rear defuser fix ques

[2fast4u]

Hey guys I have been on this board for years and finally `picked up a red and white 05 gt to go with the 96 blue and white viper..

anyway it has a small crack in the rear defuser .. The dealer wants to sell the 3 peace section I am not interested in all three.. any ideas for a fix or to buy just my part?

Thanks

ryan

 

[427Aggie]

The Defuser comes attached to the belly pan. I believe the pan retails for about 1300 bucks from a dealer.

The other option is the Stillen extended version but be aware that it will change the wind characteristics of the cars design.

matt

 

[Empty Pockets]

It's been mentioned B4 here on The 'Forum that these are made of 'glass, and can be repaired real easily if you wish.

 

[kmillen]

We now offer the rear diffusers in stock length as well as extended length.

Our diffusers are made of durable urethane which will not crack.

 

[MAD IN NC]

We now offer the rear diffusers in stock length as well as extended length.

Our diffusers are made of durable urethane which will not crack.

:banana They will take a lick'in and keep on tick'in! :banana

 

[2fast4u]

thanks guys .. i may look into fixing it, if it is that easy why not..

thanks
ryan

 

[paul b]

One last tip, when the repair is done, mask off the entire pan and just paint the fins. If you only paint the repair it tends to stand out a little more. I've done this twice and it really is that simple.

 

[Indy GT]

Stillen Aero Question

Kmillen-
This is interesting news and a welcome one at that. Stillen now sells a urethane GT diffuser which has the same dimensions as the glass OEM diffuser. Please confirm.
As an aside, because of the different aero attributes the first Stillen design "long" diffuser gives to our GT (ie the earlier long runner diffuser creates a different fore/aft load split than the original Ford engineers incorporated into our aerodynamics) why was the first design produced?

 

[t32b]

More details please

Kmillen-
This is interesting news and a welcome one at that. Stillen now sells a urethane GT diffuser which has the same dimensions as the glass OEM diffuser. Please confirm.
As an aside, because of the different aero attributes the first Stillen design "long" diffuser gives to our GT (ie the earlier long runner diffuser creates a different fore/aft load split than the original Ford engineers incorporated into our aerodynamics) why was the first design produced?

I'm also interested in the stock-shaped urethane diffusers. Great news. Please tell us more.
Also, after repeated comments about the changes in airflow with the larger urethane diffusers, what exactly are the differences, and what were you optimizing for in the design? References in the past have sounded speculative, but you're the expert when it comes to the real-world high speed use of these extended parts.
Thanks

 

[kmillen]

Kmillen-
This is interesting news and a welcome one at that. Stillen now sells a urethane GT diffuser which has the same dimensions as the glass OEM diffuser. Please confirm.
As an aside, because of the different aero attributes the first Stillen design "long" diffuser gives to our GT (ie the earlier long runner diffuser creates a different fore/aft load split than the original Ford engineers incorporated into our aerodynamics) why was the first design produced?

That is correct, we do have the stock length diffusers in urethane now. Dimensionally they are identical to the stock diffusers.

We still have the extended length and they are still on our car. We did not do any wind tunnel testing with the diffusers due to cost. We don't charge very much for the parts and wind tunnel testing would have just been too expensive. Steve has been racing sports cars for many years and his experience with the IMSA GT series Nissan 300ZX cars came into play. We utilized all of that history and knowledge as well as driver feel. When we were doing the driving tests Steve would give us the necessary feedback to make sure that whatever changes we made were beneficial.

We received a lot of interest in the stock length from people with the rear bumper deletes so we went ahead and developed that one as well.

 

[AlohaGT]

Kyle,

Thanks for hosting us back in August. I'm one with a RBD. Do you or does anyone have pix of the extended length diffuser on a RBD? If not, how about some pix on a stock FGT? I don't recall how Steve's car looked.

Kelvin

 

[jdoc7]

Kyle,

Thanks for hosting us back in August. I'm one with a RBD. Do you or does anyone have pix of the extended length diffuser on a RBD? If not, how about some pix on a stock FGT? I don't recall how Steve's car looked.

Kelvin

From an old thread: http://www.fordgtforum.com/forums/showthread.php?t=6490&highlight=stillen+diffuser&page=2

 

[AlohaGT]

Thanks Doc, these pix are helpful.

Still would like see one with a RBD if possible.

