Solid or Rubber Subframe Mounts
07-30-2019, 04:20 PM
#91
@Bill Verburg
I just installed the tilt kit from Rennline and even before reading this I started having second thoughts. Why? Because the subframe is tilted in a way that the original bolts on the front side that holds the subframe mounts to the chassis are coming in at an angle different to the threaded section in the chassis to which they are supposed to go in. I hope that makes sense. This means that they don't bolt up properly and you get the weird feeling that the thread is going to give when applying clamp force. Is this really how it's supposed to be? There is no mention of this in the installation instructions. It's goes without saying that if you tilt the subframe without tilting the chassis where the subframe attaches to, the angle on the bolt will be wrong. How did they solve this for the 993 GT2? I have a turbo car (and then some) so HP-wise the tilt kit makes sense. I am still hesitant and I'm thinking just to go back to solid flat ones and call it a day. Would you go flat even for a turbo? I also looked at that picture but I can't recall if I did put the subframe mounting point underneath like that, will have to check again. Any advice much appreciated.
I just installed the tilt kit from Rennline and even before reading this I started having second thoughts. Why? Because the subframe is tilted in a way that the original bolts on the front side that holds the subframe mounts to the chassis are coming in at an angle different to the threaded section in the chassis to which they are supposed to go in. I hope that makes sense. This means that they don't bolt up properly and you get the weird feeling that the thread is going to give when applying clamp force. Is this really how it's supposed to be? There is no mention of this in the installation instructions. It's goes without saying that if you tilt the subframe without tilting the chassis where the subframe attaches to, the angle on the bolt will be wrong. How did they solve this for the 993 GT2? I have a turbo car (and then some) so HP-wise the tilt kit makes sense. I am still hesitant and I'm thinking just to go back to solid flat ones and call it a day. Would you go flat even for a turbo? I also looked at that picture but I can't recall if I did put the subframe mounting point underneath like that, will have to check again. Any advice much appreciated.
it will only be as you are torquing the bolts that the washer/bolt deals with the angle.
still, if you don't like the process go with flat bushings.
hard to imagine tilt kit or flat will make noticeable difference for 95% of driving.
if you are just trying out the tilt kit to see if it makes a difference, damaging the threads isn't a big deal.
they are easily accessed for installing an m12 time-sert.
07-30-2019, 10:14 PM
#92
Rennlist Member
Would love to hear you elaborate more on this. I went solid and have zero regrets. I struggle to notice a NVH difference yet the chassis just seemed more responsive with em. One of the few mods without a downside IMHO.
07-30-2019, 11:56 PM
#93
Three Wheelin'
More detailed thoughts here: https://rennlist.com/forums/993-foru...monoballs.html
07-31-2019, 08:36 PM
#94
Rennlist Member
I didn’t find anything wrong with the solid bushings, to the contrary I couldn’t feel a difference between them and RS bushings - both felt great. So in my thinking, I’d rather stick with the solution that is closer to the original design philosophy. But honestly, I don’t think you can go wrong with either. You in particular have quite a bit more hp than stock, so you may be better served with solid. But in a car with a stock, normally aspirated engine RS bushings work really well.
Just another example of how we all salt the 993 to our own tastes.
Last edited by MarinS4; 07-31-2019 at 09:17 PM.
07-31-2019, 09:37 PM
#95
Three Wheelin'
It seems the original design philosophy was more grand touring than sports car. Just look at the inner front tie rod. Who’s idea was it to create such a rubber joint? The 993 was the first 911 to employ a rear sub frame and used rubber bushings. On the following models the GT3 used solid mounts and the rest used rubber. What you choose on the 993 should be dictated by your desires for a more sporting feel like GT3 or sticking with OEM grand touring style. The lower power level of the NA is not a determining factor IMHO.
Just another example of how we all salt the 993 to our own tastes.
Just another example of how we all salt the 993 to our own tastes.
08-01-2019, 11:06 AM
#96
Does anyone make solid bushings that don't move the subframe closer to the tub? I.e. if one was running ROW sport height but still wanted to run solid bushings, is there a solution for this or are all these designed for lower ride heights?
08-01-2019, 12:40 PM
#97
12-10-2021, 12:10 AM
#98
The bolts are one time use stretch bolts, they should be replaced. The factory manual does a good job of marking which nits and bolts should be replaced when redoing the suspension.
Here is my list from when I did the work.
Suspension nuts and bolts
- Upper Mount Gasket for front shocks.
- 993-341-511-01 x2
- The lock nuts that are used to secure the shock top hats both front and rear suspension. 16 nuts total.
- 900-380-005-01 x16
- Nuts and Bolts for front control arm
- 999-084-445-01 x2
- 900-082-118-01 x2
- 900-082-137-01 x2
- The lock nuts and bolts that are used to attach the front shock to the wheel carrier.
