MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG ZR ZS ZT Technical - To have a Spare, or not to have

found this idea via a friend -

http://www.ultraseal.biz/

could this be a better alternative to the spare tyre/foam sealant option on new cars?
Gary

About the same price as MG R charge for the logo'd tyre valve caps! And aboutt as attractive to the low life!
Martin

seems that even with Ultraseal if it's a gash in the tread, or any sort of hole in the sidewall you are still bu99ered for forward progress. I picked up an as-new 17 with legal tread for the ZS from a breaker for 50 quid. Sorted.
David

Got a space saver with mine. Had to use it once, found out that the spare wheel well in the boot of a ZS is not deep enough for a 17" 'hairpin' wheel.
JLD

I saw a neat coversion to a ZS180 boot to take a full size wheel. A very able carpenter made a raised false floor. Downside he lost a few inces of depth, but had he not pointed it out I would have never noticed!!

Kelv
Kelvin

The Ultraseal has repeated emphasis on the same points over and over and creates contradictions. My (extensive) experience of Dunlop Denovo 1 and 2, involving specific testing at MIRA at cost to Dunlop when suffering some quite serious failings with the later system. These failings can be clearly seen to apply to this sealing system although the effect may not be as dramatic as my previous experience shows.

1, There is great leaning on this being a fluid gel which doesn't lose this fluidity. They claim it will not cause imbalance issue, yet at another point they also say that after inatalation the gel will spread around the tyre during initial use??

My personal experience shows that Denovo 2 uses a gel contained within the tyre carcase and this spread around during use. It also was subject to becoming more fluid when heat was applied so that you could drive the SD1s to an emergency job at high speed and stop quickly. When leaving that scene you would suffer from 'square wheel syndrome' as the heat loss is much slower than the stopping and the gell naturally settles towards the lowest point. Once the speed rises and you have covered a couple of miles the gel redistributes and smooth running is restored.

I see nothing that adequately answers this question and it is something that applies to just cars, as speed and heat are needed, thus excluding commercial/military/moon buggy applications.

2, The most telling problem for any pneumatic tyre is internal air pressure variations and one of the biggest failings of Denovo was the lack of an accurate active pressure monitoring system. Pressure variation has a direct relationship to heat and stress on a tyre and again the information shows contradictory comments. Firstly that small penetrations are sealed 'immediately' and secondly that bigger penetrations will see a 'controlled loss ' of air. It goes onto say that once pressure drops to 15psi the hole will have closed and it intimates that no further pressure loss will be seen.

As the type of damage a tyre may suffer is always an unknown there is a potential for either of the above to be experienced. The other point is how many times have you inadvertantly driven on a tyre that didn't feel that soft, yet was at such a pressure. Go one stage further and think about the drivers who have no 'vehicle feel' and can drive on a near flat or actually flat tyre!!!

Real life driving conditions and real life driver ability means that without an active pressure warning system, as used with Goodyears EMT runflat tyre system, there remains the huge risk to safety in that drivers will be able to travel at speed with no perception of tyre damage until the heat build up results in tyre break up. Such were the conditions affecting cars which had tyre pressures checked three times a day before the drivers took them out, yet tyre break up still occurred through hidden tyre damage effectively covered up by the sealing agent.

Far better in the absence of pressure monitoring to have a simple controlled deflation where the problem is presented to the drives in as smmoth a way as possible, but being as obvious as possible that there is a problem.

Rog
Roger Parker

This thread was discussed between 25/07/2003 and 28/07/2003

MG ZR ZS ZT Technical index

This thread is from the archives. Join the live MG ZR ZS ZT Technical BBS now