rear coilovers,..i know i know,..but i have questions
 

ok, i have had coilovers on my last three cars, along with all poly bushings, larger sways, strut bars, top to bottom, spring rates ranged from 400f to 800r, the cars were a sti, gti, integra

anyway,...i have played around with this whole torsion bar setup numerous times, i just dont like it, period,...i want to switch to coils front and rear with 935 spring plates in the rear and do away with torsion bars all together

i am only looking at about a 300-325 spring rate in the rear, i think stock torsion bars are around 160? if i did my math right

i have talked to numerous shops, and people on this forum about the bracing of the rear shock towers, some say you need it, some say you dont,...i have looked at my shock towers and i see NO signs of wear what so ever, or cracking, still factory paint and in great condition, the car has 67k original miles, never seen a track...yet anyway

my question is with such a low spring rate, and no track time,..maybe 1-2 a year, is this something that i really need?

BIG QUESTION
i have seen some 964s and their suspension set ups, i know its completely different, BUT the rear shock towers look almost the same as the 930, why is it ok that the 964 guys all run coils without bracing,..? im sorry for the newbie question, but just looking at pictures the shock towers appear to be almost the same?

is there anyone out there running rear coils without bracing?

subscribed..... I am interested in coil overs too, but for other reasons.

914s were not known for being particularly stiff, durable, or having high spring plates. 964 chassis is designed differently and is stiffer with better welding. It might even have thicker metal.

If you run helper springs with your torsion bars, then you do not need the bracing. If you go full coil-overs, the bracing is highly recommended. I have it on my torsion bar car.

Coil-overs are really not necessary with your intended driving style. What problems are you having with the torsion bars? I would just have a good shop set it up once to how you like it- corner balance and alignment, then forget about it. Coil-overs main advantage is being able to change ride height easily.

If you are still set on coil-overs, I recommend talking to Clint at Rebel Racing: Suspension1 He can go as far with the 935 setup as you want. If you cannot get ahold of him, email me. maxsluiter@earthlink.net

i like the flexability of coils, and being able to make the minor adjustments and dial in a height

i have had the 930 corner balanced, and aligned, and i just dont like the ride, i also replaced spring plate bushings and rear shocks, and just not happy

Maybe check our the Elephant Racing rear spring plates. This might give you the rear adjustyou seek.

I believe it makes it almost as easy to adjust as the front. Maybe easer than rear coils.

See here: ELEPHANT RACING QuickChange Spring Plate, 911 Series

don't know what year your 930 is, but starting in late 1987 for the 1988 models the factory welded in small bracing gussets on the top outer sides of the shock towers making them stronger.

could be (just a guess) they knew they were going to go to coil overs in a couple years and they were tooling up and installing them in advance.

yes i had planned on ordering everything from elephant racing, its a 1980, there is no bracing backed there, trust me i looked,...

yes it has ALOT to do with adjustability, but i just dont like the "responsive-ness" and the ride of the torsion bars, i dont know how to really word it...

i really want to "update" the ride, if that makes sense

i recently put coils front and rear on a 66 mustang, and it was the greatest thing i did, i know you cant compare a mustang and a porsche, but i just like the "modern" feel of coils

A spring is a spring.

60's technology vs 90's technology, there WILL be a difference. I am going the coil over route for different reasons than you. I have looked into bracing and I will be building a cage.

incorrect, a coil will react differently than a torsion bar, there are variable rate springs etc....

A spring is a spring but for some reason it is a reoccurring conclusion from those that have changed from torsion bars to coil over's on a 911 that the ride is different.

I can see that if one chose a progressive spring why this might be but most do not.

Effective spring rate is a combination of a lot of things including the tires, bushings, suspension design, etc.

On a torsion bar car the spring has to work via an arm of some type that may or may not act as a spring its self. In the front this might be more the case than the rear but the rear still has to act through about an 18" lever which may impart some level of its own spring rate. The rear rubber bushings will become part of this spring rate to a small degree even if they are not in a direct path to the ground.

On a rear coil over, if the shock ends are rubber, they become part of the spring rate. Thus the spring becomes isolated by about 1 combined inch of rubber bushing under compression and rebound that it did not have before. I wonder if this is not the most significant reason.

Or that maybe moving the spring to the shock also changes the spring rate to a less than linear rate as the angle of the spring relative to the arm changes with compression.

Not sure about this but I wonder if there is something to what the coil over crowd seems to believe is different.

There are other points as to coil over’s.

Yes, they can be more easily adjusted in the rear.

One of the biggest advantages to the change was access to higher spring rates. Now we can get up to 35mm rear torsion bars for the 4 speed cars that are probably more than anyone would probably run on the street.

Coil over's on the front may restrict front tire width and or access to neg camber with their increased width.

Most coil over conversions rarely shorten the strut or shock so that should the suspension become unloaded the travel of the shock may be more than the spring. Helper springs may be added as a short cut and even then shock travel may exceed the length of the springs. It just seems like it would not be a great idea if the springs can come unseated from there base over a bump or when jacking up the car.

