What sort of torsion bar sizes are people using for their road going V6 75's?
Please, no mention of standard TB + Koni Yellow's as being good enough, 'cause they aint.
Currently I have standard TBs and 105lb/in coil springs over Koni Yellow's, but I want more spring rate without turning the car into a brick (sorry MD :P).
Standard TB are 22.8mm and give a wheel rate of 93lb/in.
A spring over the shock absorber gives about 62% at the wheel, so my combined TB/spring gives a 158lb/in wheel rate.
A 25.4mm TB has a WR of 143lb/in.
A 27.3mm TB has a WR of 191lb/in.
A 28.7mm TB has a WR of 233lb/in.
* A 30mm TB has a WR of 279lb/in.
* A 32mm TB has a WR of 360lb/in.
Minimum WR would be similar to 27.3mm TB, that would require a 160lb/in coil spring.
A 175lb/in spring and TB would give a 201.5lb/in WR. The extra spring rate would help control the mass better, but would it still be streetable?
I think the Koni's run to much bump valving to try and hide the lack of spring rate (which doesn't work), so revalving would be a great idea if/when I start using higher rate front springs. I emailed Toperformance (Aussie Koni distributor) about revalving (mainly bump valving) for higher spring rates, but got SFA of a reply. Does anybody know of anybody else who can revalve Koni's?
I'm running 32mm TBs on the track car, combined with yellow Konis (which haven't been revalved to suit yet), which I thought would be hellishly stiff on the road. It's actually bloody fantastic on the road, and I will be doing it to all future V6s I own. Cuts down any hint of wallow on freeways, and over expansion joints and such the car is just so flat and composed. It's definitely not too harsh over bumps (except for very, very sharp ones), and overall I would say the ride is more pleasant than with standard TBs.
My girlfriend even managed to fall asleep on the last EMR I did in the car, so the ride can't be too bad. Although as I'm doing my engine swap at the moment I did discover a couple of cracks in the headers.....Carbon Monoxide doesn't make you sleepy does it?
Are you in Melbourne Duk? If so, you're welcome to have a drive of the car when I finally get it back on the road.
Forgot to say.....
Vin will have an idea where to get the Konis revalved, he also has the specs to give them for certain TB sizes.
Should also add, concerning the ride etc, I'm definitely not one of these guys that think "the harsher the ride, the better the handling must be". Far from it, as far as I'm concerned a track car is for the track, a road car is for the road, and rarely if ever will the twain meet. I was just so surprised at how the 90 felt on the road with the big TBs, and my girlfriend, who is not interested in driving or cars at all, thought the ride was just fine as well. She hates that the footwell gets so hot these days, and that it's a bit noisy. But the ride is acceptable.
Wow, 32mm on the street being great :o. I think I'm seriously underestimating what I need here.
I calculate a wheel rate of 360lb/in for 32mm TB, quite massive! What size rims and tyres are you using?
Cheers for the offer to drive your car, but I'm in little ol' rural South Oz, would be great to have the experience tho.
*Carbon Monoxide does make you sleepy (and dead eventually :o) ;)
Quote from: Sheldon Mcintosh on August 25, 2010, 04:43:03 PM
Should also add, concerning the ride etc, I'm definitely not one of these guys that think "the harsher the ride, the better the handling must be". Far from it, as far as I'm concerned a track car is for the track, a road car is for the road, and rarely if ever will the twain meet.
I hear you ;D.
This is a road car 1st, 2nd and 3rd and my favorite piece road is fiendishly bumpy, so control is where it's at rather than a jack hammer hard, chassis smashing ride.
Cheers for your input and info :D
Quote from: Duk on August 25, 2010, 04:53:04 PM
What size rims and tyres are you using?
Standard 15x6 wheels with 205/50 Yokohama Advan A048 (that's a 'race' tyre with a reasonably stiff sidewall for those playing at home who don't know the tyre).
Quote from: Duk on August 25, 2010, 04:53:04 PM
Wow, 32mm on the street being great :o. I think I'm seriously underestimating what I need here.
I was surprised as well. And having said that, 28mm or similar might be just as good, if not better on the road. All I've tried are the various standard set-ups, and my current one.
