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Posted by: Justinp71 Sep 29 2008, 07:14 PM

I put some more horsepower in my car, so far I have just autocrossed it on street tires. I have the bolt in roll bar that has the mid bar going to the floor.

Besides that my chassis is stock and I am wondering what I should do for more re-enforcement... so I can comfortably run on slicks.

Below is a photo of the roll bar. I don't consider the roll bar to give to much chassis stiffening, but it just might help with cracking the longs.

Edit: I mainly just use the car for street and the occasional Autocross or DE


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Posted by: SirAndy Sep 29 2008, 09:04 PM

I've got a full cage but it's not tied into the shock towers (yet) ...

No other stiffening. I'm running 9" GoodYear R250 slicks. No cracks yet.
Andy

Posted by: sww914 Sep 29 2008, 11:40 PM

Judging from the cars that I've fixed, if you run hard suspension bushings and slicks without a cage tied in to the chassis you'll break the chassis eventually. The last one that I fixed had 15 breaks in the chassis behind the passenger's compartment.
I've been running my racecar for almost 10 years without any chassis reinforcement but I'm running DOT hoosiers (225's) and stock bushings, no cracks yet but it does flex around a bit.

Posted by: dlestep Sep 29 2008, 11:42 PM

...I am welding the rear stiffening kit on my car now...the only other stiffening I have is resin, high speed tape and a bottle of viagra in the glove box...

Posted by: Joe Ricard Sep 30 2008, 05:57 AM

Engman longs and a roll bar tied to rear shock towers and rear suspension ear braces. outer longs also have a plate from rear suspension pieces to mid door.

Posted by: Justinp71 Sep 30 2008, 07:07 PM

Thanks guys!

It sounds like for the small amount of track time I do I can get away with no re-enforcements beside the small roll bar, as long as I keep stock bushings... running on slicks that is...

But I always planned to do the engman kit for the longs.

Anyone else???? There has got to be more than 14 people that want to vote!

Posted by: dakotaewing Sep 30 2008, 10:10 PM

I have Brad Maures (sp) Outer Long kit, and Chris' ear reinforcements....

Posted by: Justinp71 Sep 30 2008, 11:05 PM

Where does the outer long kit sit? Under the rockers or is it only the insides of the longs (not front and back)?

Does he have a website?

Thanks!

Posted by: jcd914 Sep 30 2008, 11:59 PM

OK I guess maybe I should not be voting since the only runner of the 4 914s I have, I may have just sold. But I figured I would weigh in anyway. My 914 that I used to auto-x with had no chassis stiffening. I had upgrade suspension and ran on sticky DOT tires. My friends 914-6 (conversion) that I ran once at Thunder Hill and once at Button Willow had a 4 point cage, rear chassis stiffening kit, stiff suspension and wide tires. Latter when he started racing the car (PCA Club and PRC events) we had to tie front and rear suspension to the cage and add re-enforcements to the inner rear mount since they were cracking.

I am planning on adding a cage to my next 914 track car (which ever one that ends up being).

Jim

Posted by: Justinp71 Oct 1 2008, 10:37 AM

Well Thanks for posting anyhow Jim!

When you say

Are those the inner trailing arm mounts? How much track time do you think he had on the car when you guys noticed cracking? 2 ,10 , 30+ track days???

Posted by: Justinp71 Oct 1 2008, 10:38 AM

And how come the rear area re-enforcement vote above is zero!!!!!! I should have added the ear re-enforcements also (as a vote).

Posted by: the4u2 Oct 1 2008, 01:07 PM

how much flex is to much? have one that flex 8mm ,I cut up any tub that flex over 14mm
will a chassis stiffening kit fix that much flex (14mm)
Thank you for any info

Posted by: J P Stein Oct 2 2008, 08:58 AM

There are a pee pot load of do-dads sold to make your suspension work better.
"Up-grades" such as needle/bronze bushings, mono ball shock mounts, trick shocks, springs, AR bars, T bars....God knows what else. Couple these with modern tires that grip at some multiple of the OEM jobbies and problems are bound to arise.

