Bike engined car chains

[Jeff 8]

How do bike engined cars go with chains? They are designed for a 190kg bike with a small contact patch so how do they go in a car? I have seen sidecars break chains often and they only have one 10" slick not two and a wing. I have seen hillclimb cars with 300 horsepower bike engines so I am curious what chains they run and how long they last.

Jeff

[b1ackcr0w]

In short, extremely well. They occasionally break, but not that often. I noticed a couple of seasons ago that OMS had started putting two chains on their heavier cars. I'd reckon that proper lubrication and regular tension checks are the key to avoiding breaks.

[LCM]

In my experience, they go from excellent in a light single seater with a not too powerful engine to dreadful in a heavier sports racer with a more powerful engine.

Using a single top quality 530 pitch GP grade chain on a 1500 Radical, I got through at least one chain a day. It wasn't so much breaking that was the problem as the fact that they stretched unevenly under the initial shock loading of a standing start on sticky slicks. The uneven stretch then developed until the chain could no longer retain register the whole way round the rear sprocket. This initiated a wave motion in the chain which caused it to jump teeth under load, leading to lack of driver confidence, damaged sprockets and ultimately chain breakage.

My solution was to fit an HD output shaft, outboard support bearing and twin chains. The result is that I've run what is now a 1600 Radical nearly every weekend for a whole season on the same set of chains with total reliability and, perhaps more importantly, total driver confidence.

[marchof73]

Excellent reply LCM.
What would happen if you fitted two sets of chains,with sprockets of different numbers but same ratio?
ie 12/60 and 14/70 so overall ratio is the same.
Would this reduce wear even more?
Just a thought
Ian

[LCM]

Originally Posted by marchof73

Excellent reply LCM.
What would happen if you fitted two sets of chains,with sprockets of different numbers but same ratio?
ie 12/60 and 14/70 so overall ratio is the same.
Would this reduce wear even more?
Just a thought
Ian

I going for a cold towel to wrap round my head to think about that one (for several days), seasonal excesses of food and beverage permitting, so don't expect anything sensible before next year!

My initial reaction is that it would bring 2 difficulties.

Firstly, a practical engineering difficulty in manufacturing the components. We use one piece front and rear sprocket sets that are machined from billet ie a central cylinder with a flange at each end machined with the sprocket teeth (the rear set also has an offset flange left inside the cylinder for mounting it on the diff). This allowed us to locate the sprockets precisely on the output shaft and on the diff so as to maintain accurate chain alignment and ensure that the chains are truly parallel.

Secondly, as the chains would follow dissimilar paths, I'm not sure that you'd get quite the same degree of load equalisation as you do with similar parallel paths. We thought about the theory of twin chains a lot before doing it and encountered a lot of naysayers in the process. One of the benefits we hoped for was dynamic load equalisation but were told by many "Paddock Experts" that it would be impossible to equalise static tension on the chains and the whole system wouldn't work. Well, in practice we have found that we only have to adjust the chains roughly to balance the tension when installing them and that dynamic (and a slight amount of permanent) stretching takes care of the rest when running the car so that the load is automatically equalised between the chains.

Thirdly (yes, there's always something else when you least expect it). With a Haybusa we tend to run ratios around 15:48 (ie 1:3.2). I'm struggling to find another set of sprockets that would give the same ratio with a whole number of teeth and still fit in the chassis. Obviously other engines have different power bands and primary reduction ratios so would need different fial drive ratios.

[jedrinck]

Does a Hayabusa gearbox last long when it has to move twice the designed weight and 50% more power?

[LCM]

Originally Posted by jedrinck

Does a Hayabusa gearbox last long when it has to move twice the designed weight and 50% more power?

I suppose that it depends what you do with it!

I've now completed 2 seasons hillclimbing and sprinting on the same gearbox. Most weekends from March to October I do at least one event and some weekends two.

At the end of 2007 the standard Suzuki output shaft sheared shortly after fitting the twin chain system and while trying drag bike chains. For 2008 we fitted a heavy duty output shaft (ie with Honda external splines) and continued to run the twin chain system with an external support bearing but reverting to ERV GP chains. The gearbox has run faultlessly all season. The engine has just been stripped for a winter check and the gearbox looks perfect.

That said, I have been using the clutch for most changes (but not all up shifts) and I do tend to change gear very fast.

So far I've been pleasantly surprised how sweet and reliable the Suzuki 'box has been especially when compared with the 'box in my Caterham.

[marchof73]

Originally Posted by LCM

I going for a cold towel to wrap round my head to think about that one (for several days), seasonal excesses of food and beverage permitting, so don't expect anything sensible before next year!

Again,an excellent answer LCM,Thanks.
I don,t get to too many hillclimbs here in Houston Tx so am only talking from theory.
I can now see your ease of manufacture--always good,and it would appear I have suggested something that was not fully thought out,especially with the ratio you are running--oh well,
seasons greetings
Ian

[chris.c.thompson]

Hi there is a engineering competion run by the SAE in America called Formula SAE and the ImechE in the UK called Fromula student.
Most of these guys run chain drive bike engine single seaters. They are good to look at for ideas some run double chain, helsinki ran it in 2006, i have even seen belt drives like a snow mobile.

[LCM]

For those interested in exploring the mechanics of chain drives, there's a very good article by Forbes Aird in the April edition of Racecar Engineering.

Reading it, I realise how well I've done to get a whole season of sprinting and hillclimbing out of a single pair of chains!

[St Eval]

Hi, we used to use the high quality Superbike chains as fitted standard to Hyabusa, Blackbird etc. Never ever had a chain failure, we did 3 double driven seasons with a Blackbird in an Imp that car was sold and as far as I know it still has the same chain 8 years later. We then ran a Blackbird in a single seater for 4 years double driven again with no probs the engine was putting out in excess of 185 bhp and the seasons were around 26 meetings. In my opinion the problem that seems to occur with a lot of set ups is that the sprockets are not properly aligned, this causes premature failure in the chains.