Quote from: Duk on August 25, 2010, 04:53:04 PM
Cheers for the offer to drive your car, but I'm in little ol' rural South Oz, would be great to have the experience tho.
Oh well, if you're ever over this way, or if there is someone in the club here whose opinion you trust and whose driving I trust we could work something out. How are you working out the wheel rate? (My google is broken)
Quote from: Duk on August 25, 2010, 04:58:13 PM
so control is where it's at rather than a jack hammer hard, chassis smashing ride.
Yes, I should have mentioned control. The body control with the big TBs is just so much better. I don't have to wait for the body to stop moving before I can do the next thing anymore.
I remember years ago when playing GranTurismo2 on the Playstation, I'd always tune my cars with very stiff springs and relatively soft damping - just cos they always seemed to be easier to control and faster that way. That's what the car feels like now with the stiff TBs. It's also got 200lb rear springs, Vin suggested them as the perfect match for the 32mm TBs.
Quote from: Sheldon Mcintosh on August 25, 2010, 05:04:15 PM
How are you working out the wheel rate? (My google is broken)
The TB to wheel rates listed in my 1st post were posted on the Alfa BB (except I calculated the 28.7mm bars).
The method I use starts from the known standard rate and TB diameter, and goes:
93/(22.8^4) or 93/22.8/22.8/22.8/22.8 = 0.000344146
New WR: 0.000344146 x New TB Diameter^4
32mm TB: 0.000344146 x 32^4 or 0.000344146 x 32 x 32 x 32 x 32 = 360lb/in.
QuoteCarbon Monoxide doesn't make you sleepy does it?
Some trivia..
Carbon Monoxide has eight times the affinity to haemoglobin than oxygen which means that these cells will carry carbon monoxide around the body instead of oxygen in the presence of such atmospheres and the consequence of that is your old fella drops off..... hahaaa. ( I know you know the real consequence!)
If Konis are too had in bump, you could safely get away with a slightly thinner oil in them to adjust your bump valving. If they are adjustable, then you'll have all the adjustment in the world, even with much lower viscosity oil. Of course, this will soften rebound damping, but that's generally a good thing on a road car.
I know my Volvo's Konis are bone jarringly hard when only wound about 1/3 the way in.
Regards, Andrew.
Koni Yellow's are only adjustable for rebound. Cool idea about using a thinner oil tho 8)
I remember when I was racing motorbikes, a thinner oil, or a lighter fluid, in your forks could help adjust damping. And there was always the cautionary tale of the guy who had been advised to put a lighter fluid in his shocks, then wondered why his forks didn't work after he'd filled them with "lighter fluid".
Probably an urban myth, but they are out there, as we have learnt from other threads on this forum.....
Hey Sheldon, do you use any other suspension upgrades on the 90?
At the front I have Vin's long shank top ball joints, polyurethane top control arm and caster mount bushes and overhauled lower control arms. Seam welded the top shock mount/top control arm mount box section. Triangulated brace inside the front guards. Also planned is a K shaped top brace that will join the major engine bay box section (I have no concerns with running a coil over helper spring ;)) and possibly a brace that links the lower chassis rails and steering rack cross member, but it's gunna be a tight fit with an engine and 2 exhaust pipes down there.
The arse end has polyurethane Watt's linkage bushes and I made and installed, but have yet to try, a spherical bearing for the main Dedion pivot point. Stupid low, unknown rate King springs.
Other planned mods are bump steer correction, higher rate adjustable height rear springs to match the (as yet undecided) front springs. Fit polyurethane bushes to the anti roll bar chassis mounts and spherical rod end links (at the front). Also, modified top control arms that will let me run more caster angle and let me ditch the lower shock mount that I made (return to standard design).
Quote from: Duk on August 26, 2010, 06:23:36 PM
Hey Sheldon, do you use any other suspension upgrades on the 90?
Not yet, haven't even uprated swaybars, but most of what you list there is on the to-do list. I kinda like the idea of doing one thing at a time and seeing what difference it makes on the track. Unfortunately it means that progress is slow since we don't have that many track days per year. I definitely need to do all my bushes pretty soon though.
I would love to see and read more about what you have done there, it sounds like a very well sorted car.
I've decided to err on the slightly softer side of things. ;D
I ordered some 225lb/in, 1 7/8" diameter springs for the front. Combined with the standard TB, that will give me the same wheel rate as a set of 28mm TB (233lb/in).
