Parts required for 993 RSR front track
#1
Racer
Thread Starter
Parts required for 993 RSR front track
Hello all,
I have recently acquired a 1996 NB 993 C2 with an RSR body kit. It came with 9J ET1 front wheels which I have now replaced with 9.5J ET35 - these wheels sit too far into the arches and I don't want to use spacers to push them out. Searching through some old threads I assume that I would need the following parts if I move the suspension to the outboard position:
- 964 crossmember
- 964 side beams
- 964/993 RSR 24mm ARB - I'm guessing this is NLA so what are my options
- 993 RSR drop links for the above ARB - again I assume this is NLA too
Have I missed anything ?
Cheers,
T.
I have recently acquired a 1996 NB 993 C2 with an RSR body kit. It came with 9J ET1 front wheels which I have now replaced with 9.5J ET35 - these wheels sit too far into the arches and I don't want to use spacers to push them out. Searching through some old threads I assume that I would need the following parts if I move the suspension to the outboard position:
- 964 crossmember
- 964 side beams
- 964/993 RSR 24mm ARB - I'm guessing this is NLA so what are my options
- 993 RSR drop links for the above ARB - again I assume this is NLA too
Have I missed anything ?
Cheers,
T.
#2
Rennlist Member
I have not done the following but remember reading about the following...
From my understanding you can widen the front track by moving the subframe sides outward.
On the body pan you will see there are unused subframe mount points that are capped off that are outward than the stock mount points.
You will then need to drill some new holes into the subframe cross member so the subframe sides rear section will be equally wide as the front of it. The subframe cross member has a place for the these holes but are not drilled out.
Lastly, not sure about the tie rods but you may need some longer ones?
From my understanding you can widen the front track by moving the subframe sides outward.
On the body pan you will see there are unused subframe mount points that are capped off that are outward than the stock mount points.
You will then need to drill some new holes into the subframe cross member so the subframe sides rear section will be equally wide as the front of it. The subframe cross member has a place for the these holes but are not drilled out.
Lastly, not sure about the tie rods but you may need some longer ones?
#3
you don't need to buy any of the 964 parts, the 993 parts work fine.
remove the cross member, there is likely a ghost outline where you drill the wider holes.
the wider holes and mounting threads already exit in the tub.
then bolt the side members in the wider holes.
no reason to change sway bars.
what you do need to buy/make are bolt on collars for the sway bar, some spacers for the drop links and a spacer for the vacuum assist booster.
search for threads by juha g, he has posted pics and descriptions of this process.
remove the cross member, there is likely a ghost outline where you drill the wider holes.
the wider holes and mounting threads already exit in the tub.
then bolt the side members in the wider holes.
no reason to change sway bars.
what you do need to buy/make are bolt on collars for the sway bar, some spacers for the drop links and a spacer for the vacuum assist booster.
search for threads by juha g, he has posted pics and descriptions of this process.
#4
Banned
you don't need to buy any of the 964 parts, the 993 parts work fine.
remove the cross member, there is likely a ghost outline where you drill the wider holes.
the wider holes and mounting threads already exit in the tub.
then bolt the side members in the wider holes.
no reason to change sway bars.
what you do need to buy/make are bolt on collars for the sway bar, some spacers for the drop links and a spacer for the vacuum assist booster.
search for threads by juha g, he has posted pics and descriptions of this process.
remove the cross member, there is likely a ghost outline where you drill the wider holes.
the wider holes and mounting threads already exit in the tub.
then bolt the side members in the wider holes.
no reason to change sway bars.
what you do need to buy/make are bolt on collars for the sway bar, some spacers for the drop links and a spacer for the vacuum assist booster.
search for threads by juha g, he has posted pics and descriptions of this process.
Here is a Link to Pic fron Juha G thread - hoping I looked t his Build thread Winter 2014 - found at post 295
https://m3supercar.1g.fi/kuvat/993/G...PG/_img900.jpg
Any further insights and pics would be helpful
I am considering the widening as a DIY since I have rs bushed front A arms to install
So while I am in there - gettin slippery over here
Thanks Tom
#5
Rennlist Member
Reviving this thread
Here is a Link to Pic fron Juha G thread - hoping I looked t his Build thread Winter 2014 - found at post 295
https://m3supercar.1g.fi/kuvat/993/G...PG/_img900.jpg
Any further insights and pics would be helpful
I am considering the widening as a DIY since I have rs bushed front A arms to install
So while I am in there - gettin slippery over here
Thanks Tom
Here is a Link to Pic fron Juha G thread - hoping I looked t his Build thread Winter 2014 - found at post 295
https://m3supercar.1g.fi/kuvat/993/G...PG/_img900.jpg
Any further insights and pics would be helpful
I am considering the widening as a DIY since I have rs bushed front A arms to install
So while I am in there - gettin slippery over here
Thanks Tom
and which offset and channel is suitable for such a layout?
