Are Griff's brakes so bad??

[nic]

Hi guys (and dolls)!

I drive no Griffith - unfortunately, so I can't personally evaluate - but yesterday I stepped in the following homepages:

www.einszweidrei.de/tvr/griffith5001994-1.htm
www.einszweidrei.de/tvr/griffith5001994-2.htm

where they report terrifying stopping distances:
100 km/h (62mph) to 0 in 44 to 50 meters!!

Are Griff's brakes really soooo bad!?

Thanks!
nic

[Ballistic Banana]

Heres some stopping distances of cars from the same era all 70mph - 0mph distnace in feet. from top gear 93.

Griffith 500 - 190ft - vented discs all round - 0-60 - 4.6 secs top speed 157mph
Corvette LT-1 - 162ft - vented discs all round, ABS - 0-60 - 6.6 secs top speed 156mph
Porsche 911Turbo - 157ft - vented discs all round - 0-60 - 4.9 secs top speed 168mph
Ferrari 348ts - 160ft - vented discs all round, ABS - 0-60 - 5.8 secs top speed 161mph
Toyota Supra - 153ft - vented discs all round, ABS - 0-60 - 6.2 secs top speed 155mph

A good 12 mtrs longer than best one there which is the Supra with ABS. Thought I'd add the other stats too

I think with better Pads/discs now the distances may be less(along with many other disc brake mods) but not by much and as usuall there are many different circumstances to take in to consideration ie road/weather etc.

BB

[g-boy]

jeepers! i'm getting a griff soon and pressumed the brakes were decent ???

[Ballistic Banana]

If you want to work it theres a very simple formulae here www.csgnetwork.com/stopdistcalc.html

Strangley the highway codes states the typical stopping distances at

60mph are 73 metres (240 ft)
70mph are 96 metres (315 ft)

Which they are all well under

BB

[GreenV8S]

nic said:

terrifying stopping distances: 100 km/h (62mph) to 0 in 44 to 50 meters!! Are Griff's brakes really soooo bad!?

100 kmh equals 28 ms-1. Stopping from 28ms-1 in 44 meters indicates that you take 3.142 seconds to stop with an average decelleration of 8.9 ms-1, that's roughly 0.9 G. Under ideal conditions with hot tyres on a dry road and a perfect brake setup the limit of grip will be at around 1.15G. It would take a pretty lucky and/or talented driver to maintain perfect threshold braking the whole way. I reckon an average of 0.9 G is pretty good going. If this is terrifyingly bad, what sort of braking performance would you consider to be acceptable?

[Ballistic Banana]

GreenV8S said:

nic said: terrifying stopping distances: 100 km/h (62mph) to 0 in 44 to 50 meters!! Are Griff's brakes really soooo bad!? 100 kmh equals 28 ms-1. Stopping from 28ms-1 in 44 meters indicates that you take 3.142 seconds to stop with an average decelleration of 8.9 ms-1, that's roughly 0.9 G. Under ideal conditions with hot tyres on a dry road and a perfect brake setup the limit of grip will be at around 1.15G. It would take a pretty lucky and/or talented driver to maintain perfect threshold braking the whole way. I reckon an average of 0.9 G is pretty good going. If this is terrifyingly bad, what sort of braking performance would you consider to be acceptable?

now you put it that way it all makes sense and as they said in Autocar 1992 "One of the strongest, most reassuring set of anchors this side of a full blown racer."

BB

and to many magazine articles to quote

[nic]

Thanks for the informations!

GreenV8S said:

If this is terrifyingly bad, what sort of braking performance would you consider to be acceptable?

Actually, my Clio 172 stops from 100km/h in 40 meters (and she's 1080 kg, exactly like a Griff) ok, with ABS.
Among sportcars, some Porsches are under 35 meters.
You mean, it's all about the ABS?

[GreenV8S]

35 meters represents an average of about 1.14 G which is doing well for road tyres. But the Porsche may be on softer rubber which would potentially have slightly more grip. The TVR may not have absolutely the best brakes on the planet but they're pretty darned good, and any car that can sustain over 0.9 G under braking is not too shabby in my book.

