Friday, June 6, 2014

MiataV8 302 Exhaust

A few pictures showing the latest iteration of exhaust routing I used for the 302 Ford and 4R70W transmission.  Not the greatest, but it's only the second system I did after acquiring the exhaust bender. Excuse the rust. It looks a lot worse in the pics than in real life.


 These pics also show the lower arms I made to adapt the Tbird uprights. And the hi-tech subframe  braces.




 This exhaust stuff is harder than it looks. This routing around the trans pan took a few attempts to get it as good as it is. You may notice that the bump in the bottom of the pan appears to be the low point. There's actually another version of the pan that doesn't have that bump.


 Next time I'll put the O2 sensors on the top.



 Not really part of the exhaust, but showing the radiator mount. There's a length of 3/4" X 3/4" angle welded to the top of the mount as a stiffener and to help capture the radiator.





 
 

9 comments:

  1. What made you decide to use the Tbird upright? I thought you had successfully modified the hub to fit the Miata bearing.

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    1. The Tbird uprights with Mustang Cobra hubs were part of the original conversion that I did in 2007, when I did my original five-lug conversion as part of the V8 install. Some of the other pics on this blog are of another more recent 5-lug conversion I did for another V8 Miata using the Miata uprights and machined and re-drilled Tbird rear hubs. One of the reasons for using Tbird hubs is that they are already splined for the FFR axles that are a good solution for heavier axles when doing a V8 conversion.

      My thinking for using the Tbird uprights was that they seemed to have a better support for the hub and no real downside. But they're not for everyone because of the fabrication involved.

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    2. Interesting. I wasn't aware Factory Five sold their half shafts separately. They're not listed on their website.

      Since you've done both ways, which is your favorite? Did you get the Tbird halfshafts shortened locally?

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    3. Actually, at the time FFR, as part of their IRS upgrade, provided just the axle bars, with instructions as to how to disassemble the Tbird axles and install the shorter bars. I found a set of those bars and used those. I haven't seen another set since. However, the FFR parts department will sell the complete axles with cv's for in the neighborhood of $250 shipped per set. And they are exactly the right size. They do require a spacer to fit the seal on the Miata hub.

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    4. Link to FFR manual describing IRS install:

      https://www.factoryfive.com/wp-content/uploads/2012/11/IRS-STD-rev-K.pdf

      Some info applies to Miatas.

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    5. I'm pretty sure the FFR part number for the axles is 15508. Be sure to get the longer axles, they offer 2 lengths, one for conventional lug type hubs with 18" long axle bars, and another for the pin drive hubs, with 15 1/2" axle bars (I think). You want the axles for the lug type hubs, they are just right for a Miata with an 8.8.

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  2. Fantastic info, as always. Thank you. I'll review all of this new-found info.
    What brakes did you go with front & rear with the 5-lug conversion?

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  3. Initially I used the stock brakes off the 93 Tbird. The rears are still on there, but I found some PBR aluminum 2-piston calipers off a late model Mustang and put them on the front. They pretty much interchanged, think I had to grind a little clearance somewhere. They are relatively large and weigh almost the same as the original Miata calipers. The Tbird calipers were pretty heavy. I used a master cylinder from a 96 Explorer that bolted right up in place of the stock Miata cylinder. I did use an adjustable proportioning valve and did away with the Miata valve.

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  4. Not sure if I already posted this elsewhere, but FFR has discontinued the sale of the bargain axles. Apparently they changed their IRS setup to the newer Explorer centersection and custom axles.

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