All of this "stuff" transfers more initial loading into the poor old 914's chassis. All the suspension mounting points are more highly stressed. The chassis itself is something of a noodle anyhow and it doesn't get better with age & all this "stuff". None of this "stuff" works as well as it should because the chassis is flexing and bending (taking a semi-permanent set).... Alignments don't hold (not to mention corner balancing).
Then there is chassis cracking & total failures at the suspension mounting points.
Inconsistent handling is also a bugaboo out there on the edge.

One needs to ask one's self: Do I really want to go there, "stuffwise"?

People are willing to sell you a number of band aids that, IMO, don't cure the flex inherent in the chassis. If you finally reach the point where flex is mostly under control, these band aids will be just excess weight.

The best bet would to be to keep an eye on SSW914's thread while he builds his new race car. He will get the flex under control, I'm sure, and then you'll know what it takes. There are no shortcuts......IMO.

Posted by: 9146986 Oct 2 2008, 08:59 AM

The last full project car I built had Brad Mayeur's outer long kit, GT stiffening plates, and then I custom fitted additional plates for the inner longs, from the firewall rearward. Car was very solid to begin with and even more so after the work.

The only flaw the chassis had, and I've seen it on a few cars, was a stress crack on the left inner half of the long, right at the parking brake handle recess. I've talked with a few other 914 mechanics, and found this is fairly common, and also easy to miss.

Posted by: naro914 Oct 2 2008, 08:14 PM

I've been racing or DEing our 914 since 1994, originally with a 2.0/4, now with a 2.2/6. Originally stock suspension/body, now AIR flares, coil overs all around, 935 front set up, etc. 12" slicks on the back, 11" slicks on the front.

All I've ever had is a welded in roll cage that is tied into the A pillar of the windshield, 4 floor points, and bolted into the shoulder belt holes, and a Stable Engergies Cambar Truss for the rear shock tower points. That's it. Last time we did a corner balance/suspension set up, the shop said "this is still the most straight 914 they've ever worked on...nothing ever changes". and two of us drive it every weekend.....

Posted by: Justinp71 Oct 3 2008, 04:20 PM

Does the Engman kit reduce body flex? Or just keep the longs from cracking?

You would think it would help flexing, but if the flexing occurs mostly in the diagonal, I don't think the Engman kit keeps the body from diagonally flexing...

What do you guys think?

Posted by: jcd914 Oct 11 2008, 08:56 PM

I think anything you do to stiffen the longs will reduce the diagonal flexing ir twisting. I also think the Engman kit will do more than clam shells since it has a piece that ties each side together.

That said If you really want to reduce twisting you need to tie upper corners to lower corners, i.e. a cage or a roll bar with diagonal supports.
Without a solid roof structure our beloved cars will flex.
I plan to build a cage for mine at some point.
I even have a tubing bender sitting (never used) with 1 1/2 die and a tubing notcher.


Jim

Posted by: John Oct 23 2008, 08:28 PM

An area that seems to crack and few discuss is where the rear shock towers are supposed to attach to the rear portion of the longs. To really fix, some of the cross-members should be opened up so that the shock tower can be attached to the inner long.

The inner longs could also be braced together better. The cross member between the rear shocks is important as it attempts to keep the two longitudes aligned with each other. The next forward cross member is the lower firewall. From what I have seen, the Engman kit has a well thought out piece that welds into the inner lower firewall (that ties the two longs together).

Over time, without sufficient bracing, the metal that makes up (or attaches to) the cross members of the cars will fatigue and crack. The cross members (or areas that attach to them) that show this the worst are the rear cross member/rear trunk floor where the rear shock towers attach, and the cross member just in front of the seats (close to where the parking brake indent is in the longitudes).

The other areas cracks seem to be common are the rear suspension inner ears. In these areas, the attachment to the long seems solid enough, but over time the sheet metal part itself fatigues and cracks form just above the trailing arm attachment bolt hole. The braces that can be mounted between the lower firewall (cross member) and the inner ear (dog ear) help a lot.

The factory stiffening kit may help a little, but cars still crack with them installed. I have tracked the same 914 for over 20 years and have found and addressed all the cracks (and most of the cars crack in the same spots).

