Kid Vette

The picture I posted above is with 2 of the supplied washers under each caliper mounting bolt.

Your comment about "many other after market parts on the car" is totally bogus. The differential, halfshafts, struts, spring, trailing arms or any other suspension piece have absolutely no effect on the positioning of the caliper over the rotor. You're only showing your ignorance by suggesting these components would have some effect on the issue I'm having. By the way, the rotors are Wilwood and were purchased at the same time as the calipers.

Below is a pic of the C3 rear suspension.



As you can see the spindle assembly is a self contained unit that merely bolts to the rear trailing arms. My spindle assemblies were done by Mike Dyer, one of the best in the business and are made up of only stock GM parts. And as you can see in the pic, the dust shields are installed.

And what's your excuse for the necessity of repositioning the caliper to bleed all the air out? I suppose that's because its "a highly modified car" as well. I wish you and tech support would devote your efforts into correcting the problems with your product rather than blaming the suckers who purchased them.

RBrid

I installed the Wilwood kit in March, front and rear, with Wilwood rotors. I had to shim the rear ones too to center them.





Used Loctite for the bolts as instructed. Guess I will have to take them off again when the time comes to fill up the system. Bummer.

jb78L-82

Holy Smokes! This "bolt on" system seems like a freakin nightmare. A couple of thoughts:

In terms of the correct orientation of putting the willwood caliper on at each wheel of the car, why doesn't willwood simply just put a sticker on each caliper indicating front driver side with an arrow pointing towards front, as an example, for each caliper (rear drivers side, front arrow, etc) to eliminate the correct caliper and orientation for each wheel? Slotted aftermarket rotor manufacturers do this all the time (I know from many applications on my cars).

The shimming issue for their calipers tells me that their calipers are not made specifically for the C3 brake system...generic caliper made to fit many cars. Looks like a cost saving move. If the caliper was a direct fit replacement for the C3 cast iron brake caliper there would be no need for shimming.

I am still waiting for someone to make a caliper bracket that allows the use of the C3 stock caliper with a larger 13/14 inch rotor..not sure if there is a GM 13/14 inch rotor that could be used on a C3 spindle. I know that just going o a larger rotor with the same caliper would be beneficial in terms of increasing braking force. I just did this exact conversion on my 2001 Pontiac Grand Prix with stock 11 inch front rotor and GM W body (Grand Prix) single piston floating caliper to a 2001 Impala front caliper bracket ($10 a piece) using the same GM single piston Pontiac Grand Prix caliper which allows the use of the 12 inch vented Impala rotor. There is a noticeable increase in braking on the GP and a lot less pedal effort for $20...the rotors are the same price for the 11 inch GP and 12 inch impala rotors.

0Todd TCE

My apologies for my total ignorance on such thing. I'm new to this stuff. Clearly none of the other items on the car could be the ones to create the issue...

I'm not taking sides here folks just saying that with nearly 25yrs in the brake biz things are not always what they first appear. Caliper centering is effected by a variety of things. For those 'in the know'; where the minor changes from the C2 to C3 suspension that would make it different??

There's a clear and very easy way to determine the exact situation: compare the Wilwood parts to that of the stock ones by re fitting the stock stuff for a bit and see what you find. A simple process of elimination should quickly point out the culprit. It's either the caliper or the rotor. (or something else) I'm curious...find out.



Most of the differential bore calipers are marked for rotations. I can't say the D8-6 is however. Can't say I ever looked. *not easy to see but look at the 6 Piston





Can't really say much to the nightmare, I've sold dozens and there are clearly hundreds in service so other folks must not have the same sleep habits.

ignatz

All I want is all of the performance that is inherently there, and that I paid for. I am unclear if I don't get all the air out whether that is the case. Pressing on the pedal eventually brings the compressed air in the system to equilibrium. However it is compressible whereas hydraulic fluid is not. That means that the time domain response of the rear brakes is not that of the fronts. So what have I lost? Anybody care to explain whether there is an actual loss of braking capability? Seat of the pants, it feels like that may be the case. The only simple test I can think of is gross, get out on the road and see if I can lock up all fours. Anybody got anything better?

0Todd TCE

Clearly not getting all the air out is an issue. Please don't overlook the need for proper bleeding. We can argue day and night the design not allowing it to be bled as mounted..in the end that's irrelevant to the need for purging the system. I agree it's not the ideal situation for bleeding- removing the caliper but it's not that difficult and not worth the grief of a soft pedal and lack of responsiveness.

