The GoodGuys autocross was a bit disappointing. A short suuuper tight course led to alot of understeer, and low speeds. I ran out of time before the event to add more front camber, so I went with my street alignment. After a couple of runs I started doing my best to reduce rear grip to make the car turn in. Bumping up the swaybar position in the rear, stiffening the rear shocks, and running plenty of pressure in the rear tires did make the course manageable. I'm not going to use this event to learn anything about the car other than that it does have useful adjustments that can be made at the track. The brake pedal is still long, and takes plenty of pressure on the pedal to get maximum braking force. Here is one of the only photos I can find from the event:
Well after typing out the last 2 posts, it seems a bit obvious that I should try a larger master cylinder. Unfortunately, I just bought this 7/8" master, but I guess it was worth it to rule out a faulty cylinder. While I don't love the amount of pedal travel needed for the fresh air vent to open in the booster, and the feel of the pedal at most braking levels, I am not sure I want to spend $ trying a different booster yet. First on the menu will be firewall bracing, but a larger master will be on the short list.
Don't get discouraged. You're on the right track, and you'll get it dialed.
Thanks Scott, much appreciated. On another note, I've noticed a noise from the passenger rear recently. After investigation, the adjustable sway bar has been hitting the rear subframe:
I wonder if miatas suffer the same issue, or if I have my control arm tabs welded on slightly closer together than on a miata (causing a vertically taller link). Let's see if removing a bit of length will do the trick. If not I'll be shortening the links or repositioning the tabs.
The shaft collars on the bar were also contacting the subframe, so they were shaved a bit as well.
Back before I added the brake booster, I was using a 15/16" master from an '89 ranger (I realize now the irony of adding power and reducing the master bore at the same time). So, to check if a larger master will solve all my problems I dug it out of the box in my side yard where I put it a few years ago. To my surprise, upon disassembly the insides looked good. There is a small scratch right at the beginning of the bore, but hopefully it is in an area outside where the seals travel. So... to hook up the old master I needed new converters. The cheapest way I could find to ge 7/16-3an was to order some turbo oil feed fittings and drill them out:
After opening them up, one needed to be shortened. I also made a pushrod extender from a stainless bolt to match the pushrod depth to the 7/8 miata master but didn't end up using it.
Of course, when the fittings arrived I only checked 1 to make sure it fit... When it came time to assemble I found the second banjo had a 4an end on it instead of 3an. So out came the box of spare fittings, and a plan to make something work:
After moving the power steering reservoir mount forward for clearance, I could hook up the new (old) master:
After bleeding, the test drive felt like the dead space in the pedal was not reduced. If anything it might have a bit more dead travel. After the dead space the pedal is firmer. I'll have to bleed and adjust the pushrod again before making any judgements.
So... some of you may have read my brake booster adjustment thread: HERE. Long story short, I tried to take my single diaphragm miata brake booster apart incorrectly resulting in a broken booster:
So... this presents an opportunity to play with one of the 7" dual diaphragm boosters from fleabay. After receiving the unit, it is clearly low quality. However you may remember that firewall space in this car is extremely limited, making the tiny booster an attractive option if I can make it work. More updates to come, as I have a track day in a week and a half.
A few updates:
I made a few mock up brackets for the dual 7" booster and ovaled the holes out on the ranger master cylinder to get it mounted up.
However with a track weekend looming, I pulled back from the edge, and ordered a replacement miata booster:
I don't have any pictures, but we replaced the miata booster and reassembled with the 15/16" ranger master cylinder. On the test drive we found out that we hit booster run out before tire lock up. This means that the booster ran out of helping force too early. The result was a pedal that became rock hard near maximum braking force, but no matter how much force the driver applied, the wheels would not lock up. Although disappointing, I was glad to still have the 7/8" miata master on hand. After switching back, the longer pedal throw returned, but so did the appropriate braking force.
Next up a couple of cooling system modifications. I replaced the high pressure, but still vented, cap with a solid cap. Then replaced the capped overflow nipple with a plug.
I had been running tap water as coolant at some point in the past, so my remote radiator cap neck was corroded. I suspected that the cap was no longer sealing well. So, after an order to ebay for a cheap radiator cap bung, and a bit of machining we had most of the pieces:
This cleans things up nicely around the front of the engine. It also gets the vent up higher, and more level than it was before.
In reply to Shavarsh :
Bean is still one of my favorite GRM builds.
After an alignment and nut and bolt check we headed 3.5hr to the track to camp for the evening. Here are a couple photos from the weekend:
Photo credit @cvr_lorax.
Fantastic weekend spent at the track with my brother. Day 1 we had no hiccups, just fine tuning tire pressures and shock settings to minimize understeer. Day 2 started with a good fast session, however when preparing for session 2, we discovered a pinhole leak in the radiator. This was caused by the bumper filler trim rubbing on one of the tubes.
So we removed the bumper filler and the fins near the leak, then crimped the tube around the hole.
Then we washed the area to remove the coolant, thoroughly dried it, and packed in some right stuff rtv:
I had low expectations for our fix, but it held so nicely that we ran for the rest of the day without issues.
Most other participants had left for the day due to the heat, so we got a mostly empty track for a couple hours at the end of the day. At some point one of the front pads delaminated, so we limped it the 3.5hr home on the backing plate.
