overdrive conversion. is it worth it?
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Intermediate
Joined: Sep 2002
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From: mobile al
overdrive conversion. is it worth it?
My wife's 80 model, ZZ4, equipped coupe just puked its transmission. Is it worth the effort to put a 200r4/ 700r4 etc in it. Or do I just rebuild the original trans. Any input is greatly appreciated.
Race Director
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From: Waterloo ontario Canada
Re: overdrive conversion. is it worth it? (thebmwsource)
I think it is. It gives you a really low first gear. 3.06 in first vs 2.48 and the overdrive drops your rpm in high by 30 percent. With 4.11 gears I was turning 2200 at 60 and 2500 at 70. If I had 3.08 gears I would only be turning 1600 at 60 and 1900 at 70.
If you want a wicked 1st gear and overdrive go for it.
If you want a wicked 1st gear and overdrive go for it.
Team Owner
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
Re: overdrive conversion. is it worth it? (thebmwsource)
My overdrive transmission was the best upgrade to my '68...
:cheers:
Olivier
:cheers:
Olivier
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Joined: Mar 2001
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From: Living in the Hartland
Re: overdrive conversion. is it worth it? (thebmwsource)
Here is a good article on the TH2004R:
http://www.chevyhiperformance.com/ed...0viewtype=text
If I had an auto I would got this route rather than the 700r4.
[Modified by Fevre, 10:26 AM 11/27/2002]
http://www.chevyhiperformance.com/ed...0viewtype=text
If I had an auto I would got this route rather than the 700r4.
[Modified by Fevre, 10:26 AM 11/27/2002]
Le Mans Master
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From: Semper ubi, sub ubi
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Re: overdrive conversion. is it worth it? (thebmwsource)
TH200-4r is a good choice to replace the TH350, since they are the same length and don't require the driveshaft to be cut. They also use the same rear yoke. The only thing that might need changing is the mounting location of the tranny, I don't know how it matches up with the crossmember. Page62 just put one in his car and he loves it.
Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: overdrive conversion. is it worth it? (Smokehouse69)
I would never install a OD automatic in any performance car They are a total waste of money and HP. You will never recoupe the cost in gained gas mileage.
Manual OD is the only way to go
Manual OD is the only way to go
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From: Waterloo ontario Canada
Re: overdrive conversion. is it worth it? (gkull)
I smiled at that comming from you George. I know you have a 700 R and often wondered if you would like to change. Now I know. :) :) :)
Have a nice day George
Have a nice day George
Safety Car
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From: St Louis MO
Re: overdrive conversion. is it worth it? (thebmwsource)
Personally, I would do it. I will transplant a manual od into my 74 next summer. I've had auto/manual trannys in my past hotrods and daily drivers and od is the only way to go.
Pro
Joined: Feb 2002
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From: Carlsbad CA
Re: overdrive conversion. is it worth it? (gkull)
It more than just gas mileage. The engine wear is also reduce along with an easier ride down the freeway. And, don't forget the great hole shots with that new first gear.
Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: overdrive conversion. is it worth it? (thebmwsource)
The best thing to do is get a 2.73 rearend and a none OD 5 speed manual.
For an automatic in a sub 400 hp car I would try a 200R4 for 400+ I would do the bigger LE series trannies.
For an automatic in a sub 400 hp car I would try a 200R4 for 400+ I would do the bigger LE series trannies.
Team Owner
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
Re: overdrive conversion. is it worth it? (gkull)
Manual OD is the only way to go
:cheers:
Olivier
Le Mans Master
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From: Tampa Bay FL
Re: overdrive conversion. is it worth it? (thebmwsource)
Around town, I can't use the o-drive under 50mph without lugging the engine. I also have to address a major stumble betw 1-2 shift because it's like my car is taking a punch to the mid-section under high acceleration. If I were to do it again, I'd either install a stout TH350 or go with the 2004R since the 2004R 1st gear isn't quite as deep as the 700R4.
Race Director
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From: San Jose CA
Re: overdrive conversion. is it worth it? (thebmwsource)
It's like John Lingenfelter said. You have to match your engine to the RPM range you spend the most time in. Any engine that comes alive at high RPM is gonna hate the gear shifts of the 700R4. The 200-4R is not all that hot either. The 700 was designed with motors like the L98 in mind, IE neck snapping low end torque and out of steam @ 4500 rpm. The drop in my 700 really doesn't bother me all that much, but my motor has a 1000-3200 rpm powerband w/ the L48 cam. A shift @ 4500 rpm drops me right back in the middle/top of the band, ~2500 rpm or so. (Just guesstimating, can't remember off the top of my head.) I prefer the 700 because of the abundance of parts for it, people that know it, and so on. It'll go well with the engine in my sig, which is designed for operation between 1500 and 5500 rpm. If I had a motor that came alive past 3000 rpm, I would definitely suggest some kind of manual transmission, 5 gears or more. Gkull is absolutely right about a 2.73 and 5-speed, that would be a wicked combination for road racing and drag. (Of course, optimal for drag is that you're out of gear at the end of the strip. I know.)
-Steve
-Steve
