Golf R Observations and Questions

**Corey_R** · 24-11-2010, 03:26 PM

My feelings are that in modern cars, the rigidity comes from the frame structure underneath the body panels. The body panels themselves are quite soft/light/flexible. Therefore the addition of a sunroof would make no difference in this regard. The addition of a 2nd row of doors however, would have an effect. (For everyone getting a 5 door car, lol).

Where a sunroof will have an effect on the "physics" of your car is that it adds additional weight, and in the worst possible place - at the top of the car. This negatively affects the centre of gravity.

Having said that, no one uses even 8/10ths of a modern day car's performance on the roads. Anyone who says that they do is either criminally idiotic, or verbally masterbating. So the weight that a sunroof adds is really not a fact in day to day road use. If you were going to strip out the car and turn it into a track warrior, then the weight of a sunroof would not be ideal. But unless this is your intentions, ignore your friend and do what you would like

**HPSOV** · 24-11-2010, 03:58 PM

Unless you are taking your car on a race track, and care about a tenth of a second or two then a sunroof will make no difference to the performance.

**Maz** · 24-11-2010, 05:31 PM

Originally Posted by Corey_R

<snip> The addition of a 2nd row of doors however, would have an effect. </snip>

I'd be interested to see the data that supports this statement (seriously, not trying to stir poo).

I was always under the impression that (generally speaking) the doors added additional torsional rigidity, but the extra weight was the draw back.

**Corey_R** · 24-11-2010, 05:36 PM

I only said it would have an effect. I don't know whether it's a positive or negative effect, and I would say that it would probably vary from make and model of car. So yes, I'd like to see data related to the Golf as well.

**Converted** · 24-11-2010, 05:41 PM

veedubber,
are you a regular racer? pro racer/driver? one who tracks the car? fully tuning your vehicle for max performance? if the answer is no to these questions then its a +1 to Corey_R's comments and +1 to HPSOV.

**Angryman** · 24-11-2010, 05:43 PM

I had a 2004 club spec 7 wrx for 3 years and even on track days the addition of the sunroof made zero difference. Still kept up with the normal rexies without a problem... I agree with coreying in that extra doors may have more of an effect....maybe....

Sent from my HTC Desire using Tapatalk

**stephen8512** · 25-11-2010, 07:54 PM

fingers crossed im picking up my car tomorrow (was meant to be today but delays that couldn't be avoided happened)

just a curious question though....

do you think the Golf R will have the same Cam Follower issue as the MK5 GTI's? And theres no MK5 or MK6 specific cam follower correct? It's one size fits more or less? Because the the Golf R engine is the S3 engine, which is essentially the same as the Golf MK5 GTI?

correct me if im wrong pple

**elephino** · 26-11-2010, 12:08 PM

On a modern car, you'd only be able to pick the difference in rigidity for with and without a sunroof with specialised equipment. Even on a race track it won't affect your lap time (maybe 0.005s but I dare anyone to notice this).

Plus if you tilt the roof open, you get more downforce

**TimmyR** · 26-11-2010, 05:58 PM

Originally Posted by Mr_Bob

To use the HSA, you need to be in first gear with your foot on the clutch, and brake simultaneously.
When you release the brake, it will hold the same braking intensity for 1.5sec
Just enough time to get the revs right and find the friction point.

Hey Mr_Bob I tested this today in my R and i found that you dont have to be in first with the clutch in, all you need to do is apply the break. If the incline is steep enough when you take your foot off the break the car will stay put for 1.5 seconds just like you said.