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The bolts not lining up is a similar measurement to the door gap measurement, maybe we should use them as a qualifier for the stiffener!

This could also explain why bruce heard rubbing on his stiffener(may have read it on another thread).

And my earlier response about "unloading" the spider chassis needs revision, in this case we are in fact pre-loading the chassis (using bottle jacks to bend the chassis against its will back into original spec.). But because we are preloading in the opposite direction of the load in application its end effect is still to strengthen the car.

I'm now officially retiring from my position of internet soap-box engineer and returning to my rather sedate life of engineering student, and alfa tinkerer. Please forward all future inquirys to:
Keenta Helpya
Cheif of Public Affairs
structural dabates inc.
 

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Discussion Starter #42 (Edited)
frame/chassis stiffener

I spoke to Don Ereminas (see his ad in the Alfa Owner magazine) regarding the problem with interference between the stiffener front cross member and the tubular exhaust headers. They now have a special front cross bar or cross member that will clear the headers so that no modification to the headers should be needed. I have ordered the stiffener assembly from him specifying that I do have the headers installed. He added that if there is still an interference problem, to let him know what is needed and he will make up a front cross bar with the necessary changes to fit. Apparently, it is o.k. to drive the car with the front cross bar detached and still get some improvement in chassis stiffness if there is any concern about waiting for a further modified cross bar to be made up ands shipped, if necessary. The new stiffeners are powder coated. The important thing is that now there should be no need to go to a muffler shop to have the headers re-bent so the stiffener will fit. When it arrives (approx. 3 weeks) and I install it, I'll let you all know how it works.
Jim Evidon; Desert Spider '84
 

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bill_bain said:
I can't speak as to whether a chassis stiffener "works" or not since I don't have one, but I *can* speak about the effects of a roll bar. An old Alfa hand once proved to me with jacks and jackstands that a Spider (1981) was stiffer with the top UP than the top DOWN because the top frame helped "knit" (his words) the front end and the back end together! My 1983 Spider is much stiffer with a roll bar in than without. Pre-1982 Spiders are *much* more flexible than their later siblings...
Aha.. I had a mental theory that this might be the case.. and be the reason that I have heard varying results with the stiffener. Ususally there is a positive benifit.. though I have heard a few say that didn't make a big difference. Could be later, stiffer Spiders gaining less benefit than earlier, bendier ones.

I have a 77, and do notice a lot of bending when jacking only one corner, tight doors with the front end up on stands, etc..

It might be useful info for those putting one on, to take some basic and easy data like jackpoint to floor distance when a wheel just comes off the ground (try to match tire pressures, and don't create large differences of mileage on the tires between tests) before and after.. but I agree, getting decent numbers on "bendability" is a bit of a challange.

Don't know if anyone has addressed the ground clearance question, do they lower you any, or are other things still lower than the bars?
 

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OK my 2 cents worth.

1. If you really want a torsionally rigid Spider, go ahead and fit a properly designed and manufactured rollcage, weld the doors shut, and fit a steel roof. Oh, then call it a coupe. The world is full of compromises and you can't have your cake..........

2. For those arguing about the merits of the chassis stiffener, especially those with one already fitted, there is a relatively simple test you can do involving replacing the shocks with solid bars, a few jacks, a bit of steel tube and a couple of dial guages. If you go to Yahoo Groups and look up 'Locost Oz', you should be able to find the details there in the files section or in one of the many links.

If the test is carried out on the same vehicle, by the same people, with and without the stiffener, you should be able to gain some definitive answers, at least for that car. Merely test driving is fraught with inaccuracy.

3. I don't know about other 'formula' cars but F1 cars do have shocks and springs on the front end. They are acuated via pushrods and lay together longitudinally under the nose cowling. Makes adjustments easier and centralises weight.
 

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It's funny - every time the chassis stiffener topic comes up, it usually follows a similar flow:

1. Someone asks about the effectiveness of the stiffener :confused:

2. Someone replies that they have one and like it :)

3. Someone else replies that there are no objective tests that have been done to prove or disprove it :(

4. People then discuss the theory - which usually concludes that theoretically the idea is sound, but there is no proof that this particular design works. :cool:

5. More people pile in saying that regardless of the science - they have one and they like it and offer anecdotal evidence why they think it's good. :D

6. The thread ends inconclusively - with those that believe in it, continuing to believe, and those that don't remaining skeptical. :rolleyes:

---

For me - I have one, and I'm satisfied it makes a big difference (on my 37 year old car). I have some bushings done at the same time and had Konis put on, so the effect is impossible for me to isolate. I would certainly do it again - 40 pounds and nothing visible isn't too big a compromise for me. That being said - it would be great if someone did some objective tests one day and posted them.
 

