Rear shock geometry

[55metalmonkey]

I searched the suspension section and can’t really find the info I’m after so…
I’m looking for a guru who knows a thing or two about rear shock geometry. Well you don’t have to be a guru but someone who can give some advice all the same.

I recently did a Camaro front sub frame and installed a Camaro rear with a axle flip this dropped the frame 8+” and she is sitting nice, I had to get rid of the original rear upper shock mounts because I could tell that on the first little bump the mounts would rip the rear diff cover open (aka: pumpkin carving).

I knew before I started that I would have to relocate the shocks but am wondering what configuration to use or would be the best.
My options are pretty open because there isn’t a lot back there, eventually a fuel cell will be installed but not much else. I could easily just slap something in that would work no problem but since I’m modifying things anyway I might as well improve on it if I can.

What is the best way and why?

The options that come to mind:
1: Both mounted forward of the axle angled forward inside the frame
2: Both mounted forward of the axle angled forward outside the frame
3: Both mounted rear of the axle angled back inside the frame
4: Both mounted rear of the axle angled back outside the frame
5: One forward and one back inside the frame (like an S-10)
6: One forward and one back outside the frame
7: Angled in towards the center at the top like the originals
8: Straight up and down inside the frame
9: Straight up and down outside the frame

Thanks

[skip99]

I'd like this info also... mines a 51 with a nova rear, leafs, ..

[GhostTown]

I messed this up twice, then finally went with your option #7.

[55metalmonkey]

So what do you mean by messed it up?

I'm also wondering if anyone with rear leafs are using track locator bars, pan hard bar

[55metalmonkey]

??

[Indian113]

Metalmonkey,go to Tyler58's project and look at post 78,he did a good job on them

[lakeroadster]

Not a guru, but I have set-up a hand full of rear suspensions from scratch and modified a few others.

So it sounds like you are running leaf springs? A lot of guys think shocks are shocks, but the type of suspension you have drives shock geometry, makes a big difference: Leaf vs. coil vs. coilover vs. ladder bar (trailing arm) vs. four link etc.

If you are running leaf springs I would suggest mimicking a stock GM set-up for a leaf spring rear suspension on a truck with a light duty rear end, like the S-10 you mentioned. I doubt there is anybody on this website that is more knowledgable than the Engineers at GM when it comes to suspension geometry.

Hope this helps.

[GhostTown]

I'm running a triangulated 4 bar on my truck, so what I did may not apply to your situation. Anyway... here are a few pics of what I started with, screwed up, and then ended up with.

Started with this:



Bought the four bar and put it in, but the shock set up was all wrong:


I later decided to go with a Shockwave set up and changed it to this:



Sorry for the image size.

Different year of trucks, but I have a camaro (firebird actually) front clip and rear end too.

[55metalmonkey]

Yes it's leafs and not a 4 link or coil overs... Maybe some day for my next project
Ray, you just keep answering all my questions don't you!
thanks once again, I was thinking that a setup like Tyler's is likely the way I go.
but
I'm still curious as to the "why theory" in all the options that I listed

[Indian113]

Ray, you just keep answering all my questions don't you!

It's not me it is all of the knowledge on this site. I've found any ? I have a answer can be found on this site.

[OrrieG]

Originally Posted by lakeroadster

If you are running leaf springs I would suggest mimicking a stock GM set-up for a leaf spring rear suspension on a truck with a light duty rear end, like the S-10 you mentioned. I doubt there is anybody on this website that is more knowledgable than the Engineers at GM when it comes to suspension geometry.

That is what I did when I added the 4wd to my truck, figured GM spent millions, why mess with it unless it was failing (like stock TF front stamped shock mounts). I made my brackets but kept the stock geometry.

[bobinbc]

On the yellow truck in my avatar I used option #2. The geometry was very similar to a 67 Camaro or 68-74 Nova which is what the rearend was from, it was easy to do and it worked very well. Sorry no pics...

[55metalmonkey]

Thanks for all the input guys,
I went down and had a look and sill thinking of going with the #7 option, might have to keep an open mind on my options though, i have to figure ou the comprssed & extended length (stroke) and see what is commonly available just to keep it simple

[lakeroadster]

As I understand it, GM used the "one shock in front of the axle, one shock behind the axle" to try to minimize wheel hop on leaf spring cars. That way when the axle starts to wrap you have shocks working in opposite directions.

Also worth noting, I relocated my upper shock to get the shock inclination angle back within specification. I contacted the technical department at Monroe and they stated that the shock absorber cannot be mounted more than 30 degrees off vertical. If the angle exceeds 30 degrees they may tend to have lapses in dampening.

[solidaxel]

I like option #2 with Bilstine Shocks!

[solidaxel]

I also beleive they are set at 30*

[55metalmonkey]

Originally Posted by lakeroadster

As I understand it, GM used the "one shock in front of the axle, one shock behind the axle" to try to minimize wheel hop on leaf spring cars. That way when the axle starts to wrap you have shocks working in opposite directions.

Also worth noting, I relocated my upper shock to get the shock inclination angle back within specification. I contacted the technical department at Monroe and they stated that the shock absorber cannot be mounted more than 30 degrees off vertical. If the angle exceeds 30 degrees they may tend to have lapses in dampening.

Thanks, it makes sence that as one would compress while the other extended would help keep the axle from hopping, I always wondered why they would off set them like that, I'm wondering if the same theory might apply to my rear brakes as one is on the leading edge of the rotor (fwd side) and the other is on the trailing (rear side) of the rotor.... but thats a completely different subject.

Good info in the angle, I'll have to keep that in mind as I mock things up today.
Thanks

[OrrieG]

My understanding on brake rotor placement is to get the mass closer to the center of gravity of the auto and closer to the master cylinder, every little bit helps.