Dave_KE30

Thanks altezzaclub, it's definitely getting better based on lap times, and getting more and more enjoyable to drive. Yeah picking up the wheels looks pretty crazy, and that's a 4th gear corner. I was just a little bit rough on the turn in and gear change and the body just got up a little bit more momentum and managed to pick up both wheels, but from in the car I didn't really feel what had happened. Below is a video from inside the car: I did have an exciting moment on the first lap after changing the rear leaf spring springs, spinning out on a 150km/h corner after momentarily locking the rear brakes. It just so happens that I was passing my Dad's KE20 at the time so he got front row seats haha.

Just a little update, I've rebuilt the rear leaf springs, this time replacing a full length 5mm spring for an 8mm spring. It doesn't sound like much but according to an online calculator I found the change is from a rate of 145lb/in to 185lb/in; if I ran both additional springs the rate would be 205lb/in so I have some room for more adjustment. I also had to stiffen the shock and turn down the rear brake bias. Now the relationship between the front and back springs is: front spring 300lb/in plus a 22mm swaybar, and rear spring is 185lb/in. The increase rear spring managed to maintain enough of the rear grip from the 145lb/in setup to be happy, with enough of a reduction in rear squat that the car mostly corners on 4 wheels now (compared to 3 or even 2!); this is evidenced by the photographs below from similar corners, you can even see the front wheel to arch gap is reduce with the stiffer rear spring helping to prop up the rear under acceleration and roll. Old setup with standard leafs plus 5mm full length leaf: Current setup with standard leafs plus 5mm full length leaf: Potential future test setup with standard leafs plus 5mm and 8mm full length leaf combination: Before: After: I will be looking to swap out the front 300lb/in 200mm long front springs for some 180mm long 350lb/in springs with a softening of the front swaybar hopefully.

I've made a lot of progress since the original post, substantially improved the car's traction out of the corner with softer rear springs and revised arrangement of the leaves to allow less roll resistance and more droop, added a pan hard rod which improved feel and performance markedly and also allowed for some tuning of the roll to get a nice slightly understeering balance. I will soon replace the panhard rod with a offset watts linkage to reduce the vertical movement of the roll centre. Now the springs are a little too soft to resist axle wrap, and both the leaf springs and the nose of the diff will hit the floor pan if provoked, so I plan to add some lateral links originally for an AE86 to see if I can reap some benefit from those. I also found the front springs are just about bottoming out now around the high speed corners, so will have to go for a stiffer rate, probably 300lb/in to 350lb/in. Anyway here's some videos from earlier this year:

This is my favourite, I just chucked the camera on the bumper for a test for the first run of the weekend and the footage was awesome. Being the first run it was my slowest, but still caught the 911 pretty easily haha.

Thanks for your comments Protec Racing, it seems like all the advice I am getting is point in the same direction which is great. TE27 are cool, unfortunately the Australian market mostly got K engines in the old Corolla's, and the cars with T engines were usually bigger and heavier hence a bit under powered. As a result not many people are spending money on the push rod T engines here. I used to be keen, I had an old TA22 Celica which I put twin Solex's on, then moved to Yamaha R6 injected throttle bodies and a Megasquirt computer...still wouldn't have made the power of even a stock 4age so I gave up on that haha. Have you got a 2T or 3T engine? You would think 80 or 90 hp/litre would be achievable. The boosted 3TC that are being used for drag racing though look pretty insane...

Okay, so heading back to the same track this weekend and I'm looking forward to feeling (and seeing with video) how the changes I have made have influenced the car. This is how the car sits now: I have installed the negative offset roll centre adjusters (NRCA) which has given an extra 2.4 degrees of camber giving a total of 3 degrees of camber at the front. I have also dialled in a reasonable amount more caster, both changes should be complementary. I removed the tender spring on the front which dropped the car approximately 20mm, and removed the 6mm wheel spacers on the front as the NRCA added 25mm of track and so even with the increased camber the tyres poked just outside the guards with the spacers in. I was running the spacers so that the tyre had enough clearance to the spring perch, so to compensate for the removed spacers I have raised the spring perch up away from the tyre to give about 5mm clearance, so overall the ride height hasn't changed much. Also the NRCA should have drastically moved the roll centre upward, I haven’t yet remeasured everything and plugged it into my spreadsheet but it should influence the amount of roll the front wants to do; having a guestimate I’d say it’s moved up from sump level to somewhere above the crank level. The other thing too is the NRCA has widened the track at the front by 19mm (25mm less the 6mm spacer) plus the extra camber, so now the front is noticeably wider than the rear; this will effect weight transfer). I trial fitted some 25mm spacers for the rear and the tyre wouldn’t clear the body (these worked perfect with a 205/45R16 tyre though). The bad is that I had to cut away the corner of the guard as the increased scrub radius from the NRCA caused interference, however with the increased caster I now have enough room between the rear of the tyre and the chassis to allow an extra 1/2 turn of lock. Steering is slightly harder now due to the scrub radius, and steering feel is a bit vague (which could be a number of things). Another experiment, I slid some o-rings around the shock shafts so hopefully at the end of a race I will be able to measure how much compression stroke I’m using at the front. Obviously Ignore the Honda plate...It was just a joke haha

