Floater setup--yes or no

[Matt@BOS]

Originally Posted by GregWeld

Want a perfect "race car" just buy a new $60,000 Corvette... save yourself all the hassle. I've beat on 'em for days at the track - no knock back whatsoever!

Yeah, that would probably be cheaper than buying a set of HREs and track tires for the "show car."

I await a come back Greg. Doug's thread still has tinge of relevancy right now, and you need to correct that!

[GregWeld]

Yeah - if he wasn't so cheap he'd just pony up and buy "another" race car... 3 '69 Camaro's -- Drag - Road race - and the Donk....

[Blake Foster]

Originally Posted by 69MSA

Blake, I don't remember exactly what I said, or if I accidentally typed "would" instead of "wouldn't" or something to that effect. I'm going to just play the "it was late" card right off the bat Anyway from what I remember hearing, the 10lb residiual valve wasn't a noticeable difference. It has also been interesting hearing Charlie's commentary about Jackass. From all the "internet science and engineering" we've gathered, (and I don't feel like rehashing all of the talk about m/c bore sizes, etc.) the popular belief seems to be that a larger master makes knock back less noticeable, as would 'Vette wheels, and yet Jackass's pedal would fall to the floor just like the pedal in my car with its little 7/8 master and 6" backspaced wheels.

Matt

I hear yat Matt lots of different ideas to consider, I guess it could all be a thing of the past if the bake companies just made the caliers floating??
FYI on my car with the triple master set up the worst case is that you ave to tap the brake pedal to reset the pads, and Jay and I have just got in the habit of doing that but it NEVER falls to the Floor.

[ccracin]

Originally Posted by killer69

I guess it could all be a thing of the past if the brake companies just made the calipers floating??

I think you hit the nail on the head there Blake. When the brake companies started introducing the large by huge brake packages, they did it with fixed calipers. They look awesome! These were originally racing pieces typically mounted on floating rears or IRS set-ups. This goes back to Todd's point about racing parts on the street. They seemed to be fine and look great until you start tracking a car and applying loads to the rear axles much greater than any situation you would encounter on the street. Now with the higher loads, knock back is an issue. So now the question is, do you go back to a more street caliper (floating) set-up or do you go to the more race rear end (floating). Or you come up with a solution like you and Chicane are bringing to market. This is one of the things I like about the Pro-Touring movement I'll call it, a problem arises and there are companies willing to step-up and solve it with parts available to the masses. Good Stuff! Now the hard part, what do I do on our truck? I had thought about this in the beginning and tried to make decision accordingly, but now I'm not sure. Our rear is a 9" with Big Bearing ends and tapered rollers on the 31 spline Moser Axles. The rear brakes are the 14" Wilwood 4 Piston Radial Mount deals. The rear wheel will be 10" with about 4.25 to 4.5" of back space. Speaking pretty honestly, this will not be a "Track" vehicle. Maybe once or twice just to stretch it's legs. It will spend the bulk of it's time on the street and doing some auto crossing. Is the auto crossing enough to warrant a whole sale change in rear end and expensive brakes? The brakes were mostly for looks to fill a 20" wheel. Don't know! Decisions Decisions

[GrnDragon]

Lots of good info and discussion going on here!

Does anyone know off-hand which inner axle seals will work with a 35 spline axle? I have been looking for a while and all the seals I find only claim to fit 31 spline.

And throughout this entire thread I didn't see any mention of the GMR setup, that's what I decided to buy.

[DFRESH]

Originally Posted by GrnDragon

Lots of good info and discussion going on here!

Does anyone know off-hand which inner axle seals will work with a 35 spline axle? I have been looking for a while and all the seals I find only claim to fit 31 spline.

And throughout this entire thread I didn't see any mention of the GMR setup, that's what I decided to buy.

Yeah, I was hoping Jason might chime in here--why did you decide to go with his setup?

[GrnDragon]

Originally Posted by DFRESH

Yeah, I was hoping Jason might chime in here--why did you decide to go with his setup?

I decided on his after A LOT of research, but at the time the only Full Floaters that were available were Moser, Speedway, and The GMR. I was sold on the bearing spread and MUCH cleaner hub design and finishing that GMR did.

But today there are a couple more options to consider Baer and Chicane/Speedtech. I don't really like the Baer kit, it just doesn't look as stout at the GMR setup but it does include the e-brake which is nice. When I look at it I think of a swiss army knife, there are piece/parts everywhere and it may do the job but not as well as other setups.

Now I am REALLY intrigued by the Chicane/Speedtech kit, it's a really good design and I really like the fact that they use some OEM off the shelf components. I would jump all over this if ABS was something that I really wanted to have, but again comparing hardware between GMR and this design I would say GMR is the stronger design.

This is all my opinion, and I haven't actually done any stress analysis on any of the kits nor have I run the GMR stuff yet so I don't know how it will handle the racing environment.

[JasonElvisHeard]

Originally Posted by DFRESH

Yeah, I was hoping Jason might chime in here--why did you decide to go with his setup?

I'm here, I have not read though the entire thread but are there any specific questions you would like answered?

Jason

[sik68]

I experience a lot of knockback as well, but this is coming from a guy who has floating calipers. I use C5 calipers with a 7/8 Wilwood MC.

Around Buttonwillow & Thunderhill, and the El Toro track and autocross, I can do a few laps and know reliably which braking zones I will experience knockback; some corners are completely trouble free, and some corners the pedal is undoubtedly soft in the same zone lap after lap..."gotta pump it up for turns 3,5,8...etc"

Deflection is definitely part of the problem; 28 spline axles and the original 8.2" rear aren't what I would call stiff.

But there is also another nagging problem and that's axle play (inboard/outboard motion of the axle). I'm guessing I'm not the only one who has 3/16" of axle freedom, and if you go around a combination of corners where one or both axles moves, there's another source of pads spreading. This became very clear to me in autocross; there is much more severe and abrupt lateral weight transfer and consequentially I must pump the brakes around the whole track to keep the pedal up. Also very prevalent after hitting track curbing on road courses, where you get a lot of impact that can move and deflect the braking system.

I am about to install a 5lb knockback spring under the piston (or maybe a pair under each for 10lbs) to see if it helps.

The residual valve we all know does the same thing. I bought one but haven't installed it yet. I hate messing with brake lines so I want to try the springs first. Running a quick number on residual valves: 10psi residual pressure on a 40mm diameter (C5) piston = 19lbs. So it will be pushing against the piston almost 4x harder than the spring I'm installing.

If you keep the caliper pins lubricated and free from binding, the springs or valve should be able to do their job. I don't know if 5lbs, 10lbs, or 19lbs of force is enough, but I am going to start with 5lbs and work my way up.

I will be sure to post the spring install and results after RTTC.

[Vegas69]

Get rid of that 3/16 end play and your problem will be solved. That's way to much slop for any caliper set up. I bet someone has figured out an economical solution. Otherwise you are putting lip stick on a pig.