IMSA GTU vintage racer build

[tube80z]

19 hours ago, clarkspeed said:

So do I add an intermediate shaft with 2 more joints or a 3rd U-joint? And if I add 2 more joints do I need a bearing to support?

 

 

To answer the first questions, yes and yes.  You will need another joint and a intermediate shaft support.  Do you also have clearance around the engine?  When I mocked up mine using a similar rack with the L-series block I had a small interference with the lower corner.  I had to slide the entire rack to the driver's side to clear.  The shorter V8 block didn't have that issue.

[clarkspeed]

As I suspected. Those damn u-joints are not cheap.

 

I just checked the Woodward website. They say 20degree max and I am about 25. And they need to be clocked correctly. Glad I read that.

 

I fit checked everything prior. But that does not mean I did not miss something. Plus the engine is offset about an inch.

 

Glassin' up the G-nose last 2 days. 4 layers of 6 Oz cloth on each side of cardboard forms. Didnt add much weight at all. Should be strong enough for a radiator shroud, I hope.

 

 

[calZ]

The clocking is necessary to maintain a constant rate, but in reality I don't know if you'd notice a huge difference on a steering shaft. I always love sharing this video. 

The final 2 demonstrations show why the clocking is important. 

Edited December 12, 2022 by calZ

[Exposed]

great progress, really enjoy following this build.

 

How much longer is the Gnose front end from the orginal?

[clarkspeed]

20 hours ago, calZ said:

The clocking is necessary to maintain a constant rate, but in reality I don't know if you'd notice a huge difference on a steering shaft. I always love sharing this video. 

The final 2 demonstrations show why the clocking is important. 

That's vintage. Like a Bart Simpson school movie with Troy McClure.

 

Critical stuff on a driveshaft for sure.

[clarkspeed]

On 12/12/2022 at 11:30 AM, Exposed said:

great progress, really enjoy following this build.

 

How much longer is the Gnose front end 

I don't know. I will take a measurement next time. But my g-nose is also 4" wider than a normal g-nose.

[clarkspeed]

Parts came in today so I grabbed a couple hours tonight to finish. Here is my extra knuckle solution. I clocked everything and tried to make all 3 angles about equal. Seems to be quite smooth. First time I have turned the wheels from the steering wheel. That was a good feeling.

[clarkspeed]

1 step forward, 10 steps back. Dropped it on the ground and started finding stuff. 

 

Good news-my shock lengths are spot on so almost ready to order.

Bad news- steering tie rods are at a bad angle. Need to raise the rack, but I think that will hit the oil pan. 10mm Shorter knuckles may work, but the steering is pretty quick already.

Good news- I dropped the ride height down from 5 to 4". That looked about right and the roll centers looked damn close. And I can go a little lower if needed.

Bad news- I may need to relocate the front spring perches lower. I had to remove the spring to get it that low. That will not be easy. The engine will compress the springs about an inch, and I need an inch.

 

Anyway here is a shot on the ground and my g-nose fiberglass complete. 

 

 

[calZ]

Could always just order some shorter springs rather than having to cut and weld the perches. Costs money vs time, but as time goes on I'm more and more willing to spend the former in an effort to save the latter. 

[AydinZ71]

Looking good Clark! Man, it’s got to be tough fabricating suspension mounting points since they are all so interdependent. Good luck! 

[clarkspeed]

Yea, I didn't realize I could get 7" springs. Problem solved. I thought I would have to go to 6.

I went ahead and purchased some shorter steering knuckles. I think that will work and my steering can go quicker.

Finished the front close out panel today. I like it.

 

[clarkspeed]

On 12/18/2022 at 12:05 PM, AydinZ71 said:

Looking good Clark! Man, it’s got to be tough fabricating suspension mounting points since they are all so interdependent. Good 

Well the fabricating is all complete, it's a matter of where to set things.

 

In summary, for anyone who did not catch everything earlier.

 

1. Most all the pickup points are standard for the chassis with the exception of below. I measured from my other car what I could not get from FSM drawings.

2. I raised the rear control arm inner pivots to lower roll center

3. I modified rear control arm for toe adjust but OEM length..

4. I modified steering knuckles to accept an adjustable stud so I can change RC in the front. Ball joint is a spherical bearing.

5. Front control arms are custom but set to OEM lengths.

6. I relocated top strut mount rearward to increase nominal caster to 6 degrees.

 

A lot of weird stuff. But sitting at 4" ride height, and that 4" is also lowest point on car, the "rough" geometry is about perfect for a strut car. Crossmember is 4", all chassis rails and flat floor pan are 4". Exhaust is tucked up. Most likely I will need to raise the back or lower the front to get the aero balance right. And I have that ability, I think. I am already day dreaming about track testing and what I want to try.

 

Getting excited about prospect of this car on a track. But I now have to change my mindset. The build is no longer a push for the next milestone. It is now an attempt to complete each small task and chasing every problem whether it takes 1 hour or 8 hours to complete it. Must try not to get frustrated and leave the shop too early. I ordered all the wiring material last week. I am excited about doing that.

[clarkspeed]

Merry Xmas and Happy New Year. Busting it this week to get as much done as possible before my work resumes. 