Nobody mentioned the fatigue cracks in the lower windshield pillars. I have seen many many 914's (not even track cars) that show these cracks. My windshield frame is welded to the roll cage to keep it from moving around and rubbing on the cage (which it did prior to welding it).

The more you can remove and the less you add back (stiffening) will benefit you on the track. (a 10,000 RPM race engine wouldn't hurt either).......


my 0.02

Posted by: ConeDodger Dec 4 2008, 10:47 PM

Trekkor put the Engman kit into his car and felt a big difference. Even slow speed turns into parking lots that used to have him feel the body flexing as the front wheel went over the bump and then the rear wheels were suddenly noticeably stiffer... I don't think the Engman kit will do anything to keep you from tearing off your suspension ears from the grip of slicks though...

Posted by: J P Stein Dec 7 2008, 02:30 PM

Tieing in the longs to the towers is gud. Tieing in the longs/towers too to the cage is real gud.


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Posted by: Justinp71 Jan 14 2009, 01:20 AM

Well my conclusion for my more street oriented car.




Miesto, Drum Roll Please...





GT rear kit and the Brad Mayeur Long kit!
(and probably CFR's inner trailing arm support too!)


Anyone else want to share, what they have???

Posted by: 9146986 Jan 14 2009, 10:06 AM

I forgot to add that I welded up all the seams I could. TIG where possible, and MIG everywhere else.

Posted by: Justinp71 Jan 14 2009, 12:22 PM

Did you race or a/x the car that you are describing?

Posted by: 9146986 Jan 14 2009, 12:37 PM

The customer that I built the car for did autocross, time trials, and track events.

Posted by: Justinp71 Jan 14 2009, 01:53 PM

No cage, correct?

Posted by: charliew Jan 16 2009, 08:48 AM

What makes these little cars attractive is their light weight. But the power levels when they were designed was lower and the tire tech has gotten so much better. The tricky thing is to only add as much support as is necessary to the exact weak spots that are known. This is where you originally started your quest. You seem to be off to a good start as the some of the smart guys have already assisted you a lot.

I would bet that in a lot of cases the fractures started before the reinforcements were added. You know some of these cars started as just two or three times a year racers and then bigger and sticker rubber was added and then more power and so on till it got serious and the cracks started appearing so then the repairs and stiffening started where it was obviously needed but then that moved the stress to the next weakest area and so on. If you start out knowing what the bad areas are and brace them before the stress is applied it will end up much better.
I know this is what you are doing and the reply about the cage tieing the cab up tight helped the long area a lot. The suspension ears are a problem all by themselves and need to be braced and thickened to spread the load out over a larger area.
I would like to do a permanent brace from the targa to the windshield but I don't think the windshield is strong enough as it is. I don't think there is enough room for a cage in a street car without wearing a helmet all the time. But that is the best bracing solution. Of course a exoskeleton would be the best but how stupid would that look on a street car.
I have lots of studying to do it seems.
The safest thing is to do the mods you listed and only run about 9 inch wide tires and keep the power below 250.
I find it hard to believe that these cars don't get real crooked on a rotisserie when the whole long is cut out on one side even with the diagonal brace that is used between the seat belt point and the kick panel.
I may persue the idea of a 1-1/4 tube cage that is tight up against the body at the windshield and targa and nothing overhead on the outside but two connecting tubes in the middle away from your head. This would not be as good as over the side windows but would be where maybe your head couldn't contact it in a wreck with the seatbelt on. I would also like to angle the windshield back some and that means a lower roof line but that might be asking too much.
I'm only 5'8" but both my sons are taller and they may want this car when I'm done with cars.
I have fieros and both my son's think they are too confining although I know some 6 footers with fieros.

These cars are very thin sheetmetal boxed sections and sometimes the spot welds are not as good as the engineers planned. Seam welding is the time proven helper on all unitized cars used in motorsports. I know the seam sealer is a pain but it might have come loose because of some of the twisting, where it's loose might give a indication of where the most twist is at stock levels.

