The Hillclimb RX7 - a saga
 

Figured I would post a build thread of for no other reason than to answer questions about the sport of hillclimb racing, which seems to be a bit of a niche sport.

I've been an avid autocrosser for seven years, last year winning my club championship in the SM class racing a 470 hp Acura Integra put together by Kinetic Motorworks in Hampstead, NH (great guys).


I've been a part of hillclimbing since 2009, first helping run the events and lately racing myself once I finally was in a position to do so (life gets in the way).

After racing my 1996 Miata (prepped for SCCA STS Solo racing), the missus decided i needed a full roll cage. In my first weekend racing I was 5 seconds off breakout time, which is the point where a full cage is required. Not bad for a 130k mile Miata that also serves as my daily driver.

Here's a vid: https://www.facebook.com/photo.php?v=3975152785257

Since the cage was a new requirement and this was my DD, a new car would be needed. I've always loved the sounds of rotary engines, especially since there's no sound limit at my favorite hillclimb, so I began digging around for an FC, which is a nice mix of affordable and good looking. FD's are too expensive so they were out of consideration.

I went with an N/A version over a turbo for simplicity, as I'd like to develop the chassis before adding power, but a turbo could be in the cards in the future.

I found this 1987 GXL with 113k on the clock and a 13B that had been (supposedly) rebuilt around 20k miles ago. The car looked nice and straight with zero body rust, with the only reason for its sale being a burnt out brake light switch or board. It won't pass inspection but I don't need functional brake lights.

I grabbed it for $2012 (it's a Grassroots motorsports thing) and dragged her home to begin the process of build a full-on hillclimber.

Here's how it stands right now:
Engine: K&N air filter, Racing Beat cat-back exhaust

Suspension: Koni yellow single adjustable shocks on stock springs.

Brakes: Corksport stainless steel brake lines, Brembo brake rotors, Hawk HPS brake pads

Wheels and Tires: Stock wheels with new Fuzion HRi 205/60/15 tires

Other: S5 taillights, Optima Red Top battery, recently replaced OEM radiator, silicone vacuum hoses.

OK that was lots of writing so here's some pictures.

First getting home and off the trailer:
http://img600.imageshack.us/img600/2711/imag0590s.jpg

Meeting the new room mate:
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Time to start the tearing out:
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This plate was last registered in 1989 by my aunt, so it's an homage (I'm a Vermonter born and raised and all the hillclimbs are in VT too)
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Running out of stuff to take out. Only thing left is the dash and glass:
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Wheels came in! 15x10 with a 5" back space:
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I'll be running 23.5/10.0-15 American Racer modified tires in the super soft M28 compound. That's roughly a 275/35 tire. Yes I'll need flares.

Still deciding on spring rates... I'm thinking 400lb front 300lb rear. I'll end up buying a couple sets so I can test and tune.

That's where she stands right now. I need to get the glass removed and then the process cleaning out the sound deadening and caging begins. I'll document that process as well.

This post is already too long and there's no need to lay out plans. This car will be a constant work in progress and I don't plan on being competitive until next year. Hopefully I'll have my maiden voyage this September at the SCCNH Ascutney hilliclimb #2.

Big thanks to Death Metal Fabrication for all their help.

Nice! Keep the updates coming.

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Warmup for my car. This is another FC that belongs to a fellow club member and hillclimber. Getting the a-pillar bars up and tight is a pain in the ass, especially since the owner didn't want us to cut up the dash (we still took a small notch out).

And yes I'm aware there's a lot of layback in the main hoop. That was done before I got to the barn and was apparently a request from the 6'5" owner.

What group are you doing hillclimbs with? Ive wanted to do any/all of the NEHA events however life always seems to keep me busy.

Cars been in and out of storage units and garages for 3 years now, still not done.

-Jacob

NEHA all the way!

I'm the autocross director of the Sports Car Club of New Hampshire, which is a member of NEHA. You should come to an event even if it's just to check it out. Ascutney is by far my favorite.

Well isnt it just a small world.

Ascutney does look good, ive met some of the DSG guys with there autox / hillclimb 240 a few years ago, they said the events were a blast as well.

