I would just like to know what cars came out with, (what) sizing front and rear sway bars and torsion bars
GTV 1.8 2.0
GTV6
Alfetta "" ""
Giulietta "" ""
75
90
Thanks Chris
The 3 litre V6 75s came out with:
22.8mm TBs
24mm front anti roll bar.
21mm rear anti roll bar.
I think you'll find that all of the short TB V6's were 22.8mm
Thanks for the info, i am buying some upgraded parts for my Giulietta. I know the TB of the 75 90 and late gtv6 wont fit but i just want to compare sizes.
The sizing i am getting is
Front 27.25
Rear 21
TB 28.7
Quote from: Storm_X on April 16, 2012, 07:32:14 PM
Thanks for the info, i am buying some upgraded parts for my Giulietta. I know the TB of the 75 90 and late gtv6 wont fit but i just want to compare sizes.
The sizing i am getting is
Front 27.25
Rear 21
TB 28.7
You'll be having a very big increase in the stiffness of the suspension with those TB's and front AR bar.
i thought just my konis where nice and stiff, but the stiffer the better.
Responses are a little thin on my restoration thread, so thought I'd chime in here and add some info to the thread.
Anyhow, cleaning up the torsion bars on my 1976 Alfetta GT, I can't seem to distinguish any markings on either of them. They are 989mm long, and 23mm dia (~0.90 - 0.91"). Both bars appear to be painted blue. There are neither coloured markings in the first 100mm from each end of either bar nor the "L, R, D or S" markings at the rear ends.
So, my question is why is there a separation as to left and right for the bars? Are they manufactured to resist torsional forces in that particular direction better than the other?
Sway bars are; (not exact due to grime, but very close)
Front sway bar – 0.720" (18.3mm)
Rear sway bar – 0.800" (20.32mm)
I also came across these figures in my files which were posted on a forum;
GTV6 Early model:
Stock bar:
Rate - 96lbs/in Diameter - 23.5mm Length - 989mm
Sport Bar:
Rate - 134lb/in Diameter - 25.4mm Length - 989mm
SS Bar:
Rate - 179lb/in Diameter - 27.3mm Length - 989mm
GTV6 Late and Milano:
Stock bar:
Rate - 93lbs/in Diameter - 22.8mm Length - 932mm
Sport:
Rate - 143lbs/in Diameter - 25.4mm Length – 932mm
SS:
Rate - 191lbs/in Diameter - 27.3mm Length – 932mm
Any one here run 30 mm TBs ?
Long time ago - best riding GT/GTV I ever owned. Serious. Key is the damper valving.
Quote from: Storm_X on August 17, 2012, 08:26:59 AM
Any one here run 30 mm TBs ?
30's are excellent on the track and a smooth road. The rest of the time is spent avoiding pot holes! I think they're too stiff for the road. If anyone is after (short) 30's i'm happy to do a swap for some 28's!
There is another guy who wants to swap 28s for his 30s and I'm unsure if I want stiffer
Quote from: Simon Aarons on August 17, 2012, 11:11:29 AM
Quote from: Storm_X on August 17, 2012, 08:26:59 AM
Any one here run 30 mm TBs ?
30's are excellent on the track and a smooth road. The rest of the time is spent avoiding pot holes! I think they're too stiff for the road. If anyone is after (short) 30's i'm happy to do a swap for some 28's!
Nah - good for both. :)
I'll get in on this..
I have another thread trying to swap my 30's for 28's..
30's are great.. in the dry.. the ride is firm, but not bone jarring.. If they functioned better in the wet, I would keep them.. their biggest issue for road use is weight transfer on damp or wet roads.. you just can't get weight onto the front to get decent brake force into the tyres.. (well, the tyres I am using..) I am sure someone somewhere is getting their brakeforce through the tyres or there wouldn't be a market for 30mm bars..
I have revalved koni's and 180lb rear springs, 24mm rear sway and 22 front sway.. front roll centre extended ball joints too.. It steers very well.. It's a little oversteery which is perfect(for me).. I had it too low in the front for a long time and it was horrible.. wallowy and unsure.. ride height is a little rear down now and it is much better.
StormX, you say you are running a 27mm sway bar up front with the 28mm bars?.. I think you'll find you'll have serious understeer issues with a sway bar that big.. 28mm bars are pretty firm to start with.. You'll struggle to shift weight to your outside wheel and you'll push over the tyre.. and your rear sway is a tad light.. That's just my 2 cents worth though. What rear springs are you running?