I am wondering if the front BBS E29 from the 996 CUP would fit without modification in such a configuration
#6
Rennlist Member
When you go to this wider track you are pushing the wheels carriers out 30mm on each side which if you keep the stock wheels they also go outward 30mm on each side.
I believe the stock front wheel is 8et52 so the equivalent to keep the same width of the front but with wider track would be to offset the wheels -30mm on each side so offset would be a 8et82.
Sure it could be less with camber, different ties, wheel width etc... Using this just for example purposes.
Visually it would be something to the effect like this. Notice how the face sticks out after a certain offset since you need a minimum outer lip width.
Example here
Even if you could build a wheel to that spec, not sure it will clear the suspension as you effectively moved the wheel inward toward the suspension to make room in the wheel well.
Example here
https://www.willtheyfit.com/index.ph...8-5&offset2=85
Overall, I don't see the reason to do this unless you have flares/fender extensions or custom wide fenders to accommodate the wider track and keep the original wheel offset as is which is the reason why you do this.
I believe the stock front wheel is 8et52 so the equivalent to keep the same width of the front but with wider track would be to offset the wheels -30mm on each side so offset would be a 8et82.
Sure it could be less with camber, different ties, wheel width etc... Using this just for example purposes.
Visually it would be something to the effect like this. Notice how the face sticks out after a certain offset since you need a minimum outer lip width.
Example here
Even if you could build a wheel to that spec, not sure it will clear the suspension as you effectively moved the wheel inward toward the suspension to make room in the wheel well.
Example here
https://www.willtheyfit.com/index.ph...8-5&offset2=85
Overall, I don't see the reason to do this unless you have flares/fender extensions or custom wide fenders to accommodate the wider track and keep the original wheel offset as is which is the reason why you do this.
#7
Rennlist Member
Overall, I don't see the reason to do this unless you have flares/fender extensions or custom wide fenders to accommodate the wider track and keep the original wheel offset as is which is the reason why you do this.
I measured the available space and I came to the conclusion that if I want to widen RSR style the front track I must use the 17" wheels, which allow it, without any problem.
If I want to use the 18", probably I can do it with the 8J ET 52, but only considerably encreasing the camber, while the 9J BBS e29 with 46mm offset would be "just" 25mm out of the wheel arch...😅
observing the 992 proportions, I came to the conclusion, that she is capable of such good handling if compared to the 991, mainly because Porsche widened the front track.
Doing the same on the 993 should bring to a visible cornering speed improvement.
Last edited by nothingbutgt3; 03-20-2021 at 03:27 PM.
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#8
When widening the track there are several things to consider in the front, the back is more straightforward
factory RSSR did use the outer holes which moves the lower control arms out by 30mm per side
they also used 964 longitudinals which pull the lower control arms back in 12.5mm per side
so the net here is 17.5mm out
the front wheels were 9.5ET38 compared to the 8.5ET54 I use on my narrow body a 9.5ET38 increases the wheel front space by 28.7mm, backspace is reduced by 3.3mm
so adding the relocation data to the wheel data the outer face of the wheel was moved out 46.2mm or ~1.8"
The cars were delivered w/ 245/645 x18 and 285/645 x18 tires
the usual DoT R equivalent is 245/35 & 285/30 though 255/35 & 295/30 would work too, If you go much bigger you start to pay an increasingly large price in terms of torque just to spin the wheels, GT3 et al get away w/ that by using 500hp motors, which 993 can't match, best 993 i've seen is a frends Rothsport 4.0 @~400+a little depending on exhaust and rev limit
factory RSSR did use the outer holes which moves the lower control arms out by 30mm per side
they also used 964 longitudinals which pull the lower control arms back in 12.5mm per side
so the net here is 17.5mm out
the front wheels were 9.5ET38 compared to the 8.5ET54 I use on my narrow body a 9.5ET38 increases the wheel front space by 28.7mm, backspace is reduced by 3.3mm
so adding the relocation data to the wheel data the outer face of the wheel was moved out 46.2mm or ~1.8"
The cars were delivered w/ 245/645 x18 and 285/645 x18 tires
the usual DoT R equivalent is 245/35 & 285/30 though 255/35 & 295/30 would work too, If you go much bigger you start to pay an increasingly large price in terms of torque just to spin the wheels, GT3 et al get away w/ that by using 500hp motors, which 993 can't match, best 993 i've seen is a frends Rothsport 4.0 @~400+a little depending on exhaust and rev limit
#9
Rennlist Member
they also used 964 longitudinals which pull the lower control arms back in 12.5mm per side
so the net here is 17.5mm out
so the net here is 17.5mm out
I was wondering what would be the advantage using an 8,5 J wheel instead of an 8J: is it because this way the tire shoulders work better?
