Brake testing

[keith reed]

I have mentioned more than once or twice etc that I took the 4 pot calipers brakes off my VT Clubsport and put them on my VH. The VT has ABS that the VH doesn't have so perhaps the results won't be the same. I once had to do a panic stop on the VT, the way it pulled up was to put it mildly staggering. I have often toyed with putting ABS on the VH but first I want to find a straight empty road and see if the brakes do lock up. Not this weekend because it is raining but perhaps during the week.

Under normal to hard braking they are very good but I have never had to stop in a great hurry. Roll on next week.

 

[Lacksballs]

I’ll be interested in the test results, you don't mention the pad material, booster nor master cylinder set up.
The front and rear axle weights of a VH compared to the VT are different so you may find the rear is over braked with VT clubsport 4 pot Brembo’s all round.
Just with the std VT front upgrade M/C & VS booster on Gen 1 Commodores its a huge improvement over STD. In a panic stop mine lock up all 4 wheels.

 

[Smitty]

.. I run VX SS (booster, master, calipers etc) on the race car
with the right pads and braided lines, it has taken some to time
and a WILWOOD balance valve to get it to the point where
the fronts lock just before the rears

yes, I realize this is on a race circuit with a car with not-street
spec suspension but it is one thing I have aimed for with this car
... just nail the brake pedal (at 200+) and it stops as it should!
Weight transfer getting the fronts to do 85-90% of the retardation

Gettin 'em to go fast is easy, getting them to stop before you crash
.. another!

 

[keith reed]

I’ll be interested in the test results, you don't mention the pad material, booster nor master cylinder set up.
The front and rear axle weights of a VH compared to the VT are different so you may find the rear is over braked with VT clubsport 4 pot Brembo’s all round.
Just with the std VT front upgrade M/C & VS booster on Gen 1 Commodores its a huge improvement over STD. In a panic stop mine lock up all 4 wheels.

The pad material is Remsa, the booster is VS and not quite sure but I think the master cylinder is VT.

The brakes have been on the car for many years now and have been no problem. Not quite correct as I nearly got rear ended about two weeks ago. AlI heard was a big squeal of brakes behind me. On a country road I do brake late and quite heavy as the person behind me found out.

There may be a weight difference between a VH and a VT. The front of a series 1 would be comparable the series 2 would be lighter. Keep in mind there would be a big difference between a VT with one person than another with say four extra people each weighing 100 k each. Brake systems have to cope with this.

I did a panic brake stop when these brakes were on my previously owned VT Clubsport. They halled up very quick with no lockup. Perhaps you have other problems.

This is the third car I have put big brakes on and if I were to start all over again I would do exactly the same. I hold to the belief that the brakes and suspension are the first modification, not an after thought.

 

[keith reed]

I have just got back from testing the brakes. I braked as hard as I could three times from 100k. It stopped in a straight line with no lock up. It was as I had expected though very pleased with the results.

I didn't mention it earlier but part of the braking is due to the tyres. On all my vehicles I have Bridgestone RE003's with a tyre pressure of 45 psi.

 

[vc commodore]

I've had a couple of hard stops in my VC....That has a double diaphram booster and 15/16 M/C from the VC era...Front brakes are std VT twin pot calipers and rears are std VC style calipers.

Front pads are Bendix and rears are EBC (from memory)....Tyre pressures are 36 PSI with my Kumhos....Never had a lock up myself....

And my personal thing is, why would you want to lock up.....There is no control when that occurs....

Glad you posted up your results

 

[Smitty]

I have just got back from testing the brakes. I braked as hard as I could three times from 100k. It stopped in a straight line with no lock up. It was as I had expected though very pleased with the results.

I didn't mention it earlier but part of the braking is due to the tyres. On all my vehicles I have Bridgestone RE003's with a tyre pressure of 45 psi.

wow...way too much pressure

a tyre stops rotating quicker as it has more grip... when it gets distorted
with heavy braking. The weight of the vehicle is also a factor here
Very high pressures like that (45psi) simply don't allow this. Very little
or no tyre distortion with pressures that high. The side wall will be solid as

The first thing with any vehicle used on a skid pan, wet or dry, is to blow
the tyres up to 45-50psi ..... why? simply as they have less grip.

Again, motor racing... but I start with my semi slicks at 26-28 psi as they
warm up to about 34 when sticky. Full slicks?... 22 psi when cold warms
up after a lap or two. Track surface temps also play a part here...

still 45psi is way too high in my opinion


ps... I run 42psi on the front of my HSV R8, low 35 series 20" tyres will wear
the shoulders horribly if i don't (say my mates who own a TyrePower and BJ store)

 

[keith reed]

wow...way too much pressure

a tyre stops rotating quicker as it has more grip... when it gets distorted
with heavy braking. The weight of the vehicle is also a factor here
Very high pressures like that (45psi) simply don't allow this. Very little
or no tyre distortion with pressures that high. The side wall will be solid as

The first thing with any vehicle used on a skid pan, wet or dry, is to blow
the tyres up to 45-50psi ..... why? simply as they have less grip.

Again, motor racing... but I start with my semi slicks at 26-28 psi as they
warm up to about 34 when sticky. Full slicks?... 22 psi when cold warms
up after a lap or two. Track surface temps also play a part here...

still 45psi is way too high in my opinion


ps... I run 42psi on the front of my HSV R8, low 35 series 20" tyres will wear
the shoulders horribly if i don't (say my mates who own a TyrePower and BJ store)

I went on a driving course in about 1987, That was what they suggested and I have done so since then. Tyre wear has always been good and even. Your 42psi is not too far astray than my 45psi on 18" wheels.

I understand that on a race track with slicks or semi slicks that due to tyres heating up quicker lower temperatures are needed. I did buy some used V8 racing semi slicks. I got to pick what was there and my intention was to have a play on the track. However when I put coilovers on the front of my VH the tyres wouldn't clear so I gave that idea away.

 

[Immortality]

Yeah, I run 40psi or slightly more on 17/18's, any less and I find the tire wear is not even. I also tend to find the higher pressures the car tends to ride better.

I was watching a video from the Nurburgring with a AGM 63C Merc, First guy driving was driving it but not full send and tyre temps were around the 60-70°C, then the owner went full send and tyre temps topped out over 100°C. Not long after the driver noted the tyres were done with. Tyre temps went up a heap too but I can't remember the numbers as they were in KPa.

 

[Immortality]

Here you go if you have a spare 30 minutes. This thing is a beast.