Joined
·
1,015 Posts
there was a thread on here (which I cant find) which showed a strengthening unit that bolted on under the car to reduce scuttle shake.
anyone know where it is ?
anyone know where it is ?
lost thread re: scuttle shake
1 - 15 of 15 Posts
Joined
·
1,171 Posts
I recently installed a chassis stiffener on my 92. At the same time, I replaced all the rear bushings (poly where available) and replaced a broken driveshaft support and cracked Giubo. The car is almost as solid as a coupe, its awesome! Because I did so much stuff at once, I can't say how much of the difference is in the chassis stiffener.
As I have now exhausted my budget both in dollars and in screaming in vulgar Italian from under my car, the rest of the Summer will be spent driving the hell out of it.
Next year I start on figuring out how to get the additional 50 - 75 HP to the wheels that will offset the cars weight!
As I have now exhausted my budget both in dollars and in screaming in vulgar Italian from under my car, the rest of the Summer will be spent driving the hell out of it.
Next year I start on figuring out how to get the additional 50 - 75 HP to the wheels that will offset the cars weight!
Joined
·
4,311 Posts
I installed a chassis stiffener during my restoration but, as with others, I also completely rebuilt the entire suspension system as well. There was a discussion about this on the Alfa Digest a few months ago and the point was raised that it's almost impossible to genuinely quantify the effective results of installing the stiffener. Someone suggested driving one corner onto a ramp and using a laser level or something to measure chassis flex with and without the stiffener but even if you did that, what would those numbers mean?
The reports you get from those who have installed the stiffener, and I'll give you mine as well, are not entirely objective. After an owner spends 200+ dollars and probably an entire day working under the car on the garage floor his analysis is probably going to be somewhat biased.
So, that being said, here's my report:
The stiffener is a fairly easy "bolt on" mod that can be done in less than a day. There is one significant flaw in the instructions however that could cause you some problems. They instruct you to mount the forward plates to the steering and damper boxes first and then install the rear through bolts at the forward ends of the trailing arms. If you are off even 1/16th of an inch you're gonna be cussing after about half an hour of futile struggle. If you, instead, install the rear mounts first it is very easy to use a suitable sized punch or pry bar to align the other two holes of the forward mount plate and install the bolts.
The chassis stiffener will not eliminate cowl or "scuttle" shake but it will reduce it significantly in certain circumstances and will make quite a difference in the feel and handling characteristics that, as I said, are hard to quantify. It's also difficult to describe the changes other than to say they are positive and I wouldn't even consider removing the stiffener. You should also be aware that the stiffener is going to add about 40 pounds of weight to the car.
In my opinion it's a worthy mod. They may seem a bit pricey but these things are hand built and not stamped out en-mass by some ironworks in Shanghai. There's nothing high tech about them, you could make one yourself if you were so inclined but it would be quite a bit of work to try save a hundred bucks.
The reports you get from those who have installed the stiffener, and I'll give you mine as well, are not entirely objective. After an owner spends 200+ dollars and probably an entire day working under the car on the garage floor his analysis is probably going to be somewhat biased.
So, that being said, here's my report:
The stiffener is a fairly easy "bolt on" mod that can be done in less than a day. There is one significant flaw in the instructions however that could cause you some problems. They instruct you to mount the forward plates to the steering and damper boxes first and then install the rear through bolts at the forward ends of the trailing arms. If you are off even 1/16th of an inch you're gonna be cussing after about half an hour of futile struggle. If you, instead, install the rear mounts first it is very easy to use a suitable sized punch or pry bar to align the other two holes of the forward mount plate and install the bolts.
The chassis stiffener will not eliminate cowl or "scuttle" shake but it will reduce it significantly in certain circumstances and will make quite a difference in the feel and handling characteristics that, as I said, are hard to quantify. It's also difficult to describe the changes other than to say they are positive and I wouldn't even consider removing the stiffener. You should also be aware that the stiffener is going to add about 40 pounds of weight to the car.
In my opinion it's a worthy mod. They may seem a bit pricey but these things are hand built and not stamped out en-mass by some ironworks in Shanghai. There's nothing high tech about them, you could make one yourself if you were so inclined but it would be quite a bit of work to try save a hundred bucks.
Here's a question then for you stiff chassis guys...when you drive over a little dip in the road straight ahead or encounter rough pavement, does it handle it more like "normal cars" do? My front wheels seem to handle the initial bump pretty well but by the time the chassis is done flexing the car "lands" in a different spot afterwards...with plenty of jarring and the requirement for a steering correction of some type.
