Ron Sutton Offset 3-Link install

[rustomatic]

That biscuit bar looks familiar, but much nicer than mine. I recently swapped my biscuit bar out for a straight shaft/tube, because one of the multitude of joints always seemed to work its way loose after a bit of street driving/track thrashing, creating a horrifically irritating screech/vibe. Granted, I'm no skilled builder, and my tubing sizes have probably just not been containing enough thread engagement or something.

I'd like to re-enlist the biscuit bar eventually, because it very clearly worked overtime at all kinds of frequencies of axle movement--is there a secret to keeping all the threaded joints happy (with or without Locktite)?

I can see Ron's setup working its way onto a lot of future hotrods, because it's basic, strong, and has clearly included "awesome sauce" in the recipe...

[Flash68]

Originally Posted by Ron in SoCal

I can see Ron's setup working its way onto a lot of future hotrods, because it's basic, strong, and has clearly included "awesome sauce" in the recipe...

And the Sutton secret awesome hot sauce sprinkled on cheese balls can make even Ron Myers (TBD) and Sieg (already determined) FAST... just ask Sieg.

[Ron in SoCal]

^ creative editing right there

Davey

[Ron Sutton]

Originally Posted by Flash68

And the Sutton secret awesome hot sauce sprinkled on cheese balls can make even Ron Myers (TBD) and Sieg (already determined) FAST... just ask Sieg.

Aren't those YOUR cheeseballs ... Cheesball?

[Ron Sutton]

Originally Posted by Ron in SoCal

Quick tech updates on this 3-link ...

A. With all 4-link, centered 3-link, torque arm, leaf spring & truck arm rear suspensions ... we experience a degree of "torque steer" ... where the left rear tire receives more loading ... and more grip ... under corner acceleration. This makes cars tighter on the exit of LH corners & looser exit of RH corners.

B. In an offset 3-link, we offset the top link to the passenger side a specific amount to eliminate torque steer, so the tire loading & grip are equal on both LH & RH corner exits.

C. The amount to offset the top link is based on calculations I do involving the friction in the rear end assembly & track width.

D. I do a lot of 3-links for racers where the top link is a typical tube with no torque absorber. If you have plenty of tire for the power output, they work fine. The torque absorber top link ... does just what its name implies ... absorbs some of the initial torque when the driver cracks the throttle. This softens the "hit" or "shock" to the rear tires ... which is especially helpful to tires of low profile, stiff sidewall, radial, harder rubber (58+ duro) ... or some combination of these designs.

E. I work out the durometer/spring rate of poly bushings to use ... and the number of bushings ... based on the power, gearing, length of upper mount, angle of top link, car weight & tires used in each application. I have 32 different combinations. For Ron Myers' track car ... with slicks, we only use 2 accel bushings & 1 decel bushing. All 3 are 80 durometer. The 2 accel bushings will compress about .70" with 1050# of force.

F. The top link mount you see clamped to the round tube is a top link screw adjuster. In Ron's car, a small aluminum rod with an upside down aluminum cone will pass through a bushing in his sheetmetal structure above the 3-link & behind the roll cage main hoop. Ron will be able to fine tune the top link angle easily with a 1/2" ratchet dropped into that cone. It is fine tunable as 3 full turns is 1 degree of top link angle change.

G. On track or autocross days when the track surface is not very grippy (too cold, too hot, dusty, old asphalt, etc) Ron can adjust the top link down in the front (increasing the top link angle) to add more initial grip. If you go too far & it pushes on exit ... simply raise it back up some.
* On really grippy days, too much down angle will provide initial bite but get the back end loose near the end of the corner exit. In this case, the tuner adjusts the front of the top link up until the "late loose" condition goes away.

H. If a tuner gets too greedy going for initial grip ... by lowering the front of the top link too far ... the car will start to get free or loose on entry. With a quick-n-easy adjuster like this, Ron can tune for optimum balance without ever getting under the car.

I. One of THE most important design points on any link suspension is ... how long are the "levers" ... which is what the upper & lower housing brackets really are. The length of the upper & lower housing brackets determine how the rear end's rotational torque is distributed.

J. Just to help understand what we're dealing with ... a car with 550# of torque, a 2nd gear ratio of 1.76, rear gear ratio of 3.70 puts almost 3600# of torque attempting to rotate the housing (exiting a corner in 2nd gear).

K. With this Camaro, the lower link mounts 5.5" below the axle CL & the upper link mounts 5" above the axle CL. That ratio puts 52% of this 3600# torque through the lower links pushing the chassis forward ... puts 48% through the top link pulling up ... lifting the chassis & loading the rear tires. This ratio matters MORE than anti-squat, but is rarely understood.

L. Yes, a car can have too much or too little "lift & load" ratio. It all comes down to the power, gearing, car weight & tires. Every car has a different "optimum set-up."

M. I have had occasional guys tell me they tried torque absorbers & it didn't work for them. They didn't understand the "lift & load" ratio ... and didn't understand the torque absorber bushing package has to be matched well to the "lift & load ratio."

[carbuff]

As always, love the detailed explanation Ron! One simple question...

If the top link comes all the way up to the roll bar of the car, how will / do you isolate it from the outside of the car? It will pass through a firewall where the rear seat was, but given that you want internal access to adjust it, where would you seal off the rear firewall to isolate the interior of the car?

Probably a simple answer that I'm just not thinking of at the moment...

[Ron Sutton]

Originally Posted by carbuff

As always, love the detailed explanation Ron! One simple question...

If the top link comes all the way up to the roll bar of the car, how will / do you isolate it from the outside of the car? It will pass through a firewall where the rear seat was, but given that you want internal access to adjust it, where would you seal off the rear firewall to isolate the interior of the car?

Probably a simple answer that I'm just not thinking of at the moment...

Hi Bryan,
Great question. there are three different ways we have done what you're asking about. The original illustration I provided Ron Myers (that he posted) did not show how we do that. The illustration at the bottom shows the option Ron Myers choose.

In this case, Mike Tolle of Tolle Fab will build the upright tube that the top link adjuster clamps to (light blue bar in the illustration) ... with a bottom curve in it. This curved tube butts & welds to the back side of the 2"x3" crossmember. There is horizontal cross bar from one leg of the main hoop to the other. It is also curved to set it back. The upright tube attaches to this horizontal cross bar. You can see them both (light blue) in the illustration.

We do this to set the upright tube & the toplink adjuster back behind the main hoop. Then the green dotted line shows where the aluminum sheet metal work goes ... sealing the rear suspension off from the cockpit. The top link adjuster sticks through the sheet metal with a special bushing. It is just behind the passenger seat (remember ... the top link is offset) for easy access & tuning.

Make sense?



.

[Ron in SoCal]

Way to bring it Ron!

Happy New Year

[Vegas69]

I'd like to see one modification to the design. A major adjustment available to the driver. He'll clearly be out of excuses when this one hits the road in his golden years.

[carbuff]

Originally Posted by Ron Sutton

Make sense?


.

Got it... Makes perfect sense.

One other question while I'm here... From a top-view, are the 2 lower arms parallel to each other, or do you angle them inward towards the front of the car? You have likely touched on this in a post somewhere. I'm not sure if anyone else makes them this way, but the Lateral Dynamics 3-link that a few cars here ran angled the LCA's inward as they went forward. I'm not sure if I've ever known what the reason for that was...