Knee Dragger

Before I ask any specific questions, I'll give a little background info. I recently picked up a 1994 Touring model RX-7 that I'm using as my daily transportation for the time being, but I'm building for aggressive street driving/track days. I'm setting the car up with playing in mind, but I need to keep the car at least livable on the street. I'm willing to put up with quite a bit in the name of performance, but, there has to be a limit.

Once I get my car back from the dyno shop I'll be done with the power mods and all that remains is suspension, wheels, and tires. I've been using a friends FD as a template for many of my mod choices, but his car is a weekend only trackday and aggressive mountain road car, so he is able to sacrifice some elements that I can't due to mine also being transportation. His car is using 17 wheels with 275 front/315 rears with V710's, AD coil overs from M2 performance (650/475), and tubular swaybars from tripoint. His car is an absolute monster, but I don't want to do any modifying to fit that amount of rubber, I won't be running race compound tires, and his car is brutally punishing if the road surface isn't like glass.

My car, being bone stock, probably has suspension elements that are worn out due to the age and ~60k miles on the chassis. I don't have any real experience with car suspension mods or setup, but I've done a bit of it on my race bikes. My basic plan at this point is as follows: I had planned to buy a bushing kit, probably stock to avoid additional noise. I also have read that pillow ball mounts wear out frequently, so I plan to replace them as well. I will be looking for some sort of a front and rear adjustable sway bar solution with beefier mounts, coil overs, and a toe link/ trailing arm kit. What I'd like to do is first find out if there is anything in addition to these items that I would be wise to replace if I'm looking to do suspension as a 1 shot deal. I want to do this once and do it right. Next, I will need to determine a parts combination suited for my application. Finally, I will need to decide on a wheel and tire size combination to compliment my suspension choices. I know at this point that I want a 17" wheel, and if possible I would like to run the same sizes at all four corners to retain the ability to rotate them. I don't know if this will be possible to achieve maximum performance, but it would be nice if it is. I will go as wide as I can without running into clearance issues or needing to majorly modify anything.

I suppose the best way to start getting specific suggestions would be to list some of the items I have been considering after the researching I'e done thus far.

30% stiffness increase Mazda bushing kit
Widefoot sway bar mount kit
"Complete Traction" kit from rx7.com (toe links, trailing arms, solid diff mount)
Ground Control coilover kit
Tokico Illumina shocks
Cusco front/rear strut bars
Sway bars I haven't decided on yet. Something adjustable front and rear would be preferable, but I've not found anything to sway me toward and one brand yet (no pun intended).
Wheels I haven't picked out yet, but I am going to research whether or not I can get away with running 17x10's all the way around without clearance modification.

Aside from the few questions I've asked, I'm just looking for suggestions on hardware, and I also would like to know how to determine spring rates and sway bar sizes to match a given application. Once I get everything purchased I'll have an alignment/corner weight done and get my buddy with the FD track car to help me dial it in.

Thanks for any information anyone can provide!

ptrhahn

iTrader: (9)

You've got the basics.

1. Bushings: Fresh stock ones might do you fine, or you could get Wanklin's poly bushings when the full set is available to save money over the MS's.

2. Solid diff mount will be noisy, and unless you're doing drag launches not terribly necessary.

3. Try a 500/400 or 550/450 GC spring combo w/ Tokicos or Konis.

4. Yes, do use strut braces.

5. Lot's of good sway bar options... bracing/re enforcing the mount is a nice idea.

6. Wheels. If you want to run 17"x10's or 17x9.5"'s all around w/ 275/40/17's, you'll want to get something with the right offsets to help w/ clearance (+50), not run too low, and roll your front fenders. You can also do 18x10 +50 w/ 285/30/18 that will offer more fender liner clearance, but you should still roll the fenders up front.

A less aggressive option is a 17x9 w/ 255/40/17 all around, but I'd roll fenders up front w/ ANY aftermarket wheel/tire combo.

rynberg

I strongly suggest you drive the car on the track at least a few times with the stock suspension. Unless you are a really good driver, the stock suspension will certainly not be a limiting factor for you.

Secondly, if you are trying to build up a reliable aggressive/track day car, you'll need to also focus on brakes, as well as cooling (please search through the Racing and 3rd gen sub-forums for track car advice).

ptrhahn

iTrader: (9)

Indeed, this goes without saying, thought it's worth saying again.

Knee Dragger

I've done a decent amount of sports car driving in the past, but am definitely not what I would consider a great driver. But, given my specific situation and my background with racing bikes I would like to go ahead and bring the car up to the level that I want to ultimately have it at, even if my driving is not necessarily reflective of that level yet. Once I get the car up to an apropriate handling level I'll have more free money for the level of maintenance required to keep a tracked car going. I don't want to jump into that just yet. I definitely agree with that line of thinking for any form of motorsports, though.

Cooling mods are either already done or in the works. Really all I need at this point is a second oil cooler for track use. I've done a few small things, but major brake mods will be a little later down the road. I wouldn't have chosen this order to do everything (power, handling, then brakes), but the previous owner had begun modding the car for a different type of use than what I intend to do.

