Upgrading to a Coil over set up in my early 911
12-27-2003, 07:18 PM
#1
Instructor
Thread Starter
Upgrading to a Coil over set up in my early 911
Hello:
I'm trying to find information on the possiblity of updating to 935 type suspension on the front and rear of my 1970 911rs Clone. I use the car on the street as much as the track and prefer not to put in a full roll cage that ties into the suspension pick up points. I know that this is the most common way to re-enforce the pick up points and allow the transfer of the car's weight from the torsion bars to the top of the shock perches. Is there a way to successfully engineer the re-enforcement of the pick up points with out the installation of a serious roll cage?
Thanks
I'm trying to find information on the possiblity of updating to 935 type suspension on the front and rear of my 1970 911rs Clone. I use the car on the street as much as the track and prefer not to put in a full roll cage that ties into the suspension pick up points. I know that this is the most common way to re-enforce the pick up points and allow the transfer of the car's weight from the torsion bars to the top of the shock perches. Is there a way to successfully engineer the re-enforcement of the pick up points with out the installation of a serious roll cage?
Thanks
12-27-2003, 08:58 PM
#2
Addict
Rennlist Member
Rennlist Member
Hey Jim;
The 935 stuff is not really for street use. All those alloy arms and heim joints don't fare all that well out in the real world. They like the fantasy world of the track much better. They also like the the comfort of short service intervals! Oh... did I mention that stuff is really EXPENSIVE too?
The stock front wheel locating hardware is one of the most brilliantly simple and pure designs of all time, and it can indeed continue to serve you well - if somewhat innaccurately - compared to the pricey race stuff.
You are wise to think of mount reinforcement. The front of a 911 chassis is indeed quite weak in general, but the real worry is the rear. The stock shock mounts can't really even handle the load of a stiff shock let alone ALL of the suspension forces.
You do not have to do a cage, as that is obviously quite invasive, but you definitely should STRONGLY consider that rear reinforcement.
http://www.redlinerennsport.com
Leda/Hypercoil/Racer's Edge/Tarret Engineering Suspension Components
The 935 stuff is not really for street use. All those alloy arms and heim joints don't fare all that well out in the real world. They like the fantasy world of the track much better. They also like the the comfort of short service intervals! Oh... did I mention that stuff is really EXPENSIVE too?
The stock front wheel locating hardware is one of the most brilliantly simple and pure designs of all time, and it can indeed continue to serve you well - if somewhat innaccurately - compared to the pricey race stuff.You are wise to think of mount reinforcement. The front of a 911 chassis is indeed quite weak in general, but the real worry is the rear. The stock shock mounts can't really even handle the load of a stiff shock let alone ALL of the suspension forces.
You do not have to do a cage, as that is obviously quite invasive, but you definitely should STRONGLY consider that rear reinforcement.
http://www.redlinerennsport.comLeda/Hypercoil/Racer's Edge/Tarret Engineering Suspension Components
12-28-2003, 01:36 AM
#3
RL Technical Advisor
Hi Jim:
I'd concur with John; from long-time experience, the ERP stuff is not really suited for street use.
I also agree that all of the shock mounting points need extra and extensive reinforcement.
At this point, I'll also go on record as stating that the 911 chassis's shock mounts were never designed nor intended to handle the static & dynamic suspension loadings and using coilovers without a full cage results in a more flexible handling car than a torsion-bar equipped one.
For street and track use, I would recommend using your T-bars (properly sized, of course), the superb Elephant Racing polybronze bushings in the A-arms and spring plates for much improved suspension compliance without any squeaking or frictional issues.
Its as close as you can get to spherical bearings.
I'd concur with John; from long-time experience, the ERP stuff is not really suited for street use.
I also agree that all of the shock mounting points need extra and extensive reinforcement.
At this point, I'll also go on record as stating that the 911 chassis's shock mounts were never designed nor intended to handle the static & dynamic suspension loadings and using coilovers without a full cage results in a more flexible handling car than a torsion-bar equipped one.
For street and track use, I would recommend using your T-bars (properly sized, of course), the superb Elephant Racing polybronze bushings in the A-arms and spring plates for much improved suspension compliance without any squeaking or frictional issues.
Its as close as you can get to spherical bearings.
12-28-2003, 07:47 PM
#4
Addict
Rennlist Member
Rennlist Member
Hey jim;
Steve makes an excellent point. I remember at the time I came into Project GT3S911, the car was full coilover and very stiff spring wise, but the owner complained that his suspension tuning made no difference anymore. I suggested to him that this was because the chassis could only handle so much load, and then simply delfected. Tuning the sway bars was absolutely futile. They just aint very stiff. Why do you think 911s had rubber gasket windshields for so long?!
Now, he had gone nuts with his spring rates (550/750), but... A little tube framing (well... a LOT really) and the car was stiff as a board. Sway bar adjustments meant something again!
Now, I feel you could go up a significant amount in spring rate from where you are now and not get too awfully twisted around. Considering the stock t-bars are in the 125-175lb neighborhood, there is plenty of room for stiffening without getting too carried away. Up to perhaps 2-300FR/350-450RR. In lieu of coilovers, you do have the advantage of T-bars being fairly easy to index on a 911, so that might be a thought.
The front is not really a failure mode, as the towers - while flexible - will take reasonable high suspension loads. However, that rear shock mount will still need reinforcing.
All-in-all, I'd say if you just want it stiffer, go with Steve's T-bar suggestion. If you want to get into serious tuneability, then coilovers are your deal!
www.redlinerennsport.com
Steve makes an excellent point. I remember at the time I came into Project GT3S911, the car was full coilover and very stiff spring wise, but the owner complained that his suspension tuning made no difference anymore. I suggested to him that this was because the chassis could only handle so much load, and then simply delfected. Tuning the sway bars was absolutely futile. They just aint very stiff. Why do you think 911s had rubber gasket windshields for so long?!
Now, he had gone nuts with his spring rates (550/750), but... A little tube framing (well... a LOT really) and the car was stiff as a board. Sway bar adjustments meant something again!
Now, I feel you could go up a significant amount in spring rate from where you are now and not get too awfully twisted around. Considering the stock t-bars are in the 125-175lb neighborhood, there is plenty of room for stiffening without getting too carried away. Up to perhaps 2-300FR/350-450RR. In lieu of coilovers, you do have the advantage of T-bars being fairly easy to index on a 911, so that might be a thought.
The front is not really a failure mode, as the towers - while flexible - will take reasonable high suspension loads. However, that rear shock mount will still need reinforcing.
All-in-all, I'd say if you just want it stiffer, go with Steve's T-bar suggestion. If you want to get into serious tuneability, then coilovers are your deal!
www.redlinerennsport.com
