Mustang SVO RallyCross/Stage Rally

olso3904 said:

In reply to irish44j :

That's a good idea, I'm trying to do a rough layout of the cage and was looking at the best way to mount the main hoop. Looks like most people put a hole in the floor just in front on the crossmember and run a spreader across the floor to the crossmember and door frame. I like the box idea, but does it give you enough room to drop the cage down far enough to weld the top seams?

Also is it easier to run a halo bar or separate side bars with a windshield bar, or do tech inspectors have a preference?

 

yeah, it allows you to get low enough to do the top welds assuming the box has several inches of height.. Plinth boxes are really the "industry standard" for good cages - both because using them doesn't structurally weaken the floor and that they are simply much, much stronger than mounting to floor plates thanks to being tied in on mutliple planes and sides to the chassis.  I've seen too many pictures of rolled rally/track cars where the feet of the main hoop get punched through the floor, even with plates properly installed. Floors simply aren't that strong unless you bolt directly to a frame member or something - which usually aren't present out near the rockers that far back on a car. 

Most cars I've seen at rally run side bars with a windshield bar (including mine). You can get the a-pillar bars tighter to the pillar with this method. Mine are pretty much touching the a-pillars (and have connector plates as well). With a halo car, since there's a bend there, it's sometimes harder to get the a-pillar bar tucked in tight. I don't know that tech inspectors care one way or the other, as long as its all within spec in terms of distances from corners (read the rules closely on this, I had to re-do my roof bars because they were 20mm off at the front ends).

Also: not required, but highly recommend two optional additions to the cage:

1) dash bar (not only makes everything way stronger in a side impact, but also a great place to mount rally electronics and stuff if you cut out the passenger side of the dash like we did (see my thread for pics). 

2) extension forward into the footwell. I still need to add this to mine but I think it's pretty important for protection in rally, and it also adds structural support to the cowl and firewall area.

Another note is the rear downbar arrangement. It's totally dependent on how your roof bars are (there are three options - X, V, and upside-down V). On ours we have the roof bars reverse of the diagram above (i.e. it gets wider going forward). This provides better support for the front of the A-pillar curve, which takes the brunt of the impact in most rally-style wrecks.If you do that, the rear down-bars have to be different, in a "double-V" arrangement. The only downside to this is it kind of limits you to a single center air vent rather than twins, but we've never felt that we needed a second one anyhow.

note: in the pic below....if I was doing it over again, I'd probably flip the windshield bar the opposite direction. We did it this way with the thought of keeping sun visors, but that didn't work out anyhow (and black vinyl works better anyhow!). You definitely learn some lessons when you build the cage, and will end up with a couple regrets no matter what you do :)

We also used an X-bar on the doors, which are stronger and make better accessibility getting in and out than teh straight bar. Keep in mind a door sill bar is also required. Keep the door bars as low as you can within the regulations. You get in and out of the car quite a bit in rally compared to road racing ;)

Ours are actually a bit lower than these in another e30 (can't find a pic of mine though)

olso3904 said:

 

 

Next project is to weld on the subframe connectors and then start laying out the cage.

On that note, ARA, NASA and RallyAmerica all recommend 1.75x.095 tubing for main bars and I am on the fence about going to .120 for main bars, just because any wheel to wheel bodies require it. Do most rally cages use .120 or os .095 the norm?

I think most people use .095 for weight savings, but most people also make up for it by adding extra (optional) bars to triangulate things and make the cage stronger. We used 1.75 for our main required components and 1.50 for everything else - which is legal for lighter cars like ours. The big heavy boys (STis and such) I think have to use 1.75 all around over a certain weight. In the end, you can add a hundred pounds of cage weight using the bigger/thicker stuff everywhere, extra bars, etc. It's all a tradeoff of performance/weight vs. safety. I have a low-power car that isn't that fast, so I'm ok with .095 and 1.50 on secondary bars, with the understanding that I added plenty of triangulating bars and extra gussets. All a tradeoff. Talk to some other experienced stage rally guys about what works best for them.

ALSO since you have a 2-door, consider what cage backstay arrangement is best for access and behind-the-seats arrangement. Probably doesn't matter much since you have a hatchback and not a back-seat area like we do, but it's something worth sketching out and considering. 

In reply to AnthonyGS :

Im in the same boat of thinking going to a 3-link, but I will probably start with Johnny Joint uppers on the housing side and a track bar, once I decide if I am keeping the 7.5. A homemade torquearm sounds like a good winter project for next year.

There seems to be a mix of good information and complete misinformation about Fox body suspensions. I read alot about the SN95 arm swap for SVOs and there were lots of warnings of the suspension being useless or not fitting unless I also bought, coilovers, SN95 spindles, adjustable control arms blah $$$$ blah.  Doing the install I found all I really needed was C/C plates and the right springs.

I think after the cage I will just try to get a good baseline and figure out what needs attention next. I have a hard time dropping big money on questionable suspension components when I know the biggest issue is how flimsy these chassis's are. While it was up on jackstands the doors needed to be pushed down to close properly.....

