fit. Whatever you are running make sure they are allowing for smooth suspension movement.

My experience is autocross only, but i would agree with all the comments on rear toe, without a little toe in on the rear it can be lively and sometimes unpredictable.
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Andyrew
post Nov 25 2015, 11:41 AM
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QUOTE(Cracker @ Nov 24 2015, 07:06 PM) *

John - I did fail to mention that the front and rear bushings are all new - poly. All very tight...thanks. I have thought about possibly bringing the toe in some in the rear too but the front is on the verge of scary - even at just 80-90! What Camber do you run?

It could be that I'm just rusty and being a wussy...but I don't believe so in this case.

Also. I'll be running Hoosier R7's, 650 lb rear springs and 23mm T bars up front.

T


650lb springs??? I ran 275's in the rear with the SBC and thought that was a nice FIRM setup for the street... 21mm Tbars up front.. Do you have some 400's to try? That MIGHT help your darting issue...

Last I checked camber it was -1.7 front -1.2 rear towed 1/16 out front and 1/16 in rear.
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Cracker
post Nov 25 2015, 05:50 PM
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Andys - I agree. Yes, I do have a tire temp probe gauge.

The poly bushing are from Patrick Motorsports however I'm installing Rebel racing's system in the rear next week - less noisy.

I have 550 lb springs on there now - quite comfortable to me but will be installing the 650's before the event. I'm running a wing which is wing tunnel tested and developed to have the "capacity to produce" up to 600 lbs of downforce. Due to airflow inefficiencies we'll be waaayy under that figure but still substantial (I hope). At a track like Roebling I'll have it down. Those spring rates are much lower than my two other and previous race cars - I don't see the big deal here.

No rear swar bar but I might fabricate one eventually - probably a T-bar actually.

Spoke with Chris F. this morning...I believe the feedback regarding rear toe seems to be
accurate and the next step. Thanks to all!

Tony
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r_towle
post Nov 25 2015, 07:19 PM
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You have some unique setup requirements for that car.

Might be worth mounting a go pro underneath to watch what is going on to make y adjustments.
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andys
post Nov 25 2015, 07:43 PM
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Tony,

Careful with the aero balance at those kinds of speeds (150MPH). Can you post photos of your car with the wing and spoiler? With regard to the springs, keep in mind the rear trailing arm motion ratio; think it's 1.17:1, so your wheel rate will be higher. On Terry Stewart's SBC/914, we ran 450# springs with a big wing.

Forgot to ask. Open diff or LSD?

Andys
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Cracker
post Nov 25 2015, 08:52 PM
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Andys: Guard LSD 40/60

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QUOTE(andys @ Nov 25 2015, 08:43 PM) *

Tony,

Careful with the aero balance at those kinds of speeds (150MPH). Can you post photos of your car with the wing and spoiler? With regard to the springs, keep in mind the rear trailing arm motion ratio; think it's 1.17:1, so your wheel rate will be higher. On Terry Stewart's SBC/914, we ran 450# springs with a big wing.

Forgot to ask. Open diff or LSD?

Andys

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r_towle
post Nov 25 2015, 09:13 PM
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I think the rear wing is too small....
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messix
post Nov 25 2015, 09:15 PM
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whats the caster at?

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