US 83 SC Trombone to 28 Tube Cooler Mounting

[2jmotorsports]

Hello Pelicans,

I am trying to mount a 28 tube oil cooler where there was previously a trombone on an 83 SC US-market coupe.

I have the upper "open hook" style mount and an inner fenderwell threaded hole about 2/3 of the way down the tube cooler:





I have reviewed this thread on fabricating your own mounts:

https://forums.pelicanparts.com/porsche-911-technical-forum/189269-28-tube-cooler-owners-question-pics-needed.html#post1583153

As well as this thread on mounting on a 77:

https://forums.pelicanparts.com/porsche-911-technical-forum/409395-oil-cooler-upper-mounting-bracket-questions.html

Id like to mount it with the factory bracket shown here:



Does this bracket use the existing hole plus a second drilled and threaded rivnut in my car or would it require drilling and rivnuts in 2 locations? What is the part number for this lower bracket?

Thanks in advance.

[Ayles]

Keep in mind my install was a standard carrera oil cooler. Not the brass one you have.

At the headlight I had the same thing you do. I cut it off and used this bolted to the back of the headlight bucket:
https://www.pelicanparts.com/More_Info/93020792100.htm?pn=930-207-921-00-OEM&SVSVSI=811

The horns had to be relocated forward with this bracket though you don’t have a fan so might not be needed: https://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=911-504-080-00-GRV-OEM&catalog_description=Late%20Carrera%20Inner%20Right %20Fender%20Strut%20%28for%20horn%20relocation%29n ecessary:

The lower bracket in my case could not use the existing bolt. One rivnut at the bottom and a drilled hole at the top. Using this bracket:
https://www.pelicanparts.com/More_Info/91150149001GRV.htm?pn=911-501-490-01-GRV-OEM&SVSVSI=811

Measure, measure, then test fit, then measure it again. Make sure you have lock to lock tire clearance in your final location.

[billybek]

Post photos of your progress, please.

[Litle brother]

Following


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[Koizumi]

Interesting, my 28 tube cooler is brass color. Is yours coated somehow?

[2jmotorsports]

Thanks for the feedback. I'll get the lines all hooked up and mock up the locations.

@Koizumi: it was painted satin black after I had it cleaned and pressure tested.

[2jmotorsports]

Guys, I could use some pointers in mounting this thing.

I got the factory oil cooler bracket and this part of the fenderwell seems like it roughly lines up with the bracket profile. However I cant find exact dimensions for the location.





The other difficulty is I have a pair of new front hoses but they are straight and very difficult to both get mounted on the cooler.





So I have a bit of a catch-22. I dont have the cooler hard mounted to muscle the hoses into place, nor can I muscle the hoses into place with the cooler dangling about.

Should I find a pair of used junk hoses that have already hardened into their "bent" position to connect the cooler and locate the bottom bracket?

Or I can connect the short one, locate the cooler as best I can, drill & mount, then hopefully muscle the longer hose in place.

[smadsen]

You might put a little heat to the rubber hoses. Not a torch, but a hot air gun or even a hair dryer. Remember, the hot oil runs over 200 degrees, so a little hot air might make the hose more pliable while you place everything.

[2jmotorsports]

Ok I will give that a shot. Thank you.

[2jmotorsports]

Update. I found a good lower bracket location that does everything right: Lets me use the upper hook mount, clears horns, and has good cooler-tire clearance at full steering lock. Per others' results the lower bracket top hole is a thru hole into the frunk and the lower hole requires a nutsert. Ill post photos and reference dimensions when I have it all buttoned up.

What kind of nutsert tool did everyone use to get an M8 zinc plated carbon steel one installed in that tight space? Everything I am seeing tool-wise only does M6 steel or M8 aluminum nutserts tops for the compact rivet gun style tools or they are huge tools with long lever arms that wont fit. I guess worst case scenario I can remove the fender...

[Litle brother]

Originally Posted by 2jmotorsports

Update. I found a good lower bracket location that does everything right: Lets me use the upper hook mount, clears horns, and has good cooler-tire clearance at full steering lock. Per others' results the lower bracket top hole is a thru hole into the frunk and the lower hole requires a nutsert. Ill post photos and reference dimensions when I have it all buttoned up.

What kind of nutsert tool did everyone use to get an M8 zinc plated carbon steel one installed in that tight space? Everything I am seeing tool-wise only does M6 steel or M8 aluminum nutserts tops for the compact rivet gun style tools or they are huge tools with long lever arms that wont fit. I guess worst case scenario I can remove the fender...

