Anti Dive.

[robbieraver]

i have been reading up on some old posts on R32 GTR setups and im curious about the term antidive, i wonder if someone has experience with this could explain it.

my understanding of this could be a combination of lower control arm heights/ weight transfer/ spring rate/ shock valving to pitch the car either forward under braking and squat under accleration.

how can this be removed ?

Edited January 28, 2008 by robbieraver

[trism]

you cant. even if you could, why would you want to remove it? its there to help the car handle better.

its got to do with the upper and lower control arms taking load off the springs on braking/accleration

[robbieraver]

you cant. even if you could, why would you want to remove it? its there to help the car handle better.

its got to do with the upper and lower control arms taking load off the springs on braking/accleration

i need a little more info.

this still hasnt been answered.

[robbieraver]

i ask this as sydneykid was stating that the dive could be dialed out.

i do understand about the lower control arm angles/height.

am i missing anything, im am very sure there is so much more to this!

Edited January 28, 2008 by robbieraver

[robbieraver]

were is SK when you need him.

[Sydneykid]

I'm here, just busy. I am not sure what it is exactly that you want to know, so I will guess, let me know if it doesn't cover what you want.

Getting rid of the small amount of standard anti dive is not a good idea as the car will simply dive more under brakes. We actually increase the front anti dive so that we can run softer front spring rates and not have too much dive. Increasing the front anti dive is simply a matter of spacing the front mounting brackets of the radius rods down from the subframe. We use 3 mm thick alloy shims stacked so we can adjust the amount of anti dive.

Changing the rear squat is just a matter of changing the angle of the rear subframe. Getting rid of the small amount of standard rear anti squat is a good idea for a drag car as it increase the weight transfer onto the rear tyres under acceleration. On the circuit cars we actually decrease the rear squat on the 4wd's as it helps with the corner exit understeer. On 2wd's for road and/or track we run the cradle in the standard postion. You change angle of the rear subframe by using the Whiteline rear subframe alignment kits as per their instructions.

Cheers

Gary

[robbieraver]

thanks for the info, maybe i should have said what is requried to stop the front dive...not incereasing dive, but from what you have said shimming up the front caster rods down to flatten the radius rod sounds like what im after.

cheers.

[robbieraver]

also this sounds very similar to the anti lift kit in the wrx, the rear of the front lower control arm is spaced down.

[260DET]

................................................................................

Changing the rear squat is just a matter of changing the angle of the rear subframe. Getting rid of the small amount of standard rear anti squat is a good idea for a drag car as it increase the weight transfer onto the rear tyres under acceleration. On the circuit cars we actually decrease the rear squat on the 4wd's as it helps with the corner exit understeer. On 2wd's for road and/or track we run the cradle in the standard postion. You change angle of the rear subframe by using the Whiteline rear subframe alignment kits as per their instructions.

Cheers

Gary

With the 2WD's, for road/track what is the downside if some of the anti squat is dialled out? Other than it will squat

[robbieraver]

SK, correct me if im wrong but the front of the radius rod bracket is the front sub frame on the 32 GTR,it is one large frame, im sure its the same as the GTST this is where the shims go ?

if they do it makes sense, angle the sub frame down at the front and the arms will flaten out at bit to change the the dive.

[salad]

The GTS-t is different to the GTR in front, has seperate brackets for the caster rods, compared to the GTR where it's just one subframe.

Anyway, to increase the anti-dive, you need to change the side view angle of the virtual wishbone (caster rod + LCA). So you want the chassis mount of the LCA to be higher than chassis mount of the caster rod. I'm not sure how you'd go about it on a GTR, but that's what you have to do anyway.

Hope this helps.

[Sydneykid]

With the 2WD's, for road/track what is the downside if some of the anti squat is dialled out? Other than it will squat

They actually have squat geometry standard, not anti squat. If you remove the squat they don't transfer as much weight to the rear and so you have less traction on acceleration. For a drag car you add squat, for a drift car you subtract squat, for a 2wd circuit car we tend to leave the subframe at the standard angle but use the Whiteline Rear Subframe Alignment Kit (pineapples) to remove some of the compliance. A very high powered RWD R33 and R34 circuit car usually benefits from a bit more squat. R32's in have a bit too much rear squat, whereas R33's and R34's have a much more circuit friendly amount. If an R32GTR suffers from corner exit understeer then we subtract a bit of squat, same as what we did on John's Z32 as they have similar amounts of squat geometry standard.