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Discussion Starter #46
O.K., O.k. It's true that everyone that has installed a stiffener has done a lot of other suspension changes at the same time so that while they like the overall result, they don't know exactly what caused the improvement. Well, I'm doing something radical. I have been making my changes incrementally. I installed the adjustable control arms on the front suspension about six or seven months ago without doing any other changes. That did make a big difference by dialing in the front end geometry changing the Spider from a heavy understeerer to a near neutral handler. I have now ordered the chassis stiffener and will install it when it arrives in a few weeks. I should then be able to report how much of a change the stiffener alone has made. Since my 1984 car is fairly low mileage and the original rubber bushings are in pretty good shape (I don't race and therefore don't use the poly bushings...comfort being still important to me), I should get a fairly objective comparison. Once that is done, I'll probably swap out the crappy but near new Pirelli 400's that car came with for some good rubber, like Sumitomo's or Falkens. If there is anyone out there who has also made incremental changes and has a stiffener installed, it would be good to hear his/her evaluation as well.
 

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Discussion Starter #47 (Edited)
Now for something different. A comment on the chassis stiffener by a user who only installed the stiffener without doing a lot of other suspension,tire and wheel modifications at the same time. That's me. First of all, let me clarify the issue of whether it fits without modification. It does. It appears that the hole misalignment commented on by others is due to chassis flex and not misplaced holes on the stiffener, which seems to be very precise. So basic equipment should include four jack stands at the jacking points. Next, a bottle jack in addition a floor jack to relieve the chassis sag which then brings the holes on the chassis into alignment with the stiffener so the bolts install without any binding. A word of caution. The top bolts attaching the steering box on the left and the steering gear on the right are real knuckle busters. But even with my very large hands, it's doable. Be certain to torque the steering box, steering gear and rear shackle bolts using the shop manual figures. I also put lock-tite on all the bolts. The interference problem commented on by some who had installed the tubular performance headers has now been taken care of by the stiffener manufacturer. The front cross bar is now lower and further forward and clears my headers by about 1/2 to 3/4 of an inch.
Now for the results: (1) The scuttle shake is now pretty much gone along with the various body squeaks and rattles which occurred when cornering and going over undulating or rough pavement. It really stiffened the car a lot. (2) Cornering seems to be much flatter and the rear end more controlable when sliding out.
(3) The person who said it is best to install the stiffener with the car on a lift is correct. I did it on my garage floor using jack stands, et.,al. It is a dirty and physically stressful job (on my 71 year old bones). A lift would have made the job faster and less of a strain.
Final comments: (1) Don Ereminas who designed , manufactures and sells the stiffener (he also makes them for IAP and Centerline) was very helpful with his comments by phone and e-mail. Don, if you are reading this, you are a real gentleman.
(2) The stiffener is a worthwhile modification and while I wouldn't claim that the Spider is now as stiff as a new roadster manufactured with '90's or 2000 technology, it is certainly a real improvement and feels stiffer than many soft-top cars made in the '80's and '90's.

Jim, Desert Spider '84
 

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rust prevantion

My 2 cents it prevents chassis flex that can cause to paint craking and rust.
 

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I have one of these on my Duetto. I bought it a few years ago from a guy on the Alfa Digest who copied it and made a small run. It only cost $225 I think.

Anyway, the thing works. I have had numerous compliments about how my car is so tight and new feeling. I also have not noticed any visible twisting when jacking it up or driving on steep driveways at an angle.

The way it works was described to me this way ( by an aerospace engineer and Alfa nut ): When the body twists it is lengthening or stretching between the front and rear suspensions. The stiffener acts to reduce this by tying them together. I believe that Milanos also have some longitudinally mounted stiffeners to do the same thing

Sorry to have rehashed most of the obvious points.

