21 replies to this topic

[grizzler73]

Hi All

I am starting my racing Heerey GTM build in earnest, beginning with the Front subframe, as standard the GTM was supplied with a lengthened lower arm to give it the correct camber with no engine in the front, it equates to 1.5 degrees neg. I was wondering as mine will be used on the track whether 2 degree arms would be beneficial. what do you think? 

[mini13]

Just stick adjustable ones on it?

[tiger99]

You should make the camber equal on both sides, which it often is not, due to tolerances, so adjustable arms woukd be a good idea. I would suggest that 2 deg is a bit much, 1 to 1.5 should be sufficient.

Don't forget to use Triumph Herald/Spitfire track rod ends to get sufficient thread engagement.

Have fun with the build. I like the GTM.

[nicklouse]

Hi All

I am starting my racing Heerey GTM build in earnest, beginning with the Front subframe, as standard the GTM was supplied with a lengthened lower arm to give it the correct camber with no engine in the front, it equates to 1.5 degrees neg. I was wondering as mine will be used on the track whether 2 degree arms would be beneficial. what do you think? 

as mentioned fit adjustable.

 

if you can not use them in race use then you have loads of testing to do to see what you need when and fit the correct ones accordingly.

 

I ran 1 degree on 10s and 13s on the front.

[grizzler73]

As Nicklouse mentions, I can't get away with adjustables, I can have adjustable tie rods though which helps a bit. I am going to spend a good deal of time setting up the subframe alignment front and rear so at least I am starting from a good place! I think 1.5 degree should be a good starting point.

I have redesigned the rear hub bracket to stiffen it and use the reverse wishbone with an adjustable bush much like the adjustable bottom arm you can get so the rear should be fully adjustable.

[nicklouse]

1.5 is too much you don't get much body roll on the GTM and as it is already lowered you get more neg with movement as well.

[grizzler73]

The GTM build manual quotes between 1/2 and 1 1/2 degrees as ok. bit of a wide margin! Can you get 1 degree bottom arms?

[grizzler73]

Actually I guess standard ones are about 1 degree....

[hhhh]

Stock Minis are about 1/2 degree positive camber to help give understeer.

Edited by hhhh, 30 March 2017 - 04:01 PM.

[grizzler73]

GTM added 3/8" to the lower arm so I have asked mini spares what the diff is between standard and 1.5 degree arms.

[absx2]

I`m driving a mini on 10`s at the moment with about 2 degrees of negative camber and I have to say it is not great in the road holding department as any lift off mid corner makes the back overtake the front unless I hit the power hard which is obviously not safe in an emergency.

 

Other than the camber everything else checks out in terms of the four wheel alignment so I guess I will be adding some adjustable arms to the shopping list.

 

For myself and the many members that will read this topic can somebody please explain why too much negative camber affects the minis road manners so badly so more of us don`t sacrifice the handling for styling.  

[tiger99]

The problem too much front negative camber with a standard Mini is simply that you would get more lateral grip at the front than the back, so the back lets go first in a corner. That is also related to the rear roll centre being at ground level.

What is evident is that Alec knew what he was doing, and got the correct relationship between front and rear camber. You never get such a nice driving experience with radical amounts of negative camber because the transition from power on understeer to power off oversteer, the Mini's primary safety feature that put it ahead of every other mass produced car, becomes too abrupt.

If you want to sort it out, you will end up with complex multi-link rear suspension, but then it will hardly be a Mini.

[Spider]

Forgive my ignorance here, but just so I'm not assuming anything, does the GTM use a standard Front Mini Subframe in the front of the GTM?

[nicklouse]

Forgive my ignorance here, but just so I'm not assuming anything, does the GTM use a standard Front Mini Subframe in the front of the GTM?

Yes but with a lowered ride hight and softer springs.

Originally the rubbers were machined and the trumpets were shortened,

[Spider]

OK, many thanks Nick, as they say, a picture tells a 1000 words.

 

Got it now.

 

I'll just add then, that mealy removing weight (ie, the engine) from the front won't have any effect on Camber Angles, but ride height will.

 

As Mini13 suggested, fit adjustables. The factory tolerance was + / - 2 degrees, so just by starting off with a standard subframe, you could have up to 4 degree difference from one side to the other.

Edited by Moke Spider, 30 March 2017 - 09:17 PM.