[Fot] in search of

[Barr, Scott]

It must work great or you wouldn’t have used it so successfully for 40 years, but…when under straight line braking, when the droop get arrested by the cable, doesn’t it go from whatever the spring’s rate is instantly to infinite spring rate?  Am I understanding that correctly?  And that change caused no trouble for you?

Scott (B.)


From: Fot <fot-bounces at autox.team.net> On Behalf Of rocky spitfire4.com via Fot
Sent: Thursday, March 20, 2025 12:51 PM
To: JOE CURRY <spitlist at cox.net>; FOT Triumph <fot at autox.team.net>; ralph hansen <quikrx at yahoo.com>
Subject: Re: [Fot] in search of

Are we talking the camber compensator for the Spitfire that has a middle mounting bolted to the bottom three bolts of the differential?

The scariest moment I ever had in my 1964 Spitfire, back when it was my daily driver (ca. 1967), was when my diff locked up as I was passing a semi on I-35 in Kansas City. I barely got the car over to the shoulder without getting run over, then spent six hours on the roadside waiting for AAA to send me a tow truck! (That’s when I decided not to renew my AAA membership, but I digress).

Turned out the middle mounting on that camber compensator had broken off the sections on the two end bolts because of the constant flexing on it, so only the middle bolt was holding it in place. The constant action on that one bolt eventually made the round bolt hole oval shaped, and all the diff fluid drained out. A dry diff really doesn’t work all that well.

I drove the car without a CC for a few years, then gave it to my brother (who’s a mechanic) to turn into a race car, He came up with a solution which I understand originated with Volkswagen owners to address the Beetle’s swing-axle issues.

He tied a cable to the bottom shock mount, ran it up to a pulley attached to the top shock mount, then across to the same setup on the other side.
[A diagram of a shock bolt  AI-generated content may be incorrect.]
The biggest modification was to take that big bolt at the top of the shock, drill and tap it through the head to take a shouldered 1/4-inch bolt which becomes the hub for the pulley. Not shown, a simple retainer over the top of the pulley to prevent the cable from jumping off.

He did that in 1971. He raced the car for three years, then I got it back and raced and autocrossed it through 2011. In all that time, 40 years, I replaced the cable just once.

Since it was going on a race car, we jacked the rear suspension as high as we could (filled the trunk with heavy stuff while the car was on jackstands, then sat someone in the trunk while we attached the cable) which both lowered the car and stiffened the ride. I later bought another ’64 Spit as a street car and did the same trick, but let the suspension droop more so it was softer for street use (I also didn’t autocross that car). On that one I found a pulley that came with a shroud, didn’t need the retainer.

It works as a camber compensator without that evil spring. The swing axle doesn’t swing any more. Both rear wheels remain constant with each other.

I’ve given this design to several other drivers. One came up with a clever trick – he cut an opening in the diff tunnel under the gas tank (which also provides nice access to the bolts holding the spring to the top of the diff). Then he installed a turnbuckle in the cable at that location. Adjustable suspension! Cheap and easy. And IMHO safer.

—Rocky Entriken



From: Fot <fot-bounces at autox.team.net<mailto:fot-bounces at autox.team.net>> On Behalf Of JOE CURRY via Fot
Sent: Thursday, March 20, 2025 10:02 AM
To: FOT Triumph <fot at autox.team.net<mailto:fot at autox.team.net>>; ralph hansen <quikrx at yahoo.com<mailto:quikrx at yahoo.com>>
Subject: Re: [Fot] in search of

It has been that way for years.  It became impossible for me to market them at the price that I knew was affordable for most Spitfire owners.  Therein lies the rub!

Good luck.

Joe

On Thursday, March 20, 2025 at 07:48:44 AM MST, ralph hansen via Fot <fot at autox.team.net<mailto:fot at autox.team.net>> wrote:


hello everyone,

I'm looking for a leaf spring manufacturer to make up about 25 single leaf springs. Preferably close to Milwaukee but just about anywhere might work. Must do good work and be reliable. These springs would be for the TR camber compensators. Doing some shopping around since one I've used has doubled the cost in 5 years. Thanks in advance.

Cheers,
Ralph
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