[Anthony B]

In 1967 Mclaren cars produced and developed the Mclaren M6a whith Chev V8 power, with which he won the 1967 Can Am champioship.

At the end of that year, the works team had developed the Mclaren M8A to be raced by Bruce and Denny, so they teamed up with technical partner Trojan- Tauranac raciing and developed the M6B. This version by thunderslot is of the superb Sunoco petrol sponsorship.As Bruce McLaren Motor Racing moved to developing the M8A, the M6Bs began to be delivered to customers for the 1968 season. Several of the M6As were also sold with Roger Penske purchasing one car for defending the United States Road Racing Championship (USRRC) champion Mark Donohue.
Donohue won several USRRC events that season and earned his second championship. He also later won a race in Can-Am, beating the newer McLaren M8As.
After the cancellation of the USRRC after 1968, the M6As and M6Bs continued to be used into the early 1970s but none were able to achieve victory against their newer competitors.

   

The M6A and M6B also featured prominently in the early years of the Australian Sports Car Championship (ASCC). Driving a McLaren M6B fitted with a 5.0 litre Repco V8's.



The Thunderslot version is a superb rendition of the original.

   

   

   

[Gordon Steadman]

The Thunderslot cars are very good. I got the Orange McLaren. Pretty quick but I just can't get on with the tyres as they keep coming off the rims. The wheels don't allow for fitting urethanes as the have two ridges for air tyres. Had to fill in the centre section or a dip developed.

A motor change to NSR Shark 32 is rather fun too.

This model does tempt me to try another one though.

[chrisguyw]

 Pretty quick but I just can't get on with the tyres as they keep coming off the rims. The wheels don't allow for fitting urethanes as the have two ridges for air tyres. Had to fill in the centre section or a dip developed.

Hi Gordon, not sure of your process for filling the center section of "air" wheels, but, this one works very well,......not only does it eliminate "cupping" of the rear tyres, it also allows the tyre to compress more, which allows the outside rear tyre to load more progressively, improving handling and grip.

Cheers
Chris Walker

I use 1/32 or 1/24 sponge tyre blanks......you may already have some, but, blanks can be purchased from Pendle etc.....the one in the photo is a Scaleauto sponge tyre., but several folks make them.

Cut these into strips, and use some rubber cement (not CA) to secure them.

Use a tyre truer (or sand) so that the "insert" is just a few thou. proud of the flanges............if you really want to  go to town, you can file/sand/dremel  both flanges down a few thou, (before gluing the sponge) which will add to the overall compressibility of the tyre.

Glue and true, and away you go !!

[Fluff]

So if air rims are such a problem ,and have to be filled in ,why use them ??

Steve

[chrisguyw]

So if air rims are such a problem ,and have to be filled in ,why use them ??

Steve

Hi Steve, They are not a problem., and with a bit of work, they can be excellent !!..............likely a little history will help.........When they were first introduced, the initial theory was that the unsupported middle of the tire  would expand at high speed (on the straights) giving a bit more top end, and then settle on the corners to provide more tyre surface area on the track. More importantly, "softening" the tyre by eliminating the solid center flange does help with handling/grip............the typical tyres run on most 1/32 cars are quite hard in comparison to sponge tyres, and the tiny thickness of tyre that covers the center rib of most 1/32 plastic car wheels results in a very hard tyre, and,  coupled with the relatively light weight of the cars, does not allow for much tyre compression at all.

Unfortunately, the unsupported center of the tyre resulted in inconsistent handling due to too much movement in the tyre. Soon after, most of the quicker club guys/gals, began gluing  the tyres around the complete circumference of both the inside and outside bead of the tyre and used a syringe to fill the gap with air. This provided a consistent handling tyre, and one that due to the air inside, compressed progressively, which improved grip/handling. While the tyres would lose pressure, and needed to be "filled" after a heat or so, the main issue that most of the clubs/commercial tracks had was syringes lying on everyone slot box, which was hardly the image most tracks wanted to promote, and the practice was largely banned.

In order to replicate the "air" affect without the air, many top racers looked for an alternative.........the sponge insert offers the closest performance to "air" without the negative imagery.

So, while they are a bit of work to retrieve maximum results, they are certainly worth the effort, arguably not so much for the home racer, but for top line competition, definitely.

There are a few folks now making double flanged wheels, with a flange on the extreme outside and inside of the wheels (similar to the 60's/70's designs), which have no center rib at all. These require a different shape tire (again similar to what was run in the 60's/70's) and for a given outside diameter, these tire have considerably more compression capabilities.

Cheers
Chris Walker

[Fluff]

Chris ,many thanks for a concise answer ,I expect never racing at tip level lead me to wonder why such a rim was developed .I fully understand that the increase in diameter for more speed ,this is used in drag racing but the concave bit in the corners I found a bit of a puzzle .I raced in the 60 ,s but only at club level and have never heard of injecting tyres with air before .We were still sticking tyres to the track with wintergreen .

Steve

[chrisguyw]

Chris ,many thanks for a concise answer ,I expect never racing at tip level lead me to wonder why such a rim was developed .I fully understand that the increase in diameter for more speed ,this is used in drag racing but the concave bit in the corners I found a bit of a puzzle .I raced in the 60 ,s but only at club level and have never heard of injecting tyres with air before .We were still sticking tyres to the track with wintergreen .

Steve

Hi Steve, In the 60's we were all treating our sponge tyres with wintergreen or castor oil. ........in the 70's, stickier tire additives became the norm due to the increased power of the increasingly "hotter" motors. As virtually all racing during this time (60's/70's/80's) was done on sponge tyres, which compressed well, and had gobs of grip via traction compounds, alternate designs were not needed, nor beneficial.

It is the current use of  comparatively "hard" tyres  (rubber/silicone/urethane) in most 1/32 plastic chassis based racing that was the impetus for looking for a way to "soften" the tire..........and the NSR "air" wheels, were the first design to address this issue. They did not show up until somewhat recently (I am guessing 10/12 years) , so you rightfully would not have seen/heard about these in the early days.
 
PS I think Pendle were one of the first shops to ban the "Syringe" practice.

Cheers
Chris Walker