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Discussion Starter · #1 ·
Hi, I Have a 57 Belair with a cast iron powerglide which works fine but I'm thinking of going to a overdrive 700R4 for a better ride and better fuel MPG.
The thing is I'm not sure that the swap is going to make a big differance in the ride or fuel MPG. Doug Harrell
 

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Driveability, performance and fuel mileage will DEFINATELY improve. There are a few things to work around when upgrading to a 700, such as driveshaft length, lockup converter control, etc. But in the end, you would be pleased with the results.

By the way, welcome aboard!
 

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Doug, I put a 700R4 in my 55 and love it. The 700 has a very low first gear which gets off the line quickly and the other end is the overdrive which gives you about a .70 to 1 final ratio. I run a 3.08 rear gear and at 70MPH the RPM is at 1,850. You can run a higher rear end gear like I did and not lose your bottom end power. The main addition as far as improvements falls on the top end. The biggest question for me is 'how is the car used? Mainly around town?or on the highway quite a bit? If you stay on surface streets most of the time, I don't personally think your going to gain all that much. My 55 has tunedport fuel injection so I do better on mileage than most guys do with carbs. Mine gets about 20MPG average. Last but not least, how many miles do you drive the car a year? If it's just for local driving on nice days, you aren't really driving enough to justify the investment.
As far how difficult the change will be depends on the current setup. The one thing you will need to do no matter the setup is shorten the driveshaft. The 700 is about 3 inches longer than a glide, 4 speed or turbohydromatics.
 

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Mike are you happy with the power with that 3:08? All the info i`ve been reading seems to move you in the 3:55-3:73 range. The reason i`m asking is because mine has a 3:08 in it and i don`t want to replace it if i don`t really need to,Terry.
 

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We put a 2004r in my sons camaro and it was easy. Since the 2004r is almost the same size as a turbo 350 (and a powerglide I think), there is no driveshaft cutting or yoke change needed. You will need a kit to let the lock-up torque converter work, but this is a 30 minute job and is al bolt in. It made a HUGE difference in his car and he has a 400 HP 355 engine pushing the 2004r and it worked great. Really gave him extra gas mileage and the 1st gear is even lower than the 700r4. You will be happy with either overdrive tranny, especially on the highway.
 

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Discussion Starter · #6 ·
Sounds good I drive the car about 4000 miles per year mostly on road trips. I do alot of long distance touring with the VMCCA and AACA clubs, not much on racing any more getting old I guess. Thanks Doug Harrell
 

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Discussion Starter · #7 ·
Do you know if anyone has published a how-to guide that cover the 700R4 swap that would address the most of the requirements, like linkage extra parts needed etc.. Thank you Doug Harrell
 

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700R4

Hi, Doug:
If you have a '57 block it has no provision for side mounts. Therefore you will need to acquire bellhousing mounts for your new trans. I put a 2004R in my '55 with the Danchuk bellhousing-mount kit and ran it for about 5,000 miles until I replaced the front mounts with side mounts and the rear with a crossmember. I had to do some grinding on these mounts to fit the 2004R because they are designed fit a TH350, which is what I installed in the car originally. Danchuk says they fit the 700R4. If you want less hassle and no driveshaft modifications except for a fine-splined yoke, I would recommend the 2004R. Check out Bowtie Overdrives website for great tutorials, and they carry the electricals for the 3-4 shift switch and converter-lockup solenoid. If you want my bellhousing mounts, you can have them for $25 plus shipping. Part #870, $79.95 in 2006 Danchuk catalog. Mark
 

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Bowtie overdrives has a very good reputation and some good info on their site.
http://bowtieoverdrives.com/index.shtml

Well, bowtie overdrives hasn't been much any help to me... I purchased their crossmember for my 700r4 and side 3/4'' forward motor mounts... The crossmember perch for the tranny was welded on cockeyed and does not appear to be right... Talked to them on the phone to try to get some info and they were less than willing to provide any help, also saw them at the good guys show and the guy wasn't all too friendly or helpful there either. I cut off the perch last night and had to grind on the crossmember to get it to not hit the body. I just have to stop expecting stuff to fit right! Sorry for the rant... :)
 
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