66 Chevelle rear suspension ?

[killer69]

We are starting to build an all out 66 Beaumont( chevelle ) for you boys south or the 49th. my question is what mods have been done and what has worked on the rear suspension. This car will have a 600+ inch BBC and a t56 trans with a 12 bolt. the stock 4 bar rear suspension is not a bad design but i am sure it can be improved. here are some of the parts we will be using
Michellin PS 2 335 / 35/ 20 rear tires 245/40/20 fronts with 20X12 rear wheels and 20 x 8 fronts tubalar front arms and corvette c5 brakes.
BBC with 615 inches 750 Hp with 200hp nitrous. the big ? is the rear suspension, we will convert to coil over's but the rear geometry is an issue. i was thinking a torque arm might work well. and remove the upper arms. or put a 4 bar rear suspension. what are your thoughts. i have read most of Tony's book and all i really see is the info on NASCAR type long arm. im interested to see what you all think

[dennis68]

Spherical bearings on the lower link and upper axle mount. Stock rubber bushings at the frame side of the upper link.

[Mean 69]

Convert to a three link, with a Panhard bar, or Watt's linkage. It is pretty easy on these cars due to the existing brackets, etc.

Mark

[dennis68]

:hand: You caught me sleeping Mark.

[wally8]

Well, I'm planning on something fairly close to that rear suspension too. I'd like to use a Torque Arm for packaging reasons.

The PHB and the two links are pretty straight forward. I'm just trying to figure out the torque arm length. I'll probably figruer out what the Fbody guys are using and adjust it proportionately for my wheelbase.

What are you thinking for TA length?


Wally

[Mean 69]

If I am not mistaken, Grigg's uses a 48" unit on the late Mustang conversion they do, Maximum Motorsports is about the same. I believe the effective length on the late F-body is close to 60", the forward mount is way up on the transmission. I would not suggest going any shorter than 48", the SVSA is pretty much the same as the effective length of the T/A (is, the same, actually), so here again you have the battle between anti-squat and SVSA (they fight each other). I'd personally go longer than shorter.

A slick idea to get around the potential brake hop issues with a T?A and still get huge A?S numbers is the decoupled unit from Unbalanced Engineering. Not sure on the packaging, but for the differential mounting you can even buy 9" units from Currie, et. al. that the T/A will bolt right onto. The late f body units fit alongside the driveshaft, so plan on doing some fabricating in that area. The late mustang type units are underslung relative to the driveshaft, so less cutting, but less ground clearance also.

Of course, if you are going to cut the driveshaft tunnel, well, there is the aforementioned three link......

M

[wally8]

That long?

I thought the stuff I was looking at was mid to high 30's for length. I'll have to check again. I should probably ask Jon on C-C or frraxx. I'm sure he's put mucho thought into it.

I'd like to get it figured out but haven't gotten to it yet.

I've been thinking about doing the decoupled thing. Everyone talks like it's really difficult but isn't it just a compressible link? Compressible for braking and and a rigid stop for acceleration right? There's geometry to consider of course. I've seen the UE model and I think you could do a couple variations on that.

3 link would be good, too, but I haven't decided to cut the floor, yet....

I'm not sure I want a huge AS number, actually. I'm thinking of just going with something reasonable like 50% or something. Numbers like 100% scare me when it comes to suspension parameters. To me that says I'm compromising something somewhere.....

Wally