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sptifre 1500 rotoflex conversion: yes or not ?


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It might be a silly question, but:
What is the best rear suspension stting for Spitfire 1500 ?
Standard: swing spring type & long drive-shfats
Will it be an improvement to use the rotoflex susepnsion system?

May you explain to me what will be the benefit or not to do a rotoflex conversion from GT6?

As usual: Many thanks for help and avices

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Every one has there own oppinion, and this is mine.
If you can be bothered to spend a lot of money and time, it will inprove the rear end,
But the swing spring is a cheap and easy to maintain compromise.

What will you be useing the car for??????

I have a spit mk2 and a GT6 mk1, I have put rotoflex to both.
That does not mean every one should, But I thought it worth it.

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Swing spring is cheaper to maintain, easily.

I converted my rotoflex car to swing spring in the late 70s/early 80s, as there was a memo recommending the conversion from JRT competition dept. Bought the stuff, put it on, & about 5 or 6 months later decided I liked it better the way it had been before & switched it back.  JRT made a nice little chunk of change off me, though.

Upside: I have the pieces for a swing-spring conversion if Metalastik stops producing rotoflex couplings, which I doubt will happen for some considerable time.  They're couplings for industrial machinery, & really nifty low-tech, high cross-application items.

Unless you're putting  8 bazillion hp through the rear end & would rather not spend the $120 bucks to replace the couplings every  three or so years, stick with what you've got.

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Many thanks to all of you.
The_nutter: it is a very interesting link. The weight difference is very important.
As Piero said: Every one has there own opinion.
I was reading old books about this subject and I visited website showing the conversion process: it is not an easy job...

I have a question for James:
you said "As long as it's low enough it handles great" : "with diff  spacer" for example ? or lower holes on the vertical links?

Many Many thanks again

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Were any of the Spitfires ever orignally made with rotoflex suspension?

This doesn't do much to shed more light on popeye's question, but in case it's of any use:

There were 3 rear suspension setups on the GT6, in order:
1.  Swing axle (Mk1)
2.  Rotoflex (Mk2/+, early Mk3)
3.  Swing spring (late Mk3)

The interesting article posted by the_nutter only compares the Swing Axle to Rotoflex.  It doesn't examine the later swing spring.

I can't think of a published technical comparison between the rotoflex & later swing spring.

For the morbidly curious, here's a scan of some info from the BL competition department on Spitfire & GT6 owner conversion to swing spring.  It's undated, but was probably received by me with a bunch of stuff in 1980.  I also suspect that it was originally printed before then, & sent out with other material through the years.

It is a little misleading in its reference to 'earlier cars'.  Even though the bulletin at the top mentions GT6 MkI, MkII & MkIII, I'm pretty sure it is meant to apply only to the cars with the original swing axle (i.e., the Mk1 for GT6), as the parts for the conversion are specified only as the swing spring parts  For a rotoflex car to convert to swing spring, axles, etc. must also be replaced (otherwise the car would have both rotoflex & swing spring & could barely go around the block at low speed, please don't ask how I know).

Short version:  It's a recommendation & parts list to convert the earlier (pre-rotoflex) swing axle cars to swing spring for much improved handling at low cost (& effort).

Huge size for part number legibility:

If popeye's got a swing spring car, I'd think staying with it should be fine.  Isn't GT6Steve's car swing spring?  

Cliftyhanger's point of comparing worn swing spring to new rotoflex is valid.  Thinking about that, what are the points of wear on a swing spring setup?  It looks like it would be wear from the differential's studs on the clamp plate/pivot on top, & perhaps wearing of the studs into the sides of the spring.

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None of the Spitfires were ever fitted with rotoflex.

There can't be that many points of wear on a swing-spring car - only the radius arms (and top spring eye - but that must be negligible) have bushes.

The rotoflex of course has the inner wishbone bush also - if anything is going to make the rear end tighter it must be that?

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Both my cars are swingers - the Gitfire and the PI Vitesse - no adverse effects, haven't lost a wheel (yet). The big downside for me is that this set up doesn't allow you to load the car up as much as rotoflex so when I go camping I worry about the weight going into the car!

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At present I have Rotaflex on my Spitfire (non-original).

I think there are two things on the downside.

1) unsprung weight
2) life of the coupling & cost + time

Canleys now do the wish-bone and the vertical link in aluminium so that helps the unsprung weight and there are a couple routes to do a CV conversion to replace the doughnut.

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Jason wrote:
The big downside for me is that this set up doesn't allow you to load the car up as much as rotoflex so when I go camping I worry about the weight going into the car!

Maybe you could add some of those mini adjustable coil overs & wind them up on camping weekends, or you can also get air adjustable shocks?

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Many thanks for advices and comments,

Rotoflex, I can't see any scanned documents: it seems it didn't work.
May you try again to post them in the forum ? or send me them to my private email?

For the moment, the car has the long shafts and swing spring. I often see rotoflex conversion on UK cars... but,  I haven't red good things concerning the couplings quality and reliabilty...

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Like I said, it is unclear but obviously refers to changing the swing axle cars to swing spring, not the rotoflex cars to swing spring (which requires more parts).

Actually, if I had one of the later swing spring cars, I'd be sort of relieved at not having to worry about the couplings' condition & availability.

I'd really like to see some technical info about the camber compensators that were recommended for the swing spring cars.  Didn't Kas Kastner have some experience/insight regarding them?  Jonathan Binnington had some made up at one time.

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Many thanks for these document: very nice. If you have other BL competion dept doucuments concerning spitfire about engines, suspension set up, brakes...they are very welcome.

I have heard some a GT6 owner that Kas Kastner recommended the fitting of the swing spring set up instead of the rotoflex system for  the GT6MKII. This owner told me it was written in one GT6 competition book...

Concernin the camber compensator: I know they are still produced; even if for the late spitfire and GT6. But, they required the fitting of the earlier spring to use the compensator.
If you are interested in the saler address for the compensators: I can do a research  and let you know; just let me know.

Many Many thanks again

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jcarruthers wrote:
If they are super low they handle brilliantly... of course you sacrifice ground clearance.

Doug - yours looks low enough!

Cheers James - there was a point in time I was considering raising it back up again for fear of the many Ferries I took the car on in 2007 - but while it felt like a close thing no contact was made with getting on and off the ferries so will be sticking with it as is.

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