| AlanDatsomefun wrote: |
....As I see it, your current problem arises largely because your rear suspension is soft but over-damped (a consequence of the Bilsteins slowing the action of soft standard rear springs).
Yes. 
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| Suspension http://ozdat.com.au/forum/viewtopic.php?t=34214 |
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| Author: | tds001 [ Tue May 10, 2016 2:42 pm ] |
| Post subject: | Suspension |
Hi There I have a 1981 Stanza that is very hard to keep on the autocross track oversteer problems ( Tank Slappers) Front - Std Stanza set up factory with 1.5 neg camber ( longer lower control arms ) Rear- std coils with Bilstein shockers Nolathane Bush in rear links rear diff locked up No rear sway bar 65 series 14" tyres any help would be great |
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| Author: | unfamilia [ Wed May 11, 2016 7:53 pm ] |
| Post subject: | Re: Suspension |
Get a rear sway bar |
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| Author: | AlanDatsomefun [ Thu May 12, 2016 5:03 pm ] |
| Post subject: | Re: Suspension |
You have not said what type of surface you are driving on (Autocross can be on dirt or tarmac) but with a locked diff noting that you are experiencing oversteer, you would have to be on dirt. On tarmac you would experience a very different set of problems, starting with understeer. If you have standard shocks and springs up front and standard sway bar, fitting a rear sway bar as a first step will only induce greater oversteer on the dirt. As I see it, your current problem arises largely because your rear suspension is soft but over-damped (a consequence of the Bilsteins slowing the action of soft standard rear springs). Oversteer occurs when (say, suddenly turning left) weight is quickly shifted to the opposite (right) hand side of the vehicle and the outside (right) rear wheel which now has greatest traction tends to drives the car forward and to the left, amplifying your original steering input. In an attempt to make a correction, you suddenly turn the opposite way, and any attempt to correct the see-sawing motion will result in it becoming worse. The way ahead is counter intuitive (assuming your steering is in good condition): the front springs have to be stiffer, damping rates of the front shock absorbers has to be increased (especially in compression) and a stiffer front sway bar installed to reduce body roll - in combination this will create a bias towards understeer. Only after upgrading the front suspension would I concentrate on the rear. Next, stiffen up the rear springs - by all means keep the Bilsteins but only if the front shocks have similar or marginally higher damping rate. I suggest front springs should be a bit stiffer than the rears, because of the weight distribution of the Stanza. Only after this, would I suggest fitting a rear sway bar. |
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| Author: | SR20Datsun [ Thu May 12, 2016 5:08 pm ] |
| Post subject: | Re: Suspension |
Adding a rear swaybar I think will make your oversteer problem worse. If the car was understeering, then I'd add more rear bar. The locked diff is contributing to the tank slapper aspect. You need to tune your suspension around it. Lower your front tyre pressure or raise your rear tyre pressure or both. Firmer front springs would help. You want a larger front sway bar. If you have adjustable shocks, the front shocks should be hardened up, while the rears made softer. For parts and advice, Baz at Datsport in South Aus has a fair bit of experience with Stanza's both on the gravel stuff but also the track, so should be able to sort you out with bolt on goodies and appropriate advice. |
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| Author: | SR20Datsun [ Thu May 12, 2016 5:09 pm ] |
| Post subject: | Re: Suspension |
HAhahaha... Alan beat me to it! |
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| Author: | SR20Datsun [ Thu May 12, 2016 5:11 pm ] | |
| Post subject: | Re: Suspension | |
....As I see it, your current problem arises largely because your rear suspension is soft but over-damped (a consequence of the Bilsteins slowing the action of soft standard rear springs).
Yes.
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| Author: | AlanDatsomefun [ Thu May 12, 2016 5:13 pm ] |
| Post subject: | Re: Suspension |
... and there is something reassuring about experienced "grey beards" having similar thoughts. |
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| Author: | SR20Datsun [ Thu May 12, 2016 6:50 pm ] |
| Post subject: | Re: Suspension |
I wish I could call myself experienced...Might need to grow a beard! |
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