The Civic 25XT

[sleepingperformance]

Im surprised that you were chasing more front rake as I would have thought it would have caused too much front end load under braking, resulting in a very twitchy rear end.

I have actually been setting cars up with a lower rear ride height and have been seen half a second impovements per lap at Winton

[ChargeR]

Congrats on the PB. Nice curb jumping out there on the S bend.

Thanks mate, congratulations on your excellent default PB too, look forward to seeing your times tumble as you get more comfortable in the car.

Im surprised that you were chasing more front rake as I would have thought it would have caused too much front end load under braking, resulting in a very twitchy rear end.

I have actually been setting cars up with a lower rear ride height and have been seen half a second impovements per lap at Winton

I'm not sure what you mean guy, front to rear rake isn't going to have a measureable effect on the vertical loading of the front and rear tyres under brakes. The goal in making the change in rake was mostly to reduce rear camber slightly, raise the rear roll centre along with it and gain a little negative camber at the front.

[sleepingperformance]

I understand your reasonings behind it but you need to take into consideration that Honda's like to have approx 35% of overall braking force in the rear under hard braking.

If you can get the rear lower and have more bite in the rear brakes, there will be no form of forward weight transfer as the rear brakes pull the back of the car down, reducing how twitchy the rear end is befors turn in

[ChargeR]

I understand your reasonings behind it but you need to take into consideration that Honda's like to have approx 35% of overall braking force in the rear under hard braking.

If you can get the rear lower and have more bite in the rear brakes, there will be no form of forward weight transfer as the rear brakes pull the back of the car down, reducing how twitchy the rear end is befors turn in

Sorry mate but we're not on the same page at all. I very much doubt a Honda likes to have 35% of braking force at the rear, given that the static weight distribution of many of these cars is around the 65/35 to 60/40 mark, so as soon as you hit the brakes load transfer to the front axle is going to put you at around 15-20% of the total load on the rear axle with the remainder on the front (at about 1G braking). So you should be aiming to have brake bias around that mark, 80/20 - 85/15), under hard fully developed braking.

The rear brakes don't pull the back of the car down, the only way to change the load transfer under steady state braking is to alter the height of the centre of gravity or the wheelbase. For a given WB and CoG the longitudinal load transfer under brakes will always be the same for the same deceleration. If you saw improved stability by lowering the rear ride height it was probably much more to do with the change in alignment characteristics (bump steer) at that ride height range and also the change in anti-rise geometry (because the angle of the rear trailing arm has changed at that ride height), because given the same braking deceleration the vertical load on the rear tyres did not change!

Tyres

Moving on, over the weekend I headed up to Stuckey Tyres to have a set of Dunlop Direzza Z2s fitted on my SSR MK2s. Unfortunately according to the guys at Stuckey's the 175/60R14s are on what seems to be permanent back order, they've been trying to get some from Dunlop Japan for 6 months with no success. So since I was unwilling to wait any longer I went with 185/60R14s.

Here they are fitted up, 6.5" wheel on the left and 7" on the right. The tread width is very narrow, I measured it as about 155mm from the outermost ends of the tread grooves, with the section width sitting around 200mm. Not a huge problem though as it betters my chance of fitting them under the car, and the old EF2 isn't so heavy and powerful that a narrow tyre will hurt its performance a great deal. Style over performance as always.





Here's the end result. The pictures below are before I rolled the guards and gave the fronts a light flare, so it's slightly less mexiflush now.







Here's an inside view of the front guard mods, while I was there I trimmed the guard liners in the area of most probably contact. I trimmed off the tabs on the guard where the liner clips in too as these tend to give an uneven result when the guard is rolled and flared.



It needs a lot more low, which will come once I've completed my extended upper shock mounts and saved up for another wheel alignment. Also considering either some rear camber adjustment or 10mm of spacer as I expect the rears will be pretty sunk once the rear height comes down.

[Grant@Honed]

Looks great man! What's the change in front track with those wheels on?

[ChargeR]

Looks great man! What's the change in front track with those wheels on?

Cheers! Old wheels are +38 so I guess that makes it 62mm extra track width at the front and 38mm at the rear .

[ChargeR]

Haunted Hills Re-match

The weekend before last I finally got back astride the hill climb horse, having not been back to Haunted Hills since I binned the Micra. A well run event as always and the new A course we ran in the afternoon was very cool. I was pretty happy with the performance of the car after I got over some initial gingerness going into Paddington Bend, and the handling balance of the car on cold tyres is pleasantly loose. My times for the day are below, did well enough for 14th quickest on the Figure 8 and 9th on the A course, and some rally racer guy even asked what I had in the car that made it so brisk :P. There's still plenty of room for improvement though, a few more horsepowers for the uphill wouldn't hurt so I ordered a cheap header from eBay,

Figure 8:
72.98
71.77
70.85

A course:
92.22
90.87
90.35

The following pics are thanks to P Mac, check out his album on FlickR HERE





These ones are from takeyourtopoff, check out his FlickR album from the event HERE







Excuse the dirt, I was using a bit too much of the track at some points. Heading to Winton on Monday to try out the Dunlop Z2s, so I'll report back after that.

[eskimo_firefighter]

Nice work on Haunted Hills, pretty quick times on the figure 8. Good to hear that there were no incidents on that day too :P. Also what's the 'A course'? This thread really makes me want to bring the EK out of retirement.

Should be interesting to see what lap time you can churn out with the Z2's. I'll see you on Monday at the track day most likely.

[ChargeR]

Nice work on Haunted Hills, pretty quick times on the figure 8. Good to hear that there were no incidents on that day too :P. Also what's the 'A course'? This thread really makes me want to bring the EK out of retirement.