My wife just had our babyboy a few nights ago, it might be a while still untill i get a car together

-Jacob

Ah yes the MAXI 240. Bill Washburn is a damn genius. He was supposed to be down at NJMP this weekend hunting to set the record again but I guess the car has an electrical glitch.

DSP is sponsoring our fall Ascutney event, so I'm hoping the Pleasure Evo comes out. I have a ton of photos from past events at David Estey Photography | SmugMug

Work on the car has been slow this week since I was helping my buddy get ready for the Okemo hillclimb. Today I've been working on the truck. We had a plastic bed line in it before we got the fifth wheel hitch, and it rubbed and caused rust in some areas. Cleaned up all the rust, degreased with Dawn and a pressure washer then prepped with brake cleaner and a scotch pad.

Here it is cleaned up:
[IMG]https://sphotos-a.xx.fbcdn.net/hphot...59973317_n.jpg[/IMG]

Here it is after one coat of Herculiner:
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One more coat to go. I'm drinking a beer and playing GT5 while I wait for it to dry enough for the next coat.

Progress has comprised mostly of ripping and tearing.

Just a few things left inside to remove:
http://img38.imageshack.us/img38/2778/imag0636n.jpg

Front is coming apart to get the A/C system all out:
http://img831.imageshack.us/img831/764/imag0631e.jpg

Got my GC setup in the mail too:

http://img6.imageshack.us/img6/3686/imag0635t.jpg

Don't forget to get some good brake fluid to really take advantage of your new lines and pads. Looking forward to your build. Hill climbs are tons of fun! One of the most fun RX-7's I had was a GXL exactly like yours (same color and year). It had sticky 17" tires and springs but that was all that was needed to transform it into a very fun car to drive. Can't wait to see how yours turns out :ylsuper: If you need any suspension pieces or bushings, check out my website www.j-auto.net. I'll be keeping an eye on this build and can't wait to see videos of your FC in action :nod:

It has ATE Super Blue in it right now but since it was sitting I'll probably flush it and switch over to Motul RBF 600. I've been using this stuff in my Miata for a while now so it's more a question of what I have on hand than a performance advantage over anything else.

I'm checking out your site now, thanks for the heads up.

Fell way behind on updates so I'm grabbing some from another thread I have:


Mounted up!
https://sphotos-b.xx.fbcdn.net/hphot...36321625_n.jpg

Red for race car. These are my extra calipers.
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Interior is coming together. Seat is going in tonight as is the front suspension. I'll remove the rest of the sound deadening this winter when I cage it. Right now it's "Good Nuff". No, the gauge cluster won't be zip-tied in permanantly.
https://sphotos-b.xx.fbcdn.net/hphot...08800846_n.jpg

This is the side shot I sent to Kinetic Motorworks. They're going to vinyl the car for the hillclimb. They're supporting me with little stuff so I told them the car is their canvass this year. Eventually the car will be white with blue and red stripes ALA Racingbeat's racing FC RX7 from the 80's.
https://sphotos-a.xx.fbcdn.net/hphot...64870426_n.jpg

Got the car buttoned up and good to go. These photos certainly show how much I'll have to flare things out this winter. I did run into a problem with the GC camber plates not being big enough for the strut shaft. No time to get the shaft machined down so I popped the stock top hats back in. This wasn't a test to see how fast the car would be after all, it's just a chance to put the drivetrain under pressure to see what I've got before I tear down again this winter.

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The real purpose of running in this event was to stress the drivetrain and see what I have. The answer: a damn fine running rotary. The car ran great all weekend with a slight miss at idle that I attribute to needing some fresh gas and plugs. Temps were great. No smoking and coolant stayed where it should be.

Handling was a little wonky due to my having to reuse the front top hats, which introduced some positive camber. The struts will need to be machined to fit into my camber plates. Still, the car proved very quick, taking fourth in class over a couple VERY experienced drivers in very well developed cars. My fastest of the day was a 2:34.XX.

The car is going back in the garage tonight and will be stripped even further to replace bushings, rebuild the LSD and do some seam welding before it goes to get caged. Also, the RacingBeat cat-back exhaust is for sale. The entire system will be replaced with something more in tune with track work. It sounds awesome, but is too quiet. People found it funny that the quietest car on the hill was a rotary.

