MKIV geo settings ?

[French Frie]

hello,
   
   I booked an alignment session for my MKIV for tomorrow, because I do it on all my cars quite regularly, and especially on AK1113, as the steering wheel is not straight and have a fuzzy feeling, especially on wet road...
   
   I don't think I'll have the four corners aligned, as it seems quite hard and long to set camber & castor (it means removing A arms fittings, right ?), but at least front toe-in... are the "factory" settings still relevant (see below) ?
   
   
   
   BTW, I read somewhere that alignment was not made when leaving the factory... is it true ?
   
   thanks !
   
   Olivier
   
   PS: has someone changed the pivot fixing, to allow easy camber setting ?

[French Frie]

Back from the workshop [:)]...
   
   First surprise : the MKIV was in their database, as well as the CRS and the lightweight [8D] !quite astonishing for a car produced at less than 500 ex. , and as there are less than 5 registered in France!
   
   Second surprise : my car wasn't that much out of setting for the front toe-in, as I expected, but way out at rear, with wheels which were pointing in each direction(respectively -0°47" & +1°07 )!
   Fortunately, it can be modified by operating (clockwise or anti-clockwise) the kind of anti-tramp bar at the bottom of the A-arm ...
   
   Rear Camber & castor were ok, but front camber wasn't, but as it implies to remove the upper A-arm, we didn't change it ... Front alignement (toe-in) was corrected, and now the car goes straight!
   
   Final settings are: castor 3
   Front toe-in : 0°,10" on each side (0°20" total)
   Front camber: -0°45" (I achieved zero on one side, and 0°17" on the other)
   Rear toe-out: 0°08" on each side (0°16" total)
   Rear camber: -0°45" (I achieved -0°39 and -0°47")
   
   I must say that it is the best way to spend 82€ (around £60) [:)] ! Huge improvement on handling, and a way less sensitive on bumps on the road ... And my car used to drive straight, no uneven worn out tires, etc... !

[Flyinghorse]

Olivier-Good to see some technical discussion on the forum... What rim/tyres combination are you running?
   
   The AC document you show at the start seems to mix up minutes (') & seconds (")?
   
   I looked  out my CRS "chassis" handbook and its states (they must have fixed the minutes/seconds by then as its correctly stated):
   Front camber negative 45' (minutes)  Castor 3deg 30'  toe in 20' total (10' each side)
   Rear camber negative 30'  toe in 15' (7.5' each side)
   
   Seems like CRS is pretty close to Mkiv which is what you would expect except rear toe out/in difference. Bit surprised the MkIV has rear toe out.
   
   I agree that there is no easy way to set the camber without taking the upper rose joint out off each time (on a CRS). I guess a trick adjustable rose joint would be needed.
   
   I do my own tracking with a track rite,but am looking for a recommened camber gauge as I cant see a garage wanting to fiddle about setting this.
   
   I did hear that the settings are meant to be done with a solid rod of a fixed length in place of the coilover unit. (Discussion Redline)
   
   I also assume this is for the 16" wheel set up. Again the manual is prescriptive,with best setting up done by testing & adjusting.
   
   Graham

[French Frie]

Hi Graham,
   
   I'm running stock Halibrand/Autokraft 16" wheels, with stock size dunlop SP8000  (fitted by Jim Bottini, the PO)...
   It's a pity indeed that rose joints weren't fitted as standard ! I used to "play" with few other cars, and they were far more easier to set (even if on some the camber needed shims to be adjusted)!
   I assume Kirkham, for example, has improved the original system...
   
   Regarding the rear toe-out, it was mentioned in the handbook, and that was the infos the workshop had too ... To my knowledge, toe-in in front is to help precision and because wheels tend to go out on acceleration, and toe-out on rear is to help stability, but stand to be corrected ...

[Gus Meyjes]

Kirkham is an all heim/rose joint set up.

[French Frie]

yep... quite impressive : http://www.kirkhammotorsports.com/book_aoe/aoe_12.pdf !

[DWR46]

I also agree that the manuals specify Rear Toe Out. However, this just has to be a mistake. I know of no other street car that specifies rear toe out (though somebody may be able to tell us about one). We prepare and race a number of vintage sports cars and we always set them up for as much rear toe IN as the car can stand. Rear Toe IN helps stability under braking. We race both 289 and 427 Cobras and always use 3/16-1/4 inch total rear Toe IN. On the street, excessive rear toe IN will accelarate tire wear, so you need to find the right balance between stability and acceptable tire life. The less toe in at the rear, the longer the tires will last. In racing, the tires wear so fast the the toe settings are not a factor.
   As for the front toe settings. In racing the old saying is "toe out equals turn in". Toe out setings help the car turn into the corner better, but you loose straightline stability. In a race car, you really do not care so much and sacrifice stability for lap times. On the street, you want some small amount of front toe IN for better straightline stability. Too much will add understeer and make the car less responsive and will also increase tire wear. On the track we run about 1/16 to 1/8 inch front toe out, but on the street about 1/32 to 1/16 inch front toe in. The front toe in also helps compensate for wear in the steering, as the natural tendency is for the front tires to try to pull themselves apart as they go down the road, so a little intial toe in will help offset component wear and still keep the wheels straight when moving. For a street Mark IV, we use 1/16 inch total front toe IN, and 1/8 inch total rear toe IN.

[Gus Meyjes]

Kirkham also specifies toe in.
   
   Check the spec list:
   
   http://www.kirkhammotorsports.com/about/technical/technicalquestions
   
   Gus

[French Frie]

many thanks for your answers ! I'll go back to the workshop to correct the rear toe -in...
   
   BTW, what it is the best (fastest) method to set front camber (if there's any, apart from removing wheel, disassemble the upper A-arm, try and guess the correct value, and re-assemble the whole stuff) ?
   nobody has thought about manufacturing A arm with counterwise thread, to facilitate that ?

[shep]

This may sound crazy, but we always run a nat's of toe out on the leaf sprung race cars. The logic is that under acceleration the rear wheels try to overtake the chassis, and dial out the toe out. Look at our results, it always worked, and the cars feel really stable as you apply power through a corner. I would suggest giving it a try on the coil sprung cars and see what you think. Andy.

[AKL 1333]

Has anybody the Geo-Settings for the lightweight cars
   Thanks in advance
   Juergen

[French Frie]

Hi, as said above, the geo workshop where I did the setting had the LW values... they were the same ones that for the "regular" MKIV, which dosen't sound weird to me !