Nissan GTR brake upgrade.

Hi guys,

I've got a set of Nissan gtr callipers and 750 turbo discs I want to fit to the front of my 82 264.
The piston sizes in this are substantially bigger than standard.

I've got a 550hp 383ci V8 in it, so a bit of extra power and weight up front.
On top of that I also operate the vehicle with hand controls only, being a paraplegic.
In saying that I have problems getting enough leverage with the hand controls to lock the standard brakes.

I just wanted to know two things.

Does the 82' 264 have the 5/8' or 7/8' master cylinder?

If it is the 5/8', is it possible to bore it out to accept the 7/8' piston. That way I can just get the repair kit.

Either that or any other recommendations on getting this brake system up to scratch.

Thanks!

your 383 pull much vacuum? volvo 240's have loads of vacuum assist from the factory, a cammed out 383 might not pull enough suction for the brake booster to work.

you probably need something like this first to fix your problem before you upgrade your brakes.
http://www.summitracing.com/parts/sum-760150/overview/

Yeah, depending on your cam it may not pull enough vacuum at higher throttle positions. The added vacuum chamber should help.

AFAIK, all Volvo 2-series master cylinders had a 22mm (slightly less than 7/8") bore. I second the above, but also suggest more research into the piston size of your calipers and what you need for optimum master cylinder ratio. If it does turn out that you need a larger master cylinder (unlikely, IMO), there is a bit here: http://www.davebarton.com/volvo240bigbrakes.html about fitting a master cylinder from a mustang.

Are we talking about the Brembo Lotus style 4 pistons or the 6 pistons on the R35?

the Lotus style should be fine, as they are relatively compact, the 6 pistons would require a master cylinder upgrade for sure.

Everyone seems to think your engine won't pull vacuum, just like burst I'd reccomend an additional pump if that's the case. (See link) http://www.jegs.com/i/SSBC/884/28146/10002/-1

My brother in law is also a paraplegic and I'm setting up a plow truck for him with hand controls, I'd like to see where this thread goes, always cool to see disabled guys out

This type of stuff happens a lot on motors with aggressive cams, and even some motors with not-so-aggressive cams (351 Windsors...)

You can easily mount a mustang mast to the volvo booster.

You need an M10 to M12 adapter, or replace the line from the master to the Junction block if you do the mustang MC.

I've just gone out and done some measurements. Sorry I should have provided this initially.

They are not Gtr brakes they are actually GTS-T brakes.

They have 296mm discs

The pistons are roughly 38mm x 4 each calliper

The 740 turbo discs I have are 288mm from the rough measurement I did.

I didn't have the time to measure the stock ones.
Quickly chucked a tape over the front of the front discs but was hard to get an accurate measurement from my wheelchair but I measured roughly 255mm

Also no idea what size the pistons are but I'm guessing you guys will be all over that. It's for an '82 264.

Didn't cross my mind about the vacuum issue. It has a fairly aggressive cam so I should imagine I would have a problem

As mentioned earlier I already find the brakes a problem due to the lack of leverage from the hand controls. So I'm guessing I will most definitely need to upgrade the MC to get a better hydraulic advantage.

Thanks

Well, you don't necessarily need a hydraulic advantage, you just need the brake booster is do it's job properly, which it can't due to lack of vacuum. You can test it fairly easily by just adding an inline reservoir with a check valve, just like your brake booster has going into it. Eliminate the check valve in the booster, replace it with a pass through, and put the check valve in front of your new res. That's the cheapest, and quickest option to test. If it comes down to a MC replacement, The Mustang MC comes from the 94 GT models according to Dave Barton's page, though you have to extend the ram by .8 mm.

Can you shoot a picture of your hand controls? Perhaps you just need to extend your leverage. Is the throttle controlled like a motorcycle throttle, by your left hand and the brakes being pushed by forcing the throttle lever forward? You'd be amazed how much a little extra length helps a guy out...

Personally I would ditch the booster all together and go for tilton pedals & mc's - especially since the costs of such pump. I find having your foot on the disc very nice and intuitive.

Arn02 said:

Personally I would ditch the booster all together and go for tilton pedals & mc's - especially since the costs of such pump. I find having your foot on the disc very nice and intuitive.

Click to expand...

He's got HAND braking.

if you want more hydraulic advantage you would want a smaller master cylinder bore size. using a larger master without a working booster is a bad recipe you would barely be able to slow down.

Hotdoggin said:

Well, you don't necessarily need a hydraulic advantage, you just need the brake booster is do it's job properly, which it can't due to lack of vacuum. You can test it fairly easily by just adding an inline reservoir with a check valve, just like your brake booster has going into it. Eliminate the check valve in the booster, replace it with a pass through, and put the check valve in front of your new res. That's the cheapest, and quickest option to test. If it comes down to a MC replacement, The Mustang MC comes from the 94 GT models according to Dave Barton's page, though you have to extend the ram by .8 mm.

Can you shoot a picture of your hand controls? Perhaps you just need to extend your leverage. Is the throttle controlled like a motorcycle throttle, by your left hand and the brakes being pushed by forcing the throttle lever forward? You'd be amazed how much a little extra length helps a guy out...

Click to expand...

So this is effectively increasing the volume of the master cylinder side of the booster correct? Thus giving more vacuum assistance while braking.
What would you recommend using as a reservoir?

I've actually had the same issue on my 4x4 which is diesel. The hand control setup is push for brake and pull for throttle. I couldn't lock the brakes on it, which was quite discomforting as we literally drove this thing halfway around the world and back.

I mucked around with the point where the hand control clamps to the brake pedal. The problem is that when you increase the leverage you also increase the throw. There comes a point where I was pushing the hand control into the dash but still not able to lock the brakes.
My volvo is pretty much at this point.

Putting a smaller master cylinder would decrease the effort required to push the brake but I would have the same issue as in more movement would be required to engage the pads with the discs. I kinda have this issue already with the lack of space around the actual hand control.

When I say I had issues with locking the brakes before, this was before I removed the engine and stroked it from a virtually stock 308ci to worked 383ci with a relatively aggressive cam. So I'd imagine I should have some issues with the vacuum.

So I gather that my best bet is to fit everything up then test the Booster and go from there.

It's just increasing the volume of the brake booster's own vacuum reservoir. Do you happen to know what you're pulling at idle? If it's too low, the added volume won't matter. Honestly, a lot of the added canister talk is from Mustang/Camaro/TA-land, it couldn't hurt to pop over into their world for a bit and see what they have to say. The cheap way to test, is to just add any generic in line vacuum canister you can get your hands on, some 3/8ths hose, an inline check valve (replacing the one currently in the brake booster, and replacing that with a pass through valve.) Just to see if it makes a difference, at all.

You may actually be able to tune your pedal play a little bit by adjusting the ram in the brake booster. Thread it out a bit, you won't shorten the throw that way, but it may be enough to move it into your power zone, since you can't add leverage.

Have you ever suspected the hand controls? Perhaps you can add a spacer to bring it further into the zone, so you have more room in engage the brakes?

Is it completely non-feasible to add a vacuum pump to your auxiliary drive? I've seen a few on the SBCs I have torn apart (limited experience, mostly mild drag car engines with aggressive cams)