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Jerry
Jerry HalfDork
8/13/13 3:33 p.m.

I have a lot of time to think at work while my machine is counting down it's measurements.

Weight reduction by removing the front spare, etc? Or add weight to the front selectively for better front end traction?

chaparral
chaparral HalfDork
8/13/13 3:40 p.m.

Lose weight first, adjust cornering stiffness distribution with tire sizes later. This goes double for being able to lose weight off non-drive wheels.

ransom
ransom UltraDork
8/13/13 3:43 p.m.

There may be some funny business with rallycross, dirt surfaces, etc that I'm missing, but adding weight shouldn't make the front stick better.

It'll develop more force with the greater downward pressure on the tires, but that will be more than offset by the additional work they have to do to drag the extra weight around the corner.

Now I'm going to go ahead and talk COMPLETELY out my butt so I can be utterly embarrassed when someone who knows something about these cars and/or rallycross gives real info and I look a complete fool... But I'm going to go out on a limb and guess that you're locking up the fronts and/or pushing on corner entry on brakes [that's an edit, I originally typed "no brakes", d'oh] due to having a car with a light nose and brake bias set up for the weight transfer of pavement. I bet if you installed a brake bias adjuster and moved some braking to the rear, you'd feel less like the front is skating around unweighted.
/End blithering and unsubstantiated guesses about a car and sport I have zero practical experience with...

EvanB
EvanB PowerDork
8/13/13 3:46 p.m.

Here I am trying to figure out how to take weight off the front of the Miata to make it more like your MR2 and you want to add weight to the front?

GameboyRMH
GameboyRMH UltimaDork
8/13/13 4:12 p.m.

Weight is the enemy, adding weight should be your absolute last resort.

Look at moving weight. AW11s come with the battery in the back, right?

Matt B
Matt B SuperDork
8/13/13 4:18 p.m.

Yep, battery is in the back, but moving it to the front requires some pretty heavy cables so there's some debate over whether or not it's worth it.

That said, I'd like to try it since the car is not only extremely rear-heavy (62%ish stock), but also because you get to move that weight down 1.5-2ft (rough estimate).

Jerry
Jerry HalfDork
8/13/13 4:21 p.m.

In reply to EvanB:

Didn't say I WANTED to, just "weighing" my options.

Dr. Hess
Dr. Hess UltimaDork
8/13/13 4:39 p.m.

I moved the battery on my AW11 (RIP). I put a battery box in the front where the spare was and ran cables back. Cables don't have to be that big and it's not that long a run. I did teh mats on it once, comparing the size of the original cables to the starter and what size given the extra length would result in a similar voltage drop. Don't have that with me, but some decent copper welding cables will be fine.

Knurled
Knurled UberDork
8/13/13 4:41 p.m.
EvanB wrote: Here I am trying to figure out how to take weight off the front of the Miata to make it more like your MR2 and you want to add weight to the front?

This, bears repeating, and so on and so forth.

iceracer
iceracer UberDork
8/13/13 4:53 p.m.

When moving the battery, you only need the positive cable. Can't be THAT heavy.

Nathan JansenvanDoorn
Nathan JansenvanDoorn Dork
8/13/13 5:20 p.m.

FWIW, I know auto-xers who have gone faster with weight added to the front of their aircooled 911.

Jerry
Jerry HalfDork
8/13/13 5:24 p.m.
ransom wrote: I bet if you installed a brake bias adjuster and moved some braking to the rear, you'd feel less like the front is skating around unweighted.

THIS makes sense. My whole purpose of this question was mostly for hairpin and almost-hairpin corner transits. Saturday I tried a number of different methods/combo's to get around a sharp corner in soft kinda-wet dirt.

I tried braking early and turning, tried slow precise turn, tried wide and tried narrow apex. I'm not sure which really worked best. My thought was brake early, turn in, gas and try to rotate the back end through the turn. In my head this sounded easy, in my short-lived experience it was not so easy.

Perhaps I just need more experience. Maybe something to add more oversteer to the car would help. Maybe the brake adjuster. Maybe just more ride-alongs with Chris to school me some more. (That helped Saturday...)

racerdave600
racerdave600 Dork
8/13/13 5:31 p.m.

Remove the weight. Take out the spare, jack, etc. It doesn't get you much, and it certainly won't affect much either. When I built my ITA MR2, you were required to leave the battery in the back, but I still removed as much as I could, everywhere I could. Taking those pieces out of the front doesn't have much affect on handling.

On an old autocross MR2, I did move the battery to the front and it is not at all difficult, so if rules allow, that is a bigger advantage. Not only does it move the weight from the back to the front, it allows you to lower it in the car by more than 12 inches. I consider that a bigger bonus. If I remember correctly, Hoelscher may even have his in the passenger compartment on his DP car.

In reply to ransom, It would affect overall handling balance more than weight transfer under braking. That should be more brake balance, weight transfer related.

irish44j
irish44j UberDork
8/13/13 5:42 p.m.

I prefer to brake hard in a straight line before initiating the turn. In slow out fast works best for me. I have my battery in the back (e30) and I estimate that I'm pretty close to 50-50.

All that said, one of the fastest cars in our MR class for half of last season and early this season was a V6-swapped MR2, which certainly has more weight in the rear. I know jack about driving an MR2 but have to image it's all about driving style.

Not sure how adding front weight would help you in hairpins though.

EvanB
EvanB PowerDork
8/13/13 5:53 p.m.
Jerry wrote:
ransom wrote: I bet if you installed a brake bias adjuster and moved some braking to the rear, you'd feel less like the front is skating around unweighted.