For the rear, I ordered 175lb/in springs and adjustable height spring seats.
After today's little drive (in my S13 Silvia) through my favorite little spot, it re-emphasized that overly stiff suspension is not a good idea. My basically standard suspension (standard springs but with PU bushes, gas shocks and 'bars) MR2 is much more composed and sure footed than the Silvia, and that's an AW11 MR2 with their reputation for twitchyness (which it is) ;)
Would you be able to post pics of your front set-up at some stage, I'm intrigued to see how it all goes together.
Quote from: Sheldon Mcintosh on August 30, 2010, 08:41:25 PM
Would you be able to post pics of your front set-up at some stage, I'm intrigued to see how it all goes together.
I'm planning to change the way it currently is, so when I get the new parts and make/modify bits and pieces I'll add some photo's.
Hopefully the rear springs work out. The adjustable spring seats look to be the same as those sold by Andy at Performatek (but at half the cost ;)) and the springs are 5" diameter, but I guessed at spring length (there were a few available), so hopefully I'm close.
BTW, what's a good site to use to reduce the size of photo's so I can post them ???
Quote from: Duk on August 30, 2010, 08:59:18 PM
BTW, what's a good site to use to reduce the size of photo's so I can post them ???
I do mine in Photoshop, but you can do it in Microsoft Office Picture Manager also. There's an 'edit' button up the top, from there you can resize. 600-640 pixels wide is a good size for this forum, in my experience. If you're on a Mac, sorry I've got no idea.
This little free program does the job
http://download.cnet.com/FastStone-Photo-Resizer/3000-2192_4-10319476.html
(http://download.cnet.com/FastStone-Photo-Resizer/3000-2192_4-10319476.html)
Although I still need to modify the top control arms more and make some plastic spring bushes for the rear, this is where I'm at at the moment. The rear spring seats had their lower flanges machined down to 100mm from 134mm (5.25") and will be welded to the original spring seats.
More photo's.
The spherical bearing part number: SKF GEH 25 ES-2RS. It's the 'heavy duty' version of those dimensions.
QuoteThe spherical bearing part number: SKF GEH 25 ES-2RS. It's the 'heavy duty' version of those dimensions.
Just wondering where you bought the spherical bearing from?
Quote from: AR116 on September 26, 2010, 09:58:57 PMJust wondering where you bought the spherical bearing from?
Local independent bearing supplier, but I'm sure someone like CBC or SKF (duh :P) could supply. It cost about $25 from memory.
$25 is an extremely good price. Just wanted to confirm, you are replacing the dedion bush with this
spherical bearing type. Am I correct?
Quote from: AR116 on September 27, 2010, 02:33:12 PM
$25 is an extremely good price. Just wanted to confirm, you are replacing the dedion bush with this
spherical bearing type. Am I correct?
Yep, but I am yet to try it. The bearing part number I got from GTV6.com, so I figured the guy who posted it had used it. The load rating is quite large (plenty large enough for the push from acceleration and pull from braking) and I tested the articulation of the Dedion frame and it never bound at any reasonable travel, from full drop to plenty of bump (my car doesn't have bump stops at the rear).
I be interested in hearing about your results when you install the spherical bearing.
Keep us up-to-date if you don't mind!!
Is this a direct fit or have you made up a sleeve?
Thanks, Scott
Quote from: scott.venables on September 27, 2010, 05:20:55 PM
Is this a direct fit or have you made up a sleeve?
Thanks, Scott
I take it you're also talking about the Dedion pivot bearing?
If you are, then I made the 3 pieces and bought the bearing.
I had done a 'mud map' (but with full dimension ;)) drawing, but I recon I threw it out accidentally :-[.
Quote from: Duk on September 27, 2010, 06:39:13 PM
I made the 3 pieces and bought the bearing.
I had done a 'mud map' (but with full dimension ;)) drawing, but I recon I threw it out accidentally :-[.
Bugger... I was hoping you might be taking orders :)
I temporarily put the car back on the floor with the new front springs in, and did the 'ol bounce test'. Wow, what difference in stiffness compared to standard 8). But I suppose when your new spring rates are 2.5 times the standard rate, you're gunna get that ;).