This is our cage arrangement (in yellow) plus the dash bar which I didn't draw, and the harness bar which I didn't draw.

olso3904 said:

In reply to AnthonyGS :

 

I think after the cage I will just try to get a good baseline and figure out what needs attention next. I have a hard time dropping big money on questionable suspension components when I know the biggest issue is how flimsy these chassis's are. While it was up on jackstands the doors needed to be pushed down to close properly.....

Once you cage it, you shouldn't have that problem. I can jack the whole side of the car up from either my front or rear jacking point now. Cages really stiffen stuff up!

I'd also of course recommend doing a season of rallycross in it to find out what kind of suspension "feels" right. I know stage and rally-x have some differences in suspension setups (mostly due to one of them having jumps and higher speeds), but you can get a really good feel for the car and ways to get it better balanced by doing a bunch of rally-x first. Getting on stage and finding out your spring rates make the car hard to control....isn't fun. 

irish44j said:

This is our cage arrangement (in yellow) plus the dash bar which I didn't draw, and the harness bar which I didn't draw.

 

Awesome! This cage information is exactly what I needed.

. The sidebars vs. halo makes sense as does the box vs floorplate, I think access to the roof bars are my biggest concern since I don't have a way of pulling the skin off the roof like the Subaru guys or a sunroof to sneak a welder through. Thanks for the info, I might need to reread your build!

olso3904 said:

irish44j said:

This is our cage arrangement (in yellow) plus the dash bar which I didn't draw, and the harness bar which I didn't draw.

 

 

Awesome! This cage information is exactly what I needed.

. The sidebars vs. halo makes sense as does the box vs floorplate, I think access to the roof bars are my biggest concern since I don't have a way of pulling the skin off the roof like the Subaru guys or a sunroof to sneak a welder through. Thanks for the info, I might need to reread your build!

yeah, the sunroof does make things easier for sure, but you should still be able to do it fine. Remember, the taller the boxes you make are, the farther you can drop the cage down into them. If all else fails, you CAN drill the floor under the boxes to get more clearance since the cage sits on the box "covers" and they're tied into the side sills. So it's not as bad as drilling the floors and then using plates. But it still weaken things a bit. 

Of course, nothing to say you can't "cut a sunroof" and then put a patch panel over it too ;)

I'm not pretending to be an expert on this stuff - I'm repeating a lot of things I learned fro Ozgur Simsek (who bent/designed my cage) and others, added to things I've learned since. If you're on facebook, there's a few good North American rally pages. For the best advice, look up Gene McCullough - he's out on the pacific NW area and is on multiple rules committees - always happy to discuss cage options, rules, etc. Super-friendly guy. He's on facebook if you're on there. His email is mrmagic@olynet.com last I checked.

Oh also - take the backstays to the rear shock towers and then put a crossbar (rear strut tower bar) too. It will help keep your gear in the back of the car and igve you a good tiedown place for stuff. 

EDIT: that reminds me. Before you START building the cage, talk to your local scrutineer for whatever organization you plan to have logbook it (mine is NASA logbooked) and make sure everything you plan to do is what they want ot see.  Here's a list of all the scrutineers for NASA: https://www.nasarallysport.com/main/contact

Before you do a cage read FIA 253 Appendix J, best option to build to, as it will be legal almost anywhere.

AnthonyGS said:

In reply to olso3904 :

I’m trying to squeeze a poor man’s 3 link into the challenge budget.  It’s a track bar (panhard bar) plus good lower control arms and toss driver’s side upper control arm.  I’d like to reinforce the torque boxes too.  I’m trying to squeeze that and $300 worth of higher power into $500 along with subframe connectors.....  ttadimg will be needed.  If you need any SN95 parts, I have two full cars.  Want to buy an 8.8 with trac loc and 2.73s?  trade it for other things?  

 

I was wondering about what guys were doing when adding a track bar, you really just pitch one of the uppers? Makes sense, that '66 belair I sold to buy the mustang was a "4" link with 2 lower arms, one upper and one track bar.

I'm a interested, but I will have to regear obviously.

Anything you are interested in trade? I have some pretty sweet factory SVO parts freed up

Not sure how I didn't see this until now.  I have a 2.3T powered XR4Ti rally car and previously had a Foxbody RallyX car so you're more or less building something I'm familiar with.

Chassis: Lots of weak points.  Even in rallycross use, with welded subframe connectors, mine developed big tears in the floor after only a few events.  Reinforce absolutely everything, that unibody is basically made of paper.  If you are caging it right off the bat, be sure to tie into the shock and strut towers, and either drop supports down to the torque boxes or cut out and do new upper links that don't bind.  Might as well do big enough turrets in the back that you can fit a coilover if you decide to while you're at it.

Suspension: There have been a couple Fox platform stage rally cars, I'd probably get in touch with those guys.  Obviously you can do gravel coilovers and a 4-link similar to what an Escort/Volvo 240/etc would run, but for stockish stuff from what I remember the setup was to keep all rubber bushings (quad shocks too!) in the rear, and run coilover sleeves on the front struts in addition to the stock springs on the arm- this helps unload the balljoint and keep it from popping off every time you hit a bump.

