700R4 Aftermarket

[TruckCo]

Good evening,

Many people have been a huge help through the truck project and I am forever grateful. My last question for my engine swap is i currently have a 700r4. I am under the impression they made an earlier model with 27 spline and a “newer” model with a 30 spline. I was looking at built transmissions online complete (Summit Racing) that say it their advertised trans has 27 spline input and a 30 spline output ? Does this make sense? I figured the input and output would be the same size.

I guess my question is, as long as its a 700r4 thats 2wd , will all 700r4’s fit the crank and the driveshift? I believe these transmissions are all the same as long as its 2 or 4wd unlike the 400’s that can be short or long tail etc. Or is the spline count important for the driveshaft and not the crank. Im just wondering what I need to do. Thank you, my truck is an 87. Ill have help adjusting the lash on the torque converter and will have to look up how to pre adjust the tv before final adjustment.

What im looking at.

https://www.jegs.com/i/JEGS/555/60320/10002/-1?gad_source=1&gad_campaignid=20673855490&gbraid=0AAAAAD6OBRFAlODyqaLWW801vcRAXpDfC&gclid=EAIaIQobChMIqYqGzN3FkAMVkDIIBR3dhSw8EAQYAyABEgJa8_D_BwE

 

[legopnuematic]

The input shaft spline count needs to match the torque converter.

The output shaft spline count needs to match the driveshaft yoke.

 

[Ricko1966]

Best of my knowledge,they all use the same spline drive shaft yoke. All are the same length,except for Corvette. Input spline changed mid 80s the 30 spline is supposed to be stronger. Input spline,really is NBD just be sure to use the torque converter that matches.

 

[TruckCo]

Is there any way to tell by cast numbers or part numbers on what I have?

 

[ali_c20]

Is there any way to tell by cast numbers or part numbers on what I have?

Yes.
Just google the id stamping.

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[Bloodhound1981]

Is there any way to tell by cast numbers or part numbers on what I have?

See my post here.

https://www.gmsquarebody.com/threads/700r4-help.48238/post-1031473

 

[TruckCo]

See my post here.

https://www.gmsquarebody.com/threads/700r4-help.48238/post-1031473

My number is 5MDP72A. So it appears its a 1985 Transmission, so it would have the 30 input and and 30 spline output shafts.

If i order the 27 input one from Jegs, all that would matter is me getting a 27 spline torque converter correct? And i order as a 700r4 tc not motor specific? SOunds like all 700’s had a 27 output it was just the TC side that had an update. The crank and TC will bolt to the crank fine? Other than a stall converter is a TC a TC? Or are there performance ones rated for HP.

 

[Turbo4whl]

I believe the converter spline count changed when the pumps were updated. Original 700R4's had less vanes in the oil pump. Just a couple years after the first 700R4's hit the road, the pump rotor has more vanes. 7 to 10 vanes? I forget.

 

[Gander]

Yes.
Just google the id stamping.

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So this is really interesting. My truck is a 1987 V10. Invoice for the truck is dated Oct 15 1986 so that’s around the date the truck was built. Looking at the description of the trans numbers, the numbers on my transmission match the description of the 1987-1988 numbers BUT the first digit is a 6 and according to this, it was built the 50th day of 1986 so mid-late Feb? Numbers on my transmission are 6tkm-y-00891496-050-a.

 

[Bloodhound1981]

What king of power are you making? And the real question is who is making that Jegs or Summit transmission, cause it obviously isn't them. I would encourage you to have your transmission rebuilt and beefed up by a locally reputable shop before buying a mystery trans from one of the big box stores. I see you are in MA and so am I, there are definitively some good options around here. That way, you know what you are getting, and have someone to go to if all doesn't go right.

 

[Bloodhound1981]

So this is really interesting. My truck is a 1987 V10. Invoice for the truck is dated Oct 15 1986 so that’s around the date the truck was built. Looking at the description of the trans numbers, the numbers on my transmission match the description of the 1987-1988 numbers BUT the first digit is a 6 and according to this, it was built the 50th day of 1986 so mid-late Feb? Numbers on my transmission are 6tkm-y-00891496-050-a.

Makes sense to me. Your trans was built in 1986. The 1990 Corvette 700R4 I am running was built in 1989 based on the number.

 

[ali_c20]

So this is really interesting. My truck is a 1987 V10. Invoice for the truck is dated Oct 15 1986 so that’s around the date the truck was built. Looking at the description of the trans numbers, the numbers on my transmission match the description of the 1987-1988 numbers BUT the first digit is a 6 and according to this, it was built the 50th day of 1986 so mid-late Feb? Numbers on my transmission are 6tkm-y-00891496-050-a.

That's normal they took what had have in storage. The stampings on my 74 C20 frame are mixed 73 and 74.

 

[Rebuildman]

Early models require a lot of mods to bring up to the current standards of later models. Better off starting with the later one if possible. 1985? I look at the side of case, it has a casting mark that looks like a camshaft lobe. That is the one you want.
I rebuilt mine two years ago at a parts cost of $1000. Good for 400-500 hp? Works good in my truck.

 

[electoqute]

The difference between early and late 700r4 is the valve body. Early had a 1 piece valve body which made an easy conversion for nonoverdrive cars ( 1 wire 1 pressure switch ) later 700r4 referred to auxbody used a 2 piece valvebody with the auxiliary valve controlling converter lockup. As far as strength it's the internals that have an impact. Heavy or performance are better ( more clutches 3 vs 7 vs 9, 5 pinion planetary vs 3 or 4 pinion ) upgrade i recommend regardless are BEAST sunshell, shift kit, heavy duty converter with a stall appropriate for your needs and wants, and most importantly a builder with experience and quality workmanship

 

[TruckCo]

What king of power are you making? And the real question is who is making that Jegs or Summit transmission, cause it obviously isn't them. I would encourage you to have your transmission rebuilt and beefed up by a locally reputable shop before buying a mystery trans from one of the big box stores. I see you are in MA and so am I, there are definitively some good options around here. That way, you know what you are getting, and have someone to go to if all doesn't go right.

Who do you recommend Bloodhound?