Dirt road tires for an SC

[notfarnow]

I've been dormant on the forums for a couple years, and am looking forward to wrenching on cars again now that I am set up at my new home.

I live in a rural area, with really crappy roads (frost heave) and lots of dirt roads. They are rough enough that my 996 C4s just isn't fun to drive to and from home(to the extent that I am toying with selling it) and even my 2000 4runner takes a beating.

So, what to do with my ratty old SC. I really miss driving it, and I had it out a fair bit last fall and even into the winter and found it did really well on the rough roads and even dirt roads... the suspension is much more compliant than many other cars I've driven, and the tires (16s... 245 in the back, 205 in the front) arent too wide, and have a fair bit of sidewall.

Anyway, without going all Keen wannabee, I am thinking more and more that I should set up my pre-bruised SC to be better suited for the driving I do.

I'm thinking I'll lift it 4" or so, put on some taller tires, put some amber fog lights on it for nightime driving on these narrow crappy roads (very sketchy at night sometimes in snow and fog) and a roof rack with a weatherproof bag for the kids schoolbags.

I'm not looking to geek out on poseur upgrades... just want to maximize the use of this car within its original design and specs.

With that in mind, if I re-indexed the torsion bars to lift it the 4" or so, would I be ok with the stock shocks?

Also, does anyone have experience getting taller tires without modifying the fenders? There are some nasty, nasty potholes and I don't want to bend my fuchs, so I think a bit more sidewall would help.

Has anyone else gone this route?

[Duc Hunter]

4" is asking a lot of the front control arms I think. I am currently looking at this myself for my Rat Rod. My goal is determine how high, and how low, I can go on the stack parts. Front camber adjustment is only one of a few things that get screwy as you go up high. The best you could do (I think), and the best approach, on stock parts would be to raise the front ride height as I high as you can and still keep 1/2 degree of negative front camber. Less than that and the car won't handle they way it should. Typically one side will run out before the other, so crank on max negative camber and then stat going up. Once the lowest side hits -.5 degrees, and the ride heights are close left/right, adjust the other side camber to match -.5.

I think this will kind of set the rear height as the rear seems to have more room for adjustment (others would know better than I). Based on the spec's from the factory, you then can set the rear height to maintain the front/rear balance. Many say that is 1 degree of slope (front lower than rear) as measure on the for sill.

I have found the factory had the front at about .615 of the rear if you are measuring torsion bar height. For example, the euro height measured at the torsion bar tubes is 108mm front and 16mm rear (torsion tube center height - axle center height). On my car, which has a 310 mm axle center this means Euro would be a torsion tube height of 202mm front and 326mm rear off the ground. 202/326 is .619. Other measurements I have found vary to .609, so .615 is the middle ground. Doing the math, if your rear torsion tube is 291mm off the ground (like I just raised mine to) then your front should be at 179mm off the ground.

I hope this helps a little. There are others who are FAR more knowledgeable on this (like Bill V).

[Canada Kev]

I would think you're not gonna get any where near 4" higher with stock components. That's why Elephant and others have lowered the spindles on the Bilstein struts to raise the cars about 3" or so. In that way, the front dampers won't have to be altered, as well.

On the rear, there will be likely some shock length issues if you raise the car that much.

I, too, have thought about trying to pick up another 911 to raise it for the snowy Alberta winters and playing on gravel and dirt back roads in the other four months of the year.

Good luck with your project.

[billybek]

Hey Jake!
Nice to see you back.

No vehicle fires recently?
How about non-haunted houses?

Hope all is well!

[Matt Monson]

4"? Nope. Not simple.

[wayner]

I read about a guy that ralleyed his classic 911 across country and used a pirelli truck tire

Scorpion maybe?

[notfarnow]

Originally Posted by billybek

Hey Jake!
Nice to see you back.

No vehicle fires recently?
How about non-haunted houses?

Hope all is well!

Hey Bill!

Been laying low for a couple years, just finishing up building a new house and excited to have some garage time again!

[notfarnow]

Originally Posted by Matt Monson

4"? Nope. Not simple.

I guess the question I should have asked is how much lift can I get without major mods?

I've already bottomed out a few times and dented the front valance, torn the rubber front spoiler, and dented one of the rocker covers. I think a couple inches would make a big difference. I just don't want to get into a "while I'm at it" situation where I end up going bonkers on the car. It's rough and ratty, and I like it that way. I just want to be able to drive it more, and a bit harder.