Probably the 8,5J and same time moving outer the 964 longitudinals would require to turn up the profile of the wheel arches to free up 5 mm additional space as well.
thought I had to do it only in the rear, instead now I realise probably it must be done also in the front. Did you do it as well?
#10
This is a very useful info, because considering the 8J x 18 ET 50 I already have available, using the longitudinals I would be out of approximately 10mm, while with the ones of the 964 the wheels should fit leaving few mm space.
I was wondering what would be the advantage using an 8,5 J wheel instead of an 8J: is it because this way the tire shoulders work better?
Probably the 8,5J and same time moving outer the 964 longitudinals would require to turn up the profile of the wheel arches to free up 5 mm additional space as well.
thought I had to do it only in the rear, instead now I realise probably it must be done also in the front. Did you do it as well?
I was wondering what would be the advantage using an 8,5 J wheel instead of an 8J: is it because this way the tire shoulders work better?
Probably the 8,5J and same time moving outer the 964 longitudinals would require to turn up the profile of the wheel arches to free up 5 mm additional space as well.
thought I had to do it only in the rear, instead now I realise probably it must be done also in the front. Did you do it as well?
225/40 x18 is spe'd for a range of wheel widths 7.5 - 9.0" , best grip will come from a 9 most comfort from a 7.5. While it is possible to ft a 9 in the front of a 993 the ET has to be just right, in the ET54 area
I have used 9s but it's easier to fit an 8.5 so that's what I use
similar situation in back where the tire space is the main constraint, it is possible to fit a 10.5" but 10ET65 is far easier w/ a 26/5 35 or 285/30 tire, not ideal but available and easy to fit
#11
Banned
Samurai, the reason for widening is for Limoncella aka "nothinbutgt3" to add wide cup 996 wheels.
The additional benefit of the mod is to gain a wider front track = more front end grip for track use.
How practical ? Well if $ was no object who knows. Perhaps adding the 8 1/2 x 18 front wheel negates the benefit of the mod and provides a more economical solution ?
The additional benefit of the mod is to gain a wider front track = more front end grip for track use.
How practical ? Well if $ was no object who knows. Perhaps adding the 8 1/2 x 18 front wheel negates the benefit of the mod and provides a more economical solution ?
Last edited by TJ993; 03-20-2021 at 08:23 PM. Reason: Clarity - typo
#12
There are several paths to increasing grip
widening the track reduces weight transfer, this allows the inner wheel to contribute more to grip that more than compensates for the reduced grip on the outer
lowering CoM reduces weight transfer
geometry of the suspension can either contribute to or diminish grip depending on specifics
wider wheel on the same tire can increase grip
sway bars reduce weight transfer
widening the track reduces weight transfer, this allows the inner wheel to contribute more to grip that more than compensates for the reduced grip on the outer
lowering CoM reduces weight transfer
geometry of the suspension can either contribute to or diminish grip depending on specifics
wider wheel on the same tire can increase grip
sway bars reduce weight transfer
#13
Rennlist Member
Finding a synthesis between the three targets, widening the front track and having grip and tires working best, is a fascinating exercise, and the personal experience and knowledge Bill shares is precious, he already found his synthesis, so for all of us it is possible to have a point of reference to relate with.
For sure I would like a wider tire track, closer to the one the RSR had, with a tire working effectively as much as possible for performance and for having the best amount of rubber/grip, without loosing handling, but same time offering a nice sense of support on the fast turns.
