My Dream LS7GTZ.......project underway

[GOTHALOSISM]

new desktop!!!

[Mikelly]

Matt, I'm not there yet, my friend. I have to get a few more things resolved, install more safety equipment (fire and cool suit) and troubleshoot some more issues...Hope to have this thing run a full day without issues this season. Wish you luck and hope to be there at some point in the next year...

 

I averaged 2:06. Lets not say 2:04's like I was peeling them off. I did (1) out of 100. I really feel with the right aero and seat time I could shave some time off that. The back straight at 158 feels like my world is coming apart. While in other cars that would feel quite safe and planted in this car it feels like death is eminant. I hope we can work out the details and get this car where it feels solid rather than a rocketship wrapped in cardboard. I just spoke with my chief tech at the shop and he said that he feels we might need to re engineer the rear control arms as the amount of torque and acceleration we have it has moved the diff and the rear is totally out of alighnment now and the control arms are bent and the front coil overs are loose where we did some turns. The alternator pulley as well is going to have to be changed. I'm thinking that it is too small and the engine is just wearing it out at high rev. It is melting the guts right out of it. There is melted plastic from the pulley all in my engine bay. We can machine a bigger pully to slow the spin rate down, but you see this little car is costing a fortune and were still developing things. I wonder if anyone that has used the "Track Pack" billet set up from Arizona Z Car has ever had these problems???

 

People at the track were all saying how incredible it was to see a vintage car like this out on track and how you just dont see them anymore. I look around and see all the GTR's and Porsche's and realize the reason for that is that there are very few foolish men like me that would rather have an old death machine instead of a reliable solid new racer. It's what I love and always wanted to build and thats what keeps me going. Crazy or not.

 

There is a NASA event that I am supposed to be attending in a few weeks at Road Atlanta (6/15 - 6/17). I'd love for you to come down and join me in the Vintage division.

 

Matt

[cobramatt]

I don't think anyone has posted pictures of damage on those control arms, but I've had reservations about the design of the arms and the mustache bar and have said so repeatedly. I'd like to see what happened to yours when you get them off the car, just to see if my ideas hold up.

 

If you're interested, I think I've designed a pretty good set of control arms. I have no intention of manufacturing them, but I think the design is solid, reduces bind in the suspension, and would be easy enough to copy. This thread has the whole discussion about how the arms bind and how to fix from start to finish and there are pictures of several different solutions.

 

http://forums.hybrid...rol-arm-design/

 

Here are the pics of my end result. I may still change the design so that I have studs welded into the arms instead of bolts going through the monoballs and into the arm on the inners, but I think most would probably just run the poly bushings on the inside (could cut up a set of 280Z arms to start with) and then that isn't an issue:

 

http://forums.hybrid...post__p__848687

 

Jon,

I will have pictures up tomorrow evening of the damage. When we took the torque/stress out of the diff the control arms seemed to relax which still means they are weak. They were just under a ton of bind when everything else shifted. We actually had already modified the Arizona Z setup in small ways. One main thing is we drilled up through the lower control arm support and put bolts through the mounts that kept the mounting bracket from turning and shifting under cornering g's. That worked but the lower control arm mounts/brackets are toast. They are bent badly. We are going to remove them and machine some new ones out of much stronger gauge steel, cromoly, or something. We haven't gotten that far yet so we shall see what works best. We will also need to fab some re inforcement brackets that will keep the rear end and the control arm brackets together. So under heavy torque the rear end doesn't put all the stress in one place on the mounting bracket. The other thing we have learned is that the stock pulley off a ZO6 is too small and is made of plastic, which melts in this set up. This is the second brand new alternator I have spent. We are going to increase the diameter of the pulley to slow its speed down and machine it out of billet. If that doesnt work we are going to have to change the pullyes and go with a tooth belt drive set up.

 

Took a look at the Aero today while everyone was giving their opinion. I wanted to keep the appearance of the Vintage aero three piece tail for personal reasons. After a few highspeed sessions at VIR and AMP I have decided to go with a wing set up. Its the only way to actually make the car semi safe. The original three piece tail worked fine back in the day but this application is going to require a different approach. Someone mentioned that I need a new patch on my race suit that says "test pilot". I'm no Chuck Yager but it put things in perspective. We are going to fashion a full splitter up front, most likely out of CF. We are going to have to fashion some screening in the mouth of the G nose as the radiator box is working fantastic but is creating a ton a drag. We are also looking at creating some undertray panels. They would also extend out at the rocker panels and smooth the air flow to the flares.

 

There is a NASA event at Road Atlanta the 15th -17th. Our goal is to have all the necessary items addressed and ready to to get her back out on track. We are going to order all the other items and address them as they come in. Thats a lot to do in a week. Lets get busy..............

