Overheating/Handling

[Kimbo]

Hey Guys,

I have not posted since I have purchased my car. My name is Kim and I have been following this forum for quite some time. A couple of months ago I purchased a registered, but not entirely finished car.

The car is a Harrison (No. 6) with a balanced (but otherwise stock) 302 Windsor Mustang motor. Live (SS Commodore) rear axle and was originally registered in 2003.

Monday this week I took it to Wakefield Park for a bit of a shakedown run knowing that we have a club day coming up and the nationals a bit down the track - so to speak.

Other than having a great time driving the car, I found two major issues:

Overheating
After about 6-8 laps, the engine would overheat spitting about 3 litres of coolant out during each run. It does not seem to have any water leaks that I can see and so I can only assume it is coming out of the overflow bottle. It has a thermo fan and an electric water pump driven by the Haltec engine management.

Handling
The handling of the car was exciting to say the least. It would throw you off the track for even the most minor changes of direction with virtually no warning. I changed the shock setting to full soft that helped a lot but then had the car body rolling in the corners. Front end turn in was fantastic but rear end grip was almost non-existent. To give you an idea, I was running around the track along with a stock standard V6 VN commodore wagon and he was significantly quicker around the corners - you can only imagine the embarrassment.

Any advise on the this would be very much appreciated as I am only new to this.

Thanks,
Kim

[Mrs flatchat]

Ahhh! sounds like a typical Cobra Windsors don't like being thrashed unless they're built properly ---otherwise be sure your tuning is correct for the fuel being used --timing , air fuel ratios etc water pump direction -- if that does't work, its just bad sealing head gaskets (use best quality gaskets and head studs)
Handling = big sticky tyres for the rear

[sambo]

If you have an R32/R33 rear end you may need to fit a camber kit. They replace the upper (and lower?) arms with adjustable items that allow the IRS to be setup correctly for the Harrison. I know a bloke down here that recently changed his and said it totally transformed the car. His description of how it behaved before the changes wasn't that different to yours! Also speak to Warwick Harrison, he'll have some advice.

Edit: here's an example of the adjustable camber arms on eBay.

REAR UPPER CAMBER ARM NISSAN GTR R32 R33

Nissan S14 S15 R32 R33 R34 SKYLINE REAR LOWER CAMBER

[LoBelly]

I remember my first go around Winton - circulating in about 2:10 while my nephew did mid-low 1:50s in his 1970's celica (!)

I put this down to the timekeeping

And I cooked the engine too....

yikes.

never had any trouble with the cooling in street conditions - the track is a harsh environment.

anyway - if you search you'll find some fairly consistent recommendations on set-up geometry.

If you are running harder street tyres then letting the body roll over the top of them is better and the stickier the tires the more you can firm up the roll

this car started the corner with 4inches of clearance under the sidepipe...


might try putting the sway-bar back on ...

good luck with your set up


LoBelly

[bobcowan]

I dtoesn't sond ulike you were beating on the car all that much. No faster than a V6 wagon. If the tune and build was correct, it should have handled it just fine.

Take a sample of the coolant to a good shop, and have it tested for byproducts of combustion. That will detect a head gasket leak.

As for handeling, what are your suspension settings front and rear; caster, camber, toe? Those simple adjustments make a huge impact on how the car drives and handles. Once you have those correct, then you can think about improvements like sway bars and better shocks/springs. But you gotta do the basics first, or you'll just compound the problem.

[Merv and Sharon]

Warwick has a guy there who does the suspension set up. He did mine. Talk with him. I don't believe that your experience is typical. Geof (Cob 07) may have a comment on both the suspension and the cooling issue as he has done a bit of track work in his Harrison. Later Harrisons models than yours also had very different radiators I believe and suspension changes.

Merv

[Kimbo]

Thanks for your advice guys,
I guess a process of ellimination is required for the overheating issues:
Check thermofan and electric water pump operation
Test system for signs of leaks and gasket issues
Dynotune to ensure mapping is not causing issues
look at radiator and other parts of system to assess suitability.

Originally Posted by LoBelly

LoBelly,
it is interesting that the photo that you have quoted shows my son and I in the background as spectators at this years Shelbyfest. This was the first Cobra event that we had been to and where we made the decision to buy a registered car (instead of building from a kit). I must say the the muscle car sound of your Cobra made a strong impression on us.