What tyres are you using? It'd be a real shame to go through all that only to find its the Tyres all along.
Quote from: Midda Samid on August 18, 2012, 12:27:03 AM
.. their biggest issue for road use is weight transfer on damp or wet roads.. you just can't get weight onto the front to get decent brake force into the tyres.. (well, the tyres I am using..)
I'm a bit dumb when it comes to suspension. This is the first time I've heard someone describe lack of weight transfer as a downside of stiff springs, can you explain more? I'd have thought weight transfer would mostly relate to roll centre?
Quote from: Evan Bottcher on August 18, 2012, 08:26:44 AM
Quote from: Midda Samid on August 18, 2012, 12:27:03 AM
.. their biggest issue for road use is weight transfer on damp or wet roads.. you just can't get weight onto the front to get decent brake force into the tyres.. (well, the tyres I am using..)
I'm a bit dumb when it comes to suspension. This is the first time I've heard someone describe lack of weight transfer as a downside of stiff springs, can you explain more? I'd have thought weight transfer would mostly relate to roll centre?
Weight transfer is a function of wheel base and track width dimensions. All things being equal, if the car was longer, it would dive less under braking. If it was wider, it would roll less during cornering (that's wheel base longer and track width wider). Tho more weight will transfer as the car moves around, in the same way as holding a rectangular container with liquid in it and you lower 1 corner, more weight will transfer onto that corner.
Roll centre height weight transfer only happens with lateral load (cornering) not longitudinal load (accelerating and braking).
If someone is having trouble with weight transfer during braking, simply use more braking force at the rear.
It's a common misinterpretation that in the wet, the car requires less rear brake bias, but it actually requires more rear brake bias (obviously within reason and assuming your car isn't some nose heavy front wheel drive).
Take even more advantage of the added weight over the rear wheel and get them to do more braking work. The rear brakes suck, so you will probably be looking at a rear brake upgrade to get the job done decently.
Incidentally, a few guys on here are saying that 30mm TB are fine on the street, by my calculations based on a full bodied 75 with approximately 350kgs over 1 of the front wheels (700kgs total at the front), that gives a natural frequency of the front suspension of 2.13Hz! That is dedicated track car (you know, PROPERLY DESIGNED, WELDED IN ROLL CAGE and slick tyres!!!) stiff for the heavier 75 and bonkers stiff for a lighter Alfetta type car.
And after seeing the photos that Sheldon posted showing cracks in his chassis (using 32mm bars), that says straight up, that the chassis is doing lots and lots of flexing!
Thanks Duk lots of info.
However - I still couldn't glean a simple answer - you've got to dumb things down for me :) Midda Samid said that heavier torsion bars affected weight transfer - are you saying that yes that happens because "more weight will transfer as the car moves around" (the rectangular container filled with liquid analogy)? So the heavier torsion bars reduce suspension travel under braking, which reduces weight transfer?
Quote from: Evan Bottcher on August 18, 2012, 10:30:56 AM
Thanks Duk lots of info.
However - I still couldn't glean a simple answer - you've got to dumb things down for me :) Midda Samid said that heavier torsion bars affected weight transfer - are you saying that yes that happens because "more weight will transfer as the car moves around" (the rectangular container filled with liquid analogy)? So the heavier torsion bars reduce suspension travel under braking, which reduces weight transfer?
If you built the car with totally solid suspensions (ZERO movement!) and then drove the car at a set speed and then stopped as hard as possible, there would be 'X' amount of weight transfer from the back to the front.
If you then built actual springs into the cars suspensions and performed the same test, drive at a the same set speed and then stopped as hard as possible, there would still be 'X' amount of weight transfer from the rear to the front, but now the front suspensions can compress and the rear suspension will rise, as a result of the weight transfer. This front compression and rear rise will 'pour' even more weight onto the front wheels, on top of the 'X' amount.
If stiffer springs are used at the front to resist compression during braking, then there will be less weight 'poured' onto the front wheels during braking, but the 'X' amount will always occur.
So front spring rates will effect front wheel and rear wheel braking performance by resisting some of the additional weight transfer that results from suspension compression.
Sorry but I have not installed my suspension gear yet. Will be awhile now before I do
Thanks Duk! I did a bit of research too - everything's right on t'internet right? Let's see if this sounds right:
Wikipedia says the transfer of load in the theoretical totally solid suspension is commonly called 'load transfer'. The transfer due to suspension movement (or cargo/liquids moving in the vehicle!) is commonly called 'weight transfer' - where the centre of gravity of the car actually moves.
