4R70W Drive Shaft Length?

[400BA]

Hello All!

I've been lurking around here for a while and have learned a ton from reading through builds and other posts prior to ordering a FF kit. Thank you to all of you that share information so willingly!

I am ordering a Roadster kit (as soon as I can address my issue) and would like to use a 4R70W auto tranny so that my father and son can also drive the car we are building together. I called and emailed FF Factory Five to ask if they had any other kit buyers use the same tranny, and if they did what length drive shaft to order.

The response I got was that "Factory Five does not support automatic transmissions so you are on your own for that."

For those that have used the 4R70W tranny in a Roadster build or know from others that have, what length drive shaft did you use?

Thank you all in advance!

Mike

[CraigS]

A couple of Qs for you. Any idea how long that trans is compared to a TKO or similar? Are you going w/ 3 link or IRS? W/ 3 link you need some drive shaft length so the axle can move w/o binding the driveshaft u-joints. IRS allows a shorter shaft. If you can confirm you will have enough room, then talk to a local drive shaft shop. Doing my 3 link to irs conversion I called my local shop and asked how do you want me to measure for length. I gave them a length measured the way they wanted it and no sweat, they shortened the shaft perfectly.

[400BA]

Thank you for the response, Craig!

I don't know the actual length of the 4R70W compared to TKO, so I'll spend a little time today getting that info together.

I'm using the IRS from FFR.

Its good to know that a local shop can make adjustments to the shaft. I ordered one from FF that is a bit longer than the shaft used for a TKO so I'll be hoping I can modify as you did.

Thanks again!

Mike

[FLPBFoot]

I'm building a 2nd Roadster for my wife and she wants a milder engine with an automatic. She can drive our current Roadster with the TKO but wants something that can be much more of a jump in and go "daily driver".

I got the same response from FFR and mentioned that when I talked to Blue Print Engines they indicated they have worked with FFR and the 306 with the auto trans would be no issue. Research I've done shows the TKX with quick time bell hosing is 31" from bell housing face to back of the tail. Dimensions I've found on the 4R70W shows it is 31.28" and another site at 31 3/16". So basically the same but it may require some modifications.

Big thing is output shaft spline count. From what I've found the 4R70W is a 28 spline output so I ordered that drive shaft with my Roadster kit. I can always get a shop to modify the length if needed.

[Fordguy]

I am using a Lentech 4r70w trans. mated to a 408 Cleveland. I was told that the auto trans is the same length as a TKO. I just received the driveshaft (for TKO) from F5, it was backordered.
Once I get to the point of installing driveline, I will report back if you are still in question.
Either way if the drive shaft fits or not, its not a big deal to get a custom length shaft made.

[400BA]

Thank you ILPBFoot and Fordguy! I found the same dimensions as ILPBFoot and am looking forward to hearing about your experience, Fordguy.

Have either of you selected a shifter yet? I'm currently thirsting over the Lokar units!