25.5 Rear Hoop question - Yellow Bullet Forums

Go Back   Yellow Bullet Forums > Technical Section > Chassis and Suspension - Tim McAmis Performance Parts

Chassis and Suspension - Tim McAmis Performance Parts

Reply
 
Thread Tools Display Modes
Old 01-07-2012, 09:15 PM   #1
twin69Poncho
Junior Member
Launchin
 
twin69Poncho's Avatar
 
Join Date: May 2010
Location: MO
Posts: 334
Default 25.5 Rear Hoop question

I'm putting a 25.5 moly cage in my car and have stopped at the rear bars. Using my sfi book it just shows that I can use 1.625 tubes in a X pattern back to the rear frame rails.

Most 25.5 cages I see have the rear hoop, I prefer not to add the rear hoop if I dont have too. Along with the rear hoop it seems popular to build a ladder style support that basically follows the rear frame rails. Whats the reasoning behind building it that way?

My rear bars X from the top of the main hoop back to the side of the 2X3. Adding a rear hoop doesnt seem like it would add much more support than those bars.

Any suggestions?

Here is a pic with just one of the x bars in place.


twin69Poncho is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 01-07-2012, 09:56 PM   #2
overkillrc
7.86 @ 8800DA 3365lb 275s
Smoked Another SBC
 
overkillrc's Avatar
 
Join Date: Mar 2008
Location: Loveland, CO
Posts: 4,340
Default Re: 25.5 Rear Hoop question

Its just different building styles the rear hoop isn't required. The X will be fine
__________________
Justin Kill

Overkill Race Cars 970-581-8134
Loveland, CO

www.overkillracecars.com

H-body control arms and parts
http://www.overkillracecars.com/Products.html
overkillrc is offline   Reply With Quote
Old 01-07-2012, 10:21 PM   #3
CurleysRacecars
Senior Member
Smoked Another SBC
 
Join Date: Aug 2008
Location: Granite Bay, CA
Posts: 4,457
Default Re: 25.5 Rear Hoop question

The "ladder style" seen in alot of cars is for strength. The more triangles you can make, the stronger structural unit you will have. Doing the "ladder style", then x-ing in between them will give you those triangles youre looking for.
__________________
Kyle Curley
Curley's Racecars & Components
(916)-397-3465
www.curleysracecars.com
CurleysRacecars is offline   Reply With Quote
Old 01-08-2012, 12:29 AM   #4
twin69Poncho
Junior Member
Launchin
 
twin69Poncho's Avatar
 
Join Date: May 2010
Location: MO
Posts: 334
Default Re: 25.5 Rear Hoop question

This car will have a 10.5 tire and start out at roughly 1800-2000hp. Weight will end up at 3300-3400 with me in it.

If I didnt add the rear hoop would the difference in rigidity in the chassis create a issue tuning it? Or would only slow my 60' times?

Just trying to figure out if its worth the extra effort. In my mind I cant see the rear 2X3 rails flexing or twisting enough to create inconsistencies in my launch. Thoughts?
twin69Poncho is offline   Reply With Quote
Old 01-08-2012, 12:35 AM   #5
overkillrc
7.86 @ 8800DA 3365lb 275s
Smoked Another SBC
 
overkillrc's Avatar
 
Join Date: Mar 2008
Location: Loveland, CO
Posts: 4,340
Default Re: 25.5 Rear Hoop question

Im wondering how fast your gonna use up that 25.5 cert and wish you had done a 25.3
__________________
Justin Kill

Overkill Race Cars 970-581-8134
Loveland, CO

www.overkillracecars.com

H-body control arms and parts
http://www.overkillracecars.com/Products.html
overkillrc is offline   Reply With Quote
Old 01-08-2012, 12:44 AM   #6
twin69Poncho
Junior Member
Launchin
 
twin69Poncho's Avatar
 
Join Date: May 2010
Location: MO
Posts: 334
Default Re: 25.5 Rear Hoop question

Quote:
Originally Posted by overkillrc View Post
Im wondering how fast your gonna use up that 25.5 cert and wish you had done a 25.3

I'm afraid rather quickly....Actually started with a 25.3 and someone on here reminded me I couldnt use any 2X3 for the main structual frame. I decided to move down to the 25.5 to get the project started.

Right or wrong, I'm looking at it as though this is my learning car. I'll build or buy a 4th gen firebird with a 25-3 chassis and sell this one after some time behind the wheel of a fast car.
twin69Poncho is offline   Reply With Quote
Old 01-08-2012, 07:43 PM   #7
coyote52
Senior Member
Smoked Another SBC
 
Join Date: Jul 2011
Location: Greenville, Ky.
Posts: 7,591
Default Re: 25.5 Rear Hoop question

1800-2000hp, sounds like you have built quite an engine. why not go ahead and build a strong chassis and cage to go along with it. rear loopes and all of the other bars that are'nt required might just help your car work better......not counting being a safer car to be in if you have a wreck
coyote52 is offline   Reply With Quote
Old 01-08-2012, 11:51 PM   #8
falconflyer63
Junior Member
Launchin
 
