Opel GT Forum banner

1 - 15 of 15 Posts

·
Member
Joined
·
648 Posts
Discussion Starter #1
I've heard different opinions on removing the front disc backing plate (splash shield). An old trick I was always told was to remove them to get more air flow and cooling around the disc. Now, I've been told that the disc cools better with the plate as it directs air around the disc better. How about some opinions?
Thanks,
James
 

·
Registered
Joined
·
67 Posts
Opinions? We got 'em, James. Leave the backing plates ON. Besides the cooling effect, they deflect rocks, road debris, all that kind of thing. Those engineers in Germany knew what they were doing.
 

·
Super Moderator
Joined
·
13,576 Posts
I've always cut down the backing plates. I leave the area that protects the hub grease seal, cutting the rest of the sheet metal away. I've found the rotors run cooler on the track (pyrometer testing). Another side benefit has been reduced brake dust buildup on the wheels for the street. The down side....on dirt roads anyway, I've picked up some rocks before between the caliper body and rotor. NASTY noise, and they must be removed to prevent the rotor from becoming grooved. For me, this possibility is acceptable.

Bob
 

·
Member
Joined
·
315 Posts
From a cooling standpoint (and the Opel brakes need cooling), the backing plates HURT. I do as Rally Bob suggested, and cut down the plates so that only the bearing/seal protection remains. Then as much air as possible will go by the disk.

The next thing to do is duct some air. But you can't just blow air on one side. Since the disk is solid, if one side has cool air and the other does not, then the disk will warp:( . So the way to duct air is to make a duct that wraps around the disk and puts air on both sides of the disk. You have to be sure everything clears the wheel, so the duct has to be the same short of shape as the caliper.

When Gary gets the "picture-in-post" function working again, I'll put up a picture of what we do.
 

·
Administrator
Joined
·
10,075 Posts
TGSI Racing said:
When Gary gets the "picture-in-post" function working again, I'll put up a picture of what we do.
The picture posting is working. use the "Attach File" box at the bottom of the new post screen. I need to figure out how to get the picture posts from the old board over with the threads.
 

·
Member
Joined
·
648 Posts
Discussion Starter #6
Thanks for the advice guys. I'll be pulling them apart and cutting them down soon. Nothing like help from my 2 favorite "BOBS".
James
 

·
Member
Joined
·
315 Posts
As promised, here is a picture (finally got my digital camera back from my kids) of the RIGHT way to do brake ducts for solid disks. Note that there is a splitter in the inlet. The splitter is NECESSARY so that air goes to both sides of the disk.
 

Attachments

·
Member
Joined
·
315 Posts
Here is the duct mounted. Notice again that the splitter directs about half of the air over the top and to the outside of the disk.

This is actually the first prototype for a 240Z that we are building. (This was easier to get pictures of since everything is apart). Anyway... ducts for the Opel are essentially the same.
 

Attachments

·
Member
Joined
·
315 Posts
For those who are wondering why I'm so "anal" about brakes... In 1995 TGSI Racing went to a 24hr race in Ohio. This is what the car started out looking like. Those who were there with us remember what happened when the brakes went away about 12 hours into the race...
 

Attachments

·
Member
Joined
·
315 Posts
When the brakes "went away" there was a Car & Driver magazine sponsored Ford Contour SHO in the corner in front of the Opel... that's not how we wanted to meet the Car & Driver folks. Needless to say, what they wrote about us in the magazine was not flattering.

A sawsall was used at the track to clear away sheet metal that was crushed into the wheels. We rebuilt the brake system and after about 2 hours we got back in the race. Amazingly, we finished the race.

When we got back home and surveyed the damage, this picture shows what was left after we cut out all of the stuff that "wasted"... and you can't see the stuff that's "gone" on the other side.

Rather than trying to fix the car, the shell now serves us as a platform to "mock up" custom stuff.

By the way, this is the second car that I've "bent" beyond repair because the brakes went away.
 

Attachments

·
Super Moderator
Joined
·
13,576 Posts
This is how I cut away the backing plates for my own cars. Notice this is from a Manta/Ascona, so the area holding the brake line clip would not be there on a GT

Bob
 

Attachments

·
Registered
Joined
·
4,059 Posts
This thread is a perfect example of why old threads are never necro.

I'm glad it is still here. We're looking into options for improving braking performance and ducting is first on our list.

We've already cut away the dust cover the way Bob showed, so we got that right. We'd love to have a ducting fixture like the one shown by TGSIRacing. I'm assuming that was a custom fixture fabb'ed using sheet metal.
 

·
Administrator
Joined
·
10,075 Posts
This thread is a perfect example of why old threads are never necro.
Agree. RallyBob's pic just answered a question that I had. :biggthump

Of course, I should have searched before I assembled the hubs.
 
1 - 15 of 15 Posts
Top