[wheeljack888]

nic said:

You mean, it's all about the ABS?

Not all (some of it's down to optimising front/rear brake balance) but a great deal of it is down to ABS. ABS allows the tyres to operate near the peak coefficient of adhesion aswell as allowing you to steer the vehicle under heavy braking. It is in fact bloody amazing!

>> Edited by wheeljack888 on Wednesday 8th March 23:36

[shpub]

All depends on how the ABS is setup.... Most Euroboxes have the threshold set quite low so that it kicks in before the maximum is approached.

All these brake distances (like 0-60) are very dependent on conditions, things like tyre pressures and driving technique.

[jonnyb]

If it was good enough to stop a tonne and half of Ford Sierra, I'm sure it will stop a tonne of Griff quite well! Plus there are some after market options you can consider.

[The Moosehunter]

GreenV8S said:

and any car that can sustain over 0.9 G under braking is not too shabby in my book.

I would agree, except if you tried to do that numerous times in a short space of time in which case I wouldn't hold out that much hope on the early 240mm disc Griffs.

The 260mm's I believe cope admirabley, including spirited track days.

For road use you should be fine with either (assuming all your components are in good order)

[BIG DUNC]

I have always believed that the best way to improve the brakes on a road car is to fit the very best tyres you can. Most road cars, even a road car with really naff brakes, can lock the wheels in dry conditions. Therefore, better grip will inprove the stopping distance ( as will a better driver ). I know that once you get on the track, heat build up and fade become important, and bigger brakes will be able to stop you more more than once, and probably have better feel as well. For a standard road car, I think the brakes on my Griff are pretty good. I have definately owned cars with far worse....

[GarryM]

The figures BB quoted surprised me - I thought the Griff would be better than that compared to the others. Could just be down to the test but then the Griff is the only one that stands out.

I remember a brake test undertaken by Tiff on Top Gear a few years ago on a Chim 500 (vs a M3 hatchback). The conditions were damp. He locked the brakes until it eventually came to rest and then proudly demonstated the benefit of ABS on the BMW. Hardly the best way to make the Tiv stop. Makes you wonder whether this is the standard way to test braking distances (ie just lock the wheels in the belief that many drivers would do just that)?

[BIG DUNC]

I have always assumed that in a car with ABS the quickest way to stop is just stamp on the brake and let the electronics sort it out, rather brake as hard as you dare without locking up like you would in a car with non ABS.
In the Jeep we had the ABS cut in very early and several times I thought I could have stopped quicker without it. It just seemed to cut in at any excuse ( as Steve said about Euro box's ). I know it was big and heavy, but I am sure it was too eager for its own good.
The Scooby we have now has excellent ABS. The car has great grip anyway, but you have to get silly to provoke the ABS into action. And when it does decide to work, it is very effective, definately better than an averige driver ( i.e. me ) could do.
When I get back into the Griff, I have to remind myself to be carefull, or I have a nasty fright......

[aerospoke]

Just slightly off topic bur there is allways a spiderconversion to be considered: in a test done by the german magazine sportauto the tuscan2 outbraked a porsche 997s! The stoppingdistance from 100 kmh was under 37 meters, if i remember correctly, although the Tusc was on sticcier tyres than the porker.
And it outraced the porker too!!!

So 2 ups for TVR

Cheers Jens

[mrmaggit]

I've done 70-0mph in just over 70 feet, on a Ride-drive test day, on a runway. Went about another 10 feet with two of us in the car, from the same speed.

Of course, that does not allow for thinking distance, as I was lined up on a cone.

Nobody was more surprised than I was.

[simpo two]

Can't fault the braking on mine; I nearly had to pick my teeth out of the steering wheel once...

[Toffer]

I agree with Simpo 2...the Griff brakes are really powerful when applied with vigour, most times you get nowhere near the limits of adhesion...as an earlier contributor commented, tyres make a huge difference, as of course do the road surface. 0.9G is a lot?

[GriffOz]

Tyres make a big difference to ABS as well. ABS often kicked in early on my Lexus LX470, like Big Dunc's Jeep, but since the tyres were changed from the OE Dunlops to Pirelli Scorpions the ABS has never been triggered.