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  #411  
Old 06-16-2021, 08:52 PM
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heinke heinke is offline
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Location: Livermore, CA
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Post Progress on Transaxle Shift to Header Clearance

While I was busy fabricating engine mounts, I put out a request to Pete Aardema to make a new billet, one piece shift mechanism with the objective to increase header clearance as compared to the two piece unit I had cobbled together. As a reminder, I had paired up the cast aluminum shift housing from a Tremec 6060 transmission with an adapter plate so it could mount on a Tremec TKO type housing. It resulted in about 1/8” clearance with the header mockup. Here's a picture of the two piece unit.



Pete’s machinist, Kevin Braun, machined out this very nice, one piece shift mechanism that uses the same basic internal components scavenged from the old unit.



The clearance is now about 3/8 to ½” with the same header mockup. Kevin carved it from a piece of 1 ½” aluminum billet on a CNC mill. While we were at it, the unit was upgraded so the shift shaft is now carried on ball bearings instead of bushings. This should help it to keep from tightening up when the inevitable heat soaks into it.

In addition, I’m adjusting the header design to also increase the clearance. More to come on the header re-design as I redo the header mockup for it.
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  #412  
Old 06-16-2021, 10:12 PM
Reno Reno is offline
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That looks great.
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  #413  
Old 06-17-2021, 08:58 PM
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Steve Hamilton Steve Hamilton is offline
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Hi Joel
Great teamwork and wonderful results. Where there is a will there is a way!

Thanks for sharing with the members.

Steve
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  #414  
Old 06-18-2021, 08:00 PM
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heinke heinke is offline
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Post Chassis Member Reinforcement

Now that I have cut out the chassis next to AC compressor and belt to get sufficient clearance, I decided it would be wise to add some metal back for reinforcement. I don’t know that this reinforcement was strictly needed but I thought it better safe than sorry. Here’s a picture of the vertical member that spans between the lower and upper A arm pivots after it was fully trimmed for the AC compressor clearance.





The only real option is to add the reinforcement to the outside of the frame rails. I had already installed a similar reinforcement on the drivers side so I had a good sense for how to go about it. Fortunately, I had plenty of ¼” aluminum plate still on hand to make this odd shaped piece.



Given the current heat wave here in N. CA, I decide to glue this reinforcement in place during the early morning cool to give me enough time to fully spread the glue over both surfaces and get it fully clamped in place prior to expiration of the 15 minute glue work time. One more loose end checked off the Miura project list.
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  #415  
Old 06-26-2021, 05:24 PM
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heinke heinke is offline
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Post Header Design/Mockup

Header fabrication is now underway, well at least the first stage which is full mockup fabrication to determine header tube routing optimized to get to an equal length design. The specification calls for 28 ½”primary tubes that taper from 1 5/8” to 1 7/8” over their length to 4 into 1 collectors and then 3” secondary tubes to a “Y” so all 8 exhaust pulses are mixed into to a single 4” pipe prior to routing to a muffler. The primary objective for the exhaust system design is to mimic the sound of a V12 as closely as possible even though it’s produced from a Coyote V8.

The transverse engine placement is forcing me to be very creative with primary tube routing because I can’t just duplicate tried and true designs from similar situations. There just aren’t enough mid-engine transverse V8 cars out there to have much to draw ideas from. I did get the ¾” thick header flange for use on the aft bank (aka passenger side) where there’s only minimal clearance with the transaxle shift mechanism.



I transcribed the ports and mount holes onto a ¾” thick piece of wood so I could work out how best to maximize transaxle clearance while still getting good flow into the headers. I decided to have primary tubes attach to the flange at a 50 degree angle so the tubes are basically horizontal as they pass over the transaxle. The main challenge I ran into is lack of clearance to get bolts onto the upper mounting studs. So the porting in the flanges needs to be angled away from the upper studs in addition to angling upward. I had this worked out by the 3rd from left port in my wooden flange.



I had Burns Stainless fabricate the merged collectors for these headers. The aft header uses a traditional stacked collector design and the fore header requires a flat collector design. The fore header is to be routed under the engine and the flat collector is positioned under the short part of the oil pan. I chose this under engine routing as it’s the only chance at making the secondary pipes anywhere near equal length. These collectors almost look like jewelry with perfect, tiny TIG welds on them.



