Throttle body 2nd return spring (MSA Reg)

[apjenkins]

Hi Guy's

Having replaced my cra* plastic throttle body with a 48mm Alloy one (thank's Oiley) I note that the alloy one only has one throttle return {clock type} spring as opposed to the two fitted to the plastic throttle body. Whilst I appriciate that the T.P.S. has an internal spring, I don't think that will 'wash' with the MSA Scrut's.

So what is the best solution for a second spring at the throttle body??

Pic's would be great.

Thank's

@ndrew

[Richard Price]

Andrew,

If I recall correctly, the therm is something like "one spring per throttle spindle".

 

The standard throttle body return spring has been OK with scrutineers all the time I've been running my car.

 

 

[CaterBram]

So is it Class 4 next year then 😳

 

My understanding of the regulation from what the scrutineers told me and reading the blue book is that each seperate throttle shaft should not rely on any linkage between them and therefore needs a seperate spring.

 

If you are using a single throttle body there is only one throttle shaft therefore only one spring required.

 

Page 144 Reg 5.4.2. Be equipped with a positive method of throttle closing by means of external spring/springs so that in the event of failure of any part of the throttle linkage the throttle(s) are sprung closed.

 

Edited by - CaterBram Jnr on 13 Feb 2012 20:14:54

[apjenkins]

Thank's Guy's,

My mind set was on twin DCOE's But understand and are happy with your explanations - thank's

Chris, it could be class 2 - 3 - not 4!!!!

[CaterBram]

Andy, I assumed that you were running a K series which in class 2 & 3 would need a standard production plenum rather than an alloy one. Remembered from discussions going on in the padock at Aintree last year.

 

Edited by - CaterBram Jnr on 13 Feb 2012 20:53:53

[apjenkins]

O.K. So clarification is required.

 

I have a K series 1600cc SS engine that had a plastic throttle body that was distorted.

 

I have replaced it with a S/H standard Rover 48mm Alloy throttle body.

 

Does this allow me to stay in class 2/3?

 

@ndrew

[CaterBram]

Andrew,

 

Might worth an email to Simon to clarrify the position,

 

the relevant section of the 2012 Championship regulations is

Class2&3 item 4. Rover K series 1600cc engines - provided induction is via the standard production plenum.

 

Chris.

[Lee Fowler]

Quoting Richard Price: 

Andrew,

If I recall correctly, the therm is something like "one spring per throttle spindle".

 

The standard throttle body return spring has been OK with scrutineers all the time I've been running my car.

 

 

MSA Blue Book J 5.4.2. Be equipped with a positive method of throttle closing by meams of external spring/springs so that in the event of failure of any part of the throttle linkage the throttle(s) are sprung closed.

 

Lee

[Matthew Willoughby]

Andrew,

 

I am sure that you will be fine running with an 48m alloy throttle body in class 2 or 3. The regs state that you can replace the standard tb with a 52mm one, which is what I did on my Roadsport A, so I can see no problem with going from a plastic 48mm to an alloy 48mm. Caterbram is confusing the plenum and the throttle body - you will still be using the standard plenum with the new tb so there is no problem with the regs in that respect.

 

 

[CaterBram]

now I see the light 😶‍🌫️, don't have strange things like flenum and tottle frodies on mine. Just nice webbers 😬

 

Edited by - CaterBram Jnr on 14 Feb 2012 07:57:38

[david nelson]

No problem with changing the TB from plastic to ali. I would have thought most of the paddock will have done this if they had a plastic one. I am told the plastic ones stick but never had any issues with mine.

 

David

[apjenkins]

Thank's all,

 

All makes logical sense

 

Off to the Blue Book to check out list 1a tyres 😬

 

@ndrew

 

[CaterBram]

Umm don't you mean list 1B 😬

 

Might as well go for the sticky stuff to suit you nice new Supersport 😬

 

 

[apjenkins]

I'm having a whip round 😬

[Alan Bowler]

Another £50 in the post for the Jenkins 1B tyre fund.

 

52mm TB seems to be a fairly standard upgrade for class 2/3 K's.

Also, there was an article in a recent Low Flying about modifying

the alloy 48mm to give you the same results, and saving the ~£100.

 

AB

 

[Stuart Miller 7]

Talking of return springs, has anyone ever fitted an external secondary return sping to the standard PTP throttle bodies I have on my SLR engine?

 

I had my throttles stick at Llandow 2 years ago which "we" (thank you Mark) fixed with a cable tie around the spring to hold it on the shaft properly. It stayed like that until they jammed at 8K rpm in 1st on the road. 20yards in not enough distance in which to hit the clutch, brakes and ignition, just so you know! Long front and several other bits totalling about 5.5K£ later is not something I want to repeat.

 

I've been meaning to come up with something mechanical that will shut the throttles should this happen again, but to date, I can't think how to do it. If anyone has any bright ideas, please feel free to pass them this way.

 

By the way, if you run throttle bodies, it's worth a strip down and service (graphite lube spray is excellent) every so often. There was an amazing amount of crap in there that you couldn't see until they were in bits.

 

Stuart