Who is jerking my chain? (Summit Racing and Addco content)

freestyle wrote: I had the almost exact same story unfold with Summit and an Addco sway bar order. I ordered months ahead of autocross season. Finally got them in the middle of summer. Summit in the end delivered, but it was certainly a supplier problem. Summit did a few nice things to try to make up for it. All my other Summit orders have been flawless and speedy.

My beef is that replacing the swaybar is a friggin' NIGHTMARE on this car with the motor in it. And well... i'm not far from dropping the motor in, and i don't really want to delay that.

On the flip side, the car is sketchy as hell with the big Addco rear bar and the stock 1" hollow bar up front.

Drop the rear bar and up the spring rates at all four to compensate. It will probably handle better. In my experience, huge bars aka "the solid axle conversion" on FWD cars tend to exacerbate inside wheel spin on the front when trying to exit corners. They are nice for the street since you can still have a lower spring rate with decent transitional properties, but low speed corners and rough pavement suck when trying to apply power.

If you need more oversteer when autocrossing, leave the rear bar on the car and hook it up when you get to the event. Just disconnect one side of the linkage (if possible).

Noooo... i need far LESS oversteer when autocrossing. I can't get my spring rates any higher, shocks are not available to support it.

Once i get the front bar, i'm considering going back to a stock rear bar to see how that goes.

The Addco bars ARE too big, period. The Whiteline set performs much better in a competition setting, but i'm not paying for those damn things. I'm cool with compromising with the Addcos, if i can GET them.

Swank Force One wrote:

freestyle wrote: I had the almost exact same story unfold with Summit and an Addco sway bar order. I ordered months ahead of autocross season. Finally got them in the middle of summer. Summit in the end delivered, but it was certainly a supplier problem. Summit did a few nice things to try to make up for it. All my other Summit orders have been flawless and speedy.

My beef is that replacing the swaybar is a friggin' NIGHTMARE on this car with the motor in it. And well... i'm not far from dropping the motor in, and i don't really want to delay that. On the flip side, the car is sketchy as hell with the big Addco rear bar and the stock 1" hollow bar up front.

Run any numbers to see how close you are to 50% Front TLLTD? Close and things get sketchy. Get below (ST* Civic), or above (RWD with Monster front bar) and things get controllable again.

Not sure how to do that.

Here's the weights on the car.... will be slightly different now, it's lost 100-150lbs, and improved F/R distribution slightly.

550lb springs up front, 500lbs springs in back. 7/8" solid bar in back, 1" solid if the Addco comes in, 1" hollow if it doesn't.

I have never liked the ADDCO bars except maybe for street use. Many of them use the cheap end links that rely on poly washers compressing to allow movement, and that is lost motion as far as effectiveness of the bar is concerned. You'd be far better off to have a simple bar bent up without eyes on the ends and have a couple of adjustable solid arms made up from Heims and a split end so you'd have adjustability like a real race car. After market links like ADDCO are often far less efficient than OEM stuff.

If it is a bitch to change, you can even get a straight piece that might be more easily installed with serrated ends that similarly serrated ends slip over, but obviously that would cost more.

Of course all those brilliant suggestions don't help with your current time crunch, sorry. If you can't get the front bar in time, I also vote for disconnecting one link on the rear bar.

I would up the front spring rate by about 100-150lbs/in and see if that helps balance the handling a bit.

Though personally, I'd put the car back together as it is, now that it weighs less, and run it as is to see if it is better or worse before making any more adjustments. If you find after a test that it plows in the front or rolls excessively, then up the spring rates like I described above and retest. You could find that the reduction in weight has helped enough that a slight adjustment in spring rate is needed.

Before changing springs and after a baseline test, you could also disconnect one sway bar at a time to see what effect that has on the handling as well.

Try to keep these adjustments separate so you'll know what change did what to get an idea of what adjustment might be needed next.

BTW, when I say test, I mean a favorite back road or empty parking lot, just make sure you perform similar maneuvers at similar speeds under similar conditions to get a decent idea.

Good luck and I hope this helps,

My shocks will be pretty much completely ineffective at the 650-700lb level. "Gavin" uses one of these cars for DSP use, and the calculations he got out of his car, as well as what worked best before he went full on nuts with Hoosiers was actually an identical spring rate on all 4 corners.

Worth mentioning that i believe he was running a stock rear bar and the Addco front, which would support your theory, but i'm not sure it's worth pursuing on lowly Tokico Illuminas.

wspohn,

I'm not really a fan of the Addco endlinks either, but they're cheap, and in this case, better than the factory stuff. I have a solution in play for "down the road" concerning endlinks that should remove the poly. The other problem with swaybars on these cars is that they like to rip through the control arms. I need to look into changing mounting location to a tab on the strut instead of on the arm. Would potentially let me get away with stock bars much better as well.

Good to know. Though what works for one driver doesn't always work for another. Be careful copying fellow racers, they may be winning despite what they are doing to the car tuning wise.

A friend was helping a couple running a 510 in SCCA GT racing and they were trying really hard to get the car to turn in effectively. The husband had setup the car based on what other racers had done, but it just would not turn in. Finally they had adjusted everything and were out of time on the race weekend and when the husband mentioned having to weld up another diff with a different gear set for the next track, my friend realized the issue and told them to spend the money on a proper limited slip. They did and found the next time they ran the car they were all over the inside of the corners. They removed many of the changes they had made and the car responded better. The welded diff combined with their driving styles led to the understeer they were fighting.