[Bill Douglas]

Maybe a set of 15" cookie cutters so it doesn't mater what happens to them and just buy tall 15" tires. I've found skinny tires grip better in loose gravel.

And if you got bored one day you could fabricate up a skid plate for the bottom of the engine.

[David]

Lower spindles 70mm, index the rear torsion cars and get some real rally tires (or snow tires). And welcome back!

[notfarnow]

Is Elephant Racing the best source for lowered spindles, or is that a job I could DIY if I found a used set?

Thanks for the welcome back, pretty cool to see the same names again so quickly!

Here's the car as it sits now:

[notfarnow]

I like the idea of throwing on a set of 15" cookie cutters for taller tires!

[juanbenae]

even if you were to lower the spindles the A-arm & tie-rod length could still be the issue to raise one 4". they are not long enough to span a raised suspension if at all akin to lowering one of these cars. neither will the trailing arms in the rear and if you were even able to go that high you'd need different shocks that could be hard to find. you might be able to raise it a couple inches by manipulating the stock ride height and maintain the budget you've set forth while keeping the intended suspension geometry..

are soft springs and purpose valved shocks better for the application you desire, or stiffer springs/torsion bars and shocks valved to suit that better? im not aware. might be cheapest to use the existing springs, the highest OE ride height you can get noting what ive mentioned above and having shocks purpose valved for the rough roads. maybe you can get it set up to drive around some, and handle other of these potholes....


what ever you do im watching!

[Bill Douglas]

Originally Posted by notfarnow

I like the idea of throwing on a set of 15" cookie cutters for taller tires!

Yeah, they are so horrible (again a large wink) that they are almost free. And there are plenty of tall 15" tires around.

[David]

Rally car suspension project

[notfarnow]

Originally Posted by juanbenae

are soft springs and purpose valved shocks better for the application you desire, or stiffer springs/torsion bars and shocks valved to suit that better? im not aware. might be cheapest to use the existing springs, the highest OE ride height you can get noting what ive mentioned above and having shocks purpose valved for the rough roads. maybe you can get it set up to drive around some, and handle other of these potholes....

Great thoughts, thanks. Maybe what I should do is see how much I can lift it (as per Duc Hunter's suggestion above) without throwing off the geometry too much.

I don't want to screw with the shocks and torsion bars too much, especially when it comes to making anything stiffer... my C4S is stiff and NO FUN on these roads at all.

Maybe 2" would be enough to save me flattening my oil lines. I've never seen a pic of a 911 at its max height adjustment.

[Canada Kev]

Lowered spindles will net you about 2.75" up front. Reindexing the rear torsion bars should be able to match that but you'll need longer shocks. Perhaps talk to Chuck over at Elephant.

To lower the spindles, I believe you'll need Bilstein struts. I understand it's not a big job, but will require removing spindles and re-welding back on. You might also need longer brake lines and such, front and rear.

I see no reason you can't use your existing torsion bars, front and rear. That way, damper valving shouldn't need to be adjusted unless you put on some really heavy tires and/or wheels on there.

[darrin]

What about just going a bit taller with th 16? Few grand touring/all season options at tire rack in 205/65-16 front and 225/60-16 rear - give you both around an inch more clearance and softer sidewalls at the expense of taller effective gearing-

[notfarnow]

Originally Posted by David

Rally car suspension project

Very helpful, thanks!

This picture from that thread shows their car 3" above euro height... it seems like plenty to me:

Originally Posted by Canada Kev

Lowered spindles will net you about 2.75" up front. Reindexing the rear torsion bars should be able to match that but you'll need longer shocks. Perhaps talk to Chuck over at Elephant.

To lower the spindles, I believe you'll need Bilstein struts. I understand it's not a big job, but will require removing spindles and re-welding back on. You might also need longer brake lines and such, front and rear.

I see no reason you can't use your existing torsion bars, front and rear. That way, damper valving shouldn't need to be adjusted unless you put on some really heavy tires and/or wheels on there.

I'll read up on modifying spindles to see if that is something DIYable!

I had a branch from a birch tree fall 20ft onto the roof of the car in the fall... I was pissed at first but now I feel like I've been liberated to do whatever I want with the car... not that it was a garage queen before that

[juanbenae]

Originally Posted by Canada Kev

Perhaps talk to Chuck over at Elephant.

the OP said he was on a budget...… talking with chuck is not cheap!!!!


look for some steely type wheels and put some skinny snow tires on the thing! have fall/summer/spring tires on aluminum rims and the snow studded pizza cutters for winter!