THIS makes sense. My whole purpose of this question was mostly for hairpin and almost-hairpin corner transits. Saturday I tried a number of different methods/combo's to get around a sharp corner in soft kinda-wet dirt.

I tried braking early and turning, tried slow precise turn, tried wide and tried narrow apex. I'm not sure which really worked best. My thought was brake early, turn in, gas and try to rotate the back end through the turn. In my head this sounded easy, in my short-lived experience it was not so easy.

Did you try ripping the handbrake and whipping it around? That worked pretty well for me.

JohnyHachi6
JohnyHachi6 HalfDork
8/13/13 6:43 p.m.
Jerry wrote: Perhaps I just need more experience. Maybe something to add more oversteer to the car would help. Maybe the brake adjuster. Maybe just more ride-alongs with Chris to school me some more. (That helped Saturday...)

I think some more experience will definitely help.

When I started autocrossing my 2nd gen MR2, I had a lot of issues with the front end washing out right on turn-in. I found that it took a very different driving style vs FF or FR to get it to turn in crisply. What ended up working well for me was to set up the car by tossing it towards the outside of the corner on entry (think somewhat more gentle Scandinavian flick) and tapping the brakes just at the turn in point to bring some weight back over the front tires. The car would turn in with that brake tap, then I could just bury the throttle and run through the whole corner with the car planted.

That was the great thing about running an MR car - once you got it turned in you could get on the throttle very early and not worry about loosing traction.

EvanB
EvanB PowerDork
8/13/13 6:51 p.m.

Remember, that skinny pedal on the right is pretty effective at reducing understeer when used correctly.

zipty842
zipty842 Reader
8/13/13 8:05 p.m.
racerdave600 wrote: Remove the weight. Take out the spare, jack, etc. It doesn't get you much, and it certainly won't affect much either. When I built my ITA MR2, you were required to leave the battery in the back, but I still removed as much as I could, everywhere I could. Taking those pieces out of the front doesn't have much affect on handling. On an old autocross MR2, I did move the battery to the front and it is not at all difficult, so if rules allow, that is a bigger advantage. Not only does it move the weight from the back to the front, it allows you to lower it in the car by more than 12 inches. I consider that a bigger bonus. If I remember correctly, Hoelscher may even have his in the passenger compartment on his DP car. In reply to ransom, It would affect overall handling balance more than weight transfer under braking. That should be more brake balance, weight transfer related.
zipty842
zipty842 Reader
8/13/13 8:05 p.m.
racerdave600 wrote: If I remember correctly, Hoelscher may even have his in the passenger compartment on his DP car.

This is correct. My AW is somewhat modeled after Hoelscher's Hoelscher's Photobucket

Jerry
Jerry HalfDork
8/14/13 6:52 a.m.
EvanB wrote:
Jerry wrote:
ransom wrote: I bet if you installed a brake bias adjuster and moved some braking to the rear, you'd feel less like the front is skating around unweighted.

THIS makes sense. My whole purpose of this question was mostly for hairpin and almost-hairpin corner transits. Saturday I tried a number of different methods/combo's to get around a sharp corner in soft kinda-wet dirt.

I tried braking early and turning, tried slow precise turn, tried wide and tried narrow apex. I'm not sure which really worked best. My thought was brake early, turn in, gas and try to rotate the back end through the turn. In my head this sounded easy, in my short-lived experience it was not so easy.

Did you try ripping the handbrake and whipping it around? That worked pretty well for me.

Ha. In '87 they moved the handbrake to the passenger side and forward, to "increase leg room". WTF? I'd have bought a bigger car if I wanted leg room. So it's way the berkeley up toward the dashboard. I'm considering having Colletti move it over to the driver side.

Knurled
Knurled UberDork
8/14/13 12:08 p.m.
EvanB wrote: Remember, that skinny pedal on the right is pretty effective at reducing understeer when used correctly.

And you can't steer when your front tires are sliding...

I keep having to remind myself of that one

zipty842
zipty842 Reader
8/14/13 12:56 p.m.

In reply to Jerry:

They did it to save money. 84-86 RHD cars also had it on the right, so they had to make 2 different center consoles.

dean1484
dean1484 UberDork
8/14/13 2:21 p.m.

Having raced MK1 for many years I can tell you that weight reduction in these cars is most important. Since they are underpowered to begin with so add HP by putting the car on a diet. Never add weight to an MR2 if you can avoid it. Work with the suspension to make it handle

A huge weight reduction and help to handling is removal of the sunroof. Not only is it a substantial amount of weight but it is at the highest point in the car. If it is an SCCA IT car they will require this anyway.

Then go form there. Anything you can remove cut off take out do it.

Our MR2 loved negative camber something like 3 deg negative and more in the rear really helped the handling. I don't remember caster and toe at the moment I would have to look at the cars notebook but they were hugely helpful in getting the car to rotate as well..

carbon
carbon New Reader
8/14/13 2:25 p.m.

Add lightness and tune handling with the suspension and alignment.

Jerry
Jerry HalfDork
8/14/13 2:34 p.m.

No sunroof (not even T-top) so that's a plus.

Gutted most of the interior, only thing left is headliner and maybe that will go away this weekend. And the dash. My next project is poly bushing set from Prothane and new shocks/struts (probably Koni's).

Rear sway bar? To be honest I'm not sure the front/rear sway bar situation in this car (bone stock suspension and 26yrs old except some ball joints replaced after purchase if I remember).

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