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John you know as well as I do some of the BM motors are nearly 1200cc using Doug Kiddie (now Arrow) cranks. I agree you cannot expect people who have spent a lot of money to throw the engines away but it should never been allowed to get to the stage it is now just as formula 2 went. As regard the discs the ones that look like cast iron rotors bolted to aluminium bells give them a pull sideways the majority of them move ! Bodywork, just have a good look wet lay carbon fibre (not autoclave formed) painted looks very much like fibre glass. When they changed the rules a few years ago putting Tridents in the specials class with short stroke BM,s what the ____. I could go on, I told Ian a long time ago if the rule werent tightend you would end up with a this and them, it was ok when a few years ago the grids were packed now they have tailed off quite a bit.

MallorySeptember 1972 (cut off for classics)
Dont see many monster Bm or Imps !

Well done Mike, I'm afraid that may have put an end to the debate.

June 1974 still no monster Bm's and Imps.

A few big Imps there Mike.

998 not long stroke 1200 Ian, and who knows how big the BSA's where

Your right there about the BSA's Mike.
Also, Bill Curries Weslake defo wasn't 750!

When I had Bills Weslake it was 850 with all the info in a book

Going off topic a bit, oops.
920 was the biggest Weslake Bill raced, he recond that was the biggest you could take a Weslake to in those day's. Ali cylinder not Iron.

mrequipe wrote:John you know as well as I do some of the BM motors are nearly 1200cc using Doug Kiddie (now Arrow) cranks. I agree you cannot expect people who have spent a lot of money to throw the engines away but it should never been allowed to get to the stage it is now just as formula 2 went. As regard the discs the ones that look like cast iron rotors bolted to aluminium bells give them a pull sideways the majority of them move ! Bodywork, just have a good look wet lay carbon fibre (not autoclave formed) painted looks very much like fibre glass. When they changed the rules a few years ago putting Tridents in the specials class with short stroke BM,s what the ____. I could go on, I told Ian a long time ago if the rule weren't tightend you would end up with a this and them, it was ok when a few years ago the grids were packed now they have tailed off quite a bit.

Mike, People have told me in the past that wet lay is no advantage as it is as heavy as fibre glass? I have no experience of this. Floating disc's.I don't understand your description on disc's. I have used cast iron disc's on ally bells since 1990 and they are similar to the product which you supply for the 16" wheeled chassis. I have seen the ones made by D&D the bells are bolted to the hub with the disc bolted to that which is the only type I have seen in CRMC meetings. There are others which not bolted to the hubs that are driven by drive dogs and located radially and laterally by bearings,this was done within period,by Mick Harris (I helped him with this). On a batch of 3 chassis but later dropped as we used the wrong material for the disc's. Our 750 short stroke BMW is built with Standard parts,the crank is a 450 with std barrels bored to take liners using 88mm pistons, re-ported heads and a race cam so nothing special.

Paul,the Post Classic class is dead.We just race where and when we feel like it.Still we would be happy to race against you if you decide to put one together.There is a movement on fb to try and get interest in an all 2 stroke sidecar class.
R.E the large Imps.Hillman made a small batch of Rallye Imps in 1966(I think)with a 998cc engine.This car was on sale to the public so they could homologate the engine for rallying.So although most sidecars were 875,there were definently 998cc around in preriod.
As for floating discs,remember seeing them many years ago on a 16" wheel Norton outfit,in the CRMC.

[quote][/quote]Paul, the Post Classic class is dead.
Your right there Tony, we had full grids in Forgotten Era, then the GS1000 were allowed in the class. The writing was on the wall then. How could a period Triumph compete against them?
Then the death of the class was when the TZ700/750's were allowed in, & became Post Classic. History repeating it self.
I find it rich that you state that the class is dead but then you sing the virtue's of the TZ, which put winning a sidecar race beyond the reach of the average working racer in the 70's.

As I have proven there where no big Bm and Imps in the period as you could only run a 1000cc end of. With the discs its simple they use a disc of say 7mm then use a top hat bush of 7.5mm with a bolt going though it, .5mm float ! Your engine John is in the 750 class, so does not come under what I am talking about, as I am refering to stroked big bore BMWs and Imps. Yes Carbon Fibre wet lay is still lighter than fibre glass and besides your not allowed to use it . Thats my final word on it as we could debate all day and I have bikes to build

petercaughlin wrote:Absolutely correct, Imps were in the main 875, I believe the Sunbeam Stilletto was 990 and its impossible to get a 750 BM engine out to 1200

Peter, Using an R75/5 crank you can get a BMW out to above 1170cc i am told also it is reputed that someone in Germany has them to 1220cc with this crank.

The pic I posted in a previous post shows an outfit which is one of three which was built by Mike Harris with assistance from myself, it has floating disc's of the type which Mike Richards described in his post. This was in late 60's early 70's as can be seen by the vehicles in backround.The points peeps are making against big BM's and IMP's has another defence and that is a lot of the bike engines in s/cars of the period were bored and stroked and some had OHC conversions so why shouldn't BM's and IMP's be bored and stroked. As some of us have an engineering backround we get our buzz from doing these things within the rules. Also very interesting is that it was built using mostly box tubing and yet the CRMC banned a Championship winning Imp for being constructed from this type of tubing.At one stage it was owned and raced by Bludges DAD John Smith. During this period I made a replacement s/arm for our Weslake which Ian McGee rode and one on the repair on a 60's Imp chassis,both from the same length box tubing.Ian's s/arm was banned,reason " box tube was not used in period", the Imp chassis with a Triumph fitted however was given eligibility by the same person. My point is that the S/car rules need to be tightened up before going much further as it has shown in thread that there is a wide range of interpretation on a lot of points, a lot of which should be sorted out with factual evidence and not just hearsay. There is so much pictorial evidence available that it shouldn't be to difficult. .