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Username Post: 235 with a 6l80e?        (Topic#366695)
drew1987 
"8th Year" Silver Supporting Member
Posts: 3789
drew1987
Age: 34
Loc: Rochester, New York
Reg: 02-23-14
10-13-21 05:04 PM - Post#2829113    

Was wondering if there are any concrete reasons why one can’t use a modern 6 speed automatic with an aftermarket controller box (and it’s throttle position sensor) behind a 235 with whatever adaptor plate would normally be used with a 700r4? Thought process:

235 = not too much power

4.11:1 rear end means decent pick up but way too many revs at the magic 58 mph

3 gears barely enough to split the aforementioned up nicely.

235+4.11:1 and SIX gears, with a nice 0.667 final ratio as one of TWO overdrives sounds gorgeous to me. This means modern car get-up-and go but with bone stock under the hood (just not under the floor haha)


Are there any good reasons bot to do this? Does anyone have any info on it?

I’ll be digging and will post anything relevant here

Thanks


Andrew D. Carapella (Drew)

'50 Deluxe 4dr v8 auto

Member:

Rochester Street Rods - Est. 1970
http://www.rochesterstreetrods.org

CrossMembers Car Club - Hebrews 12:2
http://www.crossmemberscc.com


 


Mike JW 
"9th Year" Gold Supporting Member
Posts: 1516
Mike JW
Loc: Arroyo Grande, CA
Reg: 01-19-06
10-13-21 05:14 PM - Post#2829114    
    In response to drew1987

I don't have any info on it but it sounds great to me. I run a 292 with a 700R4 and 411 rear. Works great. I six speed trans would be even better. Not sure I would have the talent to figure out the electronics but you would.




 
Shepherd 
Frequent Contributor
Posts: 2321

Loc: Lake George, NY
Reg: 11-11-15
10-13-21 05:59 PM - Post#2829118    
    In response to drew1987

I think you will find when it shifts to overdrive, either one, you will be dropping the engine rpm so low, the trans is going to constantly be downshifting
, because of programming in the controller and the required throttle position required to overcome the rpm drop. Keep in mind the internal complexity of the 6 speed tends to absorb some engine power, that stock engine can't afford that. Just some observations based on building street rods.



 
drew1987 
"8th Year" Silver Supporting Member
Posts: 3789
drew1987
Age: 34
Loc: Rochester, New York
Reg: 02-23-14
10-13-21 06:41 PM - Post#2829121    
    In response to Shepherd

Ahhhh bummer. Didn’t think of that. Modern stuff / driving an LS430 right now - the engine and trans work well together but I can see where and engine they “doesn’t know” it’s hooked to a 6at could be less desirable

I think 60mph with 29 inch tires and 4.11:1 rear, the rpm at 58 would be about 2000… that said , do you still expect issues?

Andrew D. Carapella (Drew)

'50 Deluxe 4dr v8 auto

Member:

Rochester Street Rods - Est. 1970
http://www.rochesterstreetrods.org

CrossMembers Car Club - Hebrews 12:2
http://www.crossmemberscc.com


 
Airlifter 
"6th Year" Gold Supporting Member
Posts: 813
Airlifter
Age: 76
Loc: Tazewell county, Virginia
Reg: 06-07-15
10-14-21 04:13 AM - Post#2829132    
    In response to drew1987

I have been considering a similar swap using a 700R4 transmission. I have the 3.55 rear so I would be running about 1725 rpm at 58 mph and around 1900 rpm at 65 mph in OD. Without the OD I am running about 2575 at 58 rpm.