Posted by: Simon Tibbett May 29 2009, 10:13 AM

I am new to 914's and looking into getting one, and will be tracking it.

I never knew the chassis cracked easily. Is this common with hard driving and upgrading suspension?

Posted by: jt914-6 Jun 1 2009, 08:50 AM

I have Brad's long. kit, GT kit, boxed trailing arms, full cage (not tied into f or r) front and rear stiffening.

Posted by: jhadler Jun 1 2009, 02:11 PM

In the first photo there, it looks like you are drawing heat for the passenger compartment off of the cooler in the front. Did I see that right? If so, I think it's brilliant!

-Josh2

Posted by: jt914-6 Jun 1 2009, 03:25 PM

Josh, yes I'm using the cooler heat for the winter. Hose from the cooler goes to a "T" and then to orignal heater hose connections. A friend tried it too with his and it works.
Run the hose from the cooler down under the old gas tank area and exit hot air under the car for summer. I have a two speed fan mounted to the cooler to pull out the hot air when needed. Using an Earl's 60 row cooler #26012. It is 7 X 19". Usually run 180 degrees and on the track in mid 70's temp around 200 degrees....

Posted by: J P Stein Jun 8 2009, 05:47 PM

After bonking my helmeted haid on my cage halo, I cut it off and did this.
Tying in the suspension towers gave the best chassis stiffening effect of all I did.


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Posted by: Joe Ricard Jun 9 2009, 05:51 AM

JP would you please show me your engine lid?
Like a dumb ass I followed your design once again with the rear shock tower to cage thing. Now I need to made an engine lid. Probably out of fiberglass and wire FOD screen.

Posted by: J P Stein Jun 9 2009, 07:38 AM

I don't have a pic of it, go figure.
I made a GT type lid then Brit notched it to clear the tubes. Stock mounting with Dzuts fasteners. I'll take a pic & get back to ya.

Posted by: Joe Ricard Jun 9 2009, 09:15 AM

Metal?

My car will have bare minimum of metal. I am thinking of removing the targa and making a fake one out of FG. The cage will actually be the support for the super thin single layer FG roof skin. It might look like a 914 but it is nothing Porsche anymore.

Posted by: J P Stein Jun 9 2009, 11:13 AM

I'm done with adding lightness. My next project will be more grip.
XP is where I'll be.

Posted by: Joe Ricard Jun 9 2009, 11:26 AM

Yea PM me with your thoughts.
I'm a looking at some 16 x 10 for the rear. I'll have more dough in rims and tires and shocks than the whole rest of the car.

Posted by: J P Stein Jun 9 2009, 02:51 PM

I may have some wheels for you in a few weeks.

Posted by: Chris Hamilton Aug 30 2009, 05:36 PM

Has anyone measured the amount of flex they had before and after the reinforcements?

Posted by: Britain Smith Sep 17 2009, 11:54 AM

Didn't measure it, but we felt it in JP's car.

-Britain

Posted by: Joe Ricard Dec 9 2009, 07:11 AM

I can 3 point lift my car and it stays level.
get a jack stand under each rear lift donut and then put a jack under either front donut. The front of the car comes up instantly with not measurable flex. Not the case in an un caged car.

Posted by: Chris Hamilton Dec 12 2009, 03:55 PM

Joe, My car does that with an autopower rollbar bolted in.

This is why it would be nice to actually MEASURE flex before and after.

Stiffening is great, and 914s need a bunch of it, but it's pretty hard to just eyeball a car and tell where it needs stiffening without some way to measure it, otherwise you're just welding lots of tubing into it and going "well that looks good", with no idea which bits actually helped and which bits didn't. The car will probably be faster and feel better afterwards, but could you have accomplished the same thing with less weight?

It cost me $500 for my aluminum pressure plate to lose a couple pounds and it is going to cost me another $500 for a fiberglass trunklid to lose a few more pounds after that. I'm sure as hell not going to add 20lbs of steel tubing until I know for sure what it's going to do.

Posted by: J P Stein Dec 12 2009, 07:01 PM

It doesn't take an engineering degree to see where the points of load are on a 914......hint....there are 4 and round black things right near em'.
Once that tough bit is over, then you gotta figure out where you can attach structure & how to bridge between them.

