Track alignment GT Tribute for race/track |
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Track alignment GT Tribute for race/track |
jhynesrockmtn |
Sep 8 2021, 07:16 PM
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#1
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Member Group: Members Posts: 418 Joined: 13-June 16 From: spokane wa Member No.: 20,100 Region Association: Pacific Northwest |
Hi, progressing with my car. GT Jager Tribute. 6 Cyl, GT bracing, Bilstein shocks all around, rears are adjustable, from PO notes the rear springs are sport, either 180 or 200 lbs, 21 or 22mm front torsion bars, rubber bushings, 22 mm front sway bar, no rear. Wheels are 15*8 rear and 15*7 front Fuchs, Toyo R888.
I had it on track for the first since putting it back together. Some issues but a good shake down weekend. My biggest issues were soft pedal which we worked on with bleeding and more bleeding. Brakes are 19mm MC, Carrera rotors and calipers, race pads. I was also getting darting under braking which caused me to be too long on the pedal and I think I either warped a rotor and/or screwed up a wheel bearing. I was getting a bad shudder at the wheel under braking at the end. It wasn't aligned properly before the weekend. I ran out of time. It goes in for that next Wednesday. Given my approximate setup, what base alignment should I give the tech who's going to work on the car. It will be used for vintage race and DE's. Thanks for any feedback. |
wndsrfr |
Sep 8 2021, 07:47 PM
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#2
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Senior Member Group: Members Posts: 1,428 Joined: 30-April 09 From: Rescue, Virginia Member No.: 10,318 Region Association: MidAtlantic Region |
Hi, progressing with my car. GT Jager Tribute. 6 Cyl, GT bracing, Bilstein shocks all around, rears are adjustable, from PO notes the rear springs are sport, either 180 or 200 lbs, 21 or 22mm front torsion bars, rubber bushings, 22 mm front sway bar, no rear. Wheels are 15*8 rear and 15*7 front Fuchs, Toyo R888. I had it on track for the first since putting it back together. Some issues but a good shake down weekend. My biggest issues were soft pedal which we worked on with bleeding and more bleeding. Brakes are 19mm MC, Carrera rotors and calipers, race pads. I was also getting darting under braking which caused me to be too long on the pedal and I think I either warped a rotor and/or screwed up a wheel bearing. I was getting a bad shudder at the wheel under braking at the end. It wasn't aligned properly before the weekend. I ran out of time. It goes in for that next Wednesday. Given my approximate setup, what base alignment should I give the tech who's going to work on the car. It will be used for vintage race and DE's. Thanks for any feedback. Start with negative 1.5 to 1.8 degrees camber front and rear. Extreme negative camber might be right for autocross but not track use in my opinion. Toe set about 1/8 inch toe in both front and rear because under hard braking it'll tend to make the wheels splay apart resulting in toe out and darty behavior... Then measure tire temps across the tread hot at the track and adjust your alignment to get them as even as you can...enjoy! |
BadToTheBown |
Sep 8 2021, 09:01 PM
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#3
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Newbie Group: Members Posts: 36 Joined: 12-July 20 From: ABQ NM Member No.: 24,488 Region Association: None |
Nice car, like the Jagers, guy in our road race club (SWMS) has the Jager nomex race suit...could you add recommendations for camber and ride height with stock suspension locations (strut spindles not raised like RSR) and I too have a GT tribute, 10" 16s in rear, 8" 15s front, please advise and thanx in advance...
