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PostPosted: April 9, 2017, 12:37 pm 
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Joined: January 11, 2017, 11:06 pm
Posts: 18
Hey everyone,

I'm gearing up to get my build going and thought I may as well start a build thread now, so I can explain my plans and get some feedback.

A little background about me: I have always loved cars and mechanical things in general, and as a Mechanical Engineering Technologist I design machines for a living. Last year I bought a Mazda RX8 with a blown motor to play around with. I figured I could cross three things off the bucket list; owning a rotary engine, rebuilding an engine with my own two hands, and having a fun car on the side that I could toss around at autocross without too much concern. Then I got absolutely hooked on autocross.

My plan now is to build something that can still be registered for the road, but will spend 90-95% of its time on the track. In addition to autox, they are building a new raceway nearby and I definitely want in on that action!

To fund the project, I am selling my summer daily driver, a mint 2011 Camaro 2SS/RS. The money I get from this car has to pay for the locost, and my winter vehicle has to be able to tow it. The car is tentatively sold and as soon as it gets picked up in May, I will start ordering parts and making a mess in the garage. ;)

I was lucky enough to get a kickstart to the project by picking up a chassis from Haler Concepts for $1000 CDN. It was old stock since they got out of the game a number of years ago. It's a book size, perfect for my needs. I also just bought a 2005 Yamaha R1 to use as a donor. I dithered about whether to buy a crashed bike or one in running condition, but finally decided on the latter because I wanted to be able to use as much as possible off it, down to the side mirrors and even headlights if possible. This one has all of 45,000 kms on it, but was just recently in for a tuneup including a valve adjustment and new stator.

So, my next step is the reason I wanted to start this thread now. I have been researching what do use for a rear end, brakes and front uprights for countless hours now, and I'm not sure if I'm over-complicating things for myself.

My wishlist is this:
-F/R brakes from the same car so they are easy to balance and easy to buy parts
-same F/R bolt pattern and hub center bore, for wheel fitment
-rear end WMS width suitable for book chassis
-LSD available
-gear ratio ~3.5:1

So, here's what I am thinking:
-Front uprights/brakes from SN95 V6 Mustang (with strut to upper balljoint adapter)
-7.5" Rear axle from 93-97 Ford Ranger, 56.5" WMS-WMS
-SN95 Mustang rear brakes are nearly a direct bolt-on

Does that all make sense so far? I drew out what the axle should look like on a book frame with 8" wide +40 offset wheels and got this:
Image

Seems reasonable to me? Does anyone know if the pinion is reasonably centered on this axle? My one problem with having bought that chassis is that the transmission tunnel is already finished and I would prefer not to have to move it. Also, since it is a book frame and I would like a passenger seat, I would be very limited in my seat options if I did move the tunnel.

Okay, that's probably good for now. Any input appreciated!

Cheers!


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PostPosted: April 10, 2017, 9:32 am 
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Joined: October 6, 2009, 9:29 am
Posts: 6550
Location: Tallahassee, FL (The Center of the Known Universe)
Yo, ZiG!
Welcome to the builder's log! Sounds like an interesting project.

From memory, most 7.5 and 8.8 diffs had the pinion offset to the passenger side. A quick Google came up with this,
http://www.therangerstation.com/tech_library/Ford-7_5-axle.shtmlwhich confirms that notion. I'd do some more research (meaning "Don't take my word and one website as the final answer") but I think you're gonna find the pinion is offset.

But don't let that stop you, there's bound to be some other combination that'll work. Thought about IRS?

Stalkers used to use Chevy S-10 axles and front hubs (I think). Maybe that'll work for you?

Any-hoo, keep working at it, you'll come up with a solution and/or some other folk in here will chime in with info.

Either way, good luck, keep us posted and take some pictures!!!

:cheers:
JDK

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PostPosted: April 10, 2017, 9:49 am 
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Joined: October 19, 2012, 9:25 pm
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Location: Summerville, SC
A book frame is pretty narrow, but the R1 motor is a good fit.
Mine used Toyota rear end and front uprights from a Corolla. Nice 4 wheel disc setup, but not nearly as easy to find aftermarket wheels as you would have with a SN95

A Miata makes a great donor and you can go IRS. the last 7 I built used the full rear subframe from the Miata for an easy bolt is setup.

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PostPosted: April 10, 2017, 10:59 am 
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Joined: January 11, 2017, 11:06 pm
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Cool, thanks for the feedback. I know the pinion is offset in the pumpkin but the pumpkin is also offset in the housing. I know this because the axles aren't the same side to side. I just can't figure out if the two offsets net you with a pinion centered between the wheels or not.

Thought about an IRS setup, but it's tough to find something that will get me a reasonable FDR. I've done the math and a 3.5:1 ratio is about right to put me at the top of second on most parts of the autox courses around here. A stock miata diff appesrs to be 4.10... Unless there are aftermarket gears available?


Last edited by ZiG on April 10, 2017, 11:09 am, edited 1 time in total.

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PostPosted: April 10, 2017, 11:06 am 
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Location: Summerville, SC
I haven't seen gear sets for a Miata in the 3.5:1 ratio you're looking for. My Toyota rear was 3.73 and I ran out of revs in second on our bigger courses.

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PostPosted: April 10, 2017, 12:07 pm 
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Joined: January 11, 2017, 11:06 pm
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Well, it seems the NB could be had with an open 3.6 ratio rear end. I'm not sure if I can stuff a clutch type LSD in there, but it looks promising. Could probably find a cheap donor since I suspect that rear end only came in automatics. Cool! Thanks for the idea! Really glad I posted this before buying anything else!


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PostPosted: April 10, 2017, 8:45 pm 
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You could also look at Ford IRS diffs. The 7.5 and 8.8 were both used in Thunderbirds and Cougars, and there should be lots of different ratios available. There's been a few people on here using the Thunderbird rear uprights too, and they are easy to redrill to 5 on 4.5".
Kristian

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PostPosted: April 10, 2017, 9:18 pm 
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Yeah, according to this thread the WMS measurement on that setup is 60.5", so I'd be shortening axles again. Not the end of the world, I suppose.


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PostPosted: April 22, 2017, 5:51 pm 
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Alright, after a lot of consideration I decided to stick with the solid axle idea. I think it will suit my needs just fine, and later on down the road I could always change it if I really wanted to.

So, I hit up the junkyard and found a '95 Ford Ranger with a v6 and a 7.5" 3.45:1 rear end. A couple hours and a bit of swearing at one of the shock mounting bolts later, I ended up with this:

Image

The width is right, but the pinion is offset about 2" to the passenger side. I think that will be manageable. I may end up modifying the tunnel a smidge on the passenger side to accommodate, but I think it's the best way. It's an open carrier and I will be ordering a clutch type carrier for it sometime before it goes in.

Still keeping a lookout for some Sn95 spindles and brakes that I can rob off all four corners. I really want to use the Kinetic front a-arms but of course they are meant for Miata spindles. I plan to use a balljoint arrangement similar to Lonnie's SN95 build, where Chrysler screw-in units are used top and bottom. That should be easy to get a sleeve and weld it into the box section of the Kinetic lower arms, but I am as yet unsure how to deal with the top. The top arms call for a ES2074R balljoint that screws into the arm's main tube. So far my best idea right now is to weld a stud onto another female screw-type balljoint sleeve like on the lower arms. Thinking that ought to work... In another two weeks I will be able to get the frame out and start mocking things up a little more seriously, so here's hoping I can find some spindles before then...


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