Clint at Rebel Racing has all you need for coil overs. He modifies struts, has custom damper setups, 935 spring plates, I think he can get the 935 front suspension, or he has his signature A-arm bearings. He uses an early 911 with coil-overs for street and track.

No...

replace the bushings with some with less friction, and you will be pleasantly surprised.. This will cost you a lot less than 935 spring plates/coils/hats/chassis/reinforcements...

If you were building a track car... that is another story...

There is a real simple solution for this and we use it in race cars to get the tires off the ground quicker in pit stops, you just have limit straps that will limit the droop of the suspension.

i thank you for your response, but i was asking if i really need bracing, not if i need coils, i know many people think coils are overkill for the street, but i never had a issue with them in the past on any street car i have owned, i am just trying to update the feel of the car,...

You will be pleasantly surprised, and your wallet will be happier if you put in some quality bushings.... reduce the friction in the joints, and let the t-bars work..

Granted you can follow the path you outline, you will have a fine set up suspension, or you can go another route and save yourself a bunch of dinero,

i am still leaning towards the coil route, i do plan to pull the trans and engine for a trans rebuild in the next year or so,..so that is probably a great time to do some bracing,...

If I go the coil over route for my project, I will fill you in on my process.

I think I can do something better than this and incorporate it into the cage.

http://www.tarett.com/items/911-series-products/911-suspension/rsr-style-rear-shock-tower-reinforcements-rsrstr-detail.htm

jim i just finished doing helper springs on my 87 930 i used clints set up with 250# springs ran it this weekend at vir and it was great i did change front to 22 mm torsions and used clints rsr a arm bearings

that is the thing, i want to do away with torsion bars all together, and i am being told that with such a low spring rate and no track time, the bracing isnt something i need to worry about

That's exactly what I did when I replaced the JRZ front struts (to be rebuilt later) with Bilsteins RSR Sport coil overs. See pic below:

http://forums.pelicanparts.com/uploa...1287519622.jpg


My '87 930 has coil overs all around using 600/250 rears and 400/150 fronts. Also, my car does not have any bracing on the rear shock towers that I can see. Mine must be an earlier '87 and bracing perhaps was added on later '87. I may be wrong. Anyway, my car was heavily tracked by previous owners. I checked for any cracks and found none.

any chance you can take a pic of your rear towers for me? thank you so much for your response and any help you can offer

Sure, here's a couple.

http://forums.pelicanparts.com/uploa...1287526070.jpg

Close up shot

http://forums.pelicanparts.com/uploa...1287526129.jpg

thank you so much

Thanks Mike, that was exactly what I was talking about..

The worst thing that can happen if you don't reinforce the shock towers is that you punch a shock through... Then you get to re-weld and reinforce..

BTW I think 325# rear springs will really disappoint you, the rear end will squat like a dog dragging his butt along the carpet..

If you get all the friction out of the rear suspension, you can run some fairly stiff springs on the street and still have a nice ride..

As a comparison my track only racecar with 935 suspension components weighs 1850# wet.. I run 400# and 600# springs on it... and think increasing the spring rate will be in my future..

anyone else with coils and no bracing?

No. I did not reinforced and had some cracks at the outside of chassis and the whole tower will get loose, welding points will fail. And mine is only street use:



http://forums.pelicanparts.com/uploa...1287662881.jpg

I highly recommend to add reinforcements and add some welds at the tower!

Go with Clint at rebel racing...i'm running 450 lbs springs up front, 850's in the rear valved accordingly with 19mm raised spindles on the front. Its the way to go.

BTW clint sells a weld in brace for the rear towers that is premade to fit the stock towers perfectly.

Reaper,

Just wondering, why not 35mm or more?

You should have the room with your rims.

Is there a limit on different types of struts as to how much they can move them?

I am guessing you lowered your front more than 19mm but I could be wrong.

More also gets you a more agressive camber curve, though with almost 4 times the stock front spring rate you probably do not see much deflection when cornering.

Just wondering.

Thx.

I raised them 19mm as this put the front suspension in perfect geometry in combination with the 17" wheels and tires I am running. The front of my car really isn't much lower than a euro 930.

Thx!

I have a set of RSR coils on my car
I believe spring rates are 300/450
Originally I had these on a 79 SC targa- no reinforcements- no issues
I did reinforce my 930 rear subframe because car will be 90% track and am thinking of giong to 800 ish rear spring rate
Not to hijack but has anyone changed the way the top of the shock mounts in the car ? ( Clevis type )

Before I tied my rear suspension into the cage I didn't reinforce when I ran only rear coils however, it was only for 3k miles. Clint at Rebel wouldn't sell a shock tower brace if it wasn't needed. If you're going for 800 lbs rears and valved right, I would reinforce as my 850 lbs coils and custom valved Rebel coils are STIFF but my car only weights 2,000 lbs so YMMV.

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