As you say; the air can be compressed and that leads to a spongy pedal. Nobody likes that. And if the fronts are bled totally they'd be grabbing more than the rears relative to bias. As well as mush sooner seeing there's no compressing of trapped air.

Hope that helps. Please take time to do it right.

Kid Vette

Well, I noticed RBrid has what appears to be Wilwood rotors same as me so maybe that's where the problem lies since we are are the only ones out of the hundreds that had to shim the calipers.

My stock calipers and rotors are long gone so I can't do the comparison you suggested. So I guess Wilwood is going to have to do their own R&D rather than have me do it for them for free. I'm curious too...let me know what they find out.

ignatz

All Wilwood needs is an old stock rotor to compare to theirs. Simple job for a new hire to measure the stock machined surfaces and compare. Surely there's a mechanical drawing for their rotors on file or in the public domain. Can't be that much effort to be at least this responsive.

0Todd TCE

Guys...really. Do you think someone just pulled numbers out of thin air to produce these parts? They were of course copied from oe parts or those supplied to them for that purpose. These entire kits came about by the request of a very large Corvette parts supplier who is also a vendor here.

Did they supply Wilwood incorrect parts? How would either of us know. But they were 'signed off' being correct by that vendor who had a somewhat exclusive on them for a bit of time.

But no...being in the business I've yet to see mechanical drawings for parts like any of this in any public domain. Wish that were the case; make my life a helluva lot easier.

And while it's noted that two owners here have Wilwood rotors and calipers sporting the reported problem...both of those cars clearly have non oe rear end items in them also. Right or wrong on this the fact that the caliper was the last item installed on the build is in no way conclusive of the cause for it. I don't profess to be a Corvette guru in any way but any number of the things I mentioned above "could and can" do cause caliper alignment issues. Neither of the cars are using bone stock parts- which of course would have been what the calipers and rotors were intended to replicate.

I have in my hands a bone stock D8 rear reman and a new Centric 121.62007 rear rotor. To be fair; I doubt anyone is using oe rear rotors at this date so this is a common part to get from a lot of companies under various labels: Centric, Stoptech, Powerstop and more...hate to tell you: it's all the same Chinese company. Honestly; could well be the supplier to Wilwood too, I don't know.

So...by the latter part of next week I'll put these parts side by side on the granite table and answer your question.

If I'm wrong I'll man up and confess it. The reason it's not what it should be I cannot say- I'm not the supplier or manufacture.

If side by side the parts mic out to be nearly identical in spec I'll expect those of you who who have issues to do the same.

Clearly neither I nor other dealers or even Wilwood would be pedaling the volume of these the past five years or so if they were that far off. And knowing the love hate some of you have with 'shims' (like the ones noted in the GM image..lol) you can be sure they'd be included in the kit.

I'll go to bat for you here. If this stuff is off by some 1/8" or so you have a right to complain. Fair enough?

ignatz

I still have my stock rotors. I use them for weights when I need such. So if you need a measurement, I should have one from long ago

Kid Vette

I always love it when aftermarket parts suppliers blame the other non oe parts on your car for why theirs don't work.

Actually off by a 1/16" (or less) will cause problems. The shims I installed were 1/16" thick. That was enough to center the caliper on the rotor and keep the caliper and bolts from rubbing.

Kid Vette

Judging by this thread, Van Steel is the "very large Corvette parts supplier" you are referring to.

And on the 2nd post on that thread someone asks, "do those just bolt on to the stock caliper brackets?" Van Steel's reply, "For the 65 & up cars, yes. There are thin shims to center the caliper."

Very interesting.

0Todd TCE

To be clear; I've not once blamed anyone for anything here. I've simply stated that a combo of aftermarket parts can lead to questions of what went wrong, where and why. I just don't jump to conclusions and further research seems to bear that out.

Interesting, yes.

Who's going to be the first to call out that vendor for screwing up the design of the the "direct replacement part"? Quick to blame it on Wilwood...kinda takes a bit of tangent now huh?

Chewing on this topic from one end to the other...clearly the parts were made to their spec approved as such, and some are not happy about it. I will say that if the shims are not supplied---- that IS an issue with the 'kit' as sold. Should they be necessary; I guess that remains open to debate. Someone didn't do their homework?