Thanks for the good information so far.

Knee Dragger

I'm strongly considering the Tein Flex coilovers with a 560/450 spring rate. They seem to be exactly what I need from what I have been able to research. What I'd like some input on is how to go about selecting a swaybar combination that is appropriate for the rest of my parts combination. Any opinions or experiences on this particular coilover are welcome as well.

Mahjik

iTrader: (1)

If you are buying new shocks to go with the GC coilovers, it just makes more sense to go with the Tein Flex instead. I'm not saying GC's are crap, but you'll be up close to the Teins in price when also purchasing the shocks for the GC's. GC's are great if you already have aftermarket shocks on the car and you are just adding the GC's only.

Knee Dragger

Should running 17x10's with 275/40/17's and Tein Flex coilovers with rolled fenders be enough to prevent clearance issues/rubbing? How is offset determined for a specific application?

Thanks

rynberg

I would never run 275/40 17s on the street (up front). They are too large in diameter for street use IMO -- unless you like replacing fender liners and wiring harnesses.

Knee Dragger

Can you elaborate on this please?

gnx7

iTrader: (10)

By putting 275 or 285 tires up front they will wear thru the plastic fender liners eventually and potentially the wiring harness that runs up in the fenderwell if the car is really slammed and the suspension travels its full range often. I removed my fender liners entirely. Driving in the rain I've never encountered any adverse affects without them either aside from an engine bay that gets dirtier a bit faster. No wiring harness rubbing; however my car isn't totally slammed either.

My street setup:
18x9 255/35/18 fronts
18x10 275/35/18 rears
Plenty of tire for the street and they are affordable.... if you need more tire you are basically pushing the limits of the car beyond what is safe for the street. This will also drive nice and not "track" every crack and uneven pavement surface in the road

race setup:
18x10 CCW 3 piece rims
285/30/18 Hoosiers all around
they track all over the place on the street; however on the track are incredible.

550/450# springs are recognized as about the limit for a streetable car that can be tracked. More spring rate and your car will be more of a race car and bumpy as hell.

17" rims provide limited big brake selection (AP Racing, Wilwood etc)
18" rims opens it up to just about any brake combo (Endless, Stoptech, Brembo etc)

Delrin bushings on the street aren't that bad. If you are serious install those and maybe the non delrin diff mount bushings. I have 20K miles on my bushings and they don't squeak. I have delrin bushings, TriPoint hollow adj front sway bar with billet Widefoot mounts, stock rear bar, 550/450 M2 coilovers (GAB 8way adj), and M2 toe/trailing arms. It rides firmly; however not bad unless you are on very bad paved roads where you simply are shaken to pieces. 49.5% front weight/50.5% rear distribution.

My car pulled 1.13g's on Michelin Pilot Sport Cup full tread depth tires in Sport Compact Car Magazines's "Ultimate Street Car Challenge" last year.

Of note- Penske is supposedly releasing a more "budget friendly" double adjustable coilover in late 2006. They will still be over $2K though. I'm planning to try them out for 2007 to replace my current GAB Super setup (rebadged Tokikos).

Knee Dragger

I asked another foum member that had given some excellent suspension input in the past similar questions and in his reply he mentioned the following:

"i suggest you rethink the wheels..... you should run what i run. 18 inches not 17. 8.5 front, 10 rear. 10 inches in the front moves thelateral pivot point of the tire almost an inch off center. scrub radius. the wheel stops rolling and scrapes accross the pavement losing MAJOR grip. you don't have that problem in the rear as the wheel doesn't turn. you also need all the grip you can get for the rear, hence big tire, soft rear suspension, lower rear tire pressure."

This is the first I've ever heard of this. Does anyone have any input regarding that quote?

Thanks

Eggie

When Howard talks suspension, I listen.

Knee Dragger

He seems to be very knowledgeable. I've picked that up in the short time I've been on the forum. I'm suprised I haven't seen that mentioned in other setup related threads yet. Running equal sized 10 inch wide wheels seems to be a pretty popular setup around here.

Thanks for all of the great info so far.

ddkkww888

This what I have on my car. The TEINs if you
wish you can paid extra for the unit the controls
everything from the interior of your car, if you are
into that. The Racing Beat is good stuff, but will add
extra weight to your car !!!

Suspension & Exhaust:

ADR Kasai wheels, front 18x8; rear 18x9 w/Hub Centric Rings
Toyo T1’Proxes tires
TEIN Type FLEX Damper Coilover (2/2005)
HKS Super draeger cat-back exhaust with Bonez hi-flo
Catalytic converter.
Front Sway bar end links (7/2006)
Front & Rear Racing Beat Sway Bar (7/2006)
with special white bracket (7/2006)
18 piece Delrin Blushing (front, rear & diff.) (7/2006)
6 Pillow blushing (Mazda) for the rear (7/2006)
4 Wheel Alignment & Speed Balance all tires (7/2006)
2nd Bonez hi flo cat 3” SS (8/2006)

Good luck !!!