Engine:  I really don't like the 2.3T at this point.  My advice is to make sure you have a good head gasket, good radiator, good oil cooler, and upgrade the aux drive if it fails even once.  Other than that make sure all ignition and fuel parts are in good shape and just run it until it doesn't have oil pressure any more.  Start hoarding extra cylinder heads at a minimum.

NGTD said:

Before you do a cage read FIA 253 Appendix J, best option to build to, as it will be legal almost anywhere.

After doing alot of digging, I think I am going to do the NASARS/ARA/RALLYAMERICA standard of 1.75X.095 for main tubes. It would be cool to option to SCCA or NASA CMC, but in reality, even if I upsized the cage, the additional tubes required to meet both would mean the car would have lots of unnecessary weight for both types of racing. Targa racing has similar cage layouts and sizing to road racing cages, which is suprising, but it's a low likelihood that I would do that.

My goal for this summer is to get a few HPDE days in and run as many RallyX days as possible. Neither of those require a cage, but ¯\_(ツ)_/¯ have already confirmed my suspicion of how floppy the Fox chassis is. 

Anyone know a good place in MN for DOM tubing?

I usually order from Discount Steel in NE and they do list 1.75 13 gauge tubing at $100/ 17ft lengths, but I haven't bought cage steel from them and wonder how consistent the thicknesses are.

I support everything that ¯\_(ツ)_/¯  has shared here.

I have been peeling the rest of the interior out, the only insulation left is on the trans tunnel and I still need to remove the dash

Once I had the driver's seat and floor insulation off, I found the drivers outside seat mount was cracked, the original owner must have beed a big boy

Since the dash is coming out, it would be a good time to simplify the engine compartment. Despite being a small engine, access is tough with all the vacuum lines and harness being poorly routed. There is a vacuum canister mounted in the passenger wheel well that I am clueless as to what it is for right now. Anyone have some experience simplifying the engine compartment on a Fox or 2.3?

Ughhh

Anyone know why the vacuum tree has this attached?

That should be a vacuum reservoir for hvac operation

I was just quoted $800 for only 100' of 1.75x.095" tubing from Discount Steel . Guess I will focus on buying some seats and wait for steel prices to stabilize a bit. Anyone know a better place for rollcage tubing around Minneapolis?

Steel will likely not get cheaper anytime soon.  The trend has been up, up, or up for quite a while now.  

In reply to AnthonyGS :

The story is any other type of steel has stabilized and although more expensive than last year, is not outrageous. Apparently DOM prices are still changing rapidly day to day, so it may be worth waiting it out to see if they drop or at least hold steady.

In comparison ERW in 1.75X.095" is still $3.10/ft retail. Not that I am going to use it

Don't ever remove the passenger side upper control arm for a poor mans three link.  I did that once, it launched like a 70's land yacht.  Hit the gas, slight weight transfer, left front fender reaches for the sky, then tire smoke.  I'll try the divers side next time. 

Progress has been slow, but I have the subframe connectors in, the upper control arm torque box reinforcements are in

and the dash is now out

The HVAC is getting pitched and replaced with smaller unit for heat/defrost and I was hoping to cleanup the wiring harness, does anyone know a good service manual with wiring diagrams? The few I have found are rudimentary and lack any pinouts. There are a few unlabeled components that I can't identify and Ford reused the same connector multiple times in the same harness 

Fun fact. In that last picture there is a vacuum hose coming out of the dash, it connects to the vacuum tree on the firewall and the brake pedal. There was always a hissing noise then I held the brakes, apparently it's a controlled boost leak when stopped? Any ideas on that one?

In reply to olso3904 :

That line actually went to a boost alarm or warning light for overboost IIRC.  That said most guys run it to an aftermarket boost gauge on the pillar.  You can search about it at turboford.org.  They know all things 2.3 turbo over there.  That line may also have an orifice inside it IIRC to control the boost amount, don't really remember clearly.  It's been over 15 years since I sold my SVO.  I'm still not happy about that sale. 

I do love your welding work on the torque boxes and subframes.  Want to come to my house and stiffen up my 94? 

also your interior is very festive Christmas colors! :)

For the wiring diagrams try ebay for an EVTM (electrical and vacuum troubleshooting manual).  Shouldn't be too expensive and it'll have the info you need.  I seek them out for every Ford project I work on.

Here's one for an '87.  I didn't see an active listing for one for an '86, but it'll come along eventually.

AnthonyGS said:

In reply to olso3904 :

That line actually went to a boost alarm or warning light for overboost IIRC.  That said most guys run it to an aftermarket boost gauge on the pillar.  You can search about it at turboford.org.  They know all things 2.3 turbo over there.  That line may also have an orifice inside it IIRC to control the boost amount, don't really remember clearly.  It's been over 15 years since I sold my SVO.  I'm still not happy about that sale. 

I do love your welding work on the torque boxes and subframes.  Want to come to my house and stiffen up my 94? 

 

 

For how much work it was to wire wheel, scrape and burn out the undercoat and seam sealer to do all that, I'm not sure I could even do it again! Well worth it though! I used to not be able to shut my doors when the car was on jackstands. Hopefully the cage helps even more!