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I'm about ready to test fit a TKX into my 1972. It was originally a Turbo 400 automatic, and has an original removable crossmember. Does anyone have suggestions for the actual mount method, without welding? So far the only aftermarket adapter I see is from Silversport and have yet to call them with some questions. But also wondering if any of the less expensive generic adapters from Summit, hooker, etc might work. There are some used OEM 68 - 79 "transmission mount support brackets" that look like may work., but the Turbo 400 sat directly on the crossmember, with just the rubber mount. ..anyone know if these "transmission mount support brackets" were used with turbo 350's or manuals, might they be used on a Tremec? https://www.volvette.com/SH101H.html
I went from a th350 to a tko 600 and because of the different tail shaft mounting point. I had to do cutting and welding. My kiesler kit actually came with the new braket to weld on.
The smartest thing to do is just buy the G-Force tubular cross member. No welding and then your exhaust system is simplified because the exhaust passes under NOT through.
I installed a TKO-600 in my '79 many years ago. I assume the TKX mounts the same way. If you can find a transmission bracket from an '82 with the 700R-4, it bolts right up. My car originally came with a TH350 which I swapped out for a 700R-4. When I installed the Tremec, everything just bolted up.
69 Fastfun -Nice/clean. I cant see the bracket in the pic though. What did you use for the bracket that extends from the crossmember to the bottom of the transmission. It would be nice if the O.E.M's would fit cause I see several used ones for sale, and they look pretty strong, but I think they are about an inch too long. As far as the 82 700R4"s, I did a search and did not even find a pic. Sounds like a good option though.
Last edited by J-Vette1; Aug 15, 2024 at 06:25 PM.
J-Vette1
It seem like you are still going to have to modify the 68-79 bracket even if you get it used (which would be smarter). It sure looks to me like that drop is a different height on the stock bracket compared to the SST bracket(??? not sure??).
Below is link on one for 50 bucks on ebay.
Notice that the item below is shaped a bit different than the one from SST...think you'd had to modify it a little anyway. https://www.ebay.com/itm/22623173797...Bk9SR_LE-Y2rZA
I would think that you would want to weld on the little vertical tabs to mount the front of the crossmember like those for the stock bracket.
I agree with gkull that the smart thing to do is to buy a crossmember that allows the exhaust to pass under, but if you're not going to do that then there's different ways to do this.
I do NOT believe your turbo-400 crossmember came with the little vertical tabs? Correct me if I am wrong, but if that is true you can make some from scrap metal and weld them on ...then just use piece of angle iron to create the proper depth / height bracket to hold the tranny. gimme a second and I'll find the bracket I made for my Richmond 6-speed.
I'll be back...meanwhile here is an image of the one being sold by sst (funny, but I cannot see holes on the side of the bracket?)
Last edited by carriljc; Aug 15, 2024 at 10:23 PM.
J-Vette1
Here.
This is the support I had holding up my richmond 6-speed for 25+ years. It is a piece of angle iron bolted horizontally onto the crossmember and into the 2 vertical supports for the former M-21 support (all were Grade-8..... just because). If you can do a little cutting and measuring you can easily duplicate something like that.
I drilled 2 horizontal holes and welded 2 nuts onto the angle iron and it all bolted together..... not even difficult. All you had to do is figure out the height that your tranny sits at ...
Last edited by carriljc; Aug 15, 2024 at 10:24 PM.
J-Vette1
after all that.....if you have to farm out the cutting and welding then you're better off just buying that 140 buck bracket.; BUT REALLY I still agree with gkull about exhaust -pass-under xmember.
carriljc - Thanks for all that detail. Good info. You are correct in that the cross member on my 72 / Turbo 400 does not have the two "ears" that a manual mount would have had. I also wonder whether an OEM manual mount would fit. Besides the difference in the amount that the original one steps down, I also came across an article in a blog that the Muncie mount location was about an inch closer to the plane of the bell housing, which may (or not) land right about where that step sits. Unfortunately its one of those things that you need either the actual dimensions, or one "in hand" to know for sure. But, I like your custom mount. For now, I will plan to be utilizing the original crossmember, in trying to keep costs down. That one in the video looks like a silver sport mount, but as you mention, the advertised pics don't show any holes for the two vertical mount tabs. It seems like a lot of the torsional/twisting strength would come from them. Maybe only needed with a big block? I need to call them and ask.