Here' the rivnut tool type I'm using:

https://m.banggood.com/no/86pcs-Nut-Rivet-Tool-Kit-Threaded-Nut-M3-M8-Insert-Riveter-Rivnut-Nutsert-Riveting-Tool-p-1200536.html?gmcCountry=NO&currency=NOK&cur_warehouse=CN&createTmp=1&ID=231&utm_source=googleshopping&utm_medium=cpc_union&utm_content=2zou&utm_campaign=ssc-no-no-all&gclid=EAIaIQobChMIt7Wk5fDo4AIVRMYYCh1E7gClEAQYCSAB EgL1JPD_BwE




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[Solamar]

Originally Posted by 2jmotorsports

What kind of nutsert tool did everyone use to get an M8 zinc plated carbon steel one installed in that tight space? Everything I am seeing tool-wise only does M6 steel or M8 aluminum nutserts tops for the compact rivet gun style tools or they are huge tools with long lever arms that wont fit. I guess worst case scenario I can remove the fender...

Do a search for "home made riv nut tool" It uses a bolt, washer and a couple nuts IIRC. Probably your best option for the limited space.

I have the same tool shown above and you need Hercules hands to set the larger steel riv nuts.

[2jmotorsports]

Originally Posted by Solamar

Do a search for "home made riv nut tool" It uses a bolt, washer and a couple nuts IIRC. Probably your best option for the limited space.

I have the same tool shown above and you need Hercules hands to set the larger steel riv nuts.

Thanks so much for this tip. Worked like a charm. Here's what I did:

I temporarily hooked up the hoses to the top of the cooler and bolted the bracket and rubber buffers to the bottom of the cooler. I was then able to mark off a location that worked well and gave me the clearances listed above.

The position that worked out tucks the top corner of the bracket under the lip in the inner fender well you see here. Since the bracket cantilevers with a heavy cooler on it, this can only serve to make the bolted connection stronger as now it wont pull away at the top.



I scribed the holes, center punched, and drilled them both out. Top hole is a thru-hole into the side of the frunk, next to the spare tire (dont worry plenty of tire clearance). Bottom hole is blind and goes into some body cavity. This will get a rivnut.



I decided to install a steel rivnut for durability but I didnt want to spend money on a giant expensive rivnut tool so I drilled 6 holes in a piece of sheetmetal and practiced first. I successfully installed all 6 steel rivnuts using a M8 bolt, a nut, a washer, and a couple of wrenches. As an added bonus I was able to torque an M8 bolt in each test rivnut to 18.4 ft-lbs (25Nm). I then felt ready to try it on the car.



Put the nut and washer on the threaded end of the bolt, thread the rivnut onto the end of the bolt so it engages all the rivnut threads, and insert into the hole. Hold the bolt static and crank down on the nut to start to collapse the rivnut. If the rivnut spins in the hole, tilt the bolt slightly and the rivnut teeth will bite into the edge of the hole and prevent it from spinning. Then the rivnut will start to collapse and bite further. Then you can straighten out the bolt and keep steadily turning the nut until you feel the rivnut fully squeeze shut. Then back off the nut slightly and screw the bolt out.



Here are very rough dimensions for my 83 SC with a trombone cooler. I suggest you use these only as a starting point and verify all your clearances in case there are variances from car to car. The hole near my thumb is for the trombone cooler bracket. Ignore that one. Center of the top hole to the corner of the sheetmetal lip is about 3 inches.



Center of the rivnut hole to the corner of the sheetmetal is a bit over 3 inches, maybe 3 1/8". The bracket and cooler are definitely inclined slightly so the top of the cooler is leaning towards the back of the car. The height of both holes is driven by the bracket itself. I shoved the bracket upward so the top wedged inside the sheetmetal lip.



Final installed bracket. I put a large fender washer inside the frunk at the top hole with 2 double nutted nylocks and blue loctite tightened as hard as I could by hand (higher than 25 Nm for sure). Bottom bolt is torqued to 25 Nm. Once I get the car on the road I may get it welded in permanently by a pro.

I reinstalled the trombone cooler nut with loctite so I wouldnt have an open hole to the frunk. Also the mounting tabs for the horns were bent forward a few degrees to clear the front of the cooler.



Cooler fit perfectly with the 2 rubber buffers below and 1 above hanging off the hook.



Hooked up the inner line with anti-seize and tightened.



Then the outer and we were done.



Thanks again for all the input. This took a long time but was worth checking everything 10 times and doing it right once.

[Fabspeed Motorsport]

Great work. I am doing a similar mod to my 78 SC.

[mike sampsel]

Yes, nice job and thanks for sharing. It will be interesting to hear about the cooling performance

[Mark Salvetti]

Thanks for this, I think you have created the most complete thread on how to install the 28-tube cooler. Hugely helpful. Will be adding one to my 79 SC.

Mark

[Solamar]

My project car came without engine, the trombone, or the hard lines. But it did come with a Carrera cooler... This is going to be most helpful when I put my cooler together.

Thank you for documenting this so well!

[911SPete]

I’m in the process of converting my 82SC trombone oil cooler to brass 28 tube cooler as described above and just read thru this thread. What are the correct oil lines (part numbers) required from the hard lines to the brass cooler? Appreciate your input.

[2jmotorsports]

The front lines I used in the procedure and photos above were 93020711105 and 93020711304. One is a bit longer than the other but I cant remember which was which.

[stevie 77 930]

If you can, get the cloth braided oil lines. They are much easier to work with