I'm exaggerating a bit, the car is by no means out of control, but you know what I mean.
I'm exaggerating a bit, the car is by no means out of control, but you know what I mean.
Joined
·
5,799 Posts
My understanding is that the early, lighter cars (like my '69) didn't have that bad a problem (as built) with cowl shake. But by the 1980 or so, there had been so much weight added to the car in the form of big bumpers, interior bits, smog stuff, etc. that the original chassis was really becoming too flexible and needed additional stiffening. This was finally accomplished in 1982. By the time that the 4th series (91-94) cars were built, yet more weight had been added with the new interiors, A/C, power windows, etc. The factory probably should have added additional stiffening and changed the suspension somewhat, but they didn't.
So, the early cars can benefit greatly from the stiffener, especially because of improved tire technology which places more stress on the chassis, the middle year (82-89) cars benefit from the chassis stiffener for the same reason and because many folks have installed wider than stock tires and improved shocks, springs and bushings. The series 4 cars really NEED the chassis stiffener because of the greater weight.
In short...it's a good idea to install one.
Rbitzer, the reason you are "road-hopping" may have more to do with your shocks, springs and/or tires and tire pressures. What are you running in those areas?
Cheers,
So, the early cars can benefit greatly from the stiffener, especially because of improved tire technology which places more stress on the chassis, the middle year (82-89) cars benefit from the chassis stiffener for the same reason and because many folks have installed wider than stock tires and improved shocks, springs and bushings. The series 4 cars really NEED the chassis stiffener because of the greater weight.
In short...it's a good idea to install one.
Rbitzer, the reason you are "road-hopping" may have more to do with your shocks, springs and/or tires and tire pressures. What are you running in those areas?
Cheers,
Joined
·
1,171 Posts
Rob, along with what Alex said, I would definitely recomend that you check the rear bushings. With approximately 60K on my 92 the trailing arm bushings were virtually non existant and the trunnion bushings were not far behind. This caused the kind of behavior that you described. If I hit a bump while cornering the entire rear end would just shift over.
Now its like a go kart, it just goes where I point it. It absorbs bumps in the road almost as well as my Eclipse coupe.
Now its like a go kart, it just goes where I point it. It absorbs bumps in the road almost as well as my Eclipse coupe.
I'll have to pull some tires and take a look around. I've looked at them before and they seemed to be "ok." In other words, the bushings looked 12 years old but not rotting to the core either. Same with the shocks & springs...its all original equipment in the suspension department so maybe this fall I can spend some time & money freshening things up a bit.
Its by no means all over the road but I tend to take it easy in the tight turns just in case I hit a good size rut.
Nice to hear that the car responds well to new equipment though. It always stinks to spend a lot of money and feel nothing new in a car's performance.
Its by no means all over the road but I tend to take it easy in the tight turns just in case I hit a good size rut.
Nice to hear that the car responds well to new equipment though. It always stinks to spend a lot of money and feel nothing new in a car's performance.
Joined
·
5,799 Posts
What kind of tires are you using? What is your tire pressure? Are you sure you have the stock shocks and springs?
Here's why I am asking:
1. Spiders are much lighter cars than most passenger car tires are built for. It is easy to have too much tire pressure. Over-inflated tires can cause rear-wheel hop and a 'darty', unpredictable feel.
2. Different tire sizes can also cause the same sort of thing. If you have a lot of sidewall flex, or not enough...the rear-end can feel unpredictable when upset by a bump in a corner (for example).
3. Additionally, some unfortunate owners have been given poor recommendations when upgrading shocks and/or springs. An example of this is using the Bilstein shocks in the rear of a Spider. These gas-charged shocks work really well on models like the Milano (75), but Bilstein seems to have gotten the damping wrong for the Spider. They are just plain TOO stiff! This causes a lack of rear suspension compliance which (on real-world roads) causes the rear of the car to bounce and lose traction when cornering if the road surface isn't perfect. This can be VERY SCARY and can be also very dangerous.
Let me know and maybe I can help you get your butt in control!
Here's why I am asking:
1. Spiders are much lighter cars than most passenger car tires are built for. It is easy to have too much tire pressure. Over-inflated tires can cause rear-wheel hop and a 'darty', unpredictable feel.
2. Different tire sizes can also cause the same sort of thing. If you have a lot of sidewall flex, or not enough...the rear-end can feel unpredictable when upset by a bump in a corner (for example).