As Brit wrote, a butt dyno reveals a huge difference. The chassis moves more like a single unit and the suspension does it's work in a more controlled manner.
This causes the car do the same thing every time when loaded....or close enuff.

BTW, there is closer to 60 lbs than 20 lbs extra. Bridges aren't light.

Posted by: Randal Dec 12 2009, 10:05 PM

I've taken JP's approach on adding front and rear bars tied in front to the shock towers, then to the front torsion bar mounting. In the back we have run the bars as close to the towers as possible, although not as nice as JP did it.

Can't wait to see the performance difference. Who knows, with a clear head, the car might be competitive.

Posted by: J P Stein Dec 13 2009, 11:06 AM

My car is no shining example. It's kinda like a house remodel.....rip this out add this here...and here.....here too.....since I've got the welder fired up & this estra stuff is just laying around. No original ideas, just built on other folks'.

IF I knew then what I know now, it would be lighter & prettier....prolly safer too. Mine is the homebuilt CSOB method......my whole 914 project was like that...learn & build as you go. I wouldn't want anyone to think I had an overall plan.


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Posted by: Chris Hamilton Dec 13 2009, 03:02 PM

This is where I think we'll have to disagree.

The 'build it so it feels better' approach isn't scientific enough for my tastes. Just like people who dyno their engines after every change I'd like to see a quantifiable result.

My 914s and yours are built specifically for autocross. This means that we are not concerned with crash protection. Are the bars in your picture of the doors actually providing structural support or are you just adding weight with those? I think it takes more than an eyeball and a welder to determine that.

Posted by: J P Stein Dec 13 2009, 04:00 PM

I've been building stuff for 40 odd years....most of it engineered by some damn good folks that I've had access to. I'm the curious type and have talked to those guys asking just why they do things as they do. No, not everyone has an "eyeball" but it can be developed over time. A good hand can make a bridge strong, but it takes an engineer to make it light.

You want to break things down to numbers...be my guest. Get/build your self a chassis rack (or rent one), drag out the load cells, strain gages, micrometers & jacks, get an engineer to interpret the data and design a cage to stiffen your 914. I would guess you'll end up with something very similar to what guys have been doing for 20 years.

You're right, those side bars are for chassis strength. The lower ones were one attempt to do the job from a few years back......but were inadequete. The upper bar tied into the front & rear shock towers is much more effective.....but not ideal because of the bend. The verticle bars twixt the side bars is an attempt to help the upper bar do what I wanted.
Again, a remodel.

The safety aspect pertains to them bunny ears on the top of the hoop. A higher roll bar would have been mo better....but the car had a lid back then and it wasn't required......remodel.

Posted by: Joe Ricard Dec 13 2009, 05:14 PM

Chris there is no way your bolt in autopower cage is anywhere near the stiffness of my car or even JP's for that Matter. You don't have any diagonal attaching upper right rear corner to lower left front corner. Tubes to tubes not body panels and tie all the suspension pick up points to the cage.

Race cars are measured in 1000's of pounds per Centimeter of deflection. (or some sort of huge factor)

Not an ME but I know a bunch of them that race cars.

Posted by: J P Stein Dec 13 2009, 05:56 PM

BTW, our trip down to your house at Marina was quantifiable enuff for me.
Andrew showed up with his usual set up (as did we) and got his hat handed to him.
His changes for the next day produced quantifiable results also......and good for him.
Did he consult your engineering type....?

For our first time on concrete, we did OK. I would definitely make some changes if we ran there full time.

Posted by: Chris Hamilton Dec 13 2009, 07:05 PM

JP, it will be fun to see how Andrew and Britain do this year at the mid engine shootout! Will you be coming to drive your old car, or bringing an MR2 to the mix?

Posted by: J P Stein Dec 14 2009, 08:30 AM

Brit is headed down that way for the SD National Tour event in April. The timing
of the shoot out is still up in the air and much will depemd on that. Of course, ya'll could setp out of your little pond & all get together at the SD event. At present, I have no plans to make it, but would for a Tour event get together.....I wouldn't miss that for the world.

