Sunday, August 21, 2016

BRAKES 3

I got the rt. side finished today but still have to get a set of bolts to fit the caliper. I'll use 3/8" bolts and make a sleeve to go on them to tighten up the fit. I hope to have the other one by maybe Tuesday and will take it for a test drive.


Took the test drive today and the brakes are fantastic. Wow, does it stop now and much less pedal pressure. I can lock the wheels if I push too hard. Better tires might prevent that. I think 32mm pistons would do just as well. This is an area where you don't know till you try it but I'm happy.

Saturday, August 20, 2016

BRAKES 2

I was not happy with the look of the Suzuki calipers and will send them back. I bought, instead, a pair of Ducati Monster calipers with four 34mm pistons and four pads per caliper. Much higher price but larger pistons so more braking effort than what I had. The Suzuki calipers have four 32mm pistons and 108mm bolt spread. The Ducati has a 100mm bolt spread. Both are about the same size but the Brembo ones are a tiny bit smaller
The 3x3x1/2" aluminum angle will be made into the mounting brackets. I roughed out one today. I plan to add Drillium to it to lighten it up and do some contouring to it also.
I think these will look great when all finished up which should be early next week.



Thursday, August 11, 2016

FRONT BRAKES

I haven't posted for some time because I've just been driving and the car has, for the most part, has performed beautifully. The one exception has been the front brakes. The calipers I got with all the parts were from Wilwood, an aftermarket supplier. They have turned out to be not up to the job. They will stop Ok but in a panic stop I have to really push hard on the pedal and the calipers over heat, boil the brake fluid and then tend to lock up. Following that they start to leak fluid. The calipers I got are described on the JZRUSA page. http://www.freewebs.com/jzrusa/07.htm

So, I have had enough and have bought new calipers.
These are from a Suzuki 600, 750 and 1300 Hayabusa bike on ebay. They have 4 pistons with 32mm pistons, similar area to the  Wilwood units and larger pad area than the Wilwood units.

Some notes on caliper area/pad area.
A single piston floating caliper with a piston area of, say 2.4 sq. in., is the same as a caliper with 2 pistons with 2.4 sq. in. area each. A 4 piston caliper with a single piston area of 1.4 sq. in is still the same as all the above. You take the number of the pistons on one side of the caliper and figure their area to find the force the caliper can create. A 4 piston caliper will have larger pads due to the larger spread of the 2 pistons on each side. Look at the width of the caliper on the web site above and look at the calipers I just bought. The piston area of the new ones is 2.5 sq. in. but are much wider.

Now for the myth of pad area. If you double the pad area you will not change the pedal effort required to stop the car!!! I know, this doesn't make sense but it is physics 101; trust me or look it up. So, what does happen by increasing the pad area is that heat is dissipated better and pad life is extended. Of course all the above requires the same master cylinder pad composition and the same pedal force. There are some other very small bits that affect pedal pressure but the above are the main areas of concern.

I'll post photos as I make the brackets and mount the new calipers. BTW the brake hose hookup will be really simple.


Saturday, November 21, 2015

HANDLING ISSUE

I've had a handling issue for most of this year. When accelerating and decelerating the car would pull to the right and to the left and when braking it would pull left. I got stuck with the idea it was the rear wheel not being in line with the chassis. After measuring the alignment of the rear wheel I found it was off by about .029"; not bad.

I then looked at the left front brake and found that the caliper bracket was not square to the rotor and that the caliper was not sliding well on it's mounting bolts. There is the problem; a dragging brake pad. This too would make the car pull each way when giving it gas and letting off and when braking. Sure enough, new pads, caliper seals, shims on the bracket and reaming the slide holes fixed it all. It now drives straight all the time.

Now I'll go back and play with toe out and tire pressures some more and see what happens. Probably nothing but I think it's worth a look.

Friday, June 26, 2015

LONG CRUISE

Last weekend I went along with a group of motorcycles on a 200 mile drive through the twisty back roads of south Alabama. This was the first long drive and the first drive on twisty roads at speeds of up to 75 MPH. It was exhilarating  to say the least but the car handled great and took the curves at speed right along with the bikes. Temperatures were in the mid 90's but I felt no heat from the engine. The drive shaft tunnel felt warm from, I assume, transmitted engine heat and heat from the driveshaft bearings. I'm looking forward to another run like that, maybe in the fall.

Wednesday, June 3, 2015

HANDLING ISSUES SORTED

I have finally gotten the handling issues sorted. With the caster now at about 7 degrees, camber at -1 degree and toe at 1/8" toe out. Front tires at 20Lbs. and rear at 40Lbs. She now drives straight up to 80 MPH. I can wiggle the steering wheel without affecting the straight line motion. Side winds will push it and require correction with the steering wheel as in any car. I've driven it through 90 deg right corners at 40 MPH and it handles them with ease.  I've put about 1200 miles on it now and it is a pleasure to drive.

One last thing to play with is scrub radius with the front wheels. The tire inner edge is offset from the kingpin line by 2". It will take a lot of work to change that so it probably won't get done.

Monday, March 9, 2015

LET THERE BE LIGHT

The alternator problem is fixed. The amperage draw dropped from 23 to 18 with high beam, 16 with low beam. The light output difference is amazing and I know they are not adjusted correctly in the photo so it will get even better.