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mlindner |
Sep 9 2021, 04:54 AM
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#4
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Senior Member Group: Members Posts: 1,515 Joined: 11-November 11 From: Merrimac, WI Member No.: 13,770 Region Association: Upper MidWest |
I did mine a month ago, same camber as yours and a little less toe in on the rear (1/16th each side). Had to elongate the holes on rear mounting consul to get the toe in. String alignment worked really well. Best, Mark
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mlindner |
Sep 9 2021, 04:59 AM
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#5
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Senior Member Group: Members Posts: 1,515 Joined: 11-November 11 From: Merrimac, WI Member No.: 13,770 Region Association: Upper MidWest |
For auto-cross, make two turns of your tie rod to give you little over 1/8 inch toe out. Great for turn-ins, when done (two turns back to normal toe in). Have fun. Mark
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ChrisFoley |
Sep 9 2021, 05:19 AM
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#6
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I am Tangerine Racing Group: Members Posts: 7,919 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None |
For auto-cross, make two turns of your tie rod to give you little over 1/8 inch toe out. Great for turn-ins, when done (two turns back to normal toe in). Have fun. Mark I recommend against front end toe out. The front end of a 914 can be made to work well enough in cornering without applying tricks that have a negative effect at other times. Toe out will make the car darty in a straight line, and add drag on the straights. Since you had to alter your outer console brackets to get toe in, that leads to the question - do your trailing arms have the boxed reinforcements? In my experience, that's one of the leading causes of toe out at the rear. |
jhynesrockmtn |
Sep 9 2021, 06:50 AM
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#7
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Member Group: Members Posts: 418 Joined: 13-June 16 From: spokane wa Member No.: 20,100 Region Association: Pacific Northwest |
For auto-cross, make two turns of your tie rod to give you little over 1/8 inch toe out. Great for turn-ins, when done (two turns back to normal toe in). Have fun. Mark It won't see much auto x use, maybe some in the future. Most of the time will be vintage road racing and DE's. Darting under braking was a big issue last weekend. |
jhynesrockmtn |
Sep 9 2021, 06:53 AM
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#8
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Member Group: Members Posts: 418 Joined: 13-June 16 From: spokane wa Member No.: 20,100 Region Association: Pacific Northwest |
For auto-cross, make two turns of your tie rod to give you little over 1/8 inch toe out. Great for turn-ins, when done (two turns back to normal toe in). Have fun. Mark I recommend against front end toe out. The front end of a 914 can be made to work well enough in cornering without applying tricks that have a negative effect at other times. Toe out will make the car darty in a straight line, and add drag on the straights. Since you had to alter your outer console brackets to get toe in, that leads to the question - do your trailing arms have the boxed reinforcements? In my experience, that's one of the leading causes of toe out at the rear. Thanks Chris, this car has several of your bits in it! Fuel line, shift linkage setup, brake MC reinforcement, firewall spherical bushing. |
mlindner |
Sep 9 2021, 09:19 AM
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#9
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Senior Member Group: Members Posts: 1,515 Joined: 11-November 11 From: Merrimac, WI Member No.: 13,770 Region Association: Upper MidWest |
Hi Chris, I also have many of your products (6 shift rod, linkage kit, bushings et.) all work great. I did box my control arms years ago, but this is the first time the cars back on the road in 30 years. I did not have to elongate much...seemed that the rear was neutral, just could not get toe in. All good now. And yes, toe out does make the car darty, most auto-cross I ran did not have much of a straight and over steer was better than under for me. I still need to purchase your shift adjuster product, gates are off just a little, like between the two splines. Best, Mark
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Justinp71 |
Sep 9 2021, 09:50 AM
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#10
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Senior Member Group: Members Posts: 1,583 Joined: 11-October 04 From: Sacramento, CA Member No.: 2,922 Region Association: None |
For auto-cross, make two turns of your tie rod to give you little over 1/8 inch toe out. Great for turn-ins, when done (two turns back to normal toe in). Have fun. Mark I recommend against front end toe out. The front end of a 914 can be made to work well enough in cornering without applying tricks that have a negative effect at other times. Toe out will make the car darty in a straight line, and add drag on the straights. Since you had to alter your outer console brackets to get toe in, that leads to the question - do your trailing arms have the boxed reinforcements? In my experience, that's one of the leading causes of toe out at the rear. So for the rear trailing arms are you saying if not boxed overtime they get deformed and you cannot get toe in anymore, is that correct? |
Cracker |
Oct 3 2021, 08:36 PM
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#11
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Advanced Member Group: Members Posts: 2,148 Joined: 2-February 10 From: Atlanta (area) Member No.: 11,316 Region Association: South East States |
One thing I have noticed when it comes to shops (even race) is that they have no idea how 914's operate in anger. They generally set the car up by the book - which does not translate well once the car has been modified (with either suspension or increased power). As Chris has been saying, there are other factors that can contribute to the handling of a 914 on track - making it difficult to advise with varying set-ups. My experience is based upon a more powerful 914 on track - it works. I have an open cockpit car - we run an aggressive set-up - positive (out) toe up front - hard to drive in a straight line - this is NOT how you want to set up a Teener.