Posted by: Joe Ricard Dec 14 2009, 10:52 AM

Raced in the little pond yesterday. PCA had an event that was supported by our / My Gulf Coast SCCA region.

Drove my buddies box stock Miata amongst the 09 Carrera S, New Caymen S and some other really nice cars.

Smoked em, like shooting fish in a barrel. Bunch of nice people that all got an invite to our next event.

Posted by: Randal Mar 31 2014, 07:59 PM

Update:

Having gone pretty much all out I believe using (essentially) a cage from the front torsion bars to the front shock towers, then back from there to the cockpit cage and back from there to the rear shock towers plus bars in the cockpit to the engine hump, all make a huge difference. In addition reinforced ears with alumimum standoffs to the firewall and Foley reinforced trailing arms, with needle bearings really work.

Reinforcing the ears is simply a requirement if your going to run big slicks, as the sheet metal won't hold up otherwise. In fact I broke mine my first time to the track.

Anyway the car not only does what you want it to do it has lost any tendency to snap spin under extreme situations. But some of that has to be credited to the tires and tire setup, which is another subject.

And you can buy this chassis if you'd like.

Posted by: Randal Mar 31 2014, 08:02 PM

Amazing how well a Miata handles, isn't it.

Anyway nice going Joe... You ought to offer to drive their cars next time.

Posted by: Joe Ricard Apr 1 2014, 05:53 AM

Geeze I was reading this thinking wtf did I do? Man that was a long time ago.

The snap oversteer I think is less now because you took some of the "spring" out of the chassis. I noticed the same thing in my old car, just point it in and it went exactly where I wanted.

Posted by: Randal Apr 1 2014, 01:35 PM

Right, there is a video, of the Medford Spring Enduro from last year on YouTube. https://www.youtube.com/watch?v=7XTxvcpka5w

At about 1:06 you see me enter a corner a bit fast, with a poor line, coming off the straight. Check how far the car rotated and then came back with a simple off throttle steering correction. Somewhat unusual for a 914, hey?

I agree with you that the stiffer chassis does help as well.

Posted by: smokey Jan 5 2015, 08:17 PM

My
Lilbasterd
Gets much stiffer wen chancing any Porsche car. Aft smoking it . She porscheeeee .always wants to rest , and it smokes a bit .
Hee he,,,,,,,,,,

Posted by: ThePaintedMan Jan 6 2015, 07:51 AM

Dafuq?

Posted by: Bullethead Sep 6 2023, 09:45 PM

How did this thread get reanimated? Last post was 1/6/2015.

Posted by: d914 Oct 9 2023, 01:13 PM

egman inner longs
tangering racing rear console support with bolt in bars, reinforced suspension ears. plate steel swing arm brackets.

cage if I start tracking car. I like the gt one but not sure how much that does.

Posted by: mlindner Dec 1 2023, 04:35 PM

I had a full roll bar cage for many years. The last upgrade while building the 914-6 GT Tribute I extended to all suspension points.

Posted by: brant Dec 2 2023, 08:31 AM

Nice work
The problem is that it’s not legal in some rules depending on class for wheel to wheel racing

Posted by: mlindner Dec 4 2023, 09:02 AM

Thanks brant. Was not intended for full racing. DE's, hill climbs etc. I'm 76 so I'm just having fun. Best, Mark

Posted by: Charles Freeborn Jan 6 2024, 01:24 AM

A 911 I'd be concerned about straying too far from the rulebook, but a 914 not so much. Yes, if you're wanting to race beyond regional, there may be some other drivers who protest your car, but, well, there's going to be one in every crowd no matter where you go. Smaller sanctioning bodies care less and less about minutiae and more about simply getting entries. I say build it to your taste and needs and go have fun.

Posted by: brant Apr 26 2024, 01:43 PM

We learned a lot about rules during the build.
so build the chassis to be legal in HMSA, stock SVRA, CSRG, CVAR, etc.....

I've run in all of those clubs including the local RMVR that probably wouldn't care.
but gave me options to see any club or track that way.