stock class mods?

[Wheelman_13]

I was contemplating fiddling with my MR2 a little with the object of offsetting the detrimental shift that my car's PAX multiplier took this year. (7th in novice class sunday, would have been 4th with last years multiplier...oh well). it's a '91 Turbo, currently absolutely stock with the exception of some removable subs. I know I would like better tires, but I may go ahead and wear out the current ones before upgrading, or buy a second set of stock rims...but that's another story.

I just wanted to throw a few questions past the board before I went spending money. Also, I did research as much as prudent before posting, so hopefully these haven't come up several dozen times before.

From what I understand from the rules, I have the option to do braided brake/clutch lines since my car is pre '92.

Also, I see I can add a cat-back exhaust (this may come later as I am poor and those are expensive)

With regards to suspension though it gets a bit fuzzy.

A) Which types of shock/strut swaps are legal, and which aren't for stock class? (to be honest I don't quite get the "two external adjustment " limit, though I'm currently reading up on the subject. I figured just asking might be the way to go)

B) Are camber bolts legal for stock class? the rules make no specfic mention of such devices. (tried a forum search, but only found some ridiculous yarn from when Mr. Bolton was putting them on a 'stang of some kind)

C) Unrelated to suspension, but I know they make carbon fiber or fiberglass T-top replacement panels for the MR2. Are these legal, or verboten based on weight savings while still helping rigidity vs. complete removal of the panels?

I know it's just novice class, but hey, gotta start somewhere.

[Wheelman_13]

Ah, one more:

harnesses. I read and understand that the passive belts cannot be removed from the car, but can I add and use a 5 or 6 point harness in stock class? (if the bar is not structurally enhancing the car of course)

[MARKP]

I'd put the harness in first. It's a relatively cheap and easy mod. It's also easier to drive the car when you aren't worried about staying in the seat.

Camber bolts and good shocks/struts would be next.

You can buy replacement camber bolts from Toyota for your car that are perfectly legal in stock for the MR2. They are commonly called 'crash bolts" since body shops use them to fix camber problems after the car has been involved in a collision.

The two method of adjustment thing refers to double adjustable shocks where you can adjust both compression and rebound independently. They are high dollar shocks that you probably don't have any use for at this time. I would suggest buying some good Koni single adjustable shocks. They have an adjuster on the top of the shaft for adjusting rebound.

If you weren't running Novice, I would tell you to buy tires and wheels ASAP. However, Novice class will kick you out after winning a certain number of events (3 maybe?). If you buy R compound tires and wheels you will probably start winning novice quickly and be moved out to the regular classes. R compound tires are a huge advantage over street tires.

I would also talk to the guys that drive the yellow MR2 in Pro class if you haven't already. That car isn't a turbo but the setup is probably very similar to what you would want, eventually.

Regarding exhaust, most of us don't spend a bunch of money on cat back exhausts. We just buy a good muffler and get a muffler shop to put a larger diameter pipe on the car from the cat back. At national events, I run a straight pipe on my CRX after the cat. It is loud and obnoxious but it works. Your turbo would quiet the exhaust more than a standard car with a cat.

Replacement of your T-tops with something else isn't legal. However, you can run without them installed in the car since that is something Toyota intended for you to do on the street.

[01badz28]

C) Unrelated to suspension, but I know they make carbon fiber or fiberglass T-top replacement panels for the MR2. Are these legal, or verboten based on weight savings while still helping rigidity vs. complete removal of the panels?

I don't have an MR2, but I always run with the tops out. They have 0 effect on rigidity (they are only glass after all), and in the unlikely event of a roll over I don't want that much glass over my head.

[Wheelman_13]

I appreciate the feedback first of all.

I think I'll probably opt for a harness and some decent front tires (not V710s or anything) first and then fiddle with the rest. The harness is important because I do plan on tracking the car outside of autocrossing, so that's a safety thing.

Exhaust would only come into the picture because, on a turbo car, it can amount to measurable hp gain. I think I'll likely wait untill the stock system actually needs replacing though due to the expense.

Camber bolts, being $20 or so, would seem a cheap option, ditto to a lesser extent the front sway bar.

As for the T-Tops, I have heard several opinions.

A) (as you said) They don't affect much, and taking 20lbs off of the roof certainly helps things, lowering the center of mass.

B) The edge rails help with chassis flex between the front & rear, as well as offering some added level of protection in case of a rollover (i.e. the structrual member being their outweighs the danger of being showered with glass pellets.)

C) Drag coefficient of the car (moot point for autocross) decreases with the tops in because they provide smoother air flow over the top of the car.

again, thanks for the replies!

