Wilwood adapter


Well-known member
Nov 5, 2011
Thought this was interesting: Wilwood 340-16920.

340-16928 or 340-16920, probably need to dig to figure out the difference.

"Includes Pushrod Eyelet" <— Must be the reason for price difference.
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Yes. The facebook marketplace photo at the top was $500. It sold very fast. It had an extra aluminum adapter for a particular car.

I was curious as I like this idea. Summit sells a $370 kit. Getting the right bore size is key. Years ago I bought some, I think 1" bore was recommended for a c3. But you know what they say about free advice….

Wilwood Master Cylinders and Tandem Mount Balance Bar Kits S0002[

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Wilwood offers a compact aluminum master cylinder specifically engineered for the manual brakes on C2 Corvettes. Not only is this an all-new, lightweight unit, but the bore is sized to make the brakes more effective with less pedal effort. Part number 260-16521, with a 15/16" bore, improves line pressure by more than 10% for a given amount of pedal force compared to the stock 1" bore. For a further reduction in pedal effort or increase in caliper clamping force, part number 260-16520 has a 7/8" bore.

Below from VanSteel

"C2/C3 Wilwood Master Cylinders
The hydraulic side of the brake system is based on leverage ratios. The overall system leverage ratio is a function of:
1. Brake pedal ratio
2. Master cylinder bore size
3. Effective caliper piston area
An OE manual brake C2 or C3 by my comparison formula has a 36:1 front circuit leverage ratio. The rear circuit is a little over 19:1. When you compare those two leverage ratios front to rear, that gives you your static front to rear bias ratio which in this case is 65/35.
If you use the 1.125″ MC on a manual brake D8 caliper car, instead of the normal 1″, your front leverage drops to 28.5:1. When you drop to the piston area of his SL6 calipers, and using the 1.125″ power brake master cylinder, your front leverage ratio drops to 21:1, representing a 39% loss in brake leverage from OE D8. That translates to requiring 39% more leg effort to get comparable clamping force.

So yes, it will make a measurable difference.

And for an FYI, the current version of the SL6 using 1.75/1.25/1.25 pistons with a 15/16″ bore master cylinder give a front circuit leverage ratio of 36.19:1 which is a hair higher than OE D8 manual, but probably not enough to feel a difference.

If you install the 7/8″ master cylinder, this will restore the front leverage ratio to 34.7:1, or almost back to to OE D8 effort levels. The pedal will be slightly firmer than an OE D8 manual brake car, but will now be able to make 39% more pressure with the same amount of pedal effort."
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I'll shout out to HP Academy.
These Kiwis have a wealth of information on YT as well as their web site.
They were running a 50% off special on some of their classes at Christmas - and I almost went for it.
Quality was good - just figured I had too much time at the PC already - and not enough in the garage.
There are a bunch of white papers (under "tech"as I recall) you can download too.

Good find.

Cheers - Jim
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