Roll Cage, Back Bracing Options

[Randal]

What is the minimum amount of bar that would need to be added from the back towers to the transmission cross member? Understanding that I am running a bar from the back hoop of the cage to the shock tower.

Could I just run a bar from a plate on the rear side of the shock, midway to the top of the transmission cross member? Just a simple triangle. Would that help?

Picture below.

[Randal]

OK added a picture for clarification.

[J P Stein]

I like the job that Anklebiter did back there.....as far as he went.
If I ever do somthing like this I would eliminate the shock towers entirely and make shock mounts that will accept the "eye" type upper mount. A great selection of hi-zoot shocks are then available to you.

[Brett W]

Eliminate everything from the firewall back except for some simple bracing to hold the bumper and trunk up. Run one tube from the firewall back to the shock towers. Copy Sheridan's car I don't have a pic on this computer.

[SirAndy]

Could I just run a bar from a plate on the rear side of the shock, midway to the top of the transmission cross member? Just a simple triangle. Would that help?

Yes, that would help.

However,
the higher the attachment point on the shock tower, the better. See the pic JP posted for reference.

You don't need the X as in the pic above, a V would be enough on your car.
(IMG:style_emoticons/default/bye1.gif) Andy

[J P Stein]

I think Randal is putting in the down tubes from the cage to the towers.

Brett, if what you are advocating is what you actually wrote...... it's drivel.

[Brett W]

I think Randal is putting in the down tubes from the cage to the towers.

Brett, if what you are advocating is what you actually wrote...... it's drivel.

Horseshit. Its a race car cut out everything not needed. That means rear shock towers, tranny crossmember, rear inner fenderwells, etc. Look at the rear structure on this car. Notice how it all ties into the main cross bar at the shock towers. Bring your down bars down from the main hoop to the top of the shock tower cross bar. The bring a bar from the shock towers forward to the firewall inline with the door bars. Create a nice triangle. Then weld on some small tubes to attache the rest of the bodywork with. Trunk lid should be glass as should rear bumper and fenders, so the remaining sheetmetal won't weigh anything.

The advantages of removing the stock rear shock towers are numerous, including the fact that you can use double eye shocks and get some nice cheap shock options.

[byndbad914]

thread I did on the bird board a few years back with Sheridan's car shown - I drove the 3hrs north of LA to take the pix and BS with him (it had been awhile since I bought his body kit and he was first building the car).

http://forums.pelicanparts.com/showthread.php?t=253609

[J P Stein]

Horseshit. Its a race car cut out everything not needed. That means rear shock towers, tranny crossmember, rear inner fenderwells, etc. Look at the rear structure on this car. Notice how it all ties into the main cross bar at the shock towers. Bring your down bars down from the main hoop to the top of the shock tower cross bar. The bring a bar from the shock towers forward to the firewall inline with the door bars. Create a nice triangle. Then weld on some small tubes to attache the rest of the bodywork with. Trunk lid should be glass as should rear bumper and fenders, so the remaining sheetmetal won't weigh anything.

The advantages of removing the stock rear shock towers are numerous, including the fact that you can use double eye shocks and get some nice cheap shock options.

This is good, but that's not what you wrote the first time then is it.

[bam914]

Something like this is what Brett is talking about I think.

[Randal]

Thanks for the responses.

I'm going to run bars from my new cage front hoop the front shock towers and also from the rear hoop to the rear shock towers.

I don't want to be adding a lot of weight, but I'm thinking at the minimum, based upon the comments received, that this might be effective, i.e., the picture below.

The question is whether this modification is worth the weight it adds.

[Chris Pincetich]

I like the tubes in Blake's car - except I can't see how the 901 mounts to that configuration...Thanks for sharing! Can't wait to see the whole thing, engine and all (IMG:style_emoticons/default/beerchug.gif)
If 222 is AX only, maybe the twisting won't interfere with shifting and grip (lsd?), so low weight is the goal? Are bolt in braces lighter?

