Which first; coilover height adjust or wheel alignment?

[davekmoore]

Car blew up at Winton over a year ago. Bits of the motor went through the rack so that has been replaced, leaving the steering wheel out of straight.

The car spun several times after the blow up, fortunately on the infield, but judging from the amount of grass and top soil in the sides of the tyres, I guess this won't have helped the alignment or anything else.

Strangely, with the new motor etc in the car, the driver's side is now lower than the passenger's side, even with no driver in the car.

Also, the front wheels have a lotof toe out, with more on one side than the other.

Finally, the back end has way more negative camber than it ever had, with more on one side than the other. It's bad enough on one side to be waving at the nearest copper to pull me over.

I know exactly what ride height, front to rear difference and alignment specs I need, but what should be done first? Ride height, straighten steering wheel or wheel alignment?

[zossy1]

None of this sounds good.

First of all, the toe on the front is no surprise. A new rack obviously means you are starting from scratch with toe settings.

Rear neg is concerning. That is not something that an engine blow should have impacted, but it sounds like spin was pretty serious. Have you checked all your control arms for straightness? They bend easily. This goes for the front also.

This will become more apparent when you try and align the car. You will find it impossible to align the car properly if the control arms (or worse - subframe(s) or the chassis) are bent.

That said, I usually start with a coilover height adjustment prior to starting the alignment. Ride height affects camber and toe and it is important you get it right before doing your alignment. However, if you then corner weigh and find that you need to make adjustments, this may affect your alignment enough to revisit the settings.

[davekmoore]

Thanks zossi.

Everything looks straight under the car. There was 3 degrees of negative on the back before the incident so maybe I'm imagining the change?

Ride height first, then keep my fingers crossed eh?

[zossy1]

Yep - get your ride height set, then align and see what happens - good luck!

If you need subframes, I can help - as can Lou and others

[beavis]

Ouch, sounds like new motor didnt last long.

set height. alignment last.

[davekmoore]

Don't panic. This is still the rebuild since Winton 14 months ago. Doing the fiddly bits at the moment including final tune on Wednesday.

[davekmoore]

Thought I'd get a final dirty job for the day out of the way tonight and finished doing the corner heights. Now all at the Tein recommended preloads and (lower than Tein recommend) at 53 metric thingos from ground to the top of the front fender edge and 58 at the back. I was aiming for 6 difference but the car does have a full tank of fuel so 5 difference now might work out ok with half a tank. For those still working in Imperial and measuring from centre of wheel to top of front wing edge that would be 1ft front, 1ft and 1/5th of an inch rear.

Will try this over my usual roads tomorrow and decide whether to go lower.

[Okibi]

Emilio did a great guide here - http://949racing.com/miata-race-alignment-info.aspx

The tein recommended heights are pretty good to.

Then get a REALLY GOOD alignment done.

[davekmoore]

Emilio did a great guide here - http://949racing.com/miata-race-alignment-info.aspx
The tein recommended heights are pretty good to.
Then get a REALLY GOOD alignment done.

Thanks. Perfectly put. I'm using exactly that guide and aiming, depending on local road hazards, decisions on front lower aero, and limits of suspension adjustability, to do a composite of the recommendations thus:

4.4" front pinch weld height, 4.65" rear with me in the car and half a tank of fuel.
Front camber -3
Caster 4.25
Front toe 0
Rear camber -2.2
Rear toe 1/8"

[Magpie]

4.4" at the pinch welds is quite low and may give you issues loading on to a trailer. What tyre pressures did you use? Was the car level when you did the heights?

For my NA6 I finished with the following heights at the pinch welds, drivers weight, half tank and tyres at 32 psi. The rake that you set will impact the height of your planned aero.

FL 126, FR 127, RL 129, RR 133, splitter 99, cross weight 49.5%

As an observation, I found that setting the coilover length first then adjusting height by preload gave me the best result, it is worth the time to do it properly. However, I will be able to define 'best result' after the next track day.

[davekmoore]

4.4" at the pinch welds is quite low and may give you issues loading on to a trailer. What tyre pressures did you use? Was the car level when you did the heights?

For my NA6 I finished with the following heights at the pinch welds, drivers weight, half tank and tyres at 32 psi. The rake that you set will impact the height of your planned aero.

FL 126, FR 127, RL 129, RR 133, splitter 99, cross weight 49.5%

As an observation, I found that setting the coilover length first then adjusting height by preload gave me the best result, it is worth the time to do it properly. However, I will be able to define 'best result' after the next track day.

I only use a trailer when the motor has blown up.

28 all round in the tyres. All corners will go up a tad with track pressures.

Level ground.

The rears will come up a touch with less fuel.

The car is also a DD hence preload left the same across axles. Mind you, SHMBO is 45kg lighter than I am so maybe I need more preload on my side?!

[Magpie]

Any speed bump issues? Being a pedant sometimes what you think is level is not. I thought that the garage floor in the place I moved into was level, but after setting a laser level up it was found to be not level. Whilst 5mm may not make much difference 20-30mm will.

'SHMBO is 45kg lighter than I am so maybe I need more preload on my side' or maybe not have the extra weight in the car?