Should be interesting to see what lap time you can churn out with the Z2's. I'll see you on Monday at the track day most likely.

Cheers guy, hope to see you at Winton on Monday. Don't bring your EK out of retirement, it will just be a distraction like this car is for me .

Here's a video of the A course to give you an idea (taken from Civic mate Mike):

It's run clockwise and after going left at the first junction it follows the course around and then you head right at the cross over and repeat the middle loop twice. Was pretty cool!

[ChargeR]

Winton, Hubs and Header



Over the weekend I put in a set of rear hubs and bearings, after pressing in new ARP wheel studs. Here's a comparison of the OEM wheel studs with the ARPs, plenty of extra length for more spacer.



And here's the hub fitted, I wish I could convey to the fools who paint their rear calipers with them still on the car how much I dislike them.



The strange noise I'd been hearing under heavy cornering load is now absent, so it was either the tyres or the rear wheel bearings. While I was there I also changed the gearbox oil with some Red Line MTL, the old stuff wasn't too shiny. Thanks to Mugsee at Autosphere for providing the MTL and the rear hubs. There's a minor leak from an axle seal but I can't be bothered fixing it.

Then on Monday I headed up to Winton to the Tampered Motorsport day. As usual there was a bunch of fools who don't look in their mirrors, and 3 separate very large oil spills on the track. Apart from that though conditions were excellent and the Z2s performed well.

First session out I only got in 4 laps with some traffic before the first of the oil incidents. Still cut 2 tenths of my previous PB, the tyres felt great and the balance of the car felt the best it did all day, but as the day wore on I believe that the little 185 front tyres were just working too hard and getting too hot. More of the same for second and third sessions.

Later on I managed to put it together and do a 1:48.7 in the last session, cutting 1.9 seconds from my PB. Here are my times for the day:

Session

2:07.4210
1:52.8380
1:50.4980
1:52.0910


Session 2

1:55.2780
2:00.9400
2:00.5430
2:10.3160
1:49.3730
1:55.0580

Session 3

1:56.9710
1:49.6480
1:49.8990
1:53.1490

Session 4

1:53.7930
1:48.7350
1:49.0400
1:49.4550
1:49.4400
2:06.0550

Below is a comparison of the sector times between my PB on Monday and the time from the May EXE event, and then a data overlay comparing the two laps (click for full size).





Looking at the numbers it looks like the majority of the time was found in sectors 2 and 3, through the boobs and the two short straights. As mentioned in my write up for the EXE day I thought that I could adjust my braking and line through the last boob to maximise the run onto the straight, and it looks to have worked, with a similar situation leading on to the back straight. Apart from that speed through the middle of most of the corners is a bit improved, though minimum speed hasn't improved much. Entry to T9 off the back straight was a lot quicker as well.

More work to do though, there's time to be found for sure and I need to find the pressures that work for the Z2s. Lower pressures seemed to give better grip but then the tyres overheated and went off more quickly.

Also my eBay header turned up yesterday, this is what 65 USD buys you. Looks like the guy who does the polishing takes the largest cut.



It's going to take a bit of adjustment to fit by the looks of things, the flanges aren't flat. Hoping to install tomorrow evening, so I'll report back then.

[ChargeR]

Last night I put my eBay header in the car. First up I gave the flanges a bit of a turn on the belt sander to flatten them off, but lost interest before too long and just put them on. Surprisingly they fit quite well, just some minor interference between a tube and one of the radiator fans. Had to replace a stud while I was there also.



Might have picked up a couple of horsepowers, hard to tell on the butt-dyno. Weighs less than the stock part anyway.

[felixR]

Shiny bits are always nice in an EF.

[eskimo_firefighter]

Once again great work out there on Monday, getting super quick. Will you be bringing the EF2 out onto a dyno anytime soon?

[ChargeR]

Shiny bits are always nice in an EF.

Cheers boss. It's getting shinier, too bad about the paint.

Once again great work out there on Monday, getting super quick. Will you be bringing the EF2 out onto a dyno anytime soon?

Thanks guy, still plenty of time to be found though. Yes I'd like to dyno it soon, as I have some future engine changes planned so a baseline would be good.

Bump Steer

Last weekend I spent some time in the workshop taking some bump steer measurements on the EF, something I've always wanted to do on the DC5 but I never got around to it.



The process I used was to set the car up on some rubber blocks to get it high enough to get the jack under it, with some squares of steel with a plastic bag full of grease between them under the tyres to allow them to rotate freely. I then removed the front shock/spring assembly on both sides. Once I'd done that I set up a pair of dial gauges on the flattest section of the rim and cycled the front of the car through its available travel using the jack, taking measurements at 5-10mm intervals.

Here's the result, a nice graph:



Static ride height is approximately 120mm to the jack points, or 310mm from hub centre to guard. I've deliberately left off the scale on the horizontal axis, I need to keep some secrets , but toe in is to the right of the graph.

The end result is that I've learned that at my current ride height when the car goes into bump travel it toes in a fairly significant amount, with minimal toe change in droop.

Since when all the action is happening at the front the suspension is in bump travel (turn in/the outside tyre mid corner etc.) I'd like to minimise the toe change in bump, and get back to something close to stock behaviour which is mild toe out in bump tending to zero toe change. I'm working on something to fix it by slightly altering the tie rod end pickup point location. Keep in mind that some bump steer is unavoidable, but I should be able to minimise it over the range of suspension travel my car uses.

I'll apply the same changes to the CR-X, but since that car has a different steering arm location on the suspension upright I'll need to re-measure the numbers, but the trend will be the same and will be the similar on any of the double wishbone Hondas given the steering rack location and similarity in control arm and upright dimensions.

[Beatz]

Wow what a cool little car! I can imagine it would be fun around the track.