 

Matt

[cobramatt]

I have posted a few pictures of the damage incurred in the rear suspension during last track day. We are going to basically re engineer the set up. Actually we are going to re machine the lower control arm tubes that mount the arms out of a stronger material. Stainless is not the answer. I do not want to act like the set up is bad and that Arizona Z did a bad job in the design because this particular car calls for a different set up and the fault lies with me 100%. We needed a starting point. One that was an improvement from basic stock set up and thats what we got. This would be an incredible set up if you were upgrading a stock rear end. As you can see from the pictures the torque of this car has really bent and distorted the geometry of the control arms. We have a solution and will work towards that. I am cheating a little because I dont have tome to do all the work necessary to fix this 100% by this weekend as I have a Vintage event at Road Atlanta so we are going to repair this set up and just get her track worthy. I see this car actually getting better at a much more rapid pace now that we are actually on track and putting her thru the paces and retrieving the data. As we progress with the re design I will post all pictures and progress.

 

Matt

[VKLR]

The damaged parts indicate to me that you are actually putting down some serious power.

[cobramatt]

I have posted a few pictures of the damage incurred in the rear suspension during last track day. We are going to basically re engineer the set up. Actually we are going to re machine the lower control arm tubes that mount the arms out of a stronger material. Stainless is not the answer. I do not want to act like the set up is bad and that Arizona Z did a bad job in the design because this particular car calls for a different set up and the fault lies with me 100%. We needed a starting point. One that was an improvement from basic stock set up and thats what we got. This would be an incredible set up if you were upgrading a stock rear end. As you can see from the pictures the torque of this car has really bent and distorted the geometry of the control arms. We have a solution and will work towards that. I am cheating a little because I dont have tome to do all the work necessary to fix this 100% by this weekend as I have a Vintage event at Road Atlanta so we are going to repair this set up and just get her track worthy. I see this car actually getting better at a much more rapid pace now that we are actually on track and putting her thru the paces and retrieving the data. As we progress with the re design I will post all pictures and progress.

 

Matt

 

I have attached a few pictures of the re design and new chromoly thicker tubing used to brace the lower control arms. We have basically boxed the whole apparatus to create a square set up. This is far better than before and will not move around. We have also used spacers behind the sway bar mounts as the geometry of the sway bar was way off. We actually plan on going to a complete hiem joint set up and lose the old school type bushings. We are just trying to get her to the track tomorrow for the weekend races. One of the biggest things we did was make the mustach bar and the mounts as one. They were completely independent of each other before. My guess is that Dave at Arizona Z never intended for this set up to work with a car putting out anything over 400 HP, much less 640. We will try this set up and I will give feedback after this weekend. I feel like this is a huge step in the right direction. More info to come.........

 

Matt

[Bob_H]

I just realized something big when looking at your pics- I never realized Arizona Z mounted the front of the diff from the bottom only. There lies your issue.

The diff wants to rotate up with power application- and it should be constrained from above, or more properly, try to rotate into a fixed upper surface. We had lots of issues with this in 8.8 swaps into the 93-95 RX7 chassis,( I was putting out 515 rwhp). You need the bushings on top mounted though a fixed upper bar/plate/whatever that transmits power into the unibody vice the suspension arms.

Wow, I consider that a big design deficiency. First, it doesn't have anything to keep the inner lower helm joints from rotating with high lateral G beyond pure friction/clamping force and the diff mounting point exerts considerable force in the mid point of a long bar.

Your solution helps- but if you keep the diff- change the mounting to the top vice the bottom and bolt/weld it to the unibody/frame.

If that is not clear- let me know.

Bobby

[roger280zx]

The pics of the wrap look so good! Cant wait to see it at the track.

[cobramatt]

I just realized something big when looking at your pics- I never realized Arizona Z mounted the front of the diff from the bottom only. There lies your issue.

The diff wants to rotate up with power application- and it should be constrained from above, or more properly, try to rotate into a fixed upper surface. We had lots of issues with this in 8.8 swaps into the 93-95 RX7 chassis,( I was putting out 515 rwhp). You need the bushings on top mounted though a fixed upper bar/plate/whatever that transmits power into the unibody vice the suspension arms.

Wow, I consider that a big design deficiency. First, it doesn't have anything to keep the inner lower helm joints from rotating with high lateral G beyond pure friction/clamping force and the diff mounting point exerts considerable force in the mid point of a long bar.

Your solution helps- but if you keep the diff- change the mounting to the top vice the bottom and bolt/weld it to the unibody/frame.

If that is not clear- let me know.