[Brett W]

Something very similar to what Blake has. Yes, JP, that is exactly what I said in my first post. I just didn't draw a verbal picture.

[SirAndy]

Here's what i think you should do ...


The green is how i would add the braces for the tranny mounts. Start them as high as you can on the shock towers.
They don't have to meet each other in the middle, that cross section is plenty strong so getting the braces to the inside of each tranny mount should give you some nice stiffening there.

IMHO, the blue bracing is only needed if you decide to cut out the rear firewall. Right now, with the firewall still in place, i don't think you'd need that bracing.

(IMG:style_emoticons/default/popcorn[1].gif) Andy

[Brett W]

Andy's mad paint skills are better than mine. His design is much better than the grey line original. Make the whole thing out of 1.75 .065 or.058 wall tubing to keep the stiffness up and the weight down. I would reinforce the mounting points with .065 sheet.

But cutting out the rear shock towers and firewall willl give you better shock options.

[Randal]

I like the job that Anklebiter did back there.....as far as he went.
If I ever do something like this I would eliminate the shock towers entirely and make shock mounts that will accept the "eye" type upper mount. A great selection of hi-zoot shocks are then available to you.

I understand what you are saying, but I wonder what the double triangle buys you when one would work, i.e., with two tubes coming from the towers meeting in the middle of the rear transmission mount cross member.

Although I guess he is adding about 5 feet of tubing, so 5lbs isn't that much and his set up would be stronger.

My "uneducated" guess is that Anklebiter's setup would be perfect if I was getting rid of the shock towers, but do I need this if I keep mine?

[J P Stein]

What Andy has drawn up will work gud if you keep the rear engine room bulkhead.

I'll probably never go to the point of eliminating the shock towers or even cutting out the trunk floor. There is a small weight loss to be had and the shock selection would be nice but the latter involves a bunch of money.
If I had those extra funds I'd spend them on fitting R25 Hoosiers radials to the car.

My winter mods are cheep this year. Lowering the car and doing something unconventional to the trans.
Sticker tires will be forthcoming, but that is conventional.

[ChrisFoley]

This is what I would do Randal:
Get rid of the top of the sheet metal behind the engine compartment and install a tube going all the way across, just ahead of the shock towers. You can terminate the main hoop braces onto the cross tube or land them on reinforcing pads at the ends like in my pic. My design improves engine compartment access, and you can add small triangulations between the rear braces and the crossbar if you want.
Then attach the tranny crossmember braces to the shock tower crossbar next to the shock towers. Don't put the rear attachments together to form a triangle. It is better to keep them apart and land them just above the tranny mounts.

[Randal]

This is what I would do Randal:
Get rid of the top of the sheet metal behind the engine compartment and install a tube going all the way across, just ahead of the shock towers. You can terminate the main hoop braces onto the cross tube or land them on reinforcing pads at the ends like in my pic. My design improves engine compartment access, and you can add small triangulations between the rear braces and the crossbar if you want.
Then attach the tranny crossmember braces to the shock tower crossbar next to the shock towers. Don't put the rear attachments together to form a triangle. It is better to keep them apart and land them just above the tranny mounts.

Do you a slightly bigger picture that shows both ends of the cross pipe Chris?

Thanks.

[Randal]

This is what I would do Randal:
Get rid of the top of the sheet metal behind the engine compartment and install a tube going all the way across, just ahead of the shock towers. You can terminate the main hoop braces onto the cross tube or land them on reinforcing pads at the ends like in my pic. My design improves engine compartment access, and you can add small triangulations between the rear braces and the crossbar if you want.
Then attach the tranny crossmember braces to the shock tower crossbar next to the shock towers. Don't put the rear attachments together to form a triangle. It is better to keep them apart and land them just above the tranny mounts.

Do you a slightly bigger picture that shows both ends of the cross pipe Chris?

Thanks.

I can't draw a picture with the tube in front of the shock towers, but you get what I mean.

Like this?




I'd still like to see a picture of what the cross pipe looks like at the ends.

Thanks again Chris.