A couple of techical questions for the "GT" cognoscenti, Seeking wisdom Options

[mountainroads]

1) I'm considering upgrading to GT-spec rear calipers and wondering if anyone has encountered clearance issues with dust shields, etc. after installing the vented rear rotors? Apparently, track cars were more concerned about cooling than keeping debris out, so dust shield were typically omitted. However, this is a road car, so I want to keep the rocks out. I've heard tell of a "Rally GT" brake system which presumably uses the dust shields, but don't know what any differences might be.

2) The GTs used a reinforced engine mount due to concerns about the increased power and stresses of racing. Although this isn't a track car, I'm running a 2.7L with modified "S" cams, so wondering if I shouldn't also add some strengthening to the stock engine mount. Are the strengthening gussets available as parts, or do these have to be fabricated for welding to the stock mount? Embedded is a pic of the mod I'm referring to. Does anyone know what they did for the 916s?

TIA,

- MR

[ConeDodger]

On the first question, I took off the dust shields long ago. I do street, autocross, and track events and I've never had a problem.

Second question, my 3.2 uses McMark's replica of the original factory six mount (for authenticity). I have no problems. Patrick Motorsports told me I'd have shifting problems from the torque of the engine twisting the shift apparatus. Nada... Mark's mount is quite nice and more people should be looking at it...

[raynekat]

I've got the GT calipers 914 Rubber put together with PMB's help. With the vented rotors, I was still able to get the shields to fit. Honestly, it's very tight but doable.

For the engine mount, I've got a factory style one made by MB911. Mines got the reinforcement I believe. I'm running a 200+ hp 2.7 in the car.

[raynekat]

Double post....pls delete.

[Dave_Darling]

On the first question, I took off the dust shields long ago. I do street, autocross, and track events and I've never had a problem.

It is very common to remove the dust shields. Few if any people report problems as a result.

Second question, my 3.2 uses McMark's replica of the original factory six mount (for authenticity). I have no problems.

I remember having some discussion with McMark about that. He kind of shut me up (*gasp*! I know!!) by showing me a photo of a 908 racer, with the engine held in by a single mount much like the 914-6 mount.

--DD

[mountainroads]

On the first question, I took off the dust shields long ago. I do street, autocross, and track events and I've never had a problem.

Second question, my 3.2 uses McMark's replica of the original factory six mount (for authenticity). I have no problems. Patrick Motorsports told me I'd have shifting problems from the torque of the engine twisting the shift apparatus. Nada... Mark's mount is quite nice and more people should be looking at it...

Thanks very much for the info, ConeDodger. I heard from someone else that the major failure concern revolved around the rubber part, not the steel. He also thought concerns might be unwarranted for a 2.7, since many are using completely stock mounts with 3.0+ engines. Just another opinion, although a very knowledgeable one. It's very late in the game for any welding anyway, as the chassis has been completely repainted and touchup would be required.

- MR

[burton73]

Pictures of mod to 914-6 #41 by Eric @ PMB.
The bracket above held the car as Jig during painting

Bob B

[gms]

I remember having some discussion with McMark about that. He kind of shut me up (*gasp*! I know!!) by showing me a photo of a 908 racer, with the engine held in by a single mount much like the 914-6 mount.

--DD

My former IMSA race car has raced since 1971 and there are no signs of cracking or separation of the engine mount. That being said I don't think it would hurt to add the side reinforcement.

I have seen an after market (weld to firewall) engine mount fail on a 914 race car.
I suspect the stock rubber engine mount lets the engine twist while a more rigid mount transfers more twisting motion to the firewall.

[mountainroads]

Thanks guys for all of the feedback. Truly appreciated. I decided to go with the dust shields and forego the engine mount reinforcement, since I hate to risk damaging and having to redo the fresh paint on the passenger side of the firewall. I know, it can be fixed, but I'd have to fab the reinforcements, then weld, then repaint. Not worth it at this point for my application, IMO. Hoping I won't regret down the road.

- MR

[mepstein]

Thanks guys for all of the feedback. Truly appreciated. I decided to go with the dust shields and forego the engine mount reinforcement, since I hate to risk damaging and having to redo the fresh paint on the passenger side of the firewall. I know, it can be fixed, but I'd have to fab the reinforcements, then weld, then repaint. Not worth it at this point for my application, IMO. Hoping I won't regret down the road.

- MR

You will be fine.

[mgphoto]

My experience, yours may vary.
Only #1

When I added the v -kit to my rear calipers to use the vented rear rotors, the addition of the spacer in the middle of the caliper offset the center of the rotor to the inside.
A shim was needed to center the rotor between the brake pads. I used the dust shield bracket as a shim, I rotated it 180* so the offset pointed out instead of in.
When I attached the shield it had an additional inch opening at the front to scoop more cool air into the rotor.
See my signature photo.

<-----

working without issue 8 years.

again your milage may vary!

[Socalandy]

I did the GT mount update on mine and deleted the shields with GT rear calipers.

No Regrets!!!