Cheers

Gary

[BHDave]

so in a track 32 gtst you'd actually space the rear of the subframe down a touch SK? how much are we talking about?

[Roy]

R32's in have a bit too much rear squat, whereas R33's and R34's have a much more circuit friendly amount. If an R32GTR suffers from corner exit understeer then we subtract a bit of squat, same as what we did on John's Z32 as they have similar amounts of squat geometry standard.

Cheers

Gary

Isnt that the reason why Tomei make rear ends for S13/R32/Z32s? The mount the lower control arm at a lower angle so that it resembles R33/34 rear suspension? They just move the pick up points on their cradles rather then tilt the whole cradle...but much of a muchness i guess.

[robbieraver]

as for r32 gtr anti dive where would the shims go, the only palce i can see would be below the front for the sub frame,

here is a side pic of a 32 gtr sub frame, sorry for the sh*ty pic.

[260DET]

They actually have squat geometry standard, not anti squat. If you remove the squat they don't transfer as much weight to the rear and so you have less traction on acceleration. For a drag car you add squat, for a drift car you subtract squat, for a 2wd circuit car we tend to leave the subframe at the standard angle but use the Whiteline Rear Subframe Alignment Kit (pineapples) to remove some of the compliance. A very high powered RWD R33 and R34 circuit car usually benefits from a bit more squat. R32's in have a bit too much rear squat, whereas R33's and R34's have a much more circuit friendly amount. If an R32GTR suffers from corner exit understeer then we subtract a bit of squat, same as what we did on John's Z32 as they have similar amounts of squat geometry standard.

Cheers

Gary

Thanks SK, that all makes sense. So basically squat is good for road/track, providing the rear suspension angles stay OK the more the better. But if it starts to push on corner exit then back off on the squat a bit.

[Sydneykid]

Isnt that the reason why Tomei make rear ends for S13/R32/Z32s? The mount the lower control arm at a lower angle so that it resembles R33/34 rear suspension? They just move the pick up points on their cradles rather then tilt the whole cradle...but much of a muchness i guess.

We just cut the rear lower control arm front pivot point brackets off the subframe, move them downwards to the limit of the IP regs and then weld them back on. We have been doing that since the mid 90's on the circuit cars (R32's, S13's and Z32's). From what I have seen that is pretty much what Tomei do. Moving the whole subframe (with pineapples) is much easier for the DIY'er as it doesn't involve cutting and welding. The bonus is you get the ability to quickly change it for different disciplines, drag, circuit, drift and road. Plus it is easily reverseable when you sell the car.

Cheers

Gary

[Sydneykid]

so in a track 32 gtst you'd actually space the rear of the subframe down a touch SK? how much are we talking about?

Depending on the track and conditions, we run from 3 mm to 12 mm of anti dive geometry.

Cheers

Gary

[Sydneykid]

as for r32 gtr anti dive where would the shims go, the only palce i can see would be below the front for the sub frame,

here is a side pic of a 32 gtr sub frame, sorry for the sh*ty pic.

We have to abide by the IP regulations, so we can't run spherical bearings, plus we have to use the standard radius rods. We can move the pivot points (within a limited radius), so we are allowed to redrill the mounting holes. Plus we use polyurethane bushes in the standard radius rods with offsets so we can adjust the anti dive through a range from around - 5 mm to + 10 mm. I'll have to stop there, as the knowledge starts to get proprietory, it belongs to the race team owner, not me. I can talk freely about the GTST's (R32 and R33) as they are my knowledge but not the GTR's.

Cheers

Gary

[robbieraver]

We have to abide by the IP regulations, so we can't run spherical bearings, plus we have to use the standard radius rods. We can move the pivot points (within a limited radius), so we are allowed to redrill the mounting holes. Plus we use polyurethane bushes in the standard radius rods with offsets so we can adjust the anti dive through a range from around - 5 mm to + 10 mm. I'll have to stop there, as the knowledge starts to get proprietory, it belongs to the race team owner, not me. I can talk freely about the GTST's (R32 and R33) as they are my knowledge but not the GTR's.

Cheers

Gary

understood, i have the rear of the gtr well set up with the cradel rebushed and with pineapple bushes but looks like im going to do my own R and D for the front changing the pivot points of the lower arms, cradel and caster rods..

cheers.