I do think at the end of the day the whole topic is grossly over weighted. I do agree that if shims are needed the should be included- that's a no brainer. I'll make a note to mail folks some on future orders. I do have them in .010 .015 .030" sizes for anyone needing them. Obviously the fit can be easily accommodated with a bit of thinking. And I guess it must not be really all that bad- they're still on the car.

I'll do the measuring on this stuff and let you know what I find. Aside from that...let's move on and just say "some shimming may be required" here.

0Todd TCE

With a Wilwood and a factory 're-man' here I measured up both and depending on exacty how I did so...(the factory casting being rough on the outside don't sit well on the granite) I'd be satisfied in saying the mount offset on the Wilwood is -.030" as shown in one of the images above. The exact reason for this I cannot say. Maybe ask the guys who started the project. We could speculate but there's no point really. I'll have to look at including a couple of .030 and maybe .015" shims to my personal customer base. And I'll pass it onto the guys as well.

I also noted too that the Wilwoods are roughly 6lbs (each) lighter than the stockers. That's nearly a 25lb weight savings, that's HUGE. And for the money well in the affordable $/lb range. ($40 a pound roughly is less than some spend on batteries~)

Kid Vette

Thanks for following up with your measurements. I would recommend also including .060" shims as well since that was required to center mine. Its hard enough to install one shim but to stack and install multiple shims would be very difficult. Maybe Van Steel will chime in with their reasoning for the shims. I would would be interested to hear their logic.

I'm guessing the bleeder screw arrangement was just an engineering oversight. Seems like it would be easy to correct though. You would just need to change the location you machine for the bleeder screws. It might be just too difficult for Wilwood/Van Steel to admit they made a mistake however.

0Todd TCE

Today I compared the Wilwood rotor to that of a Centric brand replacement.

The overall height varied by .010"

The offset of it (axle flange to inner friction surface) by .015"

The face of the Wilwood rotor was .020" wider- thus pushing the wheel out a touch.

At the end of the day...which one is right?? I'm not really sure. But the variations on the two are so minimal that it alone would not create much noticeable difference. Unless someone has an NOS part I'm going to guess that any brand will have some variation....

FirebladeDan

After all that shimming nonsense your issue of a firm pedal is definitely your speed bleeders. It's allowing fluid/air out/in. Go back to original bleeder screws, gravity bleed and boom done. You're gonna be amazed at how easy it is. Don't need speed bleeders.

ignatz

Dan: I disagree and you haven't provided me with any rationale for your statement. I doubt given the construction of the speed bleeders that any air is getting back into the caliper past the threads as is sometimes the problem with the stock bleed screws. There are no bubbles in the transparent bleed lines I am using. None. If air was getting in it would come out and show up in the line after multiple pumps on the pedal. But all I see is fluid.

It seems pretty clear to the correspondents on this thread that the piston cylinder cavity geometry has some volume that is above the bleed line and thus impossible to get the air out by any means short of vertically positioning the caliper. Look again at the first picture I posted and tell me why I am wrong!

Also my installation, while it has an offset, needs no shims. As to it being nonsense I don't think those who had to shim would agree with your assessment.

I have suggested that I could get a little more air out by compressing the pads but haven't tried that. It's a case of asymptotically smaller improvements for minimal gain. Test it like you fly it is how I learned engineering. I have to wonder if they actually installed these calipers on a C3 what they did to bleed them? A little of that practicality on the part of Wilwood as to the stock mounting position in the C3 would have prevented this PITA.

ctuinstra

I dreamed of the day the I could afford the Wilwood calipers believing they are the top of the line. I appreciate now knowing that the original OEM with an o-ring update will be just fine for me and I can look to other things to spend the money on.

gg521

I have installed the D8-4 Wilwood Brakes for road racing. I have used the stock calipers for about 20 years of racing and, yes, they work good. However, The Wilwood calipers work just a bit better. In my opinion, it is the seal design and the piston design compared to the stock design.
Installing the rear calipers does present some changes. The supplied bolts are too long. The rear calipers may need to be shimmed. This has nothing to do with quality control. It it the stock caliper mount. There is a good chance that this mount might be bent just slightly. This might be caused by anybody doing work on the rear bearings, especially if a press was used. Probably nobody has ever checked the stock caliper to see if it was centered. Shims can be had from a couple of places. Some people use distributor shims for this purpose.
I had no problem bleeding the rear calipers. I gravity bled them first and followed that by pressure bleeding.
The front calipers bolted right on and no shimming was necessary.