Both are affected by the static location of centre of gravity - hence to reduce either type of transfer it's best to keep the centre of gravity as low as possible (I just replaced my glass with lexan - yay!).
Stiffer front springs would only affect the weight transfer - as you said. I guess I would have thought that the effect of the bigger springs on the total transfer would be pretty minimal, and that you wouldn't notice it so much. There you go.
I like Saturdays when you learn something...
Can anyone recommend any good books on suspension engineering? Someone once told me that one of the Carrol Shelby books was good.
Carroll Smith, not Shelby.
http://www.carrollsmith.com
Makes it all simple. One book even gives you little templates so you can make some models to try it out yourself.
The problem with a 116 chassis is fundamentally roll centres not spring rates.
Quote from: Evan Bottcher on August 18, 2012, 03:49:04 PM
Can anyone recommend any good books on suspension engineering? Someone once told me that one of the Carrol Shelby books was good.
I have Fred Puhn's 'How to make your car handle'. It's pretty good but also quite old. The section on 'Polar Moments of Inertia' was quite an eye opener and really proved to me that just quoting weight distribution alone, says about as much about handling characteristics as quoting the engine capacity does for performance.
If you found it for a few dollars, I'd recommend, but there are newer books out there.
Quote from: aggie57 on August 18, 2012, 04:40:43 PM
The problem with a 116 chassis is fundamentally roll centres not spring rates.
It's also too narrow, has a rather floppy chassis, uses soft wheel alignment (lack of caster angle) specs and lacks spring rate.
I think the answer to making a 116 chassis work excellently, particularly as a road car, is an overall solution rather than just point at 1 or 2 particular changes and calling that/them the real fix.
Quote from: Storm_X on August 17, 2012, 06:23:31 PM
There is another guy who wants to swap 28s for his 30s and I'm unsure if I want stiffer
Yep, there is but he is after long bars and i'm after short!
I've never had a problem braking in the wet with the 30's. Maybe the extra weight in the front helps. If Melbourne had decent roads i'd keep them!
It's getting pretty technical..
My statement that weight transfer is reduced under braking can be looked at another way.. a simpler way..
In any car, with any spring rate, you can feel the result of weight transfer if you apply the brakes slowly.. Start with gentle brake pressure(pressure A) and progressively increase brake pressure to a heavy foot(pressure B) the vehicle will brake remarkably hard..
If in the same car, you just simply apply pressure B, you'll lock the brakes.. This is because the vehicles weight distribution hasn't had time to respond to the braking resistance and your resulting wheel loads are less which effectively reduces your resulting friction force..
the heavier your car is, the better your friction force will be... and when it rains, this is very important. That said however, rarely is the ideal dry setup also the ideal wet setup.
Same goes for sway bars.. if you use a sway bar that makes it difficult to shift load to the outside wheel when cornering, then you don't make the most of your friction force... Drift cars for instance use very heavy springs and sways to control weight transfer to induce slides.. infact their whole approach is zero movement.. rigid chassis and rigid suspension and serious weightloss programs.. oh, and mega horsepower.
Does anyone actually have the spring rate data for the 28mm and 30mm TB's? out of interest? I had my koni's revalved as per Vin's specs and they seem too heavy.. I don't get oscillation, I get return sponge.. front and rear.
Quote from: Midda Samid on August 18, 2012, 10:31:28 PM
Does anyone actually have the spring rate data for the 28mm and 30mm TB's?
Long 28mm TB: 193.5lb/in wheel rate. Or 2.016 times stiffer than standard.
Long 30mm TB: 255lb/in wheel rate. Or 2.656 times stiffer than standard.
Quote from: Midda Samid on August 18, 2012, 10:31:28 PMI had my koni's revalved as per Vin's specs and they seem too heavy.. I don't get oscillation, I get return sponge.. front and rear.
I'm not understanding what the problem is. The idea of a damper is to stop oscillation. What is return sponge?
Good work on the spring rate info.. cheers..
Quote from: Duk on August 19, 2012, 09:59:19 AM
I'm not understanding what the problem is. The idea of a damper is to stop oscillation. What is return sponge?
I didn't mean to hijack this thread, sorry.. I guess it is related though.