[steverife]

I'm not certain on this, but I'm not sure if track day groups will let you run a harness without a roll bar.

[thrdeye]

i wouldn't expect to gain too much with a cat back exhaust. A few HP, sure, but nothing incredible.

[Wheelman_13]

I am aware of such restrictions (with regard to the harness), and that's certainly something I will consider when I go from planning to actually putting stuff in the car. Unfortunately, I do know a fellow who rolled an MR2 while being a jackass on the street (took it off a bank), the A pillars bent a little, but the b and c pillars were not visibly deformed. Of course, track groups aren't concerned with what I just happen to have seen.

As for the exhaust, I realize that power gains are usually minimal for any non cat-deleting system...On the other hand, if my stock exhaust (which is original to a 170,000 mile car) were to need replacing for maintenance purposes, there's no reason not to replace it with something that weighs less and allows at least a little more power.

Again, thanks for the feedback, any opinions help!

[Wheelman_13]

As an update to my last post, I have done some research and I can't find many (in fact I've come across none) track day clubs or schools (NASA, Car Guys, FLMP, etc) that expressly forbid the use of harnesses in the absence of a bar/cage. The only harness related issue is the requisite of a submarine belt with any aftermarket harness. (Roll bars, are of course a requisite with any true convertible or roadster regardless of belt type)

I have also spoken with several people with 10+ years of trackday experience, and none of them could think of any such restrictions either.

I've heard what I would describe as an "urban legend" about a harness not allowing a driver to shrug down in a seat to avoid a roof being crushed during a rollover. However, this theory ignores the fact that centrifugal force would actually be trying to throw the driver towards the ceiling (or out of the car) during a flip...which a proper race harness would prevent far better than a normal passive belt.

Of course if anyone has information to the contrary, I'd like to know about it, and I'm sure anyone who is thinking about tracking their car would like to know as well.

[thrdeye]

A harness with out a bar and helmet sounds like a bad idea to me at anything above autox speeds.

[MARKP]

There's a reason why SCCA has a rule that you can't use a harness in a convertable without a roll bar.

[thrdeye]

From the rulebook -

3.3.1 Driver Restraints
Seat lap belts are required in all cars, and must be installed in cars
with passive restraint systems that do not include a lap belt. Installation
and the use of shoulder belts or harnesses is strongly recommended,
however non-factory upper body restraints may only be
used in open cars, cars with targa-tops in the open position, or cars
with T-tops in the open position when two conditions are met:
a. The roll structure must meet either the requirements of Appendix
C or Section 9.4 of the GCR.
b. The top of the roll structure may not be below the top of the
driver’s helmet when the driver is in the normal driving position.

[Wheelman_13]

non-factory upper body restraints may only be
used in open cars, cars with targa-tops in the open position, or cars
with T-tops in the open position when two conditions are met:
a. The roll structure must meet either the requirements of Appendix
C or Section 9.4 of the GCR.
b. The top of the roll structure may not be below the top of the
driver’s helmet when the driver is in the normal driving position.

A) let me qualify this by asserting that I would have no intention of doing anything with a car that is condusive to using a harness without also donning a proper helmet. I do have a sense of self preservation

B) Per the rules, in my case, I would be required to leave the T-Tops in place to use a harness sans bar.

C) I'm very conservative when it comes to safety Items, I would like to enjoy motorsports without injuring myself or anyone else. That said, I've also got a pretty strong background with physics, as well as first hand advise suggesting that a harness + helmet (without a bar) is preferred vs. standard belts & helmet only. I'm gonna dig into this a bit further this evening when I'm not shackled by the whole "job" thing.

Now I'm just curious as to the reason behind the feelings that somehow a harness & helmet setup without a bar could somehow prove lethal/damaging in a situation where a passive restraint would not. Sorry to keep bothering with this point, but I'm just analytical like that (not to be confused with anal).

thanks again!

[Wheelman_13]

Also, I could definately see the logic for the reverse. That is, I would never think of putting a cage/bar in a vehicle without also having a harness. A passive restraint could let the occupant come in "contact" with the bar/cage with detrimental results...especially if it remained in the car on the street where a helmet may not be present.

[thrdeye]

It's pretty simple. If you are strapped in to a harness tightly, you're not going to move. Makes your neck the weak point (which is why every race drive now wears a HANS).

Chances are pretty good that if your roof collapses in a rollover, you're dead. What the chance is of your roof collapsing, I don't know.

It's safe to use a harness in Solo, I use one in my WRX all the time. but I wouldn't wear one in our Miata.