That said, if you know that 650/700 is not something the struts can control effectively (very probable as many performance/street units aren't built for real spring rates, just for stock or slightly stiffer lowering springs). Then perhaps you'll have to remove the rear bar from the equation to restore balance until you can get better valved shocks, stiffer spring rates and/or better sway bar solutions.

Cancelled the order

Swank Force One wrote: Not sure how to do that. Here's the weights on the car.... will be slightly different now, it's lost 100-150lbs, and improved F/R distribution slightly. 550lb springs up front, 500lbs springs in back. 7/8" solid bar in back, 1" solid if the Addco comes in, 1" hollow if it doesn't.

Interesting. I'd have thought you'd be in search of more rear bar and remove the front bar completely. Inside wheelspin must be nuts with that car.

The car is beyond tailhappy as it is. The pro driver took out the timing box at GRM $2012 with it. Ass first. It's a total bitch to drive.

Fairly common with FWD mazdas. If you want it to feel great on the street for easy driving, big rear bar. If you want to go fast, big front bar, small rear bar.

The DSP guy has math figures and such to support the why, but I never paid attention much. Only cared about the end product. I think i'm going to put a stock rear back on it for now, then sell the addco rear to fund a splined huge speedway front bar.

Worth mentioning that the 1" hollow bar up front isn't stock. It's a late 1st gen Probe GT bar.

Swank Force One wrote: The car is beyond tailhappy as it is.

Hence my earlier comment about TLLTD. You may want to try it with zero front bar before doing anything else - its free to try. You may find that it gets less tail happy.

I once had a ST* prepped Saturn and had that exact experience, but opposite. Going up in front bar actually made it more crazy loose. The STX WRX I co-drove was the same. One event where I paxed way higher than normal the car had crazy grip and wasn't loose we found one of the front endlinks was busted and the bar was doing nothing.

You think that's worth trying if the rear bar is already 300-400% stiffer than the front bar and it's undrivable? Suppose it's free.

Well, common issue with swaybar discussions... unless you know the length from centerline to endlink attachment and the length of the bar, the diameters don't mean much. That said, if all else being equal, a 7/8" solid rear bar is not even close to 3-4x as stiff as a 1" hollow front bar. Remember, stiffness varies linearly with length and lever arm, but with diameter to the 4th power. For example, if your hollow bar has a .125 wall thickness, its still like 16% stiffer than the solid rear.

Aynway, what I'm getting at is your TLLTD may be pretty damn close to 50% which will make your car batE36 M3 crazy tailhappy. Dial that up to 60-65% like a RWD car via a big front bar and it may fix that, but unload that inside front tire a lot. Dial it the other way - well below 50% like a successful FWD ST* car and you'll still solve the loose issue but control the roll from the rear of the car allowing to front to do the best it can at putting down power.

My numbers were far off, my mistake.

Here's some numbers.

http://www.mx6.com/forums/1g-mx6-other-performance/89899-fun-swaybars.html

Unfortunately the pic of the front vs. rear doesn't show for me. But it looks like your hollow front bar is still stiffer than the Addco solid rear.

I'd say its definitely worth trying the car at an event with the front bar disconnected. Sucks it isn't easy to change though.

At the risk of being Obvious Man, make sure you check your tire pressures during these observations. Higher pressures up front and/or lower pressures in back can effectively decrease your TLLTD, leading to oversteer, and vice versa.

ProDarwin wrote: Unfortunately the pic of the front vs. rear doesn't show for me. But it looks like your hollow front bar is still stiffer than the Addco solid rear. I'd say its definitely worth trying the car at an event with the front bar disconnected. Sucks it isn't easy to change though.

Yeah, the 1" hollow front bar appears to be 16% stiffer than the rear bar i run.

volvoclearinghouse wrote: At the risk of being Obvious Man, make sure you check your tire pressures during these observations. Higher pressures up front and/or lower pressures in back can effectively decrease your TLLTD, leading to oversteer, and vice versa.

Bearing in mind that this thing autocrosses maybe twice a year... i haven't spent a whole lot of time dialing it in. Typically run 33-34 on all four corners.

I know that this an an Apples to Oranges comparison, but my SAAB c900 turbo corners much better without a front bar. It does have significantly more body roll, but I can provoke the back end to come around, even with out left foot braking if I try hard enough. Inside wheel spin is almost zero, so I can put the power down early. Wheel spin & hop was awful with the bar.

Keep in mind that this car is heavy, has double wish bone front suspension with stock springs, doesn't have torque steer problems, and definitely is nose heavy. I use Yokohama S.Drive tires.

I'd like a bit more rear bar, but they are tough to find. I also have a full poly bushings kit that needs to be installed, so I need to do that before making any other changes.

TL,DR. Try it without the front bar.

One other thought- if this car is lowered, the suspension geometry may be such that the roll center was raised when the car was lowered. This could be leading to big weight transfer in corners leading to inside front tire lifting.

This car is VERY lowered and i'm well aware that i've completely berkeleyed my roll center, and that my geometry is all kinds of terrible.

I'm not out to win national championships with this thing or anything, but i think it's very doable to at least make the thing drivable, and let power, brakes, and sheer mechanical grip do the rest. As i seem to be prone to build: Sledgehammer/wrecking ball.

Loose is fast. Drive better

HiTempguy wrote: Loose is fast. Drive better

I'd love to drive better, but if a multi-time national champion autocrosser struggles with it, E36 M3's pretty berkeleyed.