"Return sponge" is my very uneducated description of my slow return to spring ride height I get if I depress a spring.. My understanding of the job of a shockie is to control the sine wave oscillation that occurs on an undampened spring, not stop it... That said, I still want the spring to have enough push to keep my wheel on the ground after it has struck a bump.. my current setup(which might also add to my braking problems) is seemingly allowing the spring to compress, but rebound is not really allowing it to return in a reasonable time.. (that said, all my squash tests are done on cold shocks, so I am sure it will improve with some warming up)
I know very little about suspension, but my understanding of spring oscillation and rebound damping says my shocks are too much for the springs. I expect to see enough spring oscillation to enable the road wheel to follow road conditions.. Maybe 2-3 cycles from initial bump to settled spring.. (that's a guess, I have no idea what it should be, but it certainly should be more than 1.)
Quote from: Midda Samid on August 19, 2012, 10:06:51 PM
"Return sponge" is my very uneducated description of my slow return to spring ride height I get if I depress a spring.. My understanding of the job of a shockie is to control the sine wave oscillation that occurs on an undampened spring, not stop it... That said, I still want the spring to have enough push to keep my wheel on the ground after it has struck a bump.. my current setup(which might also add to my braking problems) is seemingly allowing the spring to compress, but rebound is not really allowing it to return in a reasonable time.. (that said, all my squash tests are done on cold shocks, so I am sure it will improve with some warming up)
I know very little about suspension, but my understanding of spring oscillation and rebound damping says my shocks are too much for the springs. I expect to see enough spring oscillation to enable the road wheel to follow road conditions.. Maybe 2-3 cycles from initial bump to settled spring.. (that's a guess, I have no idea what it should be, but it certainly should be more than 1.)
It does sound like you have too much rebound valving force. Have you tried to unwind some rebound valving, you've got the Koni Yellows? That is 1 thing that they have going for them.
I don't think you'd want 2 -3 cycles after negotiating a bump, to me, that would be not enough rebound valving. So long as the suspension returns to its static height quickly without over shooting, you should be close to ideal(ish).
Data logging of suspension movement when negotiating a predefined bump on a smooth road would help get you there.
With each damper set to its softest (rebound) setting, drive over the bump at a set speed. Check data log for suspension behavior to see if after the bump, the suspension extends past static height during rebound, if it does, wind in some rebound and test again.
my yellows are fully unwound.. both ends.
28's aren't going to help the situ either..
data log sounds technical and expensive? is there an ap for that? :)
I might research..
cheers,
I'd be alright if there was an app for that ;D.
You can get an acceleration/G force logging app, but pretty sure you wouldn't want to be mounting your phone on the end of a suspension arm :P.
It would actually be 1 of the best priced G force logging devices you could come up with ;D. Until you destroyed your phone 'cause it came off :o.
Not much help to you (unless you have 1 or something similar), but my Innovate LM1 wide band air fuel ratio meter can log 0-5 volt signals.
Get a regulated 5 volt power supply and a linear potentiometer (or an old throttle position sensor) and make a few little arms and brackets, mount the pot at the chassis and link it to the lower control arm, instant( :P) cheap suspension movement sensor. Very similar sensor set up that V8 Supercars use for their suspension travel logging.
I plan to do it 1 day for my Alfa.
I found that Pedders offer an "on car" suspension damping test.. they load your car onto it and adjust for car weight.. turn it on and it logs suspension travel and damping of spring by sending the wheel into oscillation and measuring effort and graphing.. might be a good start to get a baseline. It is usually used to compare info with manufacturers spec data to check wear, but might serve as a guide at least for understanding what is happening..
Also have done a little research regarding expected oscillation of a well dampened or well setup damping system for a given spring, and it reminded me of something I learned many years ago when playing with remote control cars.. if the spring is over dampened in rebound, as in it is slow to return to ride height, then multiple bumps on a single wheel will actually unload the wheel as the compression damping allows the spring to compress, but the rebound damping doesn't enable the spring to return. You in effect get a resulting 3 wheeled car..
Yep - that's know as 'pumping down'. At least thats what we used to call it. Very common especially with Koni' where the rebound is adjustable but the bump isn't.
Quote from: aggie57 on August 28, 2012, 06:57:07 AM
Yep - that's know as 'pumping down'. At least thats what we used to call it. Very common especially with Koni' where the rebound is adjustable but the bump isn't.
Also read the term 'Jacking down' a few times, tho it sounds rather counter intuitive.
and I've heard it referred to as 'packing'