 

[t32b]

No windtunnel needed

That is correct, we do have the stock length diffusers in urethane now. Dimensionally they are identical to the stock diffusers.

We still have the extended length and they are still on our car. We did not do any wind tunnel testing with the diffusers due to cost. We don't charge very much for the parts and wind tunnel testing would have just been too expensive. Steve has been racing sports cars for many years and his experience with the IMSA GT series Nissan 300ZX cars came into play. We utilized all of that history and knowledge as well as driver feel. When we were doing the driving tests Steve would give us the necessary feedback to make sure that whatever changes we made were beneficial.

We received a lot of interest in the stock length from people with the rear bumper deletes so we went ahead and developed that one as well.

No doubt the windtunnel cost, for a part like this, is prohibitive. But because you and team have such racing experience with the car, I was actually looking for the driving impression.
Is there actually any difference at all? Was there a theoretical reason for the extension? Just curious.
I assumed that the extra length would get the flow out into cleaner/smoother air. Seems like goodness to me.

 

[Indy GT]

t32b Follow-up

Kmillen thanks for the reply on the diffusers. And we Forum members certainly appreciate all the aftermarket products your company offers the FGT owners. As well as hosting a get-together out in California last August. I was there and appreciated the tour and refreshments very much! The outside dyno was very intersting.

I am, however, in t32b's camp as well and just wonder why the long run diffuser was "developed" first. How did Steve's experience "... racing sports cars for many years and his experience with the IMSA GT series Nissan 300ZX cars came into play." help zero in on a different than OEM design? What was the design goal and what paramaters optimized for the long runner shape? This is a matter of curiosity to me knowing the extensive wind tunnel testing Ford did when developing the GT areo package they sold us on our car. And documented in SAE technical report 2004-01-1254, "2005 Ford GT - Vehicle Aerodynamics - Updating a Legend".

Thanks again, and great to know the OEM dimension diffuser is now available from Stillen!

 

[Specracer]

Keep in mind, on their car (the orange car) they have an extended front splitter, and a "winglet" on the front hood (at the radiator vent exits). Both of these elements, have the intent of providing the front downforce to offset the added forces of the entended diffusers in the rear.

 

[kmillen]

Steve definitely noticed that the extended rear tunnels have helped quite a bit during high speed cornering.

We were hoping to do some more testing this weekend at California Speedway but Ricardo called and said their tech will be out next week to instruct our guys on disassembly and re-assembly of the transaxle for the 3.9 diff ratio. So we had to take the back half of the car apart again.

Steve has done alot of driving with both sets of diffusers and he will be leaving the longer version on his car.

We do have the front splitter as well as the gurney flaps on the front and back of our car. However, we have tried the rear tunnels without those parts and still notice a large improvement.

Someone asked how the longer versions would look on a car with the rear bumper delete. I don't know how they would look. I don't think that any of our customers with the extended length tunnels have the rear bumper delete. In my opinion, I don't think it would look very good. If you want to build an all out race car or want it to LOOK like a race car then it might look good. But if it were my car I think I would stick with the factory length diffusers with the rear bumper delete.

 

[B O N Y]

Someone asked how the longer versions would look on a car with the rear bumper delete. I don't know how they would look. I don't think that any of our customers with the extended length tunnels have the rear bumper delete. In my opinion, I don't think it would look very good. If you want to build an all out race car or want it to LOOK like a race car then it might look good. But if it were my car I think I would stick with the factory length diffusers with the rear bumper delete.

Pictures of my bumper delete with long defuser are on this site on the Western Rally Thread posted by Atomic GT. My concern is deflection at high speed... do you think I have a valid concern?

 

[kmillen]

Deflection at high speed should not be a concern. We've had our car at very high speed with absolutely no worries with the long diffusers. If the car were becoming unstable or unsettled at high speed due to the longer diffusers then Steve would definitely feel it. So far, he has not had any unstable moments.

If we find that the car becomes unstable at higher speed than we've reached (which is very high) then we will of course report it to all of our customers and each customer will be contacted immediately.

So far we have had the car upwards of 140-150 without any concerns and many of my customers have told me that they've been up to 170 without any problems. And of course all of these speeds were achieved at/on a race track.

 

[B O N Y]

Kyle...
I have been up over 160+ with the long difuser without any issue. My questions really relate to wot. I like the look with the bumper delete.