MR2 Roadster Owners Club

The Workshop => Performance Related => Topic started by: andyno12 on July 8, 2016, 20:32

Title: Lightness at high speed
Post by: andyno12 on July 8, 2016, 20:32
Evening, when driving at a high speed I find the car goes really light on the front which isn't a good feeling at all, doing a bit of research I see it might get better when my teins are fitted. Does anyone else have this problem? Do you thing lowering springs will make a difference? Should I maybe try a front splitter?
Title: Re: Lightness at high speed
Post by: shnazzle on July 8, 2016, 20:42
Common issue. Few resolutions;

- check for correct tyre pressures
- get 4 wheel laser alignment done
- ensure you have the air dams under the front bumper. They're little plastic strips, one in front of each wheel and a long one along the front.
- check state of the subframe.

That's the list really.

Lowering does tend to help as well. But it shouldn't do it stock either

Sent from my SM-N9005 using Tapatalk
Title: Re: Lightness at high speed
Post by: JoeCool on July 8, 2016, 21:01
Geometry.

I have no front arch liners, no front air dams (exept the central one under the bumper) and stock suspension, but I do have good tyres and a good alignment. The car is stable out past 120mph.
Title: Re: Lightness at high speed
Post by: keeper2611 on July 8, 2016, 21:27
Quote from: "JoeCool"Geometry.

I have no front arch liners, no front air dams (exept the central one under the bumper) and stock suspension, but I do have good tyres and a good alignment. The car is stable out past 120mph.
[/b]

On the track obviously   s:D :D s:D
Title: Re: Lightness at high speed
Post by: JoeCool on July 8, 2016, 22:04
Yes, the Nurburgring! 195Kph on the GPS trace!
Title: Re: Lightness at high speed
Post by: keeper2611 on July 8, 2016, 22:08
Quote from: "JoeCool"Yes, the Nurburgring! 195Kph on the GPS trace!

Impressive!
Title: Re: Lightness at high speed
Post by: andyno12 on July 8, 2016, 22:09
Quote from: "shnazzle"Common issue. Few resolutions;

- check for correct tyre pressures
- get 4 wheel laser alignment done
- ensure you have the air dams under the front bumper. They're little plastic strips, one in front of each wheel and a long one along the front.
- check state of the subframe.

That's the list really.

Lowering does tend to help as well. But it shouldn't do it stock either

Sent from my SM-N9005 using Tapatalk

Everything on your list is good, apart from the air dams (didn't know the car had any) il check in the morning.
Title: Re: Lightness at high speed
Post by: andyno12 on July 8, 2016, 22:20
Quote from: "keeper2611"
Quote from: "JoeCool"Geometry.

I have no front arch liners, no front air dams (exept the central one under the bumper) and stock suspension, but I do have good tyres and a good alignment. The car is stable out past 120mph.
[/b]

On the track obviously   s:D :D s:D

Of course the track, it's playing on the "track" a few days ago when I really noticed it. 115moh up is not a nice feeling
Title: Re: Lightness at high speed
Post by: andyno12 on July 8, 2016, 22:21
Quote from: "andyno12"
Quote from: "shnazzle"Common issue. Few resolutions;

- check for correct tyre pressures
- get 4 wheel laser alignment done
- ensure you have the air dams under the front bumper. They're little plastic strips, one in front of each wheel and a long one along the front.
- check state of the subframe.

That's the list really.

Lowering does tend to help as well. But it shouldn't do it stock either

Sent from my SM-N9005 using Tapatalk

Everything on your list is good, apart from the air dams (didn't know the car had any) il check in the morning.

I will also have the wheel alignment redone when springs are fitted
Title: Re: Lightness at high speed
Post by: shnazzle on July 8, 2016, 22:29
First time we've heard in here that the air dams by the tyres don't cause instability at high speed. Wonder if it's the centre one that does the most then.
The other factors play a much bigger role though. Especially incorrect toe settings can really mess with handling

Sent from my SM-N9005 using Tapatalk
Title: Re: Lightness at high speed
Post by: JoeCool on July 8, 2016, 22:38
I'd also add the lower steering UJ. Swapping that transformed my car from an unruly nightmare to nice and stable, but the Geo cemented it.
Title: Re: Lightness at high speed
Post by: The Other Stu on July 8, 2016, 22:46
I have the spare wheel and a heavy toolkit in the frunk.

I know when my tools aren't there, despite weighing less than 10kg
Title: Re: Lightness at high speed
Post by: andyno12 on July 8, 2016, 23:00
Quote from: "JoeCool"I'd also add the lower steering UJ. Swapping that transformed my car from an unruly nightmare to nice and stable, but the Geo cemented it.

Thanks, something else I hadn't thought of
Title: Re: Lightness at high speed
Post by: andyno12 on July 8, 2016, 23:01
Quote from: "The Other Stu"I have the spare wheel and a heavy toolkit in the frunk.

I know when my tools aren't there, despite weighing less than 10kg

I have my spare in there. I let a friend drive to hear his thoughts, he suggested a bag on sand in the frunk lol
Title: Re: Lightness at high speed
Post by: Ardent on July 9, 2016, 00:53
Geo

On these cars it makes a such a difference.

Problem is finding a company that REALLY know what they are doing.
They may have the kit. But can they use it.

I made a 180 mile round trip t get mine done. But worth it.
Title: Re: Lightness at high speed
Post by: Carolyn on July 9, 2016, 07:20
What size are the front tyres?  Correct tyre size makes a massive difference.
Title: Re: Lightness at high speed
Post by: ChrisGB on July 9, 2016, 07:25
Same make and model of tyre in the correct sizes all round?
Title: Re: Lightness at high speed
Post by: Carolyn on July 9, 2016, 12:40
The correct stagger (relative width of front and rear tyres) is very important.  Having quite a few different wheels and tyres hanging around, I've had the chance to try various combinations.  Although my daily driver is a pre-facelift, I've ended up with the standard facelift set-up as the best handling package for all-round use, which does include some naughtiness.  It is definitely the one that gives the best straight line stability.  
I don't have the same make and model of tyre front and rear.  The car is very well balanced in the twisty stuff. While I can see the argument for having the same make (the results are more predicatable), the front and rear tyres do very different jobs.  The front does most of the braking and the steering.  The rear gets the power down.  It's quite possible to find an ideal combination from different makes front and rear.  This is very common on motorbikes. Of course, you don't mix tyres on the same axle.
I also think my TRD bumper really helps at high speeds.  You can see the massive difference to the air flow under the front of the car:

(http://i959.photobucket.com/albums/ae71/CarolynneK/20150928_101304.jpg) (http://s959.photobucket.com/user/CarolynneK/media/20150928_101304.jpg.html)