Join Date: Sep 2007
Posts: 300
Default Re: 25.5 Rear Hoop question

can also use smaller dia and wall thickness tubing with the rear hoop .. tho the weight prob evens out
falconflyer63 is offline   Reply With Quote
Old 01-09-2012, 11:38 AM   #9
overkillrc
7.86 @ 8800DA 3365lb 275s
Smoked Another SBC
 
overkillrc's Avatar
 
Join Date: Mar 2008
Location: Loveland, CO
Posts: 4,340
Default Re: 25.5 Rear Hoop question

from what i see in the pics that car could be made 25.3 with out much trouble
__________________
Justin Kill

Overkill Race Cars 970-581-8134
Loveland, CO

www.overkillracecars.com

H-body control arms and parts
http://www.overkillracecars.com/Products.html
overkillrc is offline   Reply With Quote
Old 01-09-2012, 09:42 PM   #10
twin69Poncho
Junior Member
Launchin
 
twin69Poncho's Avatar
 
Join Date: May 2010
Location: MO
Posts: 334
Default Re: 25.5 Rear Hoop question

Quote:
Originally Posted by overkillrc View Post
from what i see in the pics that car could be made 25.3 with out much trouble

I thought the same thing. But was told I couldnt land my main hoop on a 2X3 tube. I thought the main hoop had to land on bar 1.

My 25.3 SFI book shows I would need to use round tube for bars 2B. I would think as long as the rear hoop is attached to the 2X3 it would actually be stronger than what they show.

What do think of the inner 41B placement? It seems a bit wide to me but it fits me with plenty of room so I dont smash my arm against it if I wreck.








Last edited by twin69Poncho; 01-09-2012 at 09:44 PM.
twin69Poncho is offline   Reply With Quote
Old 01-09-2012, 09:56 PM   #11
falconflyer63
Junior Member
Launchin
 
Join Date: Sep 2007
Posts: 300
Default Re: 25.5 Rear Hoop question

depending on the funny car hoop design u may have issues too .. i may be wrong but i thought there was a certain design allowed in the 25.5 that isnt allowed in the 25.3 or 25.2
falconflyer63 is offline   Reply With Quote
Old 01-09-2012, 10:10 PM   #12
twin69Poncho
Junior Member
Launchin
 
twin69Poncho's Avatar
 
Join Date: May 2010
Location: MO
Posts: 334
Default Re: 25.5 Rear Hoop question

Quote:
Originally Posted by falconflyer63 View Post
depending on the funny car hoop design u may have issues too .. i may be wrong but i thought there was a certain design allowed in the 25.5 that isnt allowed in the 25.3 or 25.2

I have both the 25.5 and 25.3 book and they show the same alternative funny car cage design can be used.

I think my only issue is I made the hoop land on the lower horitoztal bar instead of the rear bar that lands between the main hoop and the lower bar like whats in the picture.






I have that bar made up but my other pics just dont show it in place.

Last edited by twin69Poncho; 01-09-2012 at 10:11 PM.
twin69Poncho is offline   Reply With Quote
Old 01-09-2012, 10:23 PM   #13
falconflyer63
Junior Member
Launchin
 
Join Date: Sep 2007
Posts: 300
Default Re: 25.5 Rear Hoop question

I use the design on the left the most if the driver is forward of the main hoop never had any issue with it .. alot of the pics in the specs will match but the notes on them r different .. also if u look at some of the pics on the 25.3 they dont match the notes for them
falconflyer63 is offline   Reply With Quote
Old 01-10-2012, 12:18 PM   #14
overkillrc
7.86 @ 8800DA 3365lb 275s
Smoked Another SBC
 
overkillrc's Avatar
 
Join Date: Mar 2008
Location: Loveland, CO
Posts: 4,340
Default Re: 25.5 Rear Hoop question

the funnycar cage designs shown in the spec are "typical F/C cage designs" not the only allowed (or disallowed for that matter). the pictures in the sfi specs are for reference purposes not a map of how "you cage must look to cert" the text is the important part. you F/C cage design will be fine but you will need bars 46, 47 and 48
__________________
Justin Kill

Overkill Race Cars 970-581-8134
Loveland, CO

www.overkillracecars.com

H-body control arms and parts
http://www.overkillracecars.com/Products.html

Last edited by overkillrc; 01-10-2012 at 12:19 PM.
overkillrc is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 03-25-2012, 12:10 AM   #15
twin69Poncho
Junior Member
Launchin
 
twin69Poncho's Avatar
 
Join Date: May 2010
Location: MO
Posts: 334
Default Re: 25.5 Rear Hoop question

Finnally making some progress. All the tubes have been cut and fitted. I'm ready to pull the body and start welding in everything thats left. I decided to add the rear hoop and rear ladder for support.

With the additional bars in the floor, any chance I would have any luck getting a 25.3 cert? I still have to weld in my front #6 bar.

I removed both rocker bars since the 25.3 and 25.5 doesnt require it with a stock frame rail.



twin69Poncho is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -4. The time now is 04:00 AM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.
Resources saved on this page: MySQL 2.56%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Yellow Bullet LLC