During the last days I was imagining if the moment of momentum of a tire with a small /30 or /35 shoulder, that see the weight of the tire tread closer to the weight of wheel channel, than for example a 15" wheel with same tire diameter, where the moment of momentum resulting from the two circular crowns at different distances from the center of rotation, could have an influence in the way the car handles.
Is this a simple mental rumination of mine or, for aspirated motor around 300hp, the inertia and its distribution are more important, together with the front track, compared to 10 mm more rubber on the tarmac?
Perhaps it will be a question of the typical ones in which someone lsurely it will be a question of schools of thought
For sure I would like a wider tire track, closer to the one the RSR had, with a tire working effectively as much as possible for performance and for having the best amount of rubber/grip, without loosing handling, but same time offering a nice sense of support on the fast turns.
During the last days I was imagining if the moment of momentum of a tire with a small /30 or /35 shoulder, that see the weight of the tire tread closer to the weight of wheel channel, than for example a 15" wheel with same tire diameter, where the moment of momentum resulting from the two circular crowns at different distances from the center of rotation, could have an influence in the way the car handles.
Is this a simple mental rumination of mine or, for aspirated motor around 300hp, the inertia and its distribution are more important, together with the front track, compared to 10 mm more rubber on the tarmac?
Perhaps it will be a question of the typical ones in which someone lsurely it will be a question of schools of thought
Last edited by nothingbutgt3; 03-20-2021 at 08:47 PM.
#14
Finding a synthesis between the three targets, widening the front track and having grip and tires working best, is a fascinating exercise, and the personal experience and knowledge Bill shares is precious, he already found his synthesis, so for all of us it is possible to have a point of reference to relate with.
For sure I would like a wider tire track, closer to the one the RSR had, with a tire working effectively as much as possible for performance and for having the best amount of rubber/grip, without loosing handling, but same time offering a nice sense of support on the fast turns.
During the last days I was imagining if the moment of momentum of a tire with a small /30 or /35 shoulder, that see the weight of the tire tread closer to the weight of wheel channel, than for example a 15" wheel with same tire diameter, where the moment of momentum resulting from the two circular crowns at different distances from the center of rotation, could have an influence in the way the car handles.
Is this a simple mental rumination of mine or, for aspirated motor around 300hp, the inertia and its distribution are more important, together with the front track, compared to 10 mm more rubber on the tarmac?
Perhaps it will be a question of the typical ones in which someone lsurely it will be a question of schools of thought
For sure I would like a wider tire track, closer to the one the RSR had, with a tire working effectively as much as possible for performance and for having the best amount of rubber/grip, without loosing handling, but same time offering a nice sense of support on the fast turns.
During the last days I was imagining if the moment of momentum of a tire with a small /30 or /35 shoulder, that see the weight of the tire tread closer to the weight of wheel channel, than for example a 15" wheel with same tire diameter, where the moment of momentum resulting from the two circular crowns at different distances from the center of rotation, could have an influence in the way the car handles.
Is this a simple mental rumination of mine or, for aspirated motor around 300hp, the inertia and its distribution are more important, together with the front track, compared to 10 mm more rubber on the tarmac?
Perhaps it will be a question of the typical ones in which someone lsurely it will be a question of schools of thought
here are some comparisons of the torque in lb-ft absorbed by various tires, DoT -Rs tend to be at the low end, gearing effects are not included but are generally far more significant than mass or radius
225/40 x18 21 -25
245/40x18 20-26
245/35x18 20-25
265/35 x18 25-27
265/40x18 26-29
275/35 x18 25-27
285/30 x18 23-30
285/35 x18 28-32
245/40 x15 17-20
245/50x15 20-22
225/45 x15 17 - 19
225/50 x15 18 - 21
225/60 x15 24 -25
#15
Rennlist Member
@nothingbutgt3 got it! Did not realize you were trying to use those 996 cup wheels in front. Maybe another route is just re-lip the front outers .5" smaller so you basically convert that 18x9ET46 to what I think is a 18x8.5ET59 which is close enough and use small spacers to get the poke you want.
The WB had custom 9" Fiske wheels in the front. They can fit, but it is very tight with a rolled fender and aggressive camber. Even then the tire still rubbed in the wheel well at full compression and lock to lock.
The WB had custom 9" Fiske wheels in the front. They can fit, but it is very tight with a rolled fender and aggressive camber. Even then the tire still rubbed in the wheel well at full compression and lock to lock.