[race_prep] Guernsey Hillclimb 205 Build

[welshpug 1,661]

ahh bugger, 205 ones not listed any more, only 306 ones which are a little longer.

[wardy18 33 1 Cars]

Looks like these are the option then

 

http://www.ebay.co.uk/itm/PEUGEOT-205-REAR-STUB-AXLE-PIN-FOR-THE-TRAILER-ARM-L-126MM-D-25MM-/360508926011?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item53f001a83b

[welshpug 1,661]

might not be, disc brake ones are longer, but I can't remember what length they are specifically, might have one to hand to measure at home though.

[wardy18 33 1 Cars]

Yes i think those are the Drum axles, need to look into sizes, any ideas where else to get some?

 

Rebuilt the front calipers last night and my god did they need it, the pistons were a nightmare to get out of the caliper as they were so gunged up, serves me right for not using the correct grease last time!!

 

Hopefully a new set of stub axles for the rear and ill be sorted.

 

Doesnt look like the HiSpec calipers for the 205 will fit with my wheel offset, apparently they need 85mm from the fitting face where the caliper bolts to the hub to the outer edge of the caliper, my current Bendix calipers have needed to be shaved down a little to clear the wheels and they only measure 73mm so these hiSpec ones must be quite a wide caliper, i assume due to the pistons on both sides and not just the inner.......

 

Cant afford to space the wheels out either as they already sit only just within my arches!!

[Cameron 16]

Hmm BMTR and Avon both said to run the A15 Crossplys at -0.5deg camber optimal, now looking at the 205 standard spec the rear camper is already at -0.5deg give or take 0.3.

 

might be best allround to just stick some standard axles back in......

 

I think that's probably a dynamic requirement i.e. -0.5Deg is the "optimal" to give you max cornering force; given that you're running zero camber compensation at the rear that would mean running static camber of whatever your max body roll angle will be plus -0.5Deg.

 

-0.5Deg static is certainly a very small amount for a race car to have, even if it is on cross-ply tyres. From my limited experience during Formula Student with those very same tyres, and a car that had a camber compensation of 60-ish%, our "optimal" static camber was more like -1.5 to -2.0Deg. If you factor in a roll angle of around 1.25Deg (a saloon will have significantly more depending on geometry and spring rates) That equates to a dynamic camber value of about 0.75Deg before accounting for compliances.

Edited August 23, 2013 by Cameron

[wardy18 33 1 Cars]

Wow you lost me there mate

 

So when they say -0.5deg they don't actually mean set your camber to -0.5deg.......???

[Tom Fenton 1,542]

Wow you lost me there mate

 

So when they say -0.5deg they don't actually mean set your camber to -0.5deg.......???

 

No. They mean set it up so when the car is cornering hard the tyre is at 0.5 deg to the road.

Surely it goes without saying that using standard road car geometry on a race car using slicks is not the way to go?

As said before, get the arms machined by Bridgecraft, I'd suggest -3deg but up to you.

[wardy18 33 1 Cars]

Yeh i think i need to look into optimal camber angles a bit more.......

 

I think the best bet for the fronts is to buy a temperature probe as previously discussed in this thread,maybe something like this:

 

http://www.ebay.co.uk/itm/Racing-Tyre-Thermometer-Tire-Probe-Kit-Pyrometer-Adjustable-Needle-Probe-/290963702323?pt=UK_CarParts_Acc_Wheels_tyres_Rims_Car_Wheels_ET&hash=item43bec9c233

[Cameron 16]

Well, if you think about what the rear has to do in terms of braking it's very little, and acceleration is zero, so running too much camber isn't quite the problem it would be on the front end. Given than you can't experiment with different settings (unless you have deep enough pockets to get multiple TA's made) I'd go with an assumption that you'll be getting around 2Deg of body roll and will therefore need at least -2.5Deg of static camber. So as Tom says, get a set of arms machined to 2.5-3.0Deg and be done with it all.