Sorry corollaart, I didn't see your message. No lighting on the camera, it's just a cheap one from Kmart shooting at 720p 60f/s. I have used a GoPro and a Sony actioncam and I think for the money the Kmart one is great. Because it was cheap I didn't feel so bad putting it in such a vulnerable spot haha. Surprisingly good camera for the money. Altezzaclub, Apparently the Hilux LSD can be tightened up with shims or springs or something, but they wont stay tight for very long. Basically they are limited by design having only 4 or so plates in the LSD, compared to aftermarket ones having more than a dozen (I think the KAAZ units have about 20!). So with less surface area the Hilux ones have a shorter lifespan and are less sensitive. If I did want to change the center I think I would go for a torsen style (Detroit TrueTrac). I'm thinking of the wheel spin as the symptom rather than the cause, with the cause being the amount of weight transfer. Which is where I agree with you that the suspension changes will effect a noticable difference (hopefully improvement). Swaybars are blade adjustable front and rear, although I haven't run the rear one for a while as it made the car slower. I've made some changes to the suspension now, but wont be back at that track until mid June to get some new video.

Hi Altezzaclub, it's a Hilux with an LSD and 3.7 ratio. The LSD seems quite strong normally, but obviously on corner exit the inside wheel spins a bit with too much power, but it still accelerates strongly even with one side spinning. Obviously a 4.56 ratio would suit a Beams+J160 better for this type of driving. I hope help the wheel spin with by reducing the weight transfer with increased track and some lowering, and tune with the roll centre and swaybar adjustments.

I reckon you could go a 205 no problem if a 9 inch rim fits at the front, just use a shorter spring so the perch is further from the tyre. The height of your lower perch will depend on your spring rate, corner weight, desired ride hight and the amout of travel you want. I think 2 inches of compression and 3 inches of droop would be enough for most sporty cars (firm springs and swaybar). Use a tether strap or tender spring to keep the main spring captive on droop if your main spring is too short for the shocks travel at the desired ride height. Hopefully your tyre clearance will be better than mine. On my car I could get rid of the tender spring it would drop the car 20mm, so I could adjust the perch up away from the tyre. But then there wouldn't be enough droop to keep the inside tyre on the road at the current roll angle, which I think would be a loss. So I could run a shorter main spring, but then compression travel would only be about 54mm before the spring binds. Not may options! Yeah no RCA's yet because the front roll centre calculated out to be ok-ish. I was actually going to do an adjustable inner pivot (at the cross member), instead. But now that am commiting to getting the car lower and wider I will have to get RCA's to fix the geometry. I actually tried negative offset RCA, but the car felt terrible, and with the new wheels and tyres the increased srub radius only gave me half a turn each way before the tyre hit the guards or body, and that was after love taps and an angle grider massage haha

Haha Taz_Rx, that is a good question, my answer is a little bit embarrassing: At the front I've got about 2mm/3mm between the tyre and the coilover perch - I can't even get the ratchet strap webbing around the tyre to secure the car on the trailer! What strut are you using Taz_Rx? I run a 15"x7" rim +20 offset with a 225/50R15 tyre and a 6mm spacer up front. So far it hasn't been an issue, but if the tyre ever made contact with the coilover perch it would actually unwind the perch lock nut and it would spin down further into the tyre/wheel; catastrophic! Would I recommend it... probably not, but it hasn't been a problem so far (hundreds of laps). Eventually though I hope to get more clearance here becase different tyre brands could cause an issue. There are some different types of coilover perches as well which could offer more clearance, l like the T3 ones that use a pinch bolt instead of a lock nut. I suspect the rear tyre deflects more than the front because the live axle hold the tyre normal to the bitumen, whereas the front is influenced by camber, toe, caster and steering angle which artificially push the tyre away from inward deflection. Something else to consider from the video is that these are R-compound tyres and they grip significantly more than any road tyre (at least in my experience), and the carcase construction is slightly different, so a road tyre might behave differently. Maybe even differet brands of semi-slick might behave different too; these are Kumho V70a which I've found to be a bit faster than Toyo RA1 or the previous model Yokohama Advans. Some evidence of rubbing on the coilover perch: Calculated clearance before getting wheels made: Actual clearance: Dave

I wasn't going to bother about this, but here is the front suspension. Next time I will look at making a proper bracket so I can see more of the tyre but zip-tied to chassis worked ok this time haha. Gives a good idea of the range of travel and the change in LCA angle (and roll centre implications). Dave

