Superformance GT40 Transmission Mounting Bushes

[Robbie W.]

Hello again everyone, I haven't posted here for quite a while, just interested to know if anyone has had an issue with the upper transmission mounting bushes in the rear cross member of a Superformance GT40 melting with the heat from the exhaust system?

I was returning home from a drive when I heard a knocking sound from the rear of the car and after quite a bit of investigation I noticed that the poly bush mategislfor the upper transmission mounts had melted and the transmission retaining bolts had dropped and that caused the noise I heard.

Thanks.

Rob

 

[Robbie W.]

Apologies finger trouble, mategisl should read material. Now you see why I don't post too often!

 

[Jim Craik]

What motor are you running, what kind of clearance from the exhaust do you have?

 

[Robbie W.]

Hi Jim, I have a Roush 347 ci with a Borla Eight Stack fitted and Quaife transmission. There is about 2 inches distance between the top of the bushes and exhaust. I have made a heatshield to try and deflect some of he heat. I was wondering what other type of bushes Superformance owners have fitted to the cross member if they had experienced the same problem.
Thanks.
Rob.

 

[Robbie W.]

A few clearer photos.

 

[Richard]

I have at least 25K miles on my 40 with a 331 SBF. I've never seen any problems. Having your headers ceramic coated inside and out will also help.

 

[Robbie W.]

Hello Richard,

Thank you for your reply and your recommendation regarding ceramic coating. I have had my headers coated with a product called Zircotec which reduces the heat. But the damage to the bushes was possibly done before I had them coated as I only noticed the problem on the first run out after refitting the headers.

If you don't mind me asking, what type of transmission mounting bushes do you have fitted in the rear upper crossmember of your GT40?

And wow 25K total miles in a GT40, that's a lot of fun!

Thanks.
Rob.

 

[Richard]

25K is a guess. My My speedometer died after 1200 mi but after many long and short trips I might have more. It's whatever came in the car some sort of hard plastic if I remember correctly but I'll have a look. I wouldn't worry about it considering how many SPF cars are out there and I haven't heard of any problems. I'd worry more about the bodywork just above the headers. I had to insulate that part. I'm sure there's some fancy name for the law of how heat rises.

 

[DaveM]

Robbie,
I never had the trans mounting bushings melt, but one started to tear apart after several disassemblies (Mk!! about 32K miles).
I replaced that one bushing with a harder Delrin one from PolyBushings.com
I believe it was part # 2046.

 

[DaveM]

I was incorrect. Correct is part # 2045 and material is polyurethane, not Delrin.

 

[Robbie W.]

25K is a guess. My My speedometer died after 1200 mi but after many long and short trips I might have more. It's whatever came in the car some sort of hard plastic if I remember correctly but I'll have a look. I wouldn't worry about it considering how many SPF cars are out there and I haven't heard of any problems. I'd worry more about the bodywork just above the headers. I had to insulate that part. I'm sure there's some fancy name for the law of how heat rises.

Thank you Richard that's interesting and yes I agree with the issue of heat rising from the headers and damaging the rear clip, I had the same concerns so I lined the inside with heat protection material. I have attached a couple photos just for interest.
Thanks.
Rob.

 

[Robbie W.]

Robbie,
I never had the trans mounting bushings melt, but one started to tear apart after several disassemblies (Mk!! about 32K miles).
I replaced that one bushing with a harder Delrin one from PolyBushings.com
I believe it was part # 2046.

Hello Dave, thank you for your reply and the information you have provided. My GT40 has done no where near that mileage and the bushes that melted were of a poly type but not a very hard type and I am not sure who manufactured them. I will take a look at the part number that you have provided.
Thank you.
Rob.

 

[David Garton]

Rob, Could you share some info on the clamshell storage piece you have in your photo's? I would be interested how others store their clamshells while not on the car and installing drivetrain. Thank you, David

 

[Richard]

Robbie, I wasn't prepared for the transition of what my kids called garage furniture into something I could drive. Enjoy the experience.

 

[Robbie W.]

Rob, Could you share some info on the clamshell storage piece you have in your photo's? I would be interested how others store their clamshells while not on the car and installing drivetrain. Thank you, David

Apologies David for not replying to your question sooner. I have been away and I hope to have time tomorrow to take a few detailed photos of my clamshell storage system and will add them to this thread for you.
Rob.

 

[Robbie W.]

David, here are some photos of the system I have for removing and storing the rear clamshell.

I don't always have someone around to remove the rear clamshell so I have a foldable engine crane, removed the hook and replaced it with a spreader bar. I can then lift the clamshell off the GT40 without help.

I have fabricated a copy of the rear clamshell bracket on the GT40 and fitted it to the lower bars of the engine crane. (This is removable to fold the crane up when not in use) I lift the clamshell off the GT40 with the crane and then lower it on to this bracket. I can then move the clamshell around the garage on the crane.

I have also fitted 2 ball joints on the engine crane lower bars which I can clip the clamshell gas struts to, just like when it is fitted to the GT40. This allows me to release the pressure on the crane so that there is no strain on the rear clamshell.

I hope my explanation makes sense. If you need any other information let me know.

Rob.

 

[Robbie W.]

I forgot to mention that the one problem with my method of storing the clamshell this way is that it needs a dedicated engine crane and in my case I will use a second engine crane to remove the engine if I need to.
Rob.

 

[Chris Kouba]

That's BRILLIANT!

 

[Robbie W.]

Thank you Chris, it took me a while to work it all out.

 

[David Garton]

David, here are some photos of the system I have for removing and storing the rear clamshell.

I don't always have someone around to remove the rear clamshell so I have a foldable engine crane, removed the hook and replaced it with a spreader bar. I can then lift the clamshell off the GT40 without help.

I have fabricated a copy of the rear clamshell bracket on the GT40 and fitted it to the lower bars of the engine crane. (This is removable to fold the crane up when not in use) I lift the clamshell off the GT40 with the crane and then lower it on to this bracket. I can then move the clamshell around the garage on the crane.

I have also fitted 2 ball joints on the engine crane lower bars which I can clip the clamshell gas struts to, just like when it is fitted to the GT40. This allows me to release the pressure on the crane so that there is no strain on the rear clamshell.

I hope my explanation makes sense. If you need any other information let me know.

Rob.

Rob, Thank you for the reply and great explanation of how it works. I just received my second engine hoist as I plan on duplicating what you have already made work well. I will fine tune it and paint it Gulf colors so it will only be used for that purpose. Thanks again for sharing.

David..