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5/6 Speed Transmission Swap

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Old 11-25-2010, 08:13 AM   #1
corvette7576
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Default 5/6 Speed Transmission Swap

Hello Everyone,

I recently dropped a 383 stroker into my 75 and would like to replace my Borg Warner t-10, 4 speed with either a 5 or 6 speed. Does anyone know of a transmission that will bolt right up to my existing bell housing with out any modifications?


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Old 11-25-2010, 09:13 AM   #2
Garys 68
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Richmond 5 speed (1.00 5th, or OD 5th) or 6 speed (OD 6th gear). Uses factory bell housing, clutch, z bar, shifter location, speedo cable, driveshaft. Only mod required is to the trans mount. That cost me about $20 extra.
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Old 11-25-2010, 09:22 AM   #3
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The problem is with the welded in cross members on the 4 speed cars. The Tremec 5 speeds can be done with leaving the member in but it is real tight. I have done a bunch on coversions from auto to 5 speed and 4 to 5 speeds. I always make the cross member removeable. It makes it way easier and for any future works it makes removal a breeze. I can drop the 5 speeds out in about 1/2 hour with removeable members. I had a Tremec in mine and now have a T56 6 speed. That requires a lot more work. The Tremec kits are a bolt in but are somewhat costly. There have been a lot of different 5 speeds put in C3 cars. Some bolt in some require more work. I have a car in my garage right now that I just put in a Tremec 5 speed from a Borg Warner 4 speed. Only takes a few hours now that I have done a bunch of these. Do your homework and see what you need for strength in the trans and do you want an overdrive transmission.
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Old 11-25-2010, 10:11 AM   #4
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World Class T-5 for me. Lots of fun for not a lot of coin.

http://forums.corvetteforum.com/c3-g...-finished.html

Good luck with your project !
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Old 11-25-2010, 09:44 PM   #5
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Gordon, did you just cut the crossmember out and weld plates on the ends to just bolt together when installed in the frame? Does the structural integrity of the frame change at all? I want to do one of these installs in the future, but that crossmember is such a PITA.
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Old 11-26-2010, 07:34 AM   #6
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I cut mine and welded on some brackets. Mine bolts from front to back. Some of the other installs have welded plates and bolt in side to side. I have not noticed and frame structure probelms my way. I just did another car the same way and it works out OK. Not as pretty as the other brackets but it works.
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Old 11-26-2010, 08:45 AM   #7
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If I was going to do it again, I would probably cut the original crossmember out and put in an aftermarket bolt in. I dont need the exhaust clearance since I'm running sidepipes.
http://www.speedwaymotors.com/Straig...ount,3279.html
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Old 11-26-2010, 06:28 PM   #8
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Quote:
Originally Posted by FlyViper View Post
Gordon, did you just cut the crossmember out and weld plates on the ends to just bolt together when installed in the frame? Does the structural integrity of the frame change at all? I want to do one of these installs in the future, but that crossmember is such a PITA.
I'm guessing that a manual trans crossmember that has been cut and bolted together is at least as strong as an auto trans crossmember, probably stronger. The auto trans crossmember is held on by one main bolt and two smaller screws per side.



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Old 11-26-2010, 08:50 PM   #9
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Quote:
I'm guessing that a manual trans crossmember that has been cut and bolted together is at least as strong as an auto trans crossmember, probably stronger. The auto trans crossmember is held on by one main bolt and two smaller screws per side.
Wow, didn't know that. Well, that does make me feel better. I don't have any experience with welding, so I'll have to take it to a frame shop or something. Any guess on what it would costs to have this done?
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Old 11-26-2010, 09:09 PM   #10
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Wow, didn't know that. Well, that does make me feel better. I don't have any experience with welding, so I'll have to take it to a frame shop or something. Any guess on what it would costs to have this done?
No need to take it anywhere. Find someone local. There are plenty of guys with welders on their trucks that will do it. I have 2 guys that I use and both are very reasonable. It would take them maybe a 1/2 hour to weld on the brackets. It really is not a big weld job to do.
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Old 11-26-2010, 11:20 PM   #11
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In the process of putting in a T45Rs 5 speed overdrive right now. I have a 4 speed car with a welded in crossmember and I did not cut it out and weld in brackets. The only mod I had to make was to cut a hole in a slightly different place in the trans tunnel for the shifter but it looks stock with the shifter console back in place.

I was pulling the engine anyway to freshen it up so it was not a big deal. I will say that if I need to pull the trans or service the clutch assembly at a later date, I will cut out the crossmember instead of pulling the motor again.
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Old 11-26-2010, 11:24 PM   #12
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I figure if I'm going to put a new tranny in, I might as well cut the crossmember then, considering future work as you mentioned. I guess I'm most afraid of actually cutting my crossmember, never really done anything like that. There's two place I'd like to get patched on my frame anyways, so since I need to take it to a frame shop anyways, might as well have them do it.
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Old 11-26-2010, 11:39 PM   #13
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If you're going to a good frame shop, I am sure they can do a great job fixing your frame and modifying it so it could be returned to a factory look at a later time. That's probably what I should have done, just could not bring myself to cut it out right now. Would have made my swap a lot easier!
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Old 11-26-2010, 11:48 PM   #14
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Yep, I've already pulled the engine/tranny, sat it back in, pulled it out, etc. too many times. That damn cross member is going to be removable next time! My frame is not great, but it's not horrible. I'd like to take it to a frame shop, have them weld some areas and maybe clean up the frame. Not really sure what a frame shop's capability is with the body on, but I'm willing to pay some money to get my frame better than it is now. Perhaps they can clean it up and put some kind of protecting coating on it? I've seen awesome looking frames on here, but they're all pretty much frame-off jobs and that just isn't going to happen for me.
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Old 11-27-2010, 10:53 AM   #15
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Default Take a look...

If I had to do it again, I would use that kit in one of the messages above. All you have to add is the parking brake wheel bracket, and it would make the exhaust work a lot simpler.
But, you can see how I did mine below....


Quote:
Originally Posted by carriljc View Post


If I were to do it again, I make the cuts further inboard.
As far cutting, just use a sawzall or a circular saw. I used a rope saw to cut mine, but there's no need to be that accurate.

All stitch welds completed and painted this gray that I really like.

Last edited by carriljc; 11-27-2010 at 10:55 AM. Reason: spelling
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Old 11-27-2010, 01:28 PM   #16
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Default I cut out and put a G-force crossmember in


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Old 11-27-2010, 04:03 PM   #17
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I swapped in a Richmond 6sp for my old M20. My crossmember was solid so had to modify it to be a 2 piece.Took some pics and details at this location.

http://69vettester.com/richmond.htm

6speed in a c3 is the cats meow , youll love it.
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