3. Additionally, some unfortunate owners have been given poor recommendations when upgrading shocks and/or springs. An example of this is using the Bilstein shocks in the rear of a Spider. These gas-charged shocks work really well on models like the Milano (75), but Bilstein seems to have gotten the damping wrong for the Spider. They are just plain TOO stiff! This causes a lack of rear suspension compliance which (on real-world roads) causes the rear of the car to bounce and lose traction when cornering if the road surface isn't perfect. This can be VERY SCARY and can be also very dangerous.
Let me know and maybe I can help you get your butt in control!
I'll have to get back to you on exact size/type of tires but I'm running the standard 14" alloy wheels. Tire pressure is at 30 psi...I think the book recommends 28 for the front tires and 26 for the back...something like that. Maybe I'll let some out to the book value and see what happens.
From the maintenance I have done/had done on the car it appears the POs took fair care of the car but I have yet to see anything non-stock or replaced on the car. Heck, I had to put a sump guard on when I bought it. Anyway, I am assuming its an old stock setup except for the tires which have a lot of life left on them.
What would you think about Koni reds all around? Keep in mind the tag on the door jamb says its a 3050lb car.
If the checkbook were to spring a leak again, I'd be leaning towards the IAP performance springs, Konis, new poly bushings, 5/8 rear sway bar, 1" front sway bar & chassis stiffener.
In the REAL world, I'd probably slowly buy those things once a month and have it all put together this winter.
From the maintenance I have done/had done on the car it appears the POs took fair care of the car but I have yet to see anything non-stock or replaced on the car. Heck, I had to put a sump guard on when I bought it. Anyway, I am assuming its an old stock setup except for the tires which have a lot of life left on them.
What would you think about Koni reds all around? Keep in mind the tag on the door jamb says its a 3050lb car.
If the checkbook were to spring a leak again, I'd be leaning towards the IAP performance springs, Konis, new poly bushings, 5/8 rear sway bar, 1" front sway bar & chassis stiffener.
In the REAL world, I'd probably slowly buy those things once a month and have it all put together this winter.
Joined
·
5,799 Posts
Rob,
It always amazes me how my car is almost 1000 lbs. lighter than a series 4 Spider like yours. Mine was rated at 984 Kgs. (just over 2100 lbs.) from the factory. Yet, these cars share the same basic spring rates!
In any event, I would definitely try lowering your air pressures to factory specs first.
Many of the Spider drivers I know swear that the best combination of shocks/ springs for a 'Street' Spider are Koni (Red) shocks (set to full soft in rear, 1/3rd soft in front), either IAP or Centerline 'sport' springs, and the use of urethane bushings from IAP, Performatek, etc. Putting 15 or 16 inch wheels and wide tires doesn't seem to be that good an idea (according to many in the know Alfisiti), although if you were to do the shock, spring, chassis stiffener and urethane bushings, you might be able to make good use of a set of 15 inch Panasports, or maybe 16 inch Serpent Auto Wheels (see the wheel and tire thread elsewhere here) and some 50 series rubber.
Personally, I would get the shocks and springs (maybe you can buy the shocks a pair at a time - cheapest prices seem to be Linea Rossa or shox.com), the buy the springs...but definitely put them on together (especially important if you're paying somebody to do it, as replacing both at the same time takes almost as much labor as just doing the shocks by themselves). Then I would save up for the Chassis Stiffener.
I don't have a sump guard. I don't need one. If you keep your overall tire diameter and therefore your ride-height pretty close to stock, you won't bottom out.
I can't stress how much tires and tire pressures can change the handling of a car. I check my pressures at least weekly (on my daily driver '69 Spider), but normally I do that every time I fill up with gas.
I hope this helps!
Cheers,
It always amazes me how my car is almost 1000 lbs. lighter than a series 4 Spider like yours. Mine was rated at 984 Kgs. (just over 2100 lbs.) from the factory. Yet, these cars share the same basic spring rates!
In any event, I would definitely try lowering your air pressures to factory specs first.
Many of the Spider drivers I know swear that the best combination of shocks/ springs for a 'Street' Spider are Koni (Red) shocks (set to full soft in rear, 1/3rd soft in front), either IAP or Centerline 'sport' springs, and the use of urethane bushings from IAP, Performatek, etc. Putting 15 or 16 inch wheels and wide tires doesn't seem to be that good an idea (according to many in the know Alfisiti), although if you were to do the shock, spring, chassis stiffener and urethane bushings, you might be able to make good use of a set of 15 inch Panasports, or maybe 16 inch Serpent Auto Wheels (see the wheel and tire thread elsewhere here) and some 50 series rubber.
