I'm currently putting a 4T65E-HD tranny onto a SBC using Archie's kit. My question is, what flexplate did you use? The torque converter from the HD tranny is larger than the one from non-HD tranny's. The flexplate has 2 rows of mounting holes in it for the torque converter to bolt onto. There is one set of holes on the "flat" portion where the smaller torque converter bolts onto (the non-HD one and I think, the stock Fiero one). These holes are not at the right radius for the larger torque converter, so I was going to redrill some holes to mount the larger converter; no big deal so far. Here is the problem. There is another set of holes on the 3 raised areas of the flexplate, that seem to be unused to me. These holes are at the correct radius for the larger TQ, but if I use those holes, the TQ will sit too far out and will foul with the tranny. So I have to mount the TQ on the flat portion of the flexplate by redrilling the holes as I said. But the larger TQ can't sit on this flat portion since it interferes with the 3 raised areas (the HD torque converter bulges out a bit on the back side, where the stock Fiero and non-HD ones actually are curved in a little to clear this area).

What might work is if I machine off a portion of the raised pads, since I don't need them anyways. I don't know if this will leave the flexplate too weak, but I don't really think so. I'll round the edges of the areas I machine out so they won't crack. I'll post some pictures of all this later, but if someone has done this swap with this hardware, I hope it's clear what my concern is. I'm kind of amazed how few people have done this swap based on the number of small problem areas I've run into.

Rick

OK, here is my solution.

First, the problem:

The 4T65E-HD torque converter has to sit on the flat portion of the flexplate; if it sits on the raised pads, it is too far back and will hit the tranny bellhousing. But sitting on the flat portion, the raised pads will hit the torque converter and keep it from sitting on the mounting areas:



I tried it in the milling machine first, but it really wasn't steady enough and it was chattering too much when it was being machined:



The lathe worked better. It was an interrupted cut, but it worked out fine by going slowly with it:



This shows the finished machined flexplate sitting on the torque converter. I drilled new holes to match the pattern in the HD torque converter. The area of the 3 pads that have been removed clear the bulge on the rear side of the torque converter:



This is a close-up of one of the pads. I smoothed up the edges after machining and it clears the torque converter:



I think this is going to work out OK. If anyone has encountered this problem I would like to know how it was solved. I don't think I could use a flexplate from a 3.8 engine (that had the 4T65E-HD behind them) since I think it is a different bolt pattern and is also used to balance the engine, so it has weights on it. I can't really be the first one doing this, can I?

Rick

It would not surprise me that you are the first to do this....

The 3800 flexplate is available in a unbalanced version, but I doubt the bolt pattern to the SBC crank is the same.

quote Originally posted by darkhorizon: It would not surprise me that you are the first to do this.... ....

agreed.

not only that, but what transmission controller are you planning on using? (My guess) Most people probably would not want to go through the added hassle of wiring in the TCM, and would go for the 4T60.

I have done a TCM, but it was on a Mitsu...

[This message has been edited by IFLYR22 (edited 05-31-2009).]

I have not done it, nor do I plan on it.. But i have played with the idea of making a trans controller out of a stock PCM.. In theory all you need to do is implement a few OEM sensors and you should get fairly accurate shifting.

quote Originally posted by IFLYR22: not only that, but what transmission controller are you planning on using?

I'm going to get the Powertrain Control Solutions setup. Not cheap, I know, but it does seem like a nice unit.

Rick

I'm using a ratchet shifted on my 65e. It's a little firm on downshifts though.

quote Originally posted by couldahadaV8: I'm going to get the Powertrain Control Solutions setup. Not cheap, I know, but it does seem like a nice unit. Rick

That is a good one. I have all the install guides and quick tune manuals / software for those. The button shift is cool. We set it up with a on/off switch so that it only worked in drive.
The biggest issue I had with their software is the RS232 (serial) ports. No USB. My laptop does not have an RS232 port. That was about 3-4 years ago.

you can use a USB to Serial Port adaptor, but I had some communication issues. (Once I got them to agree to communicate with each other, then things were fine. Getting them to agree on a communication "language" was a PIMA... best way I have to describe it.)

Glad to see someone doing this.

-Dave

quote Originally posted by IFLYR22: That is a good one. I have all the install guides and quick tune manuals / software for those. The button shift is cool. We set it up with a on/off switch so that it only worked in drive. The biggest issue I had with their software is the RS232 (serial) ports. No USB. My laptop does not have an RS232 port. That was about 3-4 years ago. you can use a USB to Serial Port adaptor, but I had some communication issues. (Once I got them to agree to communicate with each other, then things were fine. Getting them to agree on a communication "language" was a PIMA... best way I have to describe it.) Glad to see someone doing this. -Dave

the USB converters are quite picky... you have to get a "keyspan" branded one to minimize the hassle.

quote Originally posted by darkhorizon: the USB converters are quite picky... you have to get a "keyspan" branded one to minimize the hassle.

Thanks for the info. Wish I knew that back then. I'll remember that if I ever have to deal with something like that again.
I have figured out the one I have, but it was annoying to say the least.

Forgot to mention: when I did it (the TCM and USB - Serial adapter), the software was for windows 95 - 98se. It worked with XP Pro by using it in 98 software compatibility.
I doubt the software I have would work with anything newer or any XP version other than Professional.

So, couldahadaV8, make sure about the software it comes with. I hope they made some changes since I worked with one.

[This message has been edited by IFLYR22 (edited 06-01-2009).]