November 26, 2020, 05:38:59 AM

Author Topic: New with a whole lot to learn.  (Read 1585 times)

Offline popsthebuilder

New with a whole lot to learn.
« on: May 12, 2020, 10:20:44 AM »
I love the rx7. Always have. Never even drove one. 80s kid I guess. Anyway. I've gotten ahold of a 91 coupe. It has a 4.3 vortec v6 setting on a cradle. I have an old f150 that came stock with 460 bbf, c6, and 9" rear. The engine started eating sparkplugs and got rebuilt to the tune of fully forged balanced dished rotating assembly with static comp. ratio of 8.5. pretty sure the rear is 4.10 but I'm not sure. The motor has a good aluminum intake and the aluminum heads are now good after the engine builder more than went through them. The engine is now running with a super sniper EFI rated for turbo usage, but it's running n/a at the moment. I really like the old 6000 pound truck would probably go in a straight line pretty well if I changed the steering box, but you can't really get into it too much without is veering badly and relatively uncontrollably, even when already at cruise. I'm sure some see where I'm going with all this. That old truck is good for work, but the engine and rx7 will be for play; as in they are gonna be playing together really well at some point hopefully.

I've done a little research and figure I'll need some level of cage. I'd really prefer the car to still handle well. Some have claimed it's not really possible, but I'm not worried about setting the engine back or doing what I have to do to keep the IRS. Back halfing the car seems like an option, and flaring the wheel wells seems inevitable.

I'm getting conflicting input on a rear for her also. For strip I'm sure the 9" on leafs would work, but that's not really what I'm going for. So if I've got 12" wide tires on the back and 1200 or so hp/tq going that direction, would the explorer 8.8" hold up? My mechanic says I'll be pissing in the wind with anything other than a Ford 9..with 27 spline axles at that.

Anyway; thanks for having me. Look forward to your input.

Offline digitalsolo

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Re: New with a whole lot to learn.
« Reply #1 on: May 12, 2020, 01:30:45 PM »
You can make an 8.8 hold up with an automatic and proper setup in a light car.   A 9" is a lot of weight penalty.
Blake MF'ing McBride
1988 Mazda RX7 - Turbo LS1/T56/ProEFI/8.8/Not Slow...   sold.
1965 Mustang Coupe - TT Coyote, TR6060, modern brakes/suspension...  project car
2016 BMW 428i xDrive Gran Coupe - Completely stock...ish

Offline popsthebuilder

Re: New with a whole lot to learn.
« Reply #2 on: May 14, 2020, 07:20:35 AM »
Good to know. Thank you.

Is there any benefit to using the rear from a mustang or gt 500 instead of the explorer or Thunderbird rear? Also is the Thunderbird rear from a supercoupe?

Thanks in advance

Offline digitalsolo

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Re: New with a whole lot to learn.
« Reply #3 on: May 14, 2020, 08:53:59 AM »
Youíre doing a solid axle right?

Iíd look at a housing that has had the tubes welded to the center.  I ripped the tubes out of my 8.8 on street tires on the highway with about 700 wheel HP in my FC.

9Ē ends or c clip eliminators are a good idea also.    Itís usually cheaper to just buy a built rear vs getting one and building it up, FWIW.
Blake MF'ing McBride
1988 Mazda RX7 - Turbo LS1/T56/ProEFI/8.8/Not Slow...   sold.
1965 Mustang Coupe - TT Coyote, TR6060, modern brakes/suspension...  project car
2016 BMW 428i xDrive Gran Coupe - Completely stock...ish

Offline popsthebuilder

Re: New with a whole lot to learn.
« Reply #4 on: May 15, 2020, 10:37:52 PM »
Starting to think I might just use the 9" rear I got, but with narrowed axles. It will need different gears for sure. I don't have a clue as to how to make that work with the rx7 though.

Offline frijolee

Re: New with a whole lot to learn.
« Reply #5 on: May 16, 2020, 03:29:33 AM »
Hey Jerry,

Welcome to the forum.  If you go IRS, Explorer is the place to be.  Thunderbirds and Mark VIII's had an 8.8 but it's an iron housing with much smaller internals.  The 03-04 Cobra used the same housing form factor from the earlier T-birds but used an aluminum housing.  The problem is that the aluminum wasn't strong enough for the undersized front mounts and that's a common failure point.

Note, it's much harder to package but it given your power goals it might be worth cutting the subframe further and getting in the later 06-2010 Explorer diff with the dual front mounts, the driver side mount interferes with the FC's vertical subframe link, which is why Ronin uses the single sided front mount, but for a max effort build the dual front mount is going to be stronger. 

It's hard to beat a solid axle for straight line work as we've been discussing.  I love the twisty stuff so IRS is hard for me to give up.  Blake (Digitalsolo) has build some heavy hitter cars so his advice is always worth listening to.

-Joel
(from RSW)
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline digitalsolo

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Re: New with a whole lot to learn.
« Reply #6 on: May 16, 2020, 09:02:00 AM »
For IRS I agree with Joel completely and his companyís stuff is top notch.

