1970 GTO Version 2.0

[bwhinnen]

Nice to see some DBA rotors there Andrew, lets see how they hold up, I have DBA4000's on my WRX, obviously not a 14" rotor though

[andrewb70]

Yesterday I took the car to get the corner weight set and to make sure that my front sway bar was installed in such a way that it was not pre-loading the suspension. I took my car to Nashville, to Earl Owens Chassis. If anyone in that area needs any kind of fabrication or setup help, Earl knows his stuff.

Here are the new corner weights:

--LF------------------RF
1094-----------------1044



--LR-----------------RR
968-----------------913

This is with driver of similar weight to me.

Total: 4019 lbs
Distribution: 53.2 Front / 46.8% rear

Cross weight 50%

This was done with the front sway bar disconnected. Minor adjustments were needed on the drivers side rear spring jack to get the cross weight to 50%. Once the weights were adjusted I installed the sway bar in such a way that it did not alter any of the corner weights. I know that the sway bar was preloading the suspension fairly heavily before. This was evident by the fact that when I made right turns, the car would handle very neutral. There was just a hint of understeer that was easily controlled with the throttle. When making left turns the car would push much harder and the understeer was less controllable with the throttle.
Now the car handles the same way whether I am making left or right turns.

After installing the AFX spindles, I had to get the car aligned again. I decided to add just a hair more negative camber.

-.7* camber
5.5* caster ( little more on the right)
0 toe

The handling is very neutral. There is just a hint of understeer that is easily modulated with the throttle. The biggest difference is going over bumps, especially when just one wheel hits a bump. Before, the car would dart and wander. I have no doubt that this was cause by the bump steer due to the b-body spindle swap. With the AFX spindles all of that is gone. The car tracks straight as an arrow when going over bumps. There is a slight tendency to track along the grooves in the road, but I attribute that to the shorter sidewall on the new tires.

Andrew

[bwhinnen]

I've always found my cars to track with grooves when I have a neutral toe Andrew. But I prefer the overall feel you get with that toe. I am also talking fr to rear as well as just front.

Is -0.7* enough camber for the front? I'm used to my car where I run -2.5* front and -1.5* rear, but lighter smaller car... Of course I don't know your driving preferences or just how good the car may feel at the moment either!

Sounds like you've got it where you want it though great work!

[andrewb70]

I've always found my cars to track with grooves when I have a neutral toe Andrew. But I prefer the overall feel you get with that toe. I am also talking fr to rear as well as just front.

Is -0.7* enough camber for the front? I'm used to my car where I run -2.5* front and -1.5* rear, but lighter smaller car... Of course I don't know your driving preferences or just how good the car may feel at the moment either!

Sounds like you've got it where you want it though great work!

For the way I use my car, -.7* should be plenty. I have a set of shims that I can install in about 10 minutes that will give me -2.5* camber and more caster, for track use.

Andrew

[bwhinnen]

For the way I use my car, -.7* should be plenty. I have a set of shims that I can install in about 10 minutes that will give me -2.5* camber and more caster, for track use.

Andrew

Nice one, that's the way it should be! Easy 10 minutes work!

Can't wait to see some vids of you on the track!

[jackfrost]

sweet. time for some ink.

[andrewb70]

Tonight I decided to take the car to the drag strip to see how my new tires worked. I got to the track, did my burn out. The car pulled hard out of the hole. I was able to launch it from about 3000 RPM, slipping the clutch a little, no tire spin. On the 1-2 shift, it felt like I missed second. No big deal. I aborted the run. Stepped on the clutch and got nothing. No pressure at all. Straight to the floor. I matched the RPM and got the car into 3rd gear and drove back to the pits. Looked under the car and saw a nice little stream of fluid coming from the bellhousing. So the hydraulic TOB puked.

I now have less than 9 days until RTTH IV. I need to order a rebuild kit. I may even order a new TOB. I am not looking forward to spending the weekend on my back, but it's better that this happened now and now a week from now.