Dan Walker
Stevenson Ranch, CA
 

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Frame stiffening

Guys, the little 1 inch tube is not adding much to the stiffness. It's the EIGHT bar (equivalent) structure of the stiffener PLUS the existing body. Think of each of the four arms as the top and bottom of an I-beam. The thin shear plate in the center of an I-beam does not carry much load (it is important), but the large space between the top and bottom beams adds a LOT to the stiffness of the I-beam. Similarly, the four-bar stiffner is spaced slightly away from the body frame, and it's this space that adds the equivalent of a 3 to 4 inch square tube to the body stiffness. hence, the seat-of-pants experience that this 'little' stiffner adds a lot to the stiffness to the car.
Those little plates that bolt to the steering and idler boxes, and to the trailing arms - which make up the spacer between the body and the stiffener tubes are a very important part of the design. The physical structure is actually a 4 foot by 5 foot sheet (the floor pan structure) stiffened by a 4-bar brace spaced 3 to 4 inches below. This is a BIG but skeletonized box beam that's about four feet wide by three inches deep.
 

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Jim,

Thanks for the chassis stiffener information. A simply-designed experiment, with documented results from changing just one thing. It's interesting how my '91 spider has significant scuttle shake while my '76 has literally none. Of course the '76 has a roll bar and very stiff springs. I accept that the roll bar stiffens the car, but I thought the springs would exaggerate the scuttle shake. Apparently there are many different ways to affect chassis / unibody vibration resonance (like putting the top up, as mentioned earlier in this thread).

I guess your '84 spider now has even more additional chassis stiffness than your old MG TC.....

desert spider said:
Now for something different. A comment on the chassis stiffener by a user who only installed the stiffener without doing a lot of other suspension,tire and wheel modifications at the same time. That's me. First of all, let me clarify the issue of whether it fits without modification. It does. It appears that the hole misalignment commented on by others is due to chassis flex and not misplaced holes on the stiffener, which seems to be very precise. So basic equipment should include four jack stands at the jacking points. Next, a bottle jack in addition a floor jack to relieve the chassis sag which then brings the holes on the chassis into alignment with the stiffener so the bolts install without any binding. A word of caution. The top bolts attaching the steering box on the left and the steering gear on the right are real knuckle busters. But even with my very large hands, it's doable. Be certain to torque the steering box, steering gear and rear shackle bolts using the shop manual figures. I also put lock-tite on all the bolts. The interference problem commented on by some who had installed the tubular performance headers has now been taken care of by the stiffener manufacturer. The front cross bar is now lower and further forward and clears my headers by about 1/2 to 3/4 of an inch.
Now for the results: (1) The scuttle shake is now pretty much gone along with the various body squeaks and rattles which occurred when cornering and going over undulating or rough pavement. It really stiffened the car a lot. (2) Cornering seems to be much flatter and the rear end more controlable when sliding out.
(3) The person who said it is best to install the stiffener with the car on a lift is correct. I did it on my garage floor using jack stands, et.,al. It is a dirty and physically stressful job (on my 71 year old bones). A lift would have made the job faster and less of a strain.
Final comments: (1) Don Ereminas who designed , manufactures and sells the stiffener (he also makes them for IAP and Centerline) was very helpful with his comments by phone and e-mail. Don, if you are reading this, you are a real gentleman.
(2) The stiffener is a worthwhile modification and while I wouldn't claim that the Spider is now as stiff as a new roadster manufactured with '90's or 2000 technology, it is certainly a real improvement and feels stiffer than many soft-top cars made in the '80's and '90's.

Jim, Desert Spider '84
Regards,
 

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sono veL.O.ce said:
The properites of the stiffener and car combination are simply additive, the rigidity of the car + the rigidty of the stiffener = the total rigidity of the system.
This is not exactly true. The stiffener becomes part of a torsion/bending support system which has a combined rigidity that is greater than the additive rigidity of the stiffener and the car itself. You are effectively building a new substructure.

How well such a thing could possibly work depends greatly on the condition of the individual car, particularly localized rust or body damage. Never tried one my self, but I would put the stiffener on the list of things to do, after replacing worn bushings, shocks etc.
 