 

Lots of little stuff going on, but here is the brake duct exit. The front spindle flange is by far the hardest thing I have ever drilled on a Z.  Routing the brake hose looks like it is going to be a real challenge with the sway bar end links in the way.

Edited December 28, 2022 by clarkspeed

[AydinZ71]

Ugh… I’m not looking forward to it. I need to adapt my caliper mounts for the s130 vented rotors and calipers. Do you think the steel here is forged/hardened? What rotors/calipers do you plan to run? Is that flange intended to feed the “hat” cavity of the rotor and have the air fan out the rotor vents?

 

good luck Clark! Great to get in some Christmas work! Merry Christmas and happy new year.  
 

 

[clarkspeed]

Forged and hardened if I had to guess. And a high quality steel to handle all that is going on there being machined out of 1 piece.

 

Yes the flange directs air actually at the rotor and center section since 3" diameter. My rotor/caliper pics are a few posts back. Wilwood 6 piston with 11.75 x 0.810 rotors. Got an email from Porterfield with 10% off so I ordered F/R pads. I think I ordered Pagid or performance friction. I know it was not Hawk.

 

What does it take to mount your caliper? Most "kits" and custom applications have some sort of special bracket to adapt the caliper to the stock ears.

 

Scored a N42 block, crank, and rods today to add to the collection. It has a newer oil pump, degree wheel, and dizzy block off plate.

Edited December 29, 2022 by clarkspeed

[AydinZ71]

Sweet man! Nice score! Count the notches on the trigger wheel. If it’s 36, with one tooth missing, it will be for a ford EDIS module. That’s what I have mounted on the L24 with the megajolt (thanks to a suggestion from this forum). 
 

So I don’t actually know of a caliper adapter for an S30 to S130 brakes. Greg said he “brazed” his on. Maybe silicone bronze? I was literally going to put the rotor on, caliper on (with some clamping force applied) then weld a bracket to the existing caliper mount. If he brazed, I’m thinking the cast strut material is forged and hardened as you said, and hence difficult or unadvisable to weld to? 
 

Il have to develop a solution. Let me know if you have any ideas  

 

whatcha got planned for the block? 

[tube80z]

On 12/28/2022 at 9:11 PM, AydinZ71 said:

So I don’t actually know of a caliper adapter for an S30 to S130 brakes. Greg said he “brazed” his on. Maybe silicone bronze? I was literally going to put the rotor on, caliper on (with some clamping force applied) then weld a bracket to the existing caliper mount. If he brazed, I’m thinking the cast strut material is forged and hardened as you said, and hence difficult or unadvisable to weld to? 

 

You can weld to it fine.  Greg most likely was worried about distortion.  What I found when doing my brakes (remember 13 inch wheels) is that the original ears the caliper bolted to will interfere with the new caliper as you try and bolt it up.  So you need to remove some section of these in order for everything to align.

 

As Clarke mentioned this is some really tough steel.  I milled one side of the bracket and it took a few days of working on it in the evenings and ruined a couple of cutters.  Next side was sliced off using a fire axe (cutting torch) and then ground smooth.  New bracket was welded to the old base.

[clarkspeed]

Sounds like Cary has the answers. I would be surprised if Greg had them brazed but I dont know. He is racing the EP car again in a couple weeks but I dont think I can make it. What caliper do you run? Stock correct?

 

I didn't count the teeth but I think it is for a 350z? I think he said that is where the sensor came from.

 

No plans for block. Just a spare. Price was right.....free.

[AydinZ71]

On 12/30/2022 at 3:31 PM, clarkspeed said:

Sounds like Cary has the answers. I would be surprised if Greg had them brazed but I dont know. He is racing the EP car again in a couple weeks but I dont think I can make it. What caliper do you run? Stock correct?

 

I didn't count the teeth but I think it is for a 350z? I think he said that is where the sensor came from.

 

No plans for block. Just a spare. Price was right.....free.

 

@clarkspeed Yep, today all I have is stock calipers and cross-drilled stock rotors (from PO). The S130 rotors are still pretty small, but its just a night-and-day difference going from a solid rotor to the vented so its well worth it. Stock spec. S130 diameter vented rotors and OEM S130 calipers are allowed on the spec. line. Oddly, Greg worked-up a solution within the rules to use an AL rear caliper, but still no idea what rotor he used or what model/spec caliper. 

 

Did you see his times posted from the Majors? He absolutely clobbered the completion! I mean, my jaw dropped. 

 

Il have to bug him more on how he did his brakes. Maybe ask him for some pictures if he still has the #2 (now #12) car handy. Its usually at his buddies place in Jacksonville. 

[AydinZ71]

On 12/30/2022 at 12:26 PM, tube80z said:

 

You can weld to it fine.  Greg most likely was worried about distortion.  What I found when doing my brakes (remember 13 inch wheels) is that the original ears the caliper bolted to will interfere with the new caliper as you try and bolt it up.  So you need to remove some section of these in order for everything to align.

 

As Clarke mentioned this is some really tough steel.  I milled one side of the bracket and it took a few days of working on it in the evenings and ruined a couple of cutters.  Next side was sliced off using a fire axe (cutting torch) and then ground smooth.  New bracket was welded to the old base.

 

Ah! hey, that's helpful Cary! Silly question, why the 13" wheels?