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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: jaredts on June 03, 2013, 10:49:43 pm
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'83 c10, rpo sheet in glovebox says 305/700r4. When I got it it had a 350/th350 (long, 9" tail). I'm swapping in a 700r4 and I'm having a terrible time trying to figure out what's up with my crossmember mounting. There is only one set of holes in the driver's side frame for the crossmember. I've seen on this site that my year should have two sets, I don't. On the passenger side there's several holes, but only the ones toward the front of the truck will line up if I use the single set of holes on the driver's side. If ignore the driver's side holes I have two other options:
1) the next set back, which matches up with all holes in that side of the crossmember (including the little top wing piece), but is nearly touching the pan and I don't think the pan could be removed. It would also require elongating the holes in the crossmember for the mount about 1/2" toward the back (okay, I already elongated them).
2) The set toward the rear, which matches up with all holes in the crossmember and wing except for the front hole on the member that is about 1/2" away from hitting a hole. To bolt up to the transmission mount the crossmember holes would have to be elongated about 1/2" at the front (okay I already elongated them that way too).
I've pretty much decided I need to use option 2 and drill new holes in the driver's side, but something isn't right. This truck had a 700r4 in it at one time.
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Shooting from the hip here.. The tranny might have come with an offset mount where it bolts to the tranny vs the cross member.
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I'm using a new energy suspension transmission mount. The tapped holes for crossmember bolts appear in line with the transmission bolt holes.
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When I went from a TH350C to a 700R4 out of a 1986 C10, put into a 1985 C10 the crossmembers were both slightly different. Holes in the frame didn't line up using either crossmember with either trans mount so I just drilled the holes I needed. Yes a pain but had to be done.
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Thanks, Zieg. Good to know I'm not the only one who has had this problem. I just don't see how a 700r4 was in this truck before???
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Hey do you mind noting any change in mpgs and if the line tq. I just got a 700r4 core i'm going to have rebuilt.
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I'll post my reactions and new mpg's, but believe it or not I have never checked it with the old setup. It wasn't too bad so I didn't really care. What's line tq?
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Off the line tq, like does it feel like it has more power
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Hopefully the lower first gear makes a noticeable difference. I'll let you know.
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Thanks
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It gave my 85 C10 some off the line power, compared with the TH350C. I had the 2.73 rear end so you should see an improvement