Andrew

[parsonsj]

That's bad news Andrew!!! You think you over-traveled the TOB? Maybe you pounded that clutch pedal more than usual?

jp

[andrewb70]

That's bad news Andrew!!! You think you over-traveled the TOB? Maybe you pounded that clutch pedal more than usual?

jp

I thought about that. The only thing that bothers me about that theory is that I have a ton of miles on the car already. If the TOB was being overtraveled I would think it would have puked by now.

Andrew

[ScotI]

I thought about that. The only thing that bothers me about that theory is that I have a ton of miles on the car already. If the TOB was being overtraveled I would think it would have puked by now.

Andrew

Ton of miles w/how many drag strip type launches? Awesome revisions BTW. Time to change the pic in your signature . . ....

I'll definitely look you up if your @ RTTH.

[parsonsj]

I was thinking that the adrenaline rush from drag-racing gave you a little more oomph on your clutch depression, either in force or travel, that might have pushed the TOB past its design point.

jp

[andrewb70]

I was thinking that the adrenaline rush from drag-racing gave you a little more oomph on your clutch depression, either in force or travel, that might have pushed the TOB past its design point.

jp

That is certainly possible. I will know more when I pull it apart. I have 2 rebuild kits on the way from Quarter Master and I also have the Howe bearing on the way. Apparently the new design has a built in stop to prevent overtraveling and the has a longer stroke than the Quarter Master bearing.

Andrew

[OLDFLM]

"... and has a longer stroke than the Quarter Master..."

That's what she said! LMAO

[Finch]

Andrew,

What clutch/TO bearing combo you running? I had a Centerforce II with a Howe setup that would blow only when I was really putting it to it. The weights on the clutch would flex the fingers out and the zero clearance TO bearing would get so much force on it the o-rings would blow.

I have that QM TO assembly from the LS6 I got from you laying around if any of those parts will work. Just let me know.

brian,

[andrewb70]

Andrew,

What clutch/TO bearing combo you running? I had a Centerforce II with a Howe setup that would blow only when I was really putting it to it. The weights on the clutch would flex the fingers out and the zero clearance TO bearing would get so much force on it the o-rings would blow.

I have that QM TO assembly from the LS6 I got from you laying around if any of those parts will work. Just let me know.

brian,

Hey Brian,

I am using a stock LS7 clutch and the Quarter Master street TOB. Little different than your Tri-Lite, but I really appreciate the offer. It is definitely possible that it blew because of "spirited" driving. It happened on the 1-2 shift. I pushed hard on the pedal and got nothing.

Howe has redesigned their bearing so I am hopeful that it is more durable. John Parsons is using a Howe bearing and as far as I know he is not having issues. Then again he does not drag race.

Maybe I should go with an external slave and fork....:/

Andrew

[jackfrost]

Apparently the new design has a built in stop to prevent overtraveling

i was just wondering why there wasn't a travel limiter in these things...

let us know how it works.

[andrewb70]

i was just wondering why there wasn't a travel limiter in these things...

let us know how it works.

The travel is limited by the installation of a pedal stop.

Andrew

[andrewb70]

No mystery here:



Based on the cut in the o-ring the problem was over traveling. I guess the excitement of drag racing made me press on the clutch pedal just a little bit more than when I drive around town. I will do some more investigating and see if I can limit the movement of the pedal and still get enough travel at the bearing to release the clutch.

Stay tuned for more.

Andrew

[andrewb70]

All fixed. It's raining so no test drive but I am sure its fine. I shortened the rod that connects the pedal to the MC. This reduced the stroke of the MC thus reducing the stroke of the TOB. I was still able to turn the output shaft easily by hand when the clutch was pressed. So I was definitely overtraveling the TOB before. Back on track for RTTH IV!

Andrew

[OLDFLM]

Glad to hear it Andrew!