The Triumph Dolomite Club - Discussion Forum

The Number One Club for owners of Triumph's range of small saloons from the 1960s and 1970s.
It is currently Fri Mar 29, 2024 2:04 am

All times are UTC




Post new topic  Reply to topic  [ 22 posts ]  Go to page Previous 1 2
Author Message
 Post subject: Re: Tyre help
PostPosted: Fri Sep 14, 2012 8:24 pm 
Offline
Future Club member hopefully!
Future Club member hopefully!
User avatar

Joined: Thu Oct 06, 2011 1:13 am
Posts: 3173
Location: The continent
As Dolomites have a lot of bump steer and all the rusty holes are panels again........ :roll:

Jeroen

_________________
Classic Kabelboom Company. For all your wiring needs. http://www.classickabelboomcompany.com


Top
   
 Post subject: Re: Tyre help
PostPosted: Sat Sep 15, 2012 10:55 pm 
I would have thought the damage is being done in the corners as oppose to the straights. The tyre in question is doing all the cornering work as it is the outside one. So the tracking is of no really consequence as the car will follow the line of that wheel. The tyre on the inside would be effected be tracking in this instance, but due to cornering forces has very little weight on it anyway. Now the outside front tyre will deform in the corner (in effect as it try's to roll off the rim) if the tyre has the correct pressure it will keep an even load throughout its foot print. Too low a pressure and the tyre will fold in the middle, too high and the tyre will load to much on the inside edge. This will in turn reduce the footprint and therefore grip which in turn will increase under steer and tyre scrubbing. The tyre will then start to overheat and lose grip, over steering more which will cause more heat and the pressure goes up and we are now in a vicious circle.


Top
   
 Post subject: Re: Tyre help
PostPosted: Sun Sep 16, 2012 12:10 am 
Offline
Future Club member hopefully!
Future Club member hopefully!
User avatar

Joined: Fri Nov 23, 2007 11:33 pm
Posts: 4727
Location: hampshire
I have been giving this little problem more thought :?: and my car looks similar while cornering to yours and most Dollies.
I think the damage is being done under braking and would look for a loose rack mount or perhaps the drag link has too much movement but the wear is so severe that there has to be movement.
See mine is just the same but my tyres always wore evenly on track days.
Image

_________________
track action maniac.

The lunatic is out................heres Jonny!


Top
   
 Post subject: Re: Tyre help
PostPosted: Sun Sep 16, 2012 1:20 am 
Offline
TDC Member
User avatar

Joined: Tue Oct 03, 2006 5:48 pm
Posts: 8446
Location: Winscombe, North Somerset, England
It's not so much the tyre wear Jon, but the fact that the tyres have ballooned in the centre.

_________________
Sprintless for the first time in 35+ years. :boggle2: ... Still Sprintless.

Engines, Gearboxes, Overdrives etc. rebuilt. PM me.


1997 TVR Chimaera 450


Image


Top
   
 Post subject: Re: Tyre help
PostPosted: Sun Sep 16, 2012 1:42 am 
Offline
TDC Member
User avatar

Joined: Fri Oct 06, 2006 9:57 am
Posts: 669
Location: Auckland, New Zealand
If you haven't experienced this before to any extent, and consensus seems to be that you are not doing anything that different to other Sprint users on the track, it could well simply be an issue with the specific tyre.

During the last decade or so of racing at 79 meetings (and counting) I've had a couple of Toyos delaminate and most recently a front Dunlop 03G showed a remarkable pattern of wear in the middle of the tread, something exactly the opposite to what I have seen before and would expect. The compounds used in race tyres have certainly got softer over time. I normally get a season out of a set, but after 6 meetings last year they were looking more like slicks and had to come off.

This is a pic from 2005 when I was running Toyos - different sizes to yours (195.60x14) and of course a stiffer suspension set up with less body roll, but the tyres do seem to be rolling over less at about 28psi front and 24 rear.

As far as i know tyres are still made individually, and I suspect you have just got a bad one or two. Maybe try something else next! A check alignment of toe, caster and camber might not go amiss first - cheaper than ruining another tyre.
Attachment:
TDC.JPG
TDC.JPG [ 26.8 KiB | Viewed 1519 times ]


Top
   
 Post subject: Re: Tyre help
PostPosted: Sun Sep 16, 2012 5:40 pm 
Offline
Future Club member hopefully!
Future Club member hopefully!
User avatar

Joined: Fri Nov 23, 2007 11:33 pm
Posts: 4727
Location: hampshire
Quote:
It's not so much the tyre wear Jon, but the fact that the tyres have ballooned in the centre.
Ah now I see the problem and I had a set of Colways that did this. They delaminated and broke up just as a set of P6 tyres that I used for a race in my MGBGTV8 at Mallory did.............err duff tyres then :(

_________________
track action maniac.

The lunatic is out................heres Jonny!


Top
   
 Post subject: Re: Tyre help
PostPosted: Tue Sep 18, 2012 11:05 am 
Looking at the photo of the tyre it appears that it has broken a belt or has belt separation. I have had this happen to both a Yokohama A032 and A048. In both cases the belt broke and the tyre went "egg" shape. Neither time could Yokohama give any real reason for this happening, except that in motor sport the tyres are pushed to the limit and sometimes over that limit.

I would imagine that these tyres are quite a few years old (tread depth has little to do with tyre life with these types of tyres), as I don't believe that A032's have been made for a few years now. From this year we have started using A050 tyres, so A032 are now 2 generation old technology.

Suspension set up is very much determined by circuit condition, driving style etc, etc. When we changed from A032 to A048 tyres we went up nearly 50% in spring rate. On a Dolly I have always run 3 to 4 deg neg camber, similar caster figures and and around 2mm toe in. From memory with A032 around 36 psi HOT, once again personal choice and what sort of car feel you want.

Mark


Top
   
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 22 posts ]  Go to page Previous 1 2

All times are UTC


Who is online

Users browsing this forum: No registered users and 11 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Limited