Grassroots Motorsports magazine, Dec. issue has 914 brake tech article Options

[SP9146]

I don't usually read this magazine but saw on the cover a mention of the 914 article so I bought it. Excellent explanation of the upgrades to BMW front calipers, etc.

This was actually one of the last articles in a series about their 914 project car. Has anyone read any of the articles, are they worth trying to find?

Pete

[seanery]

yes, its a pretty good build. Is it the green 914?

[Bleyseng]

Yeah its the green project car, Sean. All of the articles are worth reading and getting back issues.
Do they give out secret info or how to build a 130hp Djet 914? No. Still lots of good ideas worth checking out and filing away for future use.

Geoff

[Rogue]

I believe they are offering a package deal on the 914 issues.

They also have a good BBS too. Check it!

Grassroots Motorsports

[East coaster]

Has anyone else done the "back up bolt" on the cross member trick that was shown in the article??? I never saw anyone mention this mod in any of the bbs threads. It seems crude, but simple. I didn't realize there was that much flex in the pedal cluster mounting area, maybe I'll beef mine up while I have it apart. Somehow the backup bolt is just too easy, I have to make this harder on myself (IMG:style_emoticons/default/headbang.gif)

[Andyrew]

Flex if you have alot of rust...

I didnt see that much flex when I was putting my M/C in.. But hey, What do I know?

Andrew

[SP9146]

I was impressed by that trick as well, would be interested in hearing from others if it was effective. It was enough to get me to buy the back issues! Wonder what they came up with for the suspension... 100lbs rear springs and some Konis?? Thanks for the tip.

[mightyohm]

has anyone been able to find the GRM sister mag in a bookstore?
(Classic Motorsports)

[seanery]

yup

[mightyohm]

Which one?

I have looked at 2 or 3 now (Barnes and Noble and Borders I think) and no sign of it.

Is it any good? I wish they had kept the two mags together, I don't really want to subscribe to two when I hardly ever finish all of one before the next one comes out.

[seanery]

magazine shop in Hermosa Beach. I haven't seen it in Indy though

[Brad Roberts]

Found it last night @ B&N. Full blown feature on the green 914.

Funny. I found an update on the brakes they installed.. they cannot get the bias correct in the car..>LOL

DONT USE THE BMW SETUP.


B

[Brad Roberts]

Oh.. yeah.. We have used a weld in brace for years on the race cars. Not really needed for a street car unless your tub is rusted in that area.


B

[ArtechnikA]

We have used a weld in brace for years on the race cars. Not really needed for a street car unless your tub is rusted in that area.

i have -something- going on in the pedal box of the 911. there is the usual open-car surface rust in the area but it appears structurally sound; i don't think that's what i'm seeing.

with my right foot applying constant pressure to the brake (stopped at a light, for example) i can feel the pedal move when i depress the clutch. it may have got a -little- better when i rebuilt the cluster with bronze bushings (the few surviving plastic bushings were toast) but it's still evident. i didn't see any pedal shaft wear, and the pedal box bolted securely back into place (after a liberal spraying to the area of LPS-3...).

i know i'll be back in there to replace the MC when i uprate the brakes (i suspect it's a 19mm instead of the NLA 20,5 it should have ...) and i'd like to fix whatever's actually wrong when i do.

[mightyohm]

I definitely used to feel that on my 911 and it didn't have any significant rust in that area. I just thought it was bad bushings.

[F4i]

Hi, short time lurker on this site. Long time lurker on PP and DGI. Brad, What is wrong with the BMW setup? You are the first I have heard say anything bad about it. I ask because I cannot afford 911 bits/wheels etc. but want better performance. Thanks

[Brad Roberts]

Thanks for posting.. (IMG:style_emoticons/default/clap56.gif)

Porsche spec'd the calipers/pads to match the rotor thickness. Adding a larger pad/caliper to a solid rotor is playing with fire. You have now introduced more heat into an object that has trouble dissipating heat already. What you get with the BMW setup is instant gratification in the first stopping tests. What you end up with is faster brake fade because of the heat that is generated with the larger pad/caliper.

Installing larger calipers on the front and doing nothing with the rears screws up the brake balance that Porsche was trying to achive. GRM installed a rear adjustable brake bias and annouced several times that they couldnt get the bias adjusted correctly.

Several "professionals" will tell you that the stock system is more than adequate in stopping the car multiple times. People jumped on the bandwagon with the BMW stuff because it works great when you replace everything and rebuild the entire brake system (which is exactly how the stock brakes would work if replaced/rebuilt everything).

The issue is heat. Always has been always will be. Adding a larger caliper to a solid rotor is not very smart. You have "home" engineers pushing brake products on people... is this smart ??


B

[Brad Roberts]

Oh.. I'm biased.. we have a vented rotor solution coming out in the next 45 days that will allow you to keep your current wheels/tires.

I was complaining about the BMW crap long before we decided to move forward with the 4 lug hub/911 rotor setup.


b

[redshift]

If the stock brakes are in good working order, they work great. I don't autox, but we have nothing but 2 gear streets here in the city.. I do alot of stopping.

Seems like the only real step up is 911front-914/6rear, otherwise, I would use that money on seals, or new wiring.. etc.


M

[F4i]

Thanks for the response. I have noticed that yourself(Brad) and another (Mueller?) are working on an alternative solution. More information on this would be of great assistance in making decisions. 4 bolt with vented rotors ARE the ideal! I have a 74 (orig. 1.8) with a balanced euro piston 2.0 that is currently under full rusto. I wish to be driving for spring. I would like to make a couple of points to consider. As for "home" engineers wasn't one of the original proponents of the swap Mr. Kaufmen?sp. an engineer? Also, I agree that more heat is created however: 1. That is kinda the point right? Greater friction= more stopping 2. The BMW is a heaver car with solid rotors. Were there heat problems with them? I am not trying to argue by any means. I certinaly do not want my first posts here to be the start of ill will as you guys are certinaly more knowledegable than I. I am as I said more interested in you're kit than any other option. And a big fan of (brackets) Happy new Year!