increase castor using n15 lower arms

[gt1r]

I have read 1 thing online to increase your castor by using the n15 lower arms. So use n15 arms 15mm longer with the white line castor bushes. This will give you more camber and castor then get camber adjustable top hats and spin them around so instead of using the hats for camber your using them for castor adjustment.

Has any1 done this to there R? I'm guessing you will need to redrill the hats? Any input would be good just trying to get more castor.

 

[The Doc]

Yes a few of us have done this. You also get the benefit of less bumpsteer.

 

[Fast Guy]

They normally drill a new hole in the top of the inner wing for the new bolt position.

 

[KieranEG6]

How much extra camber do you get from just the bottom arm alone?

I was looking into a modified bottom arm (cut welded jobby) to increase caster without disturbing the top mount. As this way you maximize wheelbase, reduce overhang and move engine weight essentially further towards center. Minimal amounts I know, but I dont so much like the idea of increasing caster by moving the top mount further to the center instead.

I cant imagine it being that difficult to just cut off the bottom ball joint and move it forward then brace the arm.

Seen it done on many stock cars that endure A LOT more abuse than a road car ever will.

Yes a few of us have done this. You also get the benefit of less bumpsteer.

Which is it that counters the Bumpsteer? the extra caster or length(camber)

 

[The Doc]

Caster, the car needs more caster as that effectivley gives more camber when the steering is turned

 

[Fast Guy]

Are they the same bushes? I might get a pair and fit them instead of the ones I have to go on if they help so much.

 

[KieranEG6]

From what I gather the N15 bottom arms are just longer than N14 ones giving extra camber. Unsure how much.

The rear GtiR bushes need to be used and the N15 ball joints are smaller in size but have the same bolt taper for the hub.

 

[campbellju]

Do they increase the front track too if they're "longer". If so this might help with bump steer depending on how low your car is.

 

[KieranEG6]

Do they increase the front track too if they're longer

Essentialy yes. Unsure exactly how much by though. That's what I want to know. The cars already suffer from front to rear track imbalance as the rear is a fair bit less than the front.

 

[campbellju]

I played with rear track to try and balance that out. I found the car just refused to turn in as easily. Maybe I should have persevered or tried it on much faster roads like yours but at legal speeds it just made the handling worse on my car.

 

[KieranEG6]

Weird I have read a few places that adding extra rear track (well spacers) will improve stability and turn in ability.

I suppose there will be a difference to adding actual track width and just spacing wheels out. Definitely an area I am dying to get stuck into trying different things. As I have multiple sets of decent light wheels in varied offsets 15,16 and now 17, also with long studs and range of spacers to try.

Back on N15 arms though there must be someone that knows how much longer they are or even how much extra camber they add like for like with N14 arms?

 

[The Doc]

15mm and that will net you about 2 deg camber, gti and almera hub carriers fit as well and give different ackermann angles, the nme group n car had modified front arms that have increased the castor and lenthened the wheel base, on full intrax suspension handles extremely well, nissan were doing arm mods in 1992...another readon the car won the wrc that year.

 

[campbellju]

Kieran, adding spacers on the rear improved stability which is why it turned in less well. It just felt like there were 4 bags of sand in the boot. Increasing front track might help? relatively speaking your making the rear track smaller.

I'm not saying it won't work, just that I couldn't get it to. A different balance of springs, dampers, arb's and ride height might benefit from more rear track.

 

[PobodY]

Good if you want to drag the car though. - More rear track keeps it going straighter?

To my mind it's always about finding the set up that works for you rather than what other people like, so play until you're happy and share the results. If nothing else your settings might be a good starting point for someone else.

 

[red reading]

If people are serious i can get arms made to the same dimension as group a/n , they change the wheel base and castor and bumpsteer for the better, tried it myself ...all this stuff is copied of the nme cars i own.

 

[campbellju]

Sounds interesting Danny. Best get my car together first but might come back to you on this one in the future.

 

[Lynx]

Is axle length an issue for this?

 

[red reading]

Nope

 

[KieranEG6]

If people are serious i can get arms made to the same dimension as group a/n , they change the wheel base and castor and bumpsteer for the better, tried it myself ...all this stuff is copied of the nme cars i own.

Do you have any specs or estimates on what the dimensions are for the arms. Are they longer like the N15 ones or just joint further forward? or both?

I was going to adapts some n15 arms with more castor but not sure I need any extra track width. Don't want to run into arch scrubbing issues.

 

[campbellju]

Kieran, have you done the basic castor mod yet where you drill a hole in the turret and rotate the top mount? You then add additional camber at the bottom to compensate.

Alternatively your N15 arms might be another cheap route to adding some front castor and track. Have you got a picture of the N15 arms? They might be stiffer than the standard arms?

As an aside, adding front track is good for dry handling but will worsen the ability of the car to find grip in the wet. Adding track and camber from the top mount also changes your KPI which reduces steering feel or adds weight depending on how you look at it. Keeping your KPI close to standard makes for a better drive on the roads at "normal" speeds.