Jump to content
Sign in to follow this  
roulli

spitfire 1500 lift off oversteer

Recommended Posts

My son's Spitfire 1500 has quite a lot more lift off over steer than my 13/60 with swingspring conversion (heavier GT6 swingspring)

The spit has the lower TT springs and new Konis at the front and a 3/4 " lowering block at the rear. The original swing spring has been refurbished with new nylon dots.

I have kept the original rear gas dampers from Girling Decarbon, which some people say were very good dampers for the Spitfire (whatever that means...)

Rear end is polybushed.

Is this lift off oversteer normal, as the Spitfire is more powerfull and the rear spring is softer than the 13/60?

Can this be tamed by replacing the old gas dampers with Konis and increasing the rebound damping?

Another question is , am I right assuming, the radius arms will fit only oine way around, since they aren't symetric.

Thanks for sharing your wisdom

Cheers

Patrick

Share this post


Link to post
Share on other sites

Spitfire is a bit shorter and lighter at the rear than the 13/60, but I'm guessing it also has the longer driveshafts?

I'd be checking the rear toe first........

Share this post


Link to post
Share on other sites
1 hour ago, Nick Jones said:

Spitfire is a bit shorter and lighter at the rear than the 13/60, but I'm guessing it also has the longer driveshafts?

I'd be checking the rear toe first........

Yes, it has the longer driveshafts, which should actually increase stability at the rear end.

good point to check for excessive toe out

 

Share this post


Link to post
Share on other sites

Have you checked for bump steer at the front? With lowered front springs it may be necessary to put some spacers under the rack mounts ginger the geometry correct.

 

My spit is pretty tame with handling, but I can get lift off oversteer when I try (is on an autosolo, where lifting off and dabbing brakes as I turn can produce a substantial change in nose height, but it helps with turn-in and is the only time I really notice it)

But yes, checking the basic wheel geometry is the first step. Lowering affects that more than one would expect. Tape measure and 2 straight edges are your friend. Some string if you wish to get really technical.

Share this post


Link to post
Share on other sites

I was expecting some bumpsteer in deed, but I didn't notice any and steering is great , like what one can expect from a Triumph

Share this post


Link to post
Share on other sites

My Spit 1500 has lift off oversteer and bump steer with lowered front springs (Bastuck). Koni dampers.

GT6 has EXCESSIVE  lift off oversteer but no bump steer (same lowered front springs). 1/2 inch spring  spacer at the rear. Spax dampers.

Herald / Vitesse Estate with standard / uprated (James Paddock) front springs has no bump steer and no / minimal lift of oversteer. Koni dampers

Share this post


Link to post
Share on other sites
48 minutes ago, Martin said:

My Spit 1500 has lift off oversteer and bump steer with lowered front springs (Bastuck). Koni dampers.

 

Koni also at the rear end?

Are you using no lowering block?

seems that lift off oversteer is higher the less percentage of weight you have on the rear axle and the stiffer the rear spring is (Courier / Estate spring)

 

 

 

Share this post


Link to post
Share on other sites

Yes Koni as well at the rear end.

No lowering block. The rear spring is veeeery soft in the Spit but quite stiff in the GT6 (MK2 Roto).

Share this post


Link to post
Share on other sites

Wanted to close this topic,  with a feed-back-

Car handles very safely now.

I've changed the rear Girling DeCarbon dampers against GAZ dampers, which change also the rebound when you set them harder.

The gas-loaded Girlings are quite stiff on bound and soft on rebound which seems to be the opposite of what the swing spring requires.

Now I end up with Koni at the front and GAZ at the rear, which is not what most people would recommend, but it seems to work on this particular car.

The  order for the 1" front ARB has been canceled at last minute, as I was told it can rip off the fixations to the wishbones and it is not needed to make a street-able  Spitfire behave.

After the swap of the dampers I set the geometry (un-laden)

I removed 2 of 4/5 shims at the rear to give it slight toe-in

Front toe-in was set at 1,5mm/ side

Camber hasn't been changed yet. Is currently 0 - -0,5 ° at the front and -3° at the rear.

Might still add one shim at the front to achieve -1,5° of camber

 

Cheers,

Patrick

Share this post


Link to post
Share on other sites

Sounds very positive. I don’t think you’ll gain anything from increased front camber for road use but maybe loose straight-line stability and some tyre life.

I prefer a bit less toe-in at the front maybe 1.5mm total (with poly-bushes)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...