the BEST DIY rear cross member?

Post by **defdes** » 28 Jan 2007 17:33

Got the solid bushings done and a start on the sleeves for the rear swing arms:

Post by **defdes** » 28 Jan 2007 17:36

and the 8 solid bushings....

SR20Datsun · Post by **SR20Datsun** » 30 Jan 2007 13:48

I've made my own adjustable rear cross member:
http://www.ozdat.com/forum/viewtopic.ph ... &start=120

Got all the parts laser cut up, designed it all on CAD, and hopefully using a similar theory to Baz, have set it up with the 'sweet spot' (or close too

) Still not bolted onto the car, but pretty close.

Post by **thisismatt** » 30 Jan 2007 17:45

Have to log in to view pics? Boooooo.

SR20Datsun · Post by **SR20Datsun** » 30 Jan 2007 21:04

Sorry,

Here's a few.

SR20Datsun · Post by **SR20Datsun** » 30 Jan 2007 21:29

I should also add that this car is going to be street legal. In Australia we are not allowed to run ball joint suspension for street legal cars

Typically our cars get an engineers certificate to be street legal after heavy modifications (done by a qualified automotive engineer who has jumped through all the hoops and payed stupid amounts of money for insurance to cover their butts...).
Hence I am running urethane bushes, with camber and Toe adjustment. I am using the factory bolts, but slightly modifying them to suit the notch..

The information on the Ozdat forum is pretty good with heaps more photos.
I might do a members ride section in 510realm, but I've gotta finish it first!!!

Cheers!

Post by **thisismatt** » 30 Jan 2007 21:50

Are any of you guys angling the brackets? It just seems to me that anything slotted is going to have binding issues outside of the bracket sweet spot, and then what's the point of being adjustable if you already know the sweet spot?

Post by **Byron510** » 30 Jan 2007 22:03

Matt,
You'd be correct, but the binding issue is near insignificant, and not worth the engineering to make bent or arced ears to suit this application. It could be done, but not really worth the effort.
Nice work SR20Datsun.
Rich and I also in the process of perfecting a set of laser cut adjusters here. I like your approach, but I'm walking a different road with my set up. It will allow camber and toe adjustments independently of one another - both adjustments being done by replacing the inboard pivot mount. Pics soon to follow, work is in progress and Version 2 is in line for cutting.
Byron

Post by **thisismatt** » 30 Jan 2007 22:13

For all you guys building your own designs (or slight modifications of other designs), do you actually have plans to adjust or just find the right spot and leave it there?

Post by **defdes** » 30 Jan 2007 22:24

I don't know how much readjusting I will do after I get mine set up properly, this is for my race car, but I know a few people who change their settings for each track. I was really looking to make a change for strength, stiffness, but mostly reliability. My stock slotted set up with urethane bushings would move after every event....and not evenly. I would end up with about 4 degrees camber on one side 1 1/2 on the other, and toe in was really hard to get fighting the rear sway bar.

Post by **rnorrish** » 31 Jan 2007 00:56

it's all about the mod list, yo.

wait, i won't even have these on my car, dammit. stupid wagons.

I guess I'll have to make up other wagon specific bits. go go adjustable multi-link!

SR20Datsun · Post by **SR20Datsun** » 31 Jan 2007 02:47

Rnorrish, (and thisismatt),
basically what defdes said...

As you all know when you lower the 1600 (sorry 510!) she gets a heap of negative camber and toes out a fair bit.
So you make up a set of brackets to fix this, and fit them to your car. Ok so now you have fixed the problem about the heaps of negative camber, and the toe, but now when you wanna hit the track, you can't adjust it.

That's the reason i wanted to make it adjustable. So I can drive it on the road (at civilised speeds of course!!) and then hit the track with a 'modified' setup.

Most of the guys on the Ozdat forum are pretty track orientated, so out comes race pads, tyres, and springs and maybe some more camber on the front and rear and away you go. Then change it all back so you don't chew out your fav set of road tyres...

Post by **bertvorgon** » 31 Jan 2007 08:51

Once I got my rear set up, I have never changed it, other than taking some camber out for running race tires. I have left my toe-in, in the rear, as that equation in the stability issues has not changed, at least for me. Tire wear has never been an issue. Same with the front, once I got the toe set for what the car was happy with, and the castor, I have only taken some camber out, and this was done over YEARS, as street type performance tires got better, and did not require as much camber. I have not touched my suspension settings now for a LONG time. That's not to say you might find a track that might like something else, but, I think there is a sweet spot that keeps the car at it's optimun point, with out driving you crazy changing things all the time. Maybe I'm just lazy, and not that sensitive a driver. Other than changing to full track day pads, I run the same "soft as possible' pad for the street, slaloms, and hillclimb.

Post by **thisismatt** » 31 Jan 2007 17:13

I'm just thinking for someone not planning on any track driving (myself) I'll probably just pick a few brains for the optimal rear toe/camber and then just cut and reweld new brackets at the correct, perpendicular to the bushings, angles.

Post by **duke** » 31 Jan 2007 17:23

thisismatt, that would be alot easier said than done. To try and figure out the exact settings that you need and getting them right the first time would be a real challenge. Also consider that our cars were build over 30 years ago, meaning that the settings on either side might be slightly different. Just because many of the people on here very rarely change the settings, when they were first dialing them it I am sure they changed them alot.