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Diff between auto and 4-speed crossmember

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Old Feb 6, 2006 | 01:32 PM
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Default Diff between auto and 4-speed crossmember

Good afternoon all,

Apparently there are two different trans crossmembers on C3's, one for auto and one for manuals. Can someone explain to me the difference?,..photos would be great.

I'm looking for a 4-speed crossmember for my 73,..if anyone has a line on one,..let me know (none on e-bay right now).

Wes

Last edited by 73, Dark Blue 454; Feb 6, 2006 at 01:54 PM.
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Old Feb 6, 2006 | 02:55 PM
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As far as I know a 4 speed crossmember cannot be removed because it is welded onto the main frame. The auto crossmember is a bolt on to facilitate trans removal. I may be wrong but I don't think so.
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Old Feb 6, 2006 | 02:57 PM
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that is correct vettfixr

keep watching e-bay I bought one about a year ago,came with trans mounting bracket all for $75.00
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Old Feb 6, 2006 | 02:59 PM
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Originally Posted by vettfixr
As far as I know a 4 speed crossmember cannot be removed because it is welded onto the main frame. The auto crossmember is a bolt on to facilitate trans removal. I may be wrong but I don't think so.
Yep!
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Old Feb 6, 2006 | 07:55 PM
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Thanks!

I'm sure many have converted C3's with automatic tranny to 4-speeds. What needs to be done to a TH-400 crossmember to make it compatble with a Muncie 4-Speed,..or...is there an aftermarket bolt-on crossmember designed for the swap?

Advice welcome.
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Old Feb 6, 2006 | 09:55 PM
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Originally Posted by 73, Dark Blue 454
Thanks!

I'm sure many have converted C3's with automatic tranny to 4-speeds. What needs to be done to a TH-400 crossmember to make it compatble with a Muncie 4-Speed,..or...is there an aftermarket bolt-on crossmember designed for the swap?

Advice welcome.
Bow tie overdrives has an aftermarket cross member for the C3. It's intended for a 700r4 auto but it wouldn't take much to make it work with a manual. It also allows more clearance for the exhaust system.

http://www.bowtieoverdrives.com/cata...php?ITEMID=112
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Old Feb 7, 2006 | 07:43 AM
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The C-3 auto crossmember will work fine.
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Old Feb 7, 2006 | 04:24 PM
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Originally Posted by 73, Dark Blue 454
Thanks!

I'm sure many have converted C3's with automatic tranny to 4-speeds. What needs to be done to a TH-400 crossmember to make it compatble with a Muncie 4-Speed,..or...is there an aftermarket bolt-on crossmember designed for the swap?

Advice welcome.
...you do not need an aftermarket "crossmember". The stock one works perfect. Just converted my '75 L-82 automatic car to a 4spd car two years ago. Only thing I did was to replicate those little side tangs that a four speed crossmember has welded to it to bolt that transmission mount crossmember extension piece to. I just fabricated two small 3/4 inch x 3/4 inch L shaped steel stock, bolted them to the 4spd transmission extension piece, then bolted this piece to the automatic crossmember, marked my holes and drilled away. It looks so factory, most people think it is.
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Old Feb 7, 2006 | 08:04 PM
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After re-reading your original post, I don't know what I was thinking. There's no need for another x-member, the original works great. In fact, it makes the conversion easier.
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Old Feb 8, 2006 | 12:13 AM
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So my original TH-400 crossmember will work? I know on my 69 Camaros, a TH-400 crossmember won't work with Muncies without working it over.

Shafrs3,..what "little tangs" are you speaking of? Photos would be great.

Thanks for helping me out.

Wes
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