MASSIVE thanks to Death Metal Fabrication and Kinetic Motorworks for their support.

Sidenote: I love my truck. 300 miles of towing, plus running the communications wire up the hill and taking it down on Sunday and I used half a tank of diesel.

Deafening silence: Ascutney Hillclimb II practice session Sept. 15 2012 - YouTube

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Tonight begins the process of tearing it all apart again. I'm not looking forward to sorting out the wiring harness.

Sidenote: I did have a small off during the weekend, which bent one of the rear lateral linkages in the rear end. I had already planned to drop the rear subframe to clean it up and re-bush everything, but looking at the linkage design I'm considering moving to heim joints rather than the current ball-joint setup.

Anybody done that before? I would assume yes. I know groups like SuperNow make some, but they position the heim joint on a shear plane that I don't like. I would rather bolt on brackets to position the heim so it's vertical, wwhich should be much stronger given the movements it will undertake.

theres really no reason to get rid of the stock lateral links, unless you lose toe adjustement at the trailing arm.

dont use poly/delrin bushings anywhere in the rear suspension!! fine for subframe/diff mounts. either stick with stock or get bearings for anyhting that moves.

Why not?

Trailing arms move in 3 axis. You either need OEM bushinsg (flex), or bearings (full rotational feedom). Delrin/poly is meant to slide about one axis and will bind.

Which wheels are those? They look like Bassett? Do they clear the stock 5-lug front calipers without a spacer? And the GC coilovers?

My notes have the stock 16x7 as having a 5.675" backspacing and the coilovers open up some room so I was thinking a 15x10 with a 6" backspacing to help fender clearance... and most folks say they need a 0.25" spacer on the front to clear the calipers with the steel wheels...

They're Aero wheels I think you could pull of a 6" backspace, you do need to run a spacer to clear the calipers though. The basket of the wheel hits just on the inside without one.

AWR makes some toe links too, but they require you to drill out the tapered hole... and they have the same issue you don't like. I've never heard of one failing though, and a lot of people run them... (me included) it's also on the same shear plane the stock ball joint is...

Toe Link Kit - Rear - 1986-1992 RX-7 - AWR Racing Store

I also wouldn't mess with the mounting points too much. I measured the bump steer of the rear suspension with my awr links (other links may differ, but not much) and it was already amazing (less than .005" throughout the entire travel), so don't change any mounting points :)

awesome project though, I'll be following this thread.

DATA AND MEASUREMENTS! Thanks for the heads up. I'm guessing if nobody is experiencing failures the design must be sound, or the lateral links don't experience as much abuse as I imagine. I know for sure I can piece together a setup for half the cost of the AWRs though.

Flatout Motorsports (http://www.flatout-motorsports.com deals with AWR stuff so it must be good. Maybe they have some on hand so I can check them out - their shop isn't far from my place. I do know I want a set of those front strut housings.


While I'm logged on, anybody have experience with these guys: ProdBodies.com ?

Looking into my widebody options.

Car will continue coming apart once I regain the use of my jackstands. Right now they're being used as a string setup so I can throw a better alignment on my Miata for AutoX.

I've been doing some cutting:
https://sphotos-b.xx.fbcdn.net/hphot...36322303_n.jpg

np

Most of the mazdaspeed motorsports stuff is also just AWR also :)

That makes sense Josh, but is quite a different statement than "don't use delrin in the rear suspension"

well thats the typical FC purchase - "rear suspension bushing kit" (no go). i'm not aware of any off-the-shelf bushings for the spindles.

so to clarify- OEM or bearings in the trailing arms! :)

Mazdaspeed and drop engineering both sell kits that replace the rubber tri-axial hub bushing, the DTSS bushing, and the control arm bushing...

I bought one of those kits and just didn't use the control arm bushing.

The 3rd hub bushing on the hub is actually a spherical bearing, so you don't need to replace it.

Mazda RX7 Rear Lower Control Arm Kit, 1986-1992, by Drop Engineering

neither of them will sell you just the hub bushing... I tried :p:

I swear I haven't been slacking, I just keep finding ways to extend the racing season.