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This is really good. Having looked at the chassis of my s3 I see weak frame. The front & rear are not tried together. Only with the sheet metal body. Having worked with Nissan for 30 years this was a problem when they did convertible tops.The chassis flexed. There was appox. 300lbs of metal added to the chassis to fix this flex of a 350z
So I see where this added piece would help the spider. It ties the rear to the front to correct the flex
 

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Just to put in my two cents on this subject. I've just acquired an S4, am a first time Alfa owner, and was somewhat put off on the cowl shake (my old MG's were more solid in that way). I'd done a lot of reading on Spiders before buying and the chassis stiffener came up a number of times so I was prepared to deal with that issue. I don't know if I would have kept the car with the stock 'shake', if nothing could have been done about it.

My Spider has 62k and original shocks/springs (soon to be replaced) and had all bushings, etc that needed being replaced done. So the car was basically a 'stock' Spider when I put the chassis stiffener on (from IAP). So I have a good sense of what the CS does in an of itself, without other suspension mods to cloud the impression.

And WOW, what a difference. The cowl shake was cured by about 80%. It still shakes some, inherent in these cars I guess, but nothing like before where I was afraid of getting thrown off the road on curves with mottled pavement. To me the CS is the single best mod on these cars- it transforms the Spider into a much more solid, controllable machine. That said, I haven't put the konis and Alfaholics Fast Road Suspension on yet.... but the CS to me is the foundation for a great handling Spider.

Lastly, if you don't want to get run over by modern traffic, the Squadra-Tune chip is the other essential mod (even in CA with 91 octane, it has worked great for me). Way more usable torque and drivability. These Spiders can and should be massaged to their best- the S4's can be fantastic sports cars and not just boulevard cruisers.
 

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re headers

I am a little concered that it may not fit without modification since I do have performance headers and do not wish to go back to a cast manifold. Once again, thanks one and all for your comments.
Jim
Desert Spider (1984)[/QUOTE]

Mine had headers when I got it in 2000. Had a chassis stiffener put on in 2012. Much reduced flex and shake when going over RR tracks etc. Mechanic who installed it made no mention of alterations. Don't know make of header as it was installed by PO. Stiffener from IAP. If I can be of more help, let me know.
Courtney
 

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I'd love to know that they work. I have one on my spider (thanks to the PO). Still, it looks to me like they wouldn’t do much to stiffen the chassis and no one seems to have anything remotely resembling objective data on them one way or the other. I just happen to think that if they really work, there should be some objective data that support this conclusion. To me it’s the difference between knowing something and believing something. I hope I’m not being obtuse.
I know this is an ancient thread but I've wondered as well if the brace provides a noticeable stiffening of the chassis. What's odd, Bruce, is that you state that you have one on your spider but not once do you say if your car suffers from any of the obvious twisting of the "Flexible Flyer" chassis these Spiders were known to exhibit.
 

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It's an old thread, an old topic. The chassis stiffener isn't going to transform an old Alfa Spider into a 4C but sans empirical data to prove its function here's a simple explanation.

The front wheels and back wheels of a Spider are connected by a rigid flat pan comprised of the rocker panels, floor panels and transmission tunnel. There is no truss support such as is provided by a solid roof so when the front wheels hit a bump they go up and the whole pan bends. The chassis stiffener is a parallel steel bar to that pan so that if the pan were to bend that bar must either lengthen or shorten it's dimension - which it can't. Of course it could bend as well and probably does to some extent but only in compression, such as cresting a ridge. It can't bend in tension, such as hitting the bump so that's how it works.

As far as twisting, uneven surfaces it's less effective but still makes a difference. As to whether or not it's worth the weight is another question. It ain't perfect but it definitely does have an effect.
 

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you could do as I did.. between the rear and front mount,, look under the car, about midway, you will find a flat spot just forward of the front seat,, add a 3rd member at this point to tie it togeather better.
 

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Thanks for the reply. Old topic, sure, but same problem! :)

I understand that the brace should reduce torsion as it effectively makes for a sixth side to the chassis "box." I am hoping the improvement is in the form of better handling on sweeping, higher-speed turns that currently feel a little squirrelly. Bumpy roads also feel like unsorted front alignment issues but hopefully that improves as well.
 

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Yes it's an old design but much of the discontent comes from being spoiled by newer cars which are far more rigid. One way to cure that might to be to go for a ride in a 70's era Triumph Spitfire. You'll think your Alfa is rock solid in comparison afterwards. :)
 
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