Kim

[Merv and Sharon]

Also Kim - and I know this sounds puerile - but also check the radiator cap. I went thru three before I found one that sealed correctly and released into the overflow properly. I spoke to a guy at the radiator shop and he said that as many as 1 in 6 don't function correctly.

Merv

[07cob]

Kim

I took my car to the track before I had it registered and although it never actually overheated, I did end up with a lot of coolant escaping. I had run the car at road speed and had no problem, but the extra push on the track was enough to highlight some issues. Like Merv has just suggested, my radiator cap was not functioning correctly and rather than releasing excess coolant to the overflow, it was just releasing it!! This fixed, the next problem I had is that the overflow tank I have is simply too small (approx 1L) for the track. I reckon at least double that would be necessary. When I get around to replacing this, I will also put an overflow/relief cap on it as well so any extra coolant can be directed somewhere.

I also fitted a camber kit to the R32 rear and while previously I could get no better that about 2 degrees of negative camber, I can now adjust between +2 and -5 degrees. I got my kit from a supplier on the Gold Coast for around $400. That included both of the upper arms (replacing just the camber arm is not advisable for the amount of adjustment I wanted). The supplier suggested that the ones on eBay for much cheaper are indeed much cheaper. I cannot offer any details as to a great suspension setup - I am still playing around with that - but the camber kit certainly provides adjustability where I had little previously.

Cheers

Geof

[Ant]

Some good advice,

The question is I assume these kits use a Nissan R32 IRS, issues like the rear roll centre being designed in conjunction with the front suspension roll centre, can make a big difference. I assume other cobra owners of these kits work well on the track, and you are having the normal teething issues?

Toe in etc on a IRS makes a huge difference to the way the rear works for turn in etc. Your car could be only really using half of the outer tyre to put the power down with all the body rollover.
Also the car rolls excessively it might be a good idea to check the suspension motion ratio and get the right springs to work and then sort the shockies out.

Adjustability is a good thing with a camber kit, and also fitting poly bushes as rubber isnt suitable for track work. I have 100 shore poly bushes in the front of my car, but am using all rod end (rose joints) in the rear. I think you can build a good fast club race type car which is still road driveable using some nice sticky semi slick tyres, going full slicks makes the car purpose built for the track only, and race type springs and shocks generally will cause road tyres to cut out.

Bottom line if the suspension is well designed, then the next thing is getting it in the right place, and then controlling the movement, go back to basics which I tend to do things back to front myself at times....!

[spookypt]

Originally Posted by Kimbo

Thanks for your advice guys,
I guess a process of ellimination is required for the overheating issues:
Check thermofan and electric water pump operation
Test system for signs of leaks and gasket issues
Dynotune to ensure mapping is not causing issues
look at radiator and other parts of system to assess suitability.



LoBelly,
it is interesting that the photo that you have quoted shows my son and I in the background as spectators at this years Shelbyfest. This was the first Cobra event that we had been to and where we made the decision to buy a registered car (instead of building from a kit). I must say the the muscle car sound of your Cobra made a strong impression on us.

Kim

Kim that would be teh mixed dulcet tones of V8/exhaust scrape........... Takes time and effort to get that tuned in just right!

See you at the Nats Lobelly! (aka lowexhaust) Scotty and I are hopeful we will have tuned out our handling and engine probs this year!!!!!!

Spookypt

[Wazza]

Hey Guys,

All the "Rear end" advice being passed on to Kimbo is probably not going to help him much, 'cause it's all for the Nissan IRS..( Many late model Harrison's have this set up ), but the original thread indicates he has one of the Live axle Commodore rear ends.

The car is a Harrison (No. 6) with a balanced (but otherwise stock) 302 Windsor Mustang motor. Live (SS Commodore) rear axle and was originally registered in 2003.

My suggestion would be that a lot of these problems will be fixed with

1. Good wheel allignment
2. Decent tyres at correct pressures.
3. A sway bar fitted correctly.

That would get rid of most of the problems...then if you want it even better, find someone who can set up a racecar...corner weights/spring rates / toe in/out....

One good visit to a reputable operator can save months of ginning around.

My two cents worth.

Good luck with it all,,

Cheers,
Warren.

[sambo]

Well spotted Wazza. Definitely worth remember for later model Nissan/IRS Harrisons though.