Took the Miata rallycross last weekend on my autocross coilovers raised up as high as they would go. HAD A BALL!

https://www.youtube.com/watch?v=2shm...ature=youtu.be

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Need to do some parts shopping for the FC as well as a little more cutting before she moves to the barn for the cage installation. Holiday spending gets in the way, but I should have a healthy bonus this year.

Started in on the wiring today - trying to simplify the rear harness and remove the wiring from the adjustable suspension stuff. It's slow going unwrapping it.

https://sphotos-a.xx.fbcdn.net/hphot...19153690_n.jpg

OK here's a question: How muc can I expect to get from selling my RacingBeat catback exhaust? It's in great condition, but it won't match up wih my race header unless I hack it up, which would be a shame.

FC is coming along nicely! Can't wait to see it completed :ylsuper:

https://sphotos-b.xx.fbcdn.net/hphot...19517950_n.jpg

Nuff said.

Did you weigh it?

Not yet. My home scale isn't terribly accurate. I'd estimate about 4 pounds.

Picking up a 13B tomorrow to rebuild. It comes with an RB intake mani with a Webber DCOE, RB race header and exhaust from an IT7 car (not useable for mine).

https://sphotos-a.xx.fbcdn.net/hphot...52639849_n.jpg

This happened today. I also now have two race headers, one custom and one RB.

^GSL-SE drivetrain?

Recognized that it's a first gen transmission? Yes this is out of a GSL-SE.

Left stock: RacingBeat Race header: Custom Race header

https://sphotos-b.xx.fbcdn.net/hphot...24421862_n.jpg

While I was in there (dangerous words) I took the stuck 6th port actuators off and lubed them up. The sleeves were sticky too, but working them around a little seemed to free them up. Good thing, because I didn't want to pull off the intake manifold.

Alright, time to start spending money. First things first though, I needed safety gear to even be able to race this coming season:

https://sphotos-b.xx.fbcdn.net/hphot...32439908_n.jpg

Next up I'm ordering a set of 6th port sleeves from atkins: 84-91 Rx7 Atkins Designed Six Port Actuator...

And then I need to suck it up and order the rear lateral links from AWR to replace the one I bent in my little excursion.

Just a heads up, the AWR links require you to Drill out the tapered hole in the trailing arms and rear subframe with a 5/8" drill bit...

you might be better off getting the battle version toe links. you don't have to drill out the taper. You can get them here:
J-AUTO - Bushings, Suspension, Performance Upgrades for Mazda RX-7s

I didn't think drilling out was a big deal. Those are a little cheaper though, and my wallet likes cheaper after I snapped my glasses today and had to buy a new set.

you might have to drop the rear subframe which is no fun...

I would check to see if they're easy to find/replace endlink sizes (SAE?) before I got the battle version links though.

battle version is SAE rod ends, but the bolt should be the same size as the stock Mazda joint, as it can take the stock Mazda nut, off the top its a 10x1.25. at least that was how it was designed, if Alex supplies the nut, he could send you an SAE bolt, or whitworth

you should be able to install without removing the subframe

Yeah that's not a job that requires dropping the sub frame.

Doing my taxes right now and already looking at ways to blow my return!

Been working to get my garage more organized before I get elbow deep in the car:
https://sphotos-b.xx.fbcdn.net/hphot...61799499_n.jpg
Gotta love Harbor Freight magnetic strips.

Anyway, here's what the car looks like now:
https://sphotos-a.xx.fbcdn.net/hphot...05178554_n.jpg

Got my welder hooked up and now it's time to start Welding in some small tubes to hold the body parts in place and then I start cutting out some major steel from the body.

Everything below that black line will basically be gone, as will the floor of the hatch area to make room for the 5 gallon fuel cell and radiator.

The goal is to be at 2,400 lbs this season and 2,200 for the 2013 season. Hillclimb rules basically let me do anything I want as classes are based on engine displacement.

Very cool build!
I'm also working on an RX7 that I'll be using for NEHA hillclimb events. I picked up an 87 TII that was used as a drag car. It already has some good weight reduction and power adders, and shouldn't take much to get ready. Hope you're enjoying this weather... my project is on hold until it warms up a little.
Hopefully I will see you and the blue beast up in the hills some time soon.
Kurt S.