[wardy18 33 1 Cars]

Yeh that'll be the rear sorted, will have to increase my camber on the front too as im running static -0.5deg.....DOH!!

 

Why dont they teach something useful like Camber adjustment and roll angles etc when studying to become an accountant........

[wardy18 33 1 Cars]

One good thing is that i am running Andy Bakers adjustable top mounts on the front so camber adjustment is very easy HOWEVER with camber adjustment comes Toe re-allignment and that cant be done so quickly

[welshpug 1,661]

its not that hard, mark up a few known positions on the top mounts for camber, then note the number of turns it takes each side to adjust the toe back to spec, note the writing on the strut brace of the Saxo I service for ...

 

do all that now, and it wont take long at all on an event.

 

 

 

 

 

They're BBM top mounts btw, made for AB

Edited August 23, 2013 by welshpug

[Cameron 16]

Yeah you can adjust your camber and toe at home and note how many turns you need to bring the toe back into spec after adjusting camber, then you just need to do a quick adjustment whenever you change it at the track.

[Cameron 16]

Also, seeing as you have adjustable top mounts, it'd be a good idea to use one of your practise sessions to see whether -0.5Deg is any good up front, or whether it responds better to a bit more than that.

[wardy18 33 1 Cars]

I'm running -0.5 up front at the moment am rolling on the whole side wall of the tyre

 

I will preset -1.5 and -2 and maybe even -2.5

 

Will get a machined set of rear arms at somewhere between 2 and 3 -ve over the winter

[welshpug 1,661]

my road car is probably running more than that with 309 wishbones!

[wardy18 33 1 Cars]

Haha oh.....

 

Well I can't get to my mates garage with the laser alignment before the Hillclimb on Monday but I can use the level on my iPhone to get roughly the camber I want and I have spoke to a competitor friend to take his toe adjusting apparatus down the hill so I can do it before I start racing!!

 

I have previously marked my top mounts at -0.5 and -1.5 so from that I will know the distance to adjust for that 1deg movement on my current setup

 

Shouldn't be getting too much body roll these days what with 450lb springs on the front and running very low CG so 1.5 -ve should enough, may try a little further to -2

[wardy18 33 1 Cars]

Anyone have much experience with Gripper diffs???

 

Had the car jacked up on one side this morning whilst bleeding brakes and span the front wheel to check it was free and I could spin the wheel as much as I wanted, now if I remember rightly I never used to be able to do this because of the gripper diff?? Would only normally rock back and forward a little but could never rotate one wheel while the other is down on the ground....

 

Also I thought I had heard the engine rev up slightly a couple times when I know the front left wheel has unloaded round a long left hand corner

 

The diff was only rebuilt 1 1/2 years ago and the amount of running I do is minimal with hillclimbing???

 

Ideas??

[brumster 135 1 Cars]

One wheel on the ground and you can turn the other freely by hand? That 'aint right, no, there's no pre-load on there. Assuming it USED to have some resistance, it's either worn plates or something broken.

[allanallen 528 2 Cars]

As Brumster says there should be resistance there. Even If the preloads set pretty light it should require say 40lbft to turn a wheel with the other on the floor. Sounds like worn plates, if you're stuck you could reconfigure the plates for more preload and perhaps get a bit more life out of them

[wardy18 33 1 Cars]

Thanks guys, I wouldn't say the wheel would freely turn but it takes A LOT LESS effort than it used to that's for sure

 

Anyone remember if you can remove the diff with the box in place?

[allanallen 528 2 Cars]

Yes you can, bit of a pain sometimes. You need to swing then engine a bit (sump forward) and/or drop the subframe an inch or so.

[wardy18 33 1 Cars]

Woohoo new pb and new class record.... 33.71s down to 33.61s

[brumster 135 1 Cars]

Nice one; well done matey

[wardy18 33 1 Cars]

Cheers mate

 

Anyone know if these guys are the main Gripper guys?? Cant remember who i last sent the diff to for a rebuild....

 

http://www.davemacprops.com/gripper.html