Brake Upgrade

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rodavo
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Brake Upgrade

Post by rodavo »

Hey guys. I am doing a brake upgrade on my Piazza and this is what I have found so far.

I purchased a Hopper Stoppers brake upgrade kit to suit a Gemini. The kit includes commodore 300mm discs, twin piston calipers, custom hubs, brake lines bearings, etc... I have test fitted the kit to one side of the car and so far all looks good. It pushes the front track out a little so I had to get the guards rolled to allow my 16 inch wheels to fit (you need a minimum of 16 inch wheels to fit the rotors and calipers inside the wheel). I havent driven with the kit yet so I dont know if there are going to be rubbing issues when the suspension compresses or when I turn corners (the car is lowered 2 inches), more to come on this later.

The smaller of the 2 wheel bearings is exactly the same as the standard Piazza one, however the larger of the bearings has a smaller internal diameter for the Gemini. Luckily the outer race is the same diameter so you can use the standard Piazza bearing in its place.

As far as a brake master cylinder upgrade, I found that a TF Rodeo 1 inch bore MC will bolt straight on the Piazza booster with no modification at all. The only drama I see is that the Piazza booster may not be large enough for the brake upgrade. I have a feeling it will be alright but time will tell. You need the larger diameter MC so that the pedal is not too long, you have to displace more fluid due to the larger pistons in the new calipers.

I should be fitting the whole lot up for good in the next few weeks so I will update then.

Dave
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GeminiCoupe
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Post by GeminiCoupe »

I take it you fitted the kit to the standard Piazza stubs [judging by your bearing-bit]?

Also note that 15" wheels WILL fit over the discs and calipers. Why? Because its been standard fitment to all commodores VT onwards [300mm discs, twin spot calipers], and standard fitment also happens to be a 15" steel wheel.

Good research, i know someone who might need it..

Nick-
project - 76 Gemini Coupe G200z EFI Turbo
daily - 02 S15 Nissan 200SX GTspecS Turbo
wet-weather fun toy - TX 75 Gemini Sedan G200z
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Rodeobob
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Post by Rodeobob »

Thats good info, Cheers for that.

One thing i would like to know would be how do the Piazza bearings compare to a std Commodore hub.
GeminiCoupe wrote:Also note that 15" wheels WILL fit over the discs and calipers. Why? Because its been standard fitment to all commodores VT onwards [300mm discs, twin spot calipers], and standard fitment also happens to be a 15" steel wheel.
That would depend on the design of the 15" wheel. Steel rims are pretty thin compared to alloys.

Cheers. Bob.
Too many Piazzas to little money.

Currently unemployed. Watch this space.
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rodavo
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Post by rodavo »

Yeah your right Nick. 15 inch is the minimum. I had it in my head that my wheels were the smallest you can go. The link shows the kit that I bought and some info on it.

http://www.hoppers.com.au/300gemini.pdf

Bob, I am not sure about how the standard bearings compare to the commodore ones. The hubs you get in the kit are completely custom and I wouldnt think would have any resemblance to a commodore hub, if thats what you are getting at. I could be completely wrong though. The Piazza uses very common wheel bearings so they could be the same.
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Post by Bugle »

IIRC there's a problem with the caliper hitting the upper or lower arm on the Gemini on full lock.. If it's the lower arm I guess it's probably not a problem due to the different design of the Piazza lower arm.
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GeminiCoupe
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Post by GeminiCoupe »

A stop needs to be welded on to stop the wheel turning past a certain angle, youd have to put it on the Piazza and see how it goes. What about the caliper mounts? There different to the Gem ones arent they?

Nick-
project - 76 Gemini Coupe G200z EFI Turbo
daily - 02 S15 Nissan 200SX GTspecS Turbo
wet-weather fun toy - TX 75 Gemini Sedan G200z
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Rick82
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Post by Rick82 »

i dont know if its my suspension or the tyres on my car but i think my piazza is the best stoping car i have ever been in, i plant on my brakes and the thing just pulls up like no tommorow and does not slide at all.
it also pulls up very well in the rain, i have noticed tho it will want to go to the left or right sometimes when i really get stuck into them.

i have bulstien suspention allround and really cheap tyres on the standard rim.
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rodavo
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Post by rodavo »

Yeah, I have checked out the full steering lock issue and by the looks of it it will just miss the control arms. Once again I will have to wait until I get it all on properly and on the ground to find out for sure. The kit comes with the tabs to weld on.

As far as mounting the calipers, I have bought high tensile Unbrako bolts (M10 X 55 I think from memory, will check that one) and metal lock nuts. I am planning on taking some photos soon to show how it all bolts up. So far the kit looks like a fairly simple bolt on upgrade. So far!!!

As far as the stopping power of the standard brakes, I really dont like the standard brake setup. Its got too much grab at the rear end for my liking (possibly due to the larger rotors on the rear or could be a bias issue). I have stiff suspension all round as well and decent tires. Rick82, maybe your setup is better for some reason I am not sure, but I am really unhappy with mine. It doesnt help that I am use to driving a race car though!!!!

Anyway, anymore questions just ask..

Ill keep updating as I go.

Dave
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Post by Bugle »

The Commodore caliper has bigger bolt holes doesn't it? I remember the bolts being huge on my parents VT when I had to remove the calipers..
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Post by Rodeobob »

Cave, by Commodore i meant the pre VR type.
Rather than the Gemini hub, use the Commodore one they are a bit more common for the big disc kit and should be cheaper. I want my front track out a bit further as well. I might try and score an old commy hub/disc.
Or use something Falcon on the front.
I wouldnt even care if i had to go kingswood stud pattern.

I was even thinking of trying to find another front spindle thats a bit stronger to fit between the Piazza arms. Make a balljoint adapter for the bottom arm.

The Rear wont matter, it will be done to match the front, diffs got to be cut down anyway..

If my mate comes thru i should be able to get the discs and calipers for free.

Rick82, i wouldnt be surprised if that left or right thing is the rear wheels locking. Thats what happens. Not very stable and definatlely not safe.

It would be a bais issue. Smaller rear pad area would have made the rear brakes less effective as well so yeah its also to do with the rear discs being bigger. But then bigger pistons in the calipers on the back would also make them less effective at low pressure. Who the hell knows, Isuzu and Holden certainly didnt or they would have sorted it properly, it wasnt as if they werent told. Id say it was close to the main issue as to wyh they couldnt sell them. If the press had said oh it handles like magic and has the best brakes in its class they would be thick on the ground like Celicas.

Bob.
Too many Piazzas to little money.

Currently unemployed. Watch this space.
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Bugle
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Post by Bugle »

Apparently there was a bias problem that they fixed sometime around the start of 1987?
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rodavo
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Post by rodavo »

Well......brakes are on the car and it was well worth the upgrade to.

Not to many hassles getting it all on, will go into a few more details when I have more time. Brake bias seems pretty good and the car stops so much better, most notibly when you brake hard at say 100km/h. I will post up some pics when I get them off my phone. Everyone should consider this upgrade for their piazza, it is so much better than stock and safer too!!!

Dave
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rodavo
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Post by rodavo »

Here are some pics. Sorry for the crappy quality but its the best my phone could do in the dark.

Image
Image
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