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Handling issues and an incurable misfire.

Started by Scooterman, May 26, 2015, 13:33:31

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Scooterman

There is something fundamentally wrong with the way my car handles. It would appear that it is crabbing. Having changed a number of wheel bearings, put new arms on it and new shocks it appears to be worse. Basically, the better (in theory) or stiffer we make it, the worse it handles. Last year with avos on the back that were not working, a bent rear arm and a very high rear end, was the only time it would handle something like ok. Obvious things like tracking have been done.

Is it likely to be a chassis problem? Everything that I can think of has been changed.


Also at Cadwell we changed the wiring, borrowed a manifold and carb from Pete, changed the plugs, coil, reset the timing, changed the HT leads and changed a head. Had a misfire all of the time, any ideas?

I'm going to buy a Mario Ballotelli shirt, but not the fireworks.

Chris Yates

When you say it handles worse - you may have to explain that further for anyone to be able to help properly. I.e. does the back end step out in corners? If so, what part - turn-in, mid-corner or exit? Does it turn in quickly? What are you doing at the time the handling issue occurs - any sudden inputs?

You could take the car to a garage that does 4 wheel alignment. That will at least tell you if all 4 wheels are pointing in the right direction relative to each other. More than that, you'd have to fit something (a bracket or similar) to the chassis so you can measure the distance between the mid-part of the car and the front of the wheels, and then between the mid-part and the rear of the wheels. If there's a major discrepancy side-to-side, then you'll have crabbing certainly.

What's more likely is that something is moving when you load up the car in the corner. Again, your desciption of what the problem is will help here, but I suspect you're losing the rear at some point in the corner under load. Various people have had problems with arms that move (loose axle tube bearings, or "soft" arm material) which changes the rear toe during the corner. This is almost guaranteed to send you sideways or spin you.

Your rear end needs to be tight, basically ... ;)

Also, I see people going with stiffer springs a lot of the time, but with old AVOs. I wonder if the AVO shocks can 'keep up' when the springs are at 4,000 or so. If they can't, then you'll get a sort of "skipping" motion at the back end when the cornering forces overcome the grip of the tyre and there's bugger all compliance in the suspension.

Engine wise - how's your fuel pump? Is it delivering enough fuel at high revs?

Scooterman

Crabbing on the straights Mr Yates, Handling wise it's not keen on turning in, snaking under braking too.

The fuel pump is not a bad idea, but the problem seems intermittent.

Nick clarke

Ignition switches and cut off keys can be common causes of misfires try hard wiring it all see what happens

gadget

we had one of the worst misfires all due to a faulty kill switch.
on the handling, don't waste money on a 4 wheel alignment .
you need to see the ROCKHOPPER.

RLambert

Funnily enough, I'm changing the kill switch on our car as its doing a few weird things, a new one arrived today.

As for the handling, alignment and corner weight would be the first thing to do.


Paul

If raising the rear made turn in better that is because more weight was transferred to the front giving more front end grip.Is the car at minimum ride height?If not i would try lowering it . As a quick guide without crawling about, i think floor to sill should be 170/175mm at the front and !95/200mm at the rear
If you set some axles stands up with string on and put one down either side, close but not touching the wheels and make them parallel to each other  and equi-distant from the centre of the chassis you should be able to see/measure what is out of line.
I know you have changed the rear arms but have you checked the axle tube isn't bent/cracked?
I have not been happy with Willow since i rebuilt it and we came to the conclusion on wednesday night that the nearside rear arm is flexing/soft as suggested by Chris,I tried bracing it before Cadwell and it was better but was still unpredictable.   
  Did you change the condenser when trying to cure the misfire? I agree the kill switches fail, you could connect both cables to one side to eliminate that.

Alec Graham

#7
No expert. But looking at the race video 'Chris Yates'' I think. Your car generally looks like it rolls far too much. I would be looking at spring ratings, and then , ride height, alignment (to rule it out). But from the video it looks far too softly sprung.  Paul, Pete, I'm sure will be able to advise..
It's chris Yates video with James driving about 6 mins in.
James sounds like he has a woodpecker in the car with him. The first time I drove one of Tims cars it was full of ants...

Chris Yates

Quote from: Alec Graham on May 31, 2015, 23:54:31
No expert. But looking at the race video 'Chris Yates'' I think. Your car generally looks like it rolls far too much. I would be looking at spring ratings, and then , ride height, alignment (to rule it out). But from the video it looks far too softly sprung.  Paul, Pete, I'm sure will be able to advise..
It's chris Yates video with James driving about 6 mins in.

Yeah, if you look at that video at 6:15, you can see when Adam's car goes from the right to the left of the Gooseneck, it looks proper horrible, like someone actually removed one of the shockers...

https://youtu.be/fGXqB3VJclc?t=6m14s <- will start the video at the right point.

Quote
James sounds like he has a woodpecker in the car with him. The first time I drove one of Tims cars it was full of ants...

We don't talk about James' pecker - he's a bit sensitive about it.

As for Tim's ants, well he goes for bigger pests these days ;)

Simon Crook

looks really soft on the nearside front to me (but what would I know I have my own handling issues) - front shocker or broken spring perhaps - Adam if you read this - as my car is now mothballed for the rest of the season, on the shelf in my garage I have spare set of GAZ shockers if your stuck and want to give them a go.

Simon   
Simon Crook - Back Racing in 2013
LUMACA RACING

Scooterman

Thanks for your suggestions guys:-).

I've raced without working shocks on the rear until Cadwell this year. At Oulton, Croft and Pembrey last year the rear springs were stuck in a coiled position too- loads of crap had gotten in a hole that had been cut in to the can.  Don't worry tech reg police- we've covered the holes! It was very tail happy last year, crabbed and ate wheel bearings for breakfast- but it went ok. New shocks on rear were way too stiff in comparison to the fronts, I've ordered a new set for the front. ( Thanks for the offer Simon:-) ) Hopefully this will help with the terrible understeer and balance it had at Cadwell. We jacked the arse end up to try and get more weight over the front wheels- without success. It was funny getting wheel spin coming out Mansfield though! Locking the fronts up under braking less fun.

Ride Height. Paul proposed a mod at the AGM, to the shock mounts, to enable a low ride height setting without ruining the shocks. Could someone point me in the direction of how to do this?

With regard to the springs, I made a comment about them being too soft on a picture that Maria put on Facebook. Only to be corrected by Andy Smith, he built the car and said it had the uprated springs, mind you that was a few years back. Perhaps a newer, stiffer alternative has become available since then?

Misfire. Bolted a Solex on a couple of weekends ago, no misfire at all. It would appear (unless its a dormant electrical issue waiting for the next meeting) that it was predominantly Carb related.

Paul

#11
I can send you some photo's Adam ,let me know an email address or mobile number.
 Odd about the misfire when Pete loaned you a complete carb and manifold though.You wouldn't think that would give the same symptoms as yours .

Scooterman

Thanks Paul:-)

[email protected]

Attached is a picture of the cans as we found them last year.