What do you have for chassis stiffening? Options

[Justinp71]

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

[SirAndy]

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.
(IMG:style_emoticons/default/driving.gif) Andy

[sww914]

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.

[dlestep]

...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... (IMG:style_emoticons/default/biggrin.gif)

[Joe Ricard]

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.

[Justinp71]

Thanks guys!

(IMG:style_emoticons/default/dry.gif) 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!

[dakotaewing]

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

[Justinp71]

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

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!

[jcd914]

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

[Justinp71]

Well Thanks for posting anyhow Jim!

When you say

... and add re-enforcements to the inner rear mount since they were cracking.

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???

[Justinp71]

...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... (IMG:style_emoticons/default/biggrin.gif)

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

[the4u2]

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

[J P Stein]

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. (IMG:style_emoticons/default/biggrin.gif)

[IronHillRestorations]

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.

[naro914]

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.....

[Justinp71]

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...(IMG:style_emoticons/default/unsure.gif)

What do you guys think?

[jcd914]

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...(IMG:style_emoticons/default/unsure.gif)

What do you guys think?

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

[John]

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

[ConeDodger]

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...(IMG:style_emoticons/default/unsure.gif)

What do you guys think?

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...

[J P Stein]

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