J-Vette1
From all the research I did on tranny crossmembers they would be the same on a 72. You can buy the little tabs to weld on but they're easy enough to make yourself if can do a little cutting and welding. I'll go find them .....they were used manuals and for the turbo 350.
I mounted a 200-4R where my Muncie M-21 was and it bolted directly into the holes for the Turbo 400. I later made my own crossmember but that neither here nor there. The crossmembers are the same for the Manuals, the 400, and the 350 through like 1978. I'll go a link for the little tabs.
The silver sport mount has all the holes. see the video link I posted for you, he mentions the part number in the comments section and it has all the holes..... but yeah, you can make a simple mount like mine with a piece of angle iron.....
Here you are: https://www.corvettecentral.com/c3-6...r%26count%3d18
Originally Posted by J-Vette1
carriljc - Thanks for all that detail. Good info. You are correct in that the cross member on my 72 / Turbo 400 does not have the two "ears" that a manual mount would have had. I also wonder whether an OEM manual mount would fit. Besides the difference in the amount that the original one steps down, I also came across an article in a blog that the Muncie mount location was about an inch closer to the plane of the bell housing, which may (or not) land right about where that step sits. Unfortunately its one of those things that you need either the actual dimensions, or one "in hand" to know for sure. But, I like your custom mount. For now, I will plan to be utilizing the original crossmember, in trying to keep costs down. That one in the video looks like a silver sport mount, but as you mention, the advertised pics don't show any holes for the two vertical mount tabs. It seems like a lot of the torsional/twisting strength would come from them. Maybe only needed with a big block? I need to call them and ask.
Last edited by carriljc; Aug 16, 2024 at 10:57 PM.
Carriljc - got the link for the tabs. Thanks again! I'm looking at your custom mount, and it's probably strong enough even without those extra tabs, because it doesnt sit very far from the xmember. And by you bolting into the front of the xmember, it prevents twisting from the torque. Genius! If anything, maybe just closing each end of the angle iron with triangular or square pieces, but sounds like its been working just fine, without. If my #s are right, the Tremec needs to protrude more like 4.25 inch from the xmember, so "boxing" the ends are probably required, with such a long lever. Either a modified oem, or Silver Sport is looking like a sale.
Anyone have dimensions on the OEM manual transmission mount for C3's ? I am wondering how far it extends from the crossmember, before it takes that downward "step."
Last edited by J-Vette1; Aug 19, 2024 at 08:35 PM.
J-Vette1
Yeah. It's easy enough if you can do even a little fabricating and welding. The tabs are easy to make and a piece of angle iron is easy to find..... if it's 3/8" (5/16"?) thick like mine was then methinks it would be more than strong enougg, or you can brace it like the SS thing..... looks like it is easiest to just pay for that thing. If it was me I'd make the little tabs and weld them on....
Originally Posted by J-Vette1
Carriljc - got the link for the tabs. Thanks again! I'm looking at your custom mount, and it's probably strong enough even without those extra tabs, bevause it doesnt sit very far from the xmember. And by you bolting into the front of the xmember, it prevents twisting from the torque. Genius! If anything, maybe just closing each end of the angle iron with triangular or square pieces, but sounds like its been working just fine, without. If my #s are right, the Tremec needs to protrude more like 4.25 inch from the xmember, so "boxing" the ends are probably required, with such a long lever. Either a modified oem, or Silver Sport is looking like a sale.
Last edited by carriljc; Aug 19, 2024 at 08:49 PM.
Transmission Mounting for Tremec TKX