- 999-067-039-01 x2
- 999-072-006-01 x2
- 993-343-156-00 x2
- The lock nuts that attach rear suspension control arms to the wheel carrier. 8 nuts total.
- 900-380-010-01 x2 (A-arm)
- 999-084-449-09 x6 (Toe arm, Camber arm, KT arm)
- The lock nuts that attach control arms to the subframe. 10 nuts total.
- 999-084-445-01 x6 (A arm trailing, camber arm, toe arm)
- 900-380-012-01 x2 (A arm leading)
- 999-507-384-09 x2 (KT arm)
- The lock nuts that attach subframe to car
- 999-084-445-01 x8 (rear attachment points)
- 900-380-008-01 x4 (forward attachment points)
- The bolts that hold subframe onto car
- 999-072-003-09 x4 (through the bushings on each side)
- 900-378-021-01 x4 (small forward bolts)
- 900-378-061-01 x4 (50mm bottom 2 rear bolt positions)
- 900-378-052-09 x2 (80mm top rear bolts)
- 900-378-049-09 x2 (60mm second from top rear bolts)
1) Are the following typically supplied with coilovers?
- Upper Mount Gasket for front shocks
- The lock nuts that are used to secure the shock top hats both front and rear suspension. 16 nuts total.
2) Are the following typically supplied with new arms?
- The lock nuts that attach rear suspension control arms to the wheel carrier.
- The lock nuts that attach control arms to the subframe.
3) Are any of the following not needed if only the subframe bushings are being replaced (without removal of the subframe)?
- The lock nuts that attach subframe to car
- 999-084-445-01 x8 (rear attachment points)
- 900-380-008-01 x4 (forward attachment points)
- The bolts that hold subframe onto car
- 999-072-003-09 x4 (through the bushings on each side)
- 900-378-021-01 x4 (small forward bolts)
- 900-378-061-01 x4 (50mm bottom 2 rear bolt positions)
- 900-378-052-09 x2 (80mm top rear bolts)
- 900-378-049-09 x2 (60mm second from top rear bolts)
3) Should any nuts and bolts not listed be replaced?
- The bolts attaching the hubs to the uprights if the hubs are being swapped or removed?
12-10-2021, 10:31 AM
#99
Three Wheelin'
This is I incredibly helpful, thank you.
1) Are the following typically supplied with coilovers?
- Upper Mount Gasket for front shocks
- The lock nuts that are used to secure the shock top hats both front and rear suspension. 16 nuts total.
2) Are the following typically supplied with new arms?
- The lock nuts that attach rear suspension control arms to the wheel carrier.
- The lock nuts that attach control arms to the subframe.
3) Are any of the following not needed if only the subframe bushings are being replaced (without removal of the subframe)?
- The lock nuts that attach subframe to car
- 999-084-445-01 x8 (rear attachment points)
- 900-380-008-01 x4 (forward attachment points)
- The bolts that hold subframe onto car
- 999-072-003-09 x4 (through the bushings on each side)
- 900-378-021-01 x4 (small forward bolts)
- 900-378-061-01 x4 (50mm bottom 2 rear bolt positions)
- 900-378-052-09 x2 (80mm top rear bolts)
- 900-378-049-09 x2 (60mm second from top rear bolts)
3) Should any nuts and bolts not listed be replaced?
- The bolts attaching the hubs to the uprights if the hubs are being swapped or removed?
1) Are the following typically supplied with coilovers?
- Upper Mount Gasket for front shocks
- The lock nuts that are used to secure the shock top hats both front and rear suspension. 16 nuts total.
2) Are the following typically supplied with new arms?
- The lock nuts that attach rear suspension control arms to the wheel carrier.
- The lock nuts that attach control arms to the subframe.
3) Are any of the following not needed if only the subframe bushings are being replaced (without removal of the subframe)?
- The lock nuts that attach subframe to car
- 999-084-445-01 x8 (rear attachment points)
- 900-380-008-01 x4 (forward attachment points)
- The bolts that hold subframe onto car
- 999-072-003-09 x4 (through the bushings on each side)
- 900-378-021-01 x4 (small forward bolts)
- 900-378-061-01 x4 (50mm bottom 2 rear bolt positions)
- 900-378-052-09 x2 (80mm top rear bolts)
- 900-378-049-09 x2 (60mm second from top rear bolts)
3) Should any nuts and bolts not listed be replaced?
- The bolts attaching the hubs to the uprights if the hubs are being swapped or removed?
2) I needed to buy these separately.
3) You must remove the subframe (or at least loosen it) to replace the bushings. You'll need all of these.
4) Attachment points are at the shock and the a-arm so the nuts and bolts listed above should do it.