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Tyre Width Vs Available Grip - Are Wider Wheels Beneficial On A 205?


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36 replies to this topic

#21
SweetBadger

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Suspension regs:

- must use standard pickup points / damper positions

- Dampers & spring rates free

- arb free

- camber / castor changes free

 

So we're at the limit of what we can reasonably do with that (coliovers, -ve camber hubs, -ve camber trailing arms, 25mm torsion bars, big rear arb, solid susp mounts)

 

For wider tyres the tricky bit is the arches: "Reworking or modification to exterior bodywork is prohibited but any part of the arch/wing pressing folded into the wheel arch may be deformed, but not removed, to give clearance to the tyres."

 

Suggests that big sticky out arches is a no-no!

 

But the euro arches might do the job as they were fitted to 205s as standard and rumored to be wider than standard gti arches...


Edited by SweetBadger, 08 February 2017 - 08:07 PM.


#22
petert

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What front arms do you run? You need to dial in as much caster as you can. Do you think this is within the rules?

Attached Files


Edited by petert, 09 February 2017 - 01:18 AM.


#23
SweetBadger

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We run 309 front arms combined with hubs machined for -ve camber (Bridgecraft).

 

So approx 3 deg -ve camber.

 

Caster is set to the max possible using the eccentric top mounts. i.e. pointing towards the rear of the car. Not as much as shown in your pic though!

 

I think that'd be allowed within regs as it's still the original pickup points.



#24
welshpug

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sounds like you may well benefit from something like a satchell front end, they do one for a 205 using standard pickup points and damper positions but with revised track rod and wishbone angles, wishbones are adjustable so you can add castor and small adjustment in camber.



#25
petert

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If you want a reasonable amount of caster however, you have to move the top back. Otherwise the tyre hits the front spoiler. You'll be lucky to get past 4 deg. Even then you need to do some creative body work. If you look closely at pics of Colin's car, you'll notice the strut top centres are way back.

#26
SweetBadger

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Have a bit of an update on this:

 

Ended up going with 7" team dynamics pro-race 1.2, et 15. There was no way we were going to fit an 8" rim under standard or euro arches, plus the 8" rims are more pricey.

 

With -ve camber and the large body coilovers up front we still need to run 10mm spacers up front and 5mm spacers on the rear (plus a bit of rear arch persuasion inwards with a hammer and a bit of wood!). So et5 up front, et10 rear.

 

We first of all bought some Euro Raylle arches form Maximotorsport (https://www.maximotorsport.com), but after trial fitting them it was clear that they give only a very marginal increase in width over the standard arches (2mm ish), They are wider, but because they sit higher up the wing (therefore further in) the extra arch width doesn't equate to anything when fitted on the car. 

 

In fact I managed to widen the standard arches more by 'massaging' the wings outwards, and using some spacers behind the arches.

 

But sadly not enough:

 

B3280B41-B872-4BC9-9DF1-2FF49475335E.jpg

 

Tony from Maximotorsport was very helpful (despite Parcelforce's best efforts to cock things up), and swapped the euro arches with a set of his 'narrow' arches. These just cover the 205 width tyres , and only just, but I think they'll do the trick unless we get a super awkward scrutineer who gets the protractor out!

 

Trial fitting:

 

F8F78F49-F6B9-47FF-9A50-228A62A086B5.jpg

 

529154B7-5F4E-40B0-A3D5-67B1404284C7.jpg

 

The front arches needed a bit of a trim as the tyres rubbed when the suspension was compressed - all sorted easily with an oscillating saw.

 

I also totally forgot that we'd have to remove the standard trim leaving rivet holes along the side of the car - quite happy with my cheap and cheerful solution to this problem. A £20 stripe sticker set for a Peugeot 308 of ebay; fits the 205 perfectly, and looks pretty good!:

 

12CFE7A0-779B-4582-B7AD-9340FED6BCAB.jpg

 

Had a track day at brands on Monday to test the car before the new season - I cannot believe how much extra grip we had when the track dried out. The car felt fantastic and nicely balanced, it just went where you pointed it. Noticed most difference at Druids and Mclaren, far less understeer and way more traction allowing us to get on the power earlier. Can't wait for the first race of the season!