Personally, I would get the shocks and springs (maybe you can buy the shocks a pair at a time - cheapest prices seem to be Linea Rossa or shox.com), the buy the springs...but definitely put them on together (especially important if you're paying somebody to do it, as replacing both at the same time takes almost as much labor as just doing the shocks by themselves). Then I would save up for the Chassis Stiffener.
I don't have a sump guard. I don't need one. If you keep your overall tire diameter and therefore your ride-height pretty close to stock, you won't bottom out.
I can't stress how much tires and tire pressures can change the handling of a car. I check my pressures at least weekly (on my daily driver '69 Spider), but normally I do that every time I fill up with gas.
I hope this helps!
Cheers,
Thanks for the input Alex, I appreciate it. If I ever sell the car after the mods are done, I'll refer to it as a "Csank Setup"
Yeah I'll probably pay my shop to do the suspension work and do it all at once. I enjoy doing things myself and learning but that particular job doesn't hold my interest. Looks like a lot of broken knuckles and swearing....heheheh. After the engine work I'm enjoying just driving for a while.
I doublechecked the tag on the door jamb and it is, in fact, 3060lbs. Those are called "progress pounds". Even with all that weight, I don't have any trouble keeping up with anyone which is a testament to Alfas gracefully aging automobiles!
Yeah I'll probably pay my shop to do the suspension work and do it all at once. I enjoy doing things myself and learning but that particular job doesn't hold my interest. Looks like a lot of broken knuckles and swearing....heheheh. After the engine work I'm enjoying just driving for a while.
I doublechecked the tag on the door jamb and it is, in fact, 3060lbs. Those are called "progress pounds". Even with all that weight, I don't have any trouble keeping up with anyone which is a testament to Alfas gracefully aging automobiles!
Joined
·
1,171 Posts
Rob:
The tag on the door is Maximum loaded weight, not curb weight. Spider Veloce with manual trans is 2660 lbs. (according to the owner's manual) Still much more than a 1300 but not 3,100 lbs.
Like Cartman, our cars are "Big Boned"
I have 16" wheels with Yoko 205/50/16 tires, the overall diameter is virtually identical to the stock tires (195/65/15). I do have a sump guard and have scraped it a number of times since installing the IAP springs (noticably lower than stock). It could be that without the sump guard, there wouldn't be any scraping but the notion of having my oil pan ripped out going over a manhole cover sure scares the piss outa me.
The tag on the door is Maximum loaded weight, not curb weight. Spider Veloce with manual trans is 2660 lbs. (according to the owner's manual) Still much more than a 1300 but not 3,100 lbs.
Like Cartman, our cars are "Big Boned"
I have 16" wheels with Yoko 205/50/16 tires, the overall diameter is virtually identical to the stock tires (195/65/15). I do have a sump guard and have scraped it a number of times since installing the IAP springs (noticably lower than stock). It could be that without the sump guard, there wouldn't be any scraping but the notion of having my oil pan ripped out going over a manhole cover sure scares the piss outa me.
Joined
·
5,799 Posts
Yeah, there are a number of theories about sump guards. I guess I've just been pretty lucky so far and have never hit anything really hard with it yet (4 years of daily driving!).
In any event, there is one rule that DOES apply to all cars and especially convertibles:
The faster your car goes through corners without slipping means that your G-force weight (lateral weight) is increasing, and that adds additional stress to the chassis. Having sticky tires and a pretty stiff suspension means that your 'cowl-shake' will be magnified. As a result, I believe that the Chassis Stiffener and a rollbar (the street version of the Autopower rollbar still allows the top to go up and down) will help to compensate and stiffen up the car enough that the cowl shake doesn't eventually tear your car apart.
Good luck!
In any event, there is one rule that DOES apply to all cars and especially convertibles:
The faster your car goes through corners without slipping means that your G-force weight (lateral weight) is increasing, and that adds additional stress to the chassis. Having sticky tires and a pretty stiff suspension means that your 'cowl-shake' will be magnified. As a result, I believe that the Chassis Stiffener and a rollbar (the street version of the Autopower rollbar still allows the top to go up and down) will help to compensate and stiffen up the car enough that the cowl shake doesn't eventually tear your car apart.
Good luck!
1 - 15 of 15 Posts
Join the discussion
Join now to ask and comment!