For 8.8, Grannyís Speed Shop still sells a kit I think.   You could adapt that for 9Ē as well.    Or just buy a generic back half kit and graft it in, but youíll need the fab skills to back it up.

A well setup Ronin IRS will go 8s, and require very little fab work, so it really just depends on where your skills are.

Iíve worked on a couple cars with Fox Mustang rear suspension geometry conversions but again thatís a lot of fab work, relatively speaking and still not perfect.
Blake MF'ing McBride
1988 Mazda RX7 - Turbo LS1/T56/ProEFI/8.8/Not Slow...   sold.
1965 Mustang Coupe - TT Coyote, TR6060, modern brakes/suspension...  project car
2016 BMW 428i xDrive Gran Coupe - Completely stock...ish

Offline popsthebuilder

Re: New with a whole lot to learn.
« Reply #7 on: May 21, 2020, 10:41:40 AM »
Would the added weight work as a counterweight to offset it being so nose heavy?

Offline popsthebuilder

Re: New with a whole lot to learn.
« Reply #8 on: May 21, 2020, 10:45:47 AM »
It would be cheaper/ easier to put a new built 9" or 8.8" in the car, than use the one out of the 78 f150?

I'm trying to learn. Playing a lot of catch-up in bits and pieces when time and opportunity allow.

Thanks for the help

Offline popsthebuilder

Re: New with a whole lot to learn.
« Reply #9 on: May 21, 2020, 10:49:21 AM »
I was thinking the car would probably need a cage and am looking forward to the fab work sorta. Never even welded before, but I have been a carpenter for a long time, and am mechanically inclined....just freaking ignorant with a dream I guess.

Offline jwvand02

Re: New with a whole lot to learn.
« Reply #10 on: May 21, 2020, 03:01:47 PM »
I was thinking the car would probably need a cage and am looking forward to the fab work sorta. Never even welded before, but I have been a carpenter for a long time, and am mechanically inclined....just freaking ignorant with a dream I guess.
If you don't have quite a bit of experience welding I wouldn't recommend building your own cage. It's pretty easy to make MIG welds that look good and aren't that strong. Not something I'd want to count on in a wreck.

Offline Cobranut

Re: New with a whole lot to learn.
« Reply #11 on: May 21, 2020, 09:53:44 PM »
I was thinking the car would probably need a cage and am looking forward to the fab work sorta. Never even welded before, but I have been a carpenter for a long time, and am mechanically inclined....just freaking ignorant with a dream I guess.
If you don't have quite a bit of experience welding I wouldn't recommend building your own cage. It's pretty easy to make MIG welds that look good and aren't that strong. Not something I'd want to count on in a wreck.

I strongly second that.  :o
1995 FD, 7.0 Liter stroked LS3, T56, 8.8, Samberg kit.

Offline popsthebuilder

Re: New with a whole lot to learn.
« Reply #12 on: May 21, 2020, 10:08:53 PM »
Yes sir; I would likely use a prefabbed cage of high quality. My first job was an iron workers helper. I can freehand a router pretty well. I would definitely be more concerned with rigidity over great looks. Gotta settle somewhere, but not on safety on a 1000+ hp car that may well end up going to one of my boys. I can clean the crap outa ugly welds though. I won't be going it alone either. That would be a bad idea. I have testicles, and can be pretty stupid, but you gotta draw the line somewhere right?  But there are quality cages for the fc if I'm not mistaken. Couldn't bolt up units still be welded up?

Thanks for all the advise

Offline jwvand02

Re: New with a whole lot to learn.
« Reply #13 on: May 22, 2020, 10:06:57 AM »
Yes sir; I would likely use a prefabbed cage of high quality. My first job was an iron workers helper. I can freehand a router pretty well. I would definitely be more concerned with rigidity over great looks. Gotta settle somewhere, but not on safety on a 1000+ hp car that may well end up going to one of my boys. I can clean the crap outa ugly welds though. I won't be going it alone either. That would be a bad idea. I have testicles, and can be pretty stupid, but you gotta draw the line somewhere right?  But there are quality cages for the fc if I'm not mistaken. Couldn't bolt up units still be welded up?

Thanks for all the advise
Yeah, the most common recommendation is probably going to be autopower.

Offline popsthebuilder

Re: New with a whole lot to learn.
« Reply #14 on: June 08, 2020, 10:48:22 AM »
Well finally got her fired up and running. Gotta check timing I think, and the shifter is all jacked up. No kickdown either evidently. I heard a tap at high load when transmission should downshift. Very pronounced. She is also idling high. I knew the shifter was messed up, but it did seem to go into drive, reverse park and neutral....until I decided to take the car down the road. The linkage is hung up somehow and also applying pressure to the center console/ dash/ radio area. It's missing parts with other parts seemingly dislodged. Still not sure what transmission is under it, but I need a different shifter for sure. What is a good aftermarket shifter that will clear everything, have a reverse lockout, and not break the bank?

Car sounds cool to me. I wasn't expecting the 4.3 to sound exotic at all, but it sorta does. Really considering bolting up a turbo to her before doing the swap with the 9.0 liter. There's no way the v6 will push both turbos, but it may sound one.