Hardtop vs softtop drag

[Jrichards20]

When driving with the roof down, there is a noticeable difference of extra drag felt and pulls down the top speed just a touch.

Does anyone know the drag differences between the softop up and the hardtop on?

I know adding the hardtop stiffens it up a little, but then it also adds a little weight. But what are the effects on drag?

[AndyM]

I would have thought the drag on a hard top would be less but I expect marginally so in real, noticeable terms. The soft-top has the fixings, gutters, beads, etc... which make it a less fluid friendly shape (and it isn't solid). The weight is more likely to be a factor in any performance change.

[Jrichards20]

Thanks Andy, that's what I thought. I was hoping that the drag would be better though  s:( s:(  

Basically, its either all or nothing for me. Hard top with softop taken out, or no hardtop.

Pros of hardtop
Looks MUCH better!
Slightly stiffer
(less drag - not looking like much)
More head room
Less road noise

Pros of softop
Lighter
Roof down motoring
can hear the engine through the mountains better!


Just really don't know what to do  s:( s:(  I suppose once ripped the soft top out the extra weight of the hardtop really wont be much.

[JoeCool]

Soft top is more versatile, and I bet you'd regret going through stunning scenery without being able to drop the top.

On road, ANY road, but particularly on a long tour, you're not looking for extract that last few % of the potential of the car. You can't on road anyway. So make the car as comfortable, versatile and fun as can be. You won't be setting new V-maxes or testing chassis rigidity on unsighted european roads.

[AndyM]

What's driving the "all or nothing" approach to this? I think I'd need to know the context before I could give an opinion on choice.

And yes, my understanding is soft-top inc fitting and frame is a lot less than the hard top. Bear in mind the soft-top is the safer option of the two (unless you have a half cage) which may or may not be a factor if you plan to do any track time.

[tommyzoom99]

Thanks Andy, that's what I thought. I was hoping that the drag would be better though  s:( s:(  

Basically, its either all or nothing for me. Hard top with softop taken out, or no hardtop.

Pros of hardtop
Looks MUCH better!
Slightly stiffer
(less drag - not looking like much)
More head room
Less road noise

Pros of softop
Lighter
Roof down motoring
can hear the engine through the mountains better!


Just really don't know what to do  s:( s:(  I suppose once ripped the soft top out the extra weight of the hardtop really wont be much.

my 2 pence although the die hard roof down crew will flame me for it   s:flame: :flame: s:flame:    s:flame: :flame: s:flame:    s:flame: :flame: s:flame:  

i went and ripped the soft top out  s:) s:)  but that just me  s:) s:)  much prefer how the car looks and it dont bother me 1 bit not being able to put the roof down and if its a nice summers day you can always leave it at home  s:D s:D  then you'll have mucho weight loss

cheers tommy

[JoeCool]

my 2 pence although the die hard roof down crew will flame me for it   s:flame: :flame: s:flame:    s:flame: :flame: s:flame:    s:flame: :flame: s:flame:  

i went and ripped the soft top out  s:) s:)  but that just me  s:) s:)  much prefer how the car looks and it dont bother me 1 bit not being able to put the roof down and if its a nice summers day you can always leave it at home  s:D s:D  then you'll have mucho weight loss

cheers tommy

Sorry to hijack but can you answer me something:

I'm looking to ditch my soft top too, I just want to pull the frame and fabric out but leave the cross beam/seat belt support in obviously. Is there an 'easy' way to do this? CAn you just remove the hinges or something? Or did  you put in a small half cage or something? Cheers.

[Jrichards20]

my 2 pence although the die hard roof down crew will flame me for it   s:flame: :flame: s:flame:    s:flame: :flame: s:flame:    s:flame: :flame: s:flame:  

i went and ripped the soft top out  s:) s:)  but that just me  s:) s:)  much prefer how the car looks and it dont bother me 1 bit not being able to put the roof down and if its a nice summers day you can always leave it at home  s:D s:D  then you'll have mucho weight loss

cheers tommy

Sorry to hijack but can you answer me something:

I'm looking to ditch my soft top too, I just want to pull the frame and fabric out but leave the cross beam/seat belt support in obviously. Is there an 'easy' way to do this? CAn you just remove the hinges or something? Or did  you put in a small half cage or something? Cheers.

No, you need to hack saw the frame off of the seat belt and crossbeam  s:) s:)

[JoeCool]

Ok thanks. Not scared of a bit of angle grinding, but prefer to know what I'm getting myself into!

Back to you!

[Jrichards20]

Soft top is more versatile, and I bet you'd regret going through stunning scenery without being able to drop the top.

On road, ANY road, but particularly on a long tour, you're not looking for extract that last few % of the potential of the car. You can't on road anyway. So make the car as comfortable, versatile and fun as can be. You won't be setting new V-maxes or testing chassis rigidity on unsighted european roads.

Yes, that is what worries me, not seeing the scenery  s:( s:(  

The car will be used for track days so performance, even just a little bit is important to me though.

What's driving the "all or nothing" approach to this? I think I'd need to know the context before I could give an opinion on choice.

And yes, my understanding is soft-top inc fitting and frame is a lot less than the hard top. Bear in mind the soft-top is the safer option of the two (unless you have a half cage) which may or may not be a factor if you plan to do any track time.