One constant: The trailing arms are going to splay outward (positive toe) no matter what you do - you need to set your car up to minimize this affect; and anticipate the counter-action to not exceed zero conditions. Front: All the caster you can get (Back); Zero Toe; Max negative camber possible (match to the other side - equal) - typically between -1.5 to -2.0 Rear: Toe-IN (negative) 1/8 to 1/4 (I adjust to max but equal on both sides). Chris sells everything you need for the trailing arms; supports, reinforcements, adjusters, etc. - get with him if you are serious about tracking because you will need to do quite a bit of work back there... Your spongy (soft) brake could also be addressed by increasing the MC bore. Cracker |
ChrisFoley |
Oct 4 2021, 06:13 AM
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#12
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I am Tangerine Racing Group: Members Posts: 7,919 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None |
For auto-cross, make two turns of your tie rod to give you little over 1/8 inch toe out. Great for turn-ins, when done (two turns back to normal toe in). Have fun. Mark I recommend against front end toe out. The front end of a 914 can be made to work well enough in cornering without applying tricks that have a negative effect at other times. Toe out will make the car darty in a straight line, and add drag on the straights. Since you had to alter your outer console brackets to get toe in, that leads to the question - do your trailing arms have the boxed reinforcements? In my experience, that's one of the leading causes of toe out at the rear. So for the rear trailing arms are you saying if not boxed overtime they get deformed and you cannot get toe in anymore, is that correct? No, that's not what I was suggesting. I meant that boxing the trailing arms warps them in a manner that decreases their built in toe. That is undesirable so I recommend against reinforcing them by that method. |
slivel |
Oct 4 2021, 11:00 AM
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#13
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Old car....... older driver Group: Members Posts: 508 Joined: 10-July 04 From: San Diego Member No.: 2,332 Region Association: Southern California |
Beautiful car.
Hi, progressing with my car. GT Jager Tribute. 6 Cyl, GT bracing, Bilstein shocks all around, rears are adjustable, from PO notes the rear springs are sport, either 180 or 200 lbs, 21 or 22mm front torsion bars, rubber bushings, 22 mm front sway bar, no rear. Wheels are 15*8 rear and 15*7 front Fuchs, Toyo R888. I also had Bilstein shocks but had them custom valved using corner weights , alignment settings, spring rates, and track description for the shock engineer. I had Fuchs 16's in 8 and 9" running Hoosier 245/45 and 275/45. Same front sway bar, rear as needed for the given track. I had it on track for the first since putting it back together. Some issues but a good shake down weekend. My biggest issues were soft pedal which we worked on with bleeding and more bleeding. Brakes are 19mm MC, Carrera rotors and calipers, race pads. I ran the same brakes and also had soft pedal with anything less than new pads (Pagid black compound). Went to 23mm M/C and no longer had soft pedal but rather a hard pedal that was somewhat difficult to modulate. Wish there had been a 21 mm option. Eventually went to Boxster calipers fr and rr. Big improvement and lighter being aluminum. I could still use the Carerra rotors but also went with an SC rotor on rear. Lighter and worked well. I was also getting darting under braking which caused me to be too long on the pedal and I think I either warped a rotor and/or screwed up a wheel bearing. I was getting a bad shudder at the wheel under braking at the end. As you mentioned shudder could be many things from warped rotors to wheel bearings. I solved the hot rotor warping by running marine bilge fans in my cooling ducts on the front. It wasn't aligned properly before the weekend. I ran out of time. It goes in for that next Wednesday. Given my approximate setup, what base alignment should I give the tech who's going to work on the car. It will be used for vintage race and DE's. You didn't say what your measurements were regarding hot tire temps, pressures, tire were patterns, etc. In my experience it takes a while to get the car dialed in to your personal liking. I spent 23 years developing my car, but at least 2 or 3 seasons until I was pretty happy with the handling. Then I'd make a big change and had to play with my settings again, but the learning curve was much shorter. Thanks for any feedback. For what its worth I've attached a summary sheet of my specs. 1975_Porsche_914rev16.pdf ( 85.49k ) Number of downloads: 137 |
BillJ |
Oct 4 2021, 02:55 PM
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#14
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Senior Member Group: Members Posts: 1,093 Joined: 4-March 13 From: charlotte, NC Member No.: 15,610 Region Association: None |
FWIW - most of the vintage groups like SVRA and others mandate 15" wheels so make sure you are putting the right equipment on before setting everything up.
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