 

Here's the car on the grid for some promo shots for the series:

 

702F36BE-CCA4-4791-8D06-FE176E9201FF.jpg



#27
blandy

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Like the sticker idea. Ive just done exactly the same on the wheel front - ordered 8 in et15. 

 

With regards to the spacers what suspension are you currently running as i have gaz gha coilovers so imagine i will need to do the same 



#28
SweetBadger

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Running Gaz gold dampers.

 

The issue is the extra -ve camber machined into the hubs (2.5 degrees) means the inside of the wheel ends up closer to the front strut.

 

Also running -ve camber on the rear (3 degrees), so the same issue with the inside rear arches.

 

If you're running std camber, or just eccentric top mounts / wider bottom arms, you might get away with running them without spacers.



#29
blandy

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Im on the eccentric Gaz mounts so running the max they allow so around -2 on the fronts, the rear is standard at the min but considering getting the rears machined so may get away with a 5mm spacer but ill do a test fit first. Not gonig to be any time soon though as been quoted around 12 weeks for the wheels 



#30
SweetBadger

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Yeah, there was a long lead time on the 65.1 bore wheels when I enquired a few weeks back as TD make them to order.

 

I ended up getting the 73.1 bore ones with alloy spigot rings instead as those were available off the shelf.



#31
petert

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Looking good. Add more camber, then the tyre will tuck under further. You need to be -3 minimum anyway, preferably 3.5-4.0. My 7" wheels are 5ET and the 8" wheels are -4ET. I run without spacers. You'll need 15-20mm of spacer with an 8" 15ET wheel. I also have 73.1 bores with alloy spigots. They've not caused any issues.



#32
SweetBadger

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Another update on this.

 

We had to run a small ballast this year to run the wider arches (not that it made any difference, as a catastrophic engine failure has written off the season anyway).

 

Annoyingly just had an email through from the series organisers stating that next year wider arches will not be permitted, and it needs to go back to standard!

 

So:

 

Option 1: find another 2 driver series (750mc club enduro could be on the cards)!

 

Option 2: how to fit the new wheels and tyres under standard arches???

 

I think the following might just work:

 

- Go back to 205 bottom arms (-10 mm at the ball joint, estimate -5mm at the top of the tyre)

- Fit some Bilstein coilovers - thinner body, so should mean we can run without the 8mm spacers currently needed to stop the tyre hitting the damper body

- Get some BakerBM adjustable top mounts http://www.bakerbm.c...205adjtopmounts , mod the strut top, move the damper top inwards (say additional 25mm at the strut to, estimate 8-10mm at top of tyre)

- Get some euro-arches (hopefully they are permitted as there were fitted on a standard 205)

 

So that should move the front tyres inbound by 20mm ish, whilst maintaining the -ve camber lost due to going back to 205 bottom arms.

 

Not a cheap solution...

 

What a PITA!



#33
petert

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Can you run an aftermarket adjustable arm that still uses the standard pickup points? In addition to moving the strut to as far back and inwards as possible, you still dial in as much camber/castor as required, running the standard track. Driving a 205 with +6 deg of castor is a very rewarding experience.



#34
welshpug

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I don't think altering the angle of the strut like that is a clever way to do it, I've seen a wide tracked saxo using only long wishbones and it was sketchy as hell.



#35
petert

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As you have to retain the standard pick up points, one of which points the wrong way, I'd make a fixed custom control arm, with say -2 camber and +4 castor, then dial the rest in up the top.



#36
allanallen

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I've gained around a degree by altering the rear wishbone mount, much more and you'd need to trim the front bumper, not a problem on a race car but looks daft on a road car!

#37
petert

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Correct. I've trimmed 20-25mm from the front spoiler. It fouls on the tyre after approx. +3 castor with fat tyres. Check lock to lock.