1951 styline deluxe sport coupe w/'60 261 engine & 54 powerglide


Edited by Airlifter on 10-14-21 04:16 AM. Reason for edit: No reason given.

 
drew1987 
"8th Year" Silver Supporting Member
Posts: 3789
drew1987
Age: 34
Loc: Rochester, New York
Reg: 02-23-14
10-14-21 04:29 AM - Post#2829135    
    In response to Airlifter

Yea the overdrive makes a massive difference. I found the 3.08 and 3speed auto is good too but it’s got 300left of torque to manage first gear with a smile. This would a much less powerful setup. I mean, gearing is all the difference but it’s all for nothing if the tranny doesn’t know what to do

Andrew D. Carapella (Drew)

'50 Deluxe 4dr v8 auto

Member:

Rochester Street Rods - Est. 1970
http://www.rochesterstreetrods.org

CrossMembers Car Club - Hebrews 12:2
http://www.crossmemberscc.com


 
Shepherd 
Frequent Contributor
Posts: 2321

Loc: Lake George, NY
Reg: 11-11-15
10-14-21 04:34 AM - Post#2829136    
    In response to drew1987

I am not sure the trans will clear the floor pan, another issue, we put an 700r in a 40 Chev., had a stock 283, with 3.42 gears, lotta hills here where I live, anyway it was constantly " hunting" for the right gear. 3.73 would have eased that issue. I think the 6 speed is an expensive overkill with a basic sbc combo in our cars.



 
drew1987 
"8th Year" Silver Supporting Member
Posts: 3789
drew1987
Age: 34
Loc: Rochester, New York
Reg: 02-23-14
10-14-21 10:09 AM - Post#2829151    
    In response to Shepherd

Yea hunting is no good. I’m so curious… I’d love to know if anyone’s done it. That 235 would love that many gears - for sure if it was a 6 manual, but it would all be for nothing in an auto if all it did was second guess every shift

Andrew D. Carapella (Drew)

'50 Deluxe 4dr v8 auto

Member:

Rochester Street Rods - Est. 1970
http://www.rochesterstreetrods.org

CrossMembers Car Club - Hebrews 12:2
http://www.crossmemberscc.com


 
arkansas 
Member
Posts: 313

Loc: arkansas
Reg: 09-26-06
10-14-21 10:35 AM - Post#2829152    
    In response to drew1987

Seems like I remember reading somewhere that the 2004r overdrive takes less "input" power to operate than the 700r4. I've got a 700r4 in my 49 sitting behind an old school 400 sbc. It works great. I've got a build going now though with a 250 I6 mated to a built 2004r going into a '71 c10. Sadly, I've not started it yet. The truck came with a T350 and the overall length of the 2004r is the same as the T350, but with the crossmember mounted back to the location a T400 would sit at. My frame was already factory drilled for that so I just moved the crossmember back and bolted it in and didnt' have to even cut the driveshaft. The upside to the 2004r is really that it is a physically smaller transmission than the 700 or other OD's and if it does take less power to run, then it should fit a 6 cylinder even better. The OD ratio is still .67.

1949 Deluxe Coupe 400sbc, 700r4, 3.73 posi
1949 4 door Fleetline Special, all original
1949 2 door Fleetline Deluxe rustbucket parts
1971 Chevy 1/2 ton shortwheel base, 250 I6, 2004r, underconstruction
1926 Ford T bucket, 250 Chevy, T350 tranny


 
Airlifter 
"6th Year" Gold Supporting Member
Posts: 813
Airlifter
Age: 76
Loc: Tazewell county, Virginia
Reg: 06-07-15
10-14-21 04:06 PM - Post#2829173    
    In response to arkansas

My original thought was a 200 4r. I have heard that transmission was troublesome. I won't be hotroding. I'm just looking for fewer rpm`s at highway speed.

1951 styline deluxe sport coupe w/'60 261 engine & 54 powerglide


 
Shepherd 
Frequent Contributor
Posts: 2321

Loc: Lake George, NY
Reg: 11-11-15
10-14-21 05:45 PM - Post#2829180    
    In response to Airlifter

Yes the 2004r was somewhat inferior to the 700r4, input shaft, pump assy, sun gear housing were all improved in the 700, but under moderate use the 2004r held up for the most part.



 


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