Bobby

 

Here are a few other pics that show how we tied it all together. Note how the Mustache bar is now one with the lower control arm mounts. We had to actually re port the holes in the sway bar mount after we squared up the new rear end geometry. It is square to a 1000th. The sway bar mount, that we machined some 1/2 inch spacers that you can see in the pics, was off so my only conclusion is that the set up was not square from the beginning. If it was the holes would have lined up. The spacers correct the geometry of the sway bar that was offset by increasing the wheelbase. Next week we are going to take everything we learn at the track this weekend and go from there. I am excited beacause what I thought was a real downforce issue and was planning on scrapping the three piece IMSA tail for a wing could have been influenced by the fact that my cars rear end was moving all over the place due to the old set up design. I would love to be able to keep the three piece tail for period correctness. Its about the only thing thats actually vintage so I'm hangin on to it.......

 

Matt

[Bob_H]

That will definitely help - here is a thread on norotors.com about a diff mounting ears braking.

Speedfab owns a shop down in FL and his posts are worth noting. Specifically, posts #8 #16 and #27 has a good picture of a FC,(late 80's RX7) mount for a 8.8 diff constrained from the top.

 

http://www.norotors.com/index.php?topic=4344.msg59089#msg59089

 

When you shorten the diff nose - as the Q45, an 8.8 from a Ford IRS, etc.. - the force required to counter the rotational motion goes up compared to a long nose R200 - leverage plain and simple.

Your solution might work for a while - but that is a lot of force being put thorough those chromoly arms and you will likely see the washer on the top of the bushing start to bow up,(reverse mushroom), after some strong track sessions - that is what I was seeing and my washer was at least as thick as the one you have - maybe thicker.

That will also ultimately effect your alignment under accel, more so in lower gears with the higher torque multiplication.

Edit - I was thinking of someone else who took a video of their suspension on track - it was not you. So sorry! However, it is very revealing how much it does move if you can get even a lipstick cam down there for just some turns in a parking lot./edit.

 

You took some good videos of your suspension - after a track weekend - point a camera at the front of the diff and see how much it is moving up and down in 1st gear with light and heavy accel - you will be surprised I'd bet.

 

Good luck this weekend!

Edited June 15, 2012 by Bob_H

[cobramatt]

What a perfect weekend at Road Atlanta with NASA Southeast. We had a better than expected outing Saturday and Sunday and won both of our races. The weekend did however not go without some difficulties. I was having clutch issues a few weeks ago at VIR and we thought we had worked it out. NOT......... I was loosing the clutch after Saturday's morning warm up and after the qualifying session it was gone. I am very fortunate to have some guys there that were able to push me off at the start of the remaining races and sessions. We just had to rev match the entire time, which if you have ever been in that situation it actually makes you a better driver, can be hard on the tranny at lower speeds, but you really gotta focus. We are going to install a torque converter clutch (7 1/4 inch twin disc) and remove the (5 inch triple disk) and see if we can work this clutch thing out.

 

I will say that the response at the track over the car is incredible. It had quite the following after the weekend. People I didn't know coming up and telling me stories of how it brought back memories of when they were younger and would watch the IMSA GTU cars. I met one guy, Eric, who has a perfectly restored documented Bob Sharp car. I had him pull his car up to mine and take a few pictures. It is something else.

 

Matt

 

I forgot.........The new rear end suspension is working fine for now. Haven't really gotten it up in the air yet to inspect up close, but all in all it did very well.

Edited June 18, 2012 by cobramatt

[cobramatt]

A friend that owns another performance shop, Forged Performance took this shot. Turn 5 Road Atlanta. Thanks Sharif.

 

Matt

[Mikelly]

Looks like a million bucks Matt! Really diggin' the wrap...

 

Mike

[VKLR]

It sounds really nice also. I had a great time Saturday, thanks for lunch.

With the low spectator turnout I felt like i had the run of the track. Looking forward to the next NASA event.

[78zstyle]

I bet your call freaking hauls.

[cobramatt]

I have recieved 100's of pictures of The Z at this last race. I thought I would post a few of them.

 

It brings back memories of the car I remember in the same corners over 30 years ago. I would have never imagined that my dream of actually being behind the wheel would have ever come true.

 

Matt

[cobramatt]

I bet your call freaking hauls.

 

That would be a safe bet............

[1 tuff z]

Great pics, did you have any printed in large size to matte & mount in the garage or man cave?

[cobramatt]

Great pics, did you have any printed in large size to matte & mount in the garage or man cave?

 

No.......Not a bad idea though. Thank you for the idea, I'll look in to it.

 

Matt

[Madovic]

I have recieved 100's of pictures of The Z at this last race. I thought I would post a few of them.

 

It brings back memories of the car I remember in the same corners over 30 years ago. I would have never imagined that my dream of actually being behind the wheel would have ever come true.

 

Matt

 

It is impossible for me to look at pictures of your car and not smile. Thanks for sharing, it is certainly motivating to keep working on mine. Hope to have it at the track next year sometime.

 

Tim