I chose to do mockup headers in carbon steel using cheap Chinese made mandrel bends. Once I had the port spacing and primary tube to flange angle worked out, it was a bunch of cutting, tack welding, measuring, etc. etc. I found magnets removed from old computer hard drives to be very helpful in holding tubes temporarily in place for fitting and tack welding. These magnets are very strong for their small size.



There is a very small envelope of space for this header. It goes over the top of the transaxle, dives down under the rear chassis cross member, proceeds over the top of the final drive case and curving out a small hole at chassis rear. All this while bringing in each primary tube at 28 ½” length, well close anyway as I got them all within ¼” of each other and can see how to easily get them exact when I build the actual header.





And here it is with the chassis cross member back in place.





I do think some notches might be needed in the cross member for primary tube clearance. I’m not sure yet because I chose to use 1 ¾” primary tubes throughout for the mockups where the actual headers will use 1 5/8” tube there going up to 1 ¾” about 4 inches further down the pipes.

Well it’s onto mockup on the fore side header. That one will have a whole different set of challenges with very little in common with the aft header except 28 ½” primary tubes.
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  #416  
Old 06-26-2021, 07:34 PM
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Steve Hamilton Steve Hamilton is offline
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Hi Joel
Looks like you have 10 gallons of worms in a 5 gallon bucket!
I’m confident that you will find the desired results. Thanks for bringing us along on your adventure.
Steve
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  #417  
Old 06-27-2021, 03:28 PM
Mr fixit Mr fixit is offline
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WOW Joel,

That is a piece of art, even if it is just the mockup for what's too come. Not being a big engine guy, (Morris Minor 1098 cc) what about the heat around all the engine and chassis areas. I assume you will use some type of heat wrap on the pipes, but is that going to be enough to protect everything and dissipate enough heat?

Beginner just asking to learn.


This is the most awesome build to be following.

TX
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  #418  
Old 06-28-2021, 09:51 AM
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heinke heinke is offline
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Quote:
Originally Posted by Steve Hamilton View Post
Hi Joel
Looks like you have 10 gallons of worms in a 5 gallon bucket!
Steve
Looks aren't deceiving.
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  #419  
Old 06-28-2021, 10:06 AM
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heinke heinke is offline
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Quote:
Originally Posted by Mr fixit View Post
WOW Joel,

That is a piece of art, even if it is just the mockup for what's too come. Not being a big engine guy, (Morris Minor 1098 cc) what about the heat around all the engine and chassis areas. I assume you will use some type of heat wrap on the pipes, but is that going to be enough to protect everything and dissipate enough heat?

Beginner just asking to learn.


This is the most awesome build to be following.

TX
Mr fixit
Chris
Chris: heat radiated out of the pipes is a concern. I don't think the heat will hurt the chassis itself but I do plan on routing heat sensitive stuff like shift cables and wiring away from the header. I don't plan to "wrap" the headers as I've seen that be very destructive to the metal in the header. Given the cost of the parts to make these headers, I want them to last a good long time and not need replacement after a couple of years of driving. The headers will be built with 304 SS which is better than carbon steel at keeping the heat in versus radiating it out. I also plan to have them ceramic coated as an extra measure of heat retention.

I think the most effective thing to combat the effects of the heat is air flow. I'll most likely need to duct fresh air to flow across the pipes such that the heat is taken away versus building up. The nice thing about the Miura body is that what looks like a rear window is actually open louvers and a good part of the rear bodywork is a mesh that readily flows air through it. In other words, there's ample opportunity for the hot air to escape and I just need to ensure that cool air is being fed into the hot parts of the engine compartment.
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  #420  
Old 06-29-2021, 01:08 AM
Mr fixit Mr fixit is offline
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Hi Joel,

Thanks for the personal response. Your description of heat removal sounds great, if you keep the car moving fast which won't be a problem, then your heat problem really does not exist. Lol

Good thing to learn about the SS metal and the ceramic coating for heat control, sounds high tech , but then this car is nothing but high tech.

I appreciate you taking the time to share your project with all of us. Keep up the great work.

TX
Mr fixit
Chris
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