Thanks for the comments! Tyre wear is pretty bad on the outside edge to be honest. From the wear it looks like the outside quarter of the tyre is doing a lot of work, and the next quarter toward the inside is being bulged out by the lateral force and wearing this into a low spot. Tyre temps show the same, much hotter on the outside edge. Oh and hot tyre pressures are as optimal as I can get them based on tyre temps using the current settings. Anyway, the photo below was after three or four events with regular front to back rotations, after this (and replacing the flat spotted tyre haha) I had the tyres flipped on the rims to even out the wear. The only other thing which might cause the inner section to wear could be toe settings, but I don't think this is it. The conclusion is to me is: more camber required on the front. And I think the video proves this as well, particularly the way the tyre scrubs clean at the first corner, the outside edge rubs clean first around the corners. Unfortunately I can't get more camber out of the strut top, and can't lengthen the LCA within the standard front guards, so probably some fender flares or maybe some major guard rolling is required. I have some KE20 LCA that I can put in which should add 25mm track each side and go from 0.7 degrees camber (max adjustment) to 1.0-3.5 degrees (min/max adjustment). At a guess, about 2.5 degrees might be optimal? Plus with some flairs I can run some more caster which should help with dynamic camber. Also I plan to raise the front roll centre height which should help to reduce some of the body roll force and so the front roll bar can be softened which should help the inside front tyre contribute more to the cornering grip and provide some camber gain by angling the LCA up a bit more at static ride height. Does that sound logical? Any other ideas? Dave

Hey Fellow Racers, I recently shot a view from under my KE30 whilst at the track; I though some of the suspension nerds might find it interesting (me included!). There's so many little features in the footage that you just don't see from in-car video: watching the tyre contact patch, the amount of tyre deflection, suspension travel, body roll ect. From this I found some obvious ways I can improve the grip of the car through the corners, check it out: Circled in the picture below is where the (poor) camera was mounted. The lens on the case ended up smash haha, but that happened in the paddock and not on track.

Name: David Car: 1976 KE30 Corolla Coupe Motor & Driveline: 5th Gen 3sge ‘Beams’ motor from Japanese RS200 Altezza, J160 6-speed gearbox, shortened Hilux diff with LSD and 3.7 ratio Suspension & Brakes: Suspension Front - XT130 front struts | height adjustable coil over sleeve | 300lb/in [5.38kg/mm] King Springs with tender spring | Koni sports adjustable shocks | K-Mac camber and caster adjustable top mounts modified for additional camber | additional threads on caster rod | custom front adjustable antiroll bar | polyurethane bushes throughout | 3mm of toe out | not enough camber | low as possible at the front without tyre clearance and roll centre issues | front antiroll bar on full hard Rear – Reset springs with extra leaf and eyes flipped | adjustable height rear shackle | KYB AGX adjustable shocks | rear roll bar was trialled by removed Brakes Front - Hilux LN60 4-piston callipers | Peugeot 604 rotors (266mm diameter) Rear - SV20 rear callipers | Nissan N13 rotors 257mm Front and Rear QFM A1RM (0.40 cold & 0.48 hot friction, temp range 0-780℃) Master cylinder stopper | Willwood proportioning valve (10% less rear brake) Wheels & Tyres: Koya AE GM 15x7 rims +20 offset | 5mm spacer in front | Kumho V70A K90 (Medium) 225/50R15 |34 psi front 29 psi hot tyre pressure Interior: 6-point roll cage | some interior | Altezza gauge cluster and oil pressure gauge | two fixed back seats with harnesses | wide view rear vision mirror | fire extinguisher Body: 1042kg (full fuel, big battery, dual seats) | spot welded seams | strut tower brace | tow straps and tail shaft loop Other: Possible changes scoped out for the car include: lightened flywheel to replace the +12kg stock one; 4.56 rear diff ratio to make the car work in the close ratio 3rd/4th gear range instead of 2nd/3rd; revised exhaust to raise it higher toward body, reduce noise and hopefully slightly improve flow; front end lowering with some sort of roll centre correction either at chassis end or strut end; modified KE20 lower control arms for additional 2º or so camber, length adjustable panhard rod with height adjustment for rear roll centre adjustment and to limit the excessive lateral deflection of the diff under cornering; new zero offset rims to improve steering feedback by changing scrub radius, increase clearance to inboard suspension components and slight increase in track; guard roll or flares required on the front to accommodate extra track and caster. Hoping to use the roll centre adjustments to reduce weight transfer so I can soften the front sway bar and improve some grip from the inside rear tyre on corner exit, then improve front end grip and tyre wear with some additional camber and caster. HRCC TTT Day 2015 http://trapnellcreat...4187e#h2804187e http://trapnellcreat...65247#h22765247 http://trapnellcreat...906fb#h2e4906fb http://trapnellcreat...afc6a#h1c9c3b9f HRCC Sprint 2015 http://trapnellcreat...3d508#h34f3d508 http://trapnellcreat...f4c6f#h35cf4c6f http://trapnellcreat...4176b7#h24176b7 http://trapnellcreat...acff36#hfacff36 SCMSA Rnd 1 Short Circuit Sprints 2015 http://trapnellcreat...966ca#h222966ca http://trapnellcreat...c2ec7#h247c2ec7 http://trapnellcreat...490abf#ha490abf http://trapnellcreat...ef56b#h3ffef56b Leyburn 2015: http://trapnellcreat...d4271#h540d430e http://trapnellcreat...dbd7f#h540dbd7f http://trapnellcreat...de70a#h540de70a http://trapnellcreat...e2349#h540e2349 http://trapnellcreat...e4421#h540e4421 http://trapnellcreat...e6a97#h540e6a97