Well I don't want a soft top and a hard top. Too much weight, I want to keep the car under 1000kg and trying to save as much weight as possible without removing too much of the interior. I know its against some peoples feelings, but I do want me car to be the best it can without being a completely dedicated track car with all interior taking out. Whether the performance can be used on the road or not. Also, if I have a soft top, I don't see the need for a hard top and visa-versa  s:) s:)

[Jrichards20]

my 2 pence although the die hard roof down crew will flame me for it   s:flame: :flame: s:flame:    s:flame: :flame: s:flame:    s:flame: :flame: s:flame:  

i went and ripped the soft top out  s:) s:)  but that just me  s:) s:)  much prefer how the car looks and it dont bother me 1 bit not being able to put the roof down and if its a nice summers day you can always leave it at home  s:D s:D  then you'll have mucho weight loss

cheers tommy

There is someone on here that has done that and the space where the soft top used to be looks really good. That's one of the reasons why I like the idea because it actually looks good inside and opens up a lot more luggage space.

[tommyzoom99]

Yes, that is what worries me, not seeing the scenery  s:( s:(  

The car will be used for track days so performance, even just a little bit is important to me though.

you got a windscreen to look out aint you  s:) s:)

cheers tommy

[tommyzoom99]

my 2 pence although the die hard roof down crew will flame me for it   s:flame: :flame: s:flame:    s:flame: :flame: s:flame:    s:flame: :flame: s:flame:  

i went and ripped the soft top out  s:) s:)  but that just me  s:) s:)  much prefer how the car looks and it dont bother me 1 bit not being able to put the roof down and if its a nice summers day you can always leave it at home  s:D s:D  then you'll have mucho weight loss

cheers tommy

There is someone on here that has done that and the space where the soft top used to be looks really good. That's one of the reasons why I like the idea because it actually looks good inside and opens up a lot more luggage space.

yeah thats what we have done there is a carpet under the soft top which we retained which keeps it looking nice hides all the bare metal and things, i dont have any pics but can take some if you like

cheers tommy

[mrzwei]

With the softtop down a large amount of drag is generated with turbulent air behind the screen and occupants, this will be worse with the side windows down.

With softtop up or the hardtop on it is more a question of lift. There will be a better aerodynamic profile thus less drag with both but it will be more stable with the hardtop. Both will generate lift and try to pull the car off of the road, air dams and spoilers are used to counter this but the hardtop should end up the fastest option.

Watch the shape of a softop at speed on a motorway to see the lift effect.

(Ex dinghy racer so had to learn a bit about the effects of the wind, or maybe it's just a load of hot air   s:lol: :lol: s:lol:  ).

[AndyM]

Sounds to me like soft-top is the way for you to go mate if you ask me.

Sure if you are going track focused then strip the lot and save the weight, but you have stated you want it to be comfortable for touring in too.

Also, re: track performance, surely it's all relative. Without want to sound critical (I'm really not) the driving technique is what is going to make up the big seconds round a track, not having a soft-top fitted or not. You are only lapping against yourself anyway (not racing against other cars relatively) so it doesn't matter what setup you run, certainly in my opinion it's not worth compromising the other primary use of the car for the sake of 0.05 seconds down a straight that isn't even timed.  s;) s;)

As I say, not my business at the end of the day as long as you are happy with what you end up with. Just reflecting on what a track instructor at Oulton Park told me... "there's no point taking a McLaren to a track day unless you can ring the neck out of a Clio first".

[1979scotte]

I think you are going too track focused again mate if you strip out the soft top.
I love having the roof down. Did it today just for 10mins picking HWMBO from the station.
If you are so bothered about performance super charge the 1mz  s;) s;)

[JoeCool]

I think you are going too track focused again mate if you strip out the soft top.

I agree. I think it sounds like you need two MR2's really:

Get the cheapest 2ZZ car you can and strip it to bare bones for track.

Then build a nice touring build with comforts and the V6 for touring.

You'd end up spending less and getting a better car for each role that building an all in one all rounder.

[Jrichards20]

Yes I think your right Andy, shame a hardtop looks so good haha! I guess I could always take the softop out to start with, put my name down for a mohair one and see how I get on with it, the wait for J.Smith is long enough to give me a good idea on whether I can live without a softtop.

Your quite right! No critisism at all, my driving isn't good, no where near exploiting the full potential of a stock roadster, never mind a modified one! I completely agree driving technique is a much better way to spend money and improve performance. But who doesn't like extracting a bit more performance  s;) s;)  I can't really argue with the fact that hindering any other enjoyment for a bit of performance is pointless. Better give j.smith a call soon  s;) s;)  or find a second hand one!

[Jrichards20]

You all talk so much sense!!!! Your right, too track focused it's a quick tourer not a track car!

[loadswine]

Josh, I would think you would be fine with the soft top and disappointed to lose some of the v6 sound goodness, if you opted for just hardtop. I am not sure what gearbox package is fitted nowadays, but it will probably be lowered geared than the stock Roadster box anyway, coupled with a fat and even torque spread, which would give very useful acceleration in most circumstances.
This is a very exciting time, enjoy!  s:) s:)

[Jrichards20]

Yes, the more I think about it, I can have the hardtop on for looks of need be, but ultimate weight saving would actually come from just having the softop and leaving the hardtop at home. The gearbox is from the Celica if I remember correctly, so not sure about the gearing but I would imagine it's shorter if it's same one used in the 2zz swaps to stay in lift. I keep forgetting that I going for a touring car and not a track car   s:? :? s:?  

If I wanted world record speeds I should have gone for the 2gr   s:lol: :lol: s:lol:  

Once the Summer comes and it's hot I will probably miss the roof down driving. It is very exciting nige, I'm so impatient I just want the car back now!

[Topdownman]

Yes, its a 5 speed celica box.

Have you opted for the taller 5th gear?

[Jrichards20]

Yes, its a 5 speed celica box.

Have you opted for the taller 5th gear?

Yep taller 5th gear and LSD.   s:bounce: :bounce: s:bounce:

[Topdownman]

Good choice. You wont regret that.

[M.R.]

Cd values that I have found are 0.31 and 0.35. There was no information are those with hard top or soft top, so I´m assuming smaller number is for hard top.