[JLMounce]

Originally Posted by Half-Inch Stud

Since you have a 455; Find a posi for your existing rear. And Swap to TH400. Done.

The idea of a Street 455 with anything over a 3.31:1, even a 3.23:1 is fraught with yuk on the highway. If ya must, then the 4L80 with the vacuum modulator kit allows manual-shift with switches on the shifter, no computer.

HEI in place of a points dizzy.

I had 3.73's behind a standard street build 455 and moved down to a 3.31. I never missed the 3.73's and I honestly thing the car picked up with the 3.31's anyway.

From doing my 4l80e, the things you don't really hear or read about is the need for a counterbore slip yoke in the driveshaft when using 2wd variant with a bolt on tailhousing. However for cars where a factory speedometer is preferred, opt for the aftermarket mechanical drive tailshaft.

I run a dakota digital speedometer drive which works well, but it ads complexity and another electrical component.

Installing the 4l80 in the trans tunnel of a '72 should work, but there may be some coaxing with a BFH. If you have the ability, try and find a 93-96 core that has the feed and return cooling lines just behind the bell housing. It will aid in installation. You'll also want to use aftermarket cooling lines with 90* banjo fittings.

For the trans cross-over, I'd really try and use the factory unit and either move it or modify it to work. The aftermarket stuff is really big and really rigid, which transfers unnecessary NVH. Use a stock type rubber transmission mount. Stay away from the poly stuff. It's too hard and with rubber engine mounts can cause unwanted NVH as well.

While the vacuum modulator certainly works, I'd still recommend a proper computer. I run the US Shift Quick 4 and it's been great. The support from Baumann Electric is also top notch.

Based on the OP's planned build, I would run a near stock rebuild with a shift kit. Mostly just to do the pump mods and dual feed the direct drum. No need to do much with the pressures. I'd use a rebuilt factory converter.

I will say though, with the computer control and the TSP triple Kevlar disc converter is a pretty cool combination. I use the torque multiplication of the converter in 1st gear to get the car moving, then lockup the clutches in 2nd gear at 4000 rpm. It's pretty crazy to grab rubber on the 1-2 shift, then grab rubber again in 2nd as the TCC locks up.

It's a ton of work to accomplish, and not the least expensive thing I've done, but the performance and drivability gain is huge.

[Jay S]

200R4 is the easiest overdrive swap in this. It is the only OD tranny that is a direct bolt in from a TH350, same driveshaft, same transmission yoke, no bell housing adapter, speedometer hooks up stock, no electronics, add a TV cable and it is mostly done. Takes some upgrades to make them hold up to a 455, an Art Carr 200R4 is rated from 750HP for something like $3700, which is overkill on this, but a really nice transmission. Most shops can build a 200R4 cheaper than that for a 450HP combo.

I mentioned the 700R4 earlier only because I thought the 3.06 first gear would help get the car moving with the 2.73s the car has now with the 8.2 BOP rear end and still work later if it got swapped to 3.73 gears to utilize the overdrive more. 700R4 is my least favorite of the GM overdrive’s though. 700R4 is geared better for a truck than a car IMHO. 4L80 is a nice heavy duty tranny to swap in, but it is a bit of a project (read JLmouce’s post).

[HWYSTR455]

The 4L80e install thread has some good info in it:

https://forums.maxperformanceinc.com...=4L80e+install

I also on another thread did a cost comparison between a 4L80e and a 200R4, and proved the 4L80e is less expensive. And the 4L80e is even less expensive now. And considering my experiences with the 200R4, I will say they don't last in a performance app. (Not even going to go into that conversation).

You can get VSS to a cable drive box less expensive than doing a tailshaft, and that's only if you refuse to change to an electronic speedo.

Not going to get into a gear vendor debate either, but if you like changing the fluid ever 5k miles, among other things, there is no comparison to a 4L80e.

As for 8.5s, to do one 'right' costs very close to a moser 12, and the moser 12 is lightyears ahead of an 8.5 AND any OE 12 housing. I did an 8.5 for the 442, and I regret it every time I think about or see the car.

If you're going to do something, anything, do it right the first time and you will never have to worry about it again. If you don't have the money to do it right, save until you do have the money. (It costs more to do it twice).


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[HWYSTR455]

Originally Posted by JLMounce

I will say though, with the computer control and the TSP triple Kevlar disc converter is a pretty cool combination. I use the torque multiplication of the converter in 1st gear to get the car moving, then lockup the clutches in 2nd gear at 4000 rpm. It's pretty crazy to grab rubber on the 1-2 shift, then grab rubber again in 2nd as the TCC locks up.

Those are the converters I run, and they are a game-changer. WOT lockups in any gear is incredible. Luckily I picked up 2 before the prices went up.



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[Jay S]

Will get no argument from me, the 4L80E is my favorite GM OD transmission by a land slide. 200R4 is a very easy swap when coming from a TH350, advantages of a 200r4 dwindle fast beyond that.

[HWYSTR455]

Even a basic rebuilt 4L80e would be fine for something in the 500hp/500ftlbs range, and around me, they are in the $1600-$2200 range, with converter.

Most rebuild shops do several of the 'upgrades' as SOP, to avoid callbacks.

Someone was recently telling me how one of the performance shops actually sell to Summit/Jegs, who rebrand them as Summit/Jegs items. Wonder how much those are?


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[JLMounce]

Originally Posted by HWYSTR455

Even a basic rebuilt 4L80e would be fine for something in the 500hp/500ftlbs range, and around me, they are in the $1600-$2200 range, with converter.

Most rebuild shops do several of the 'upgrades' as SOP, to avoid callbacks.

Someone was recently telling me how one of the performance shops actually sell to Summit/Jegs, who rebrand them as Summit/Jegs items. Wonder how much those are?


.

The Hughes stuff through Jegs is about 3K.

I found a 95 rebuildable core and did a moderate build. Stock input shaft, full transgo HD2 kit and went with additional clutches and frictions instead of utilizing a wave plate. They say this is a typical 750hp build, but this level has proven time and again to hold well over 800 to the tires as long as you're not using a transbrake.

My core was $400.00 and the rebuild was just below 2K. You are money ahead if you find a core and have it built locally. Any trans-builder should be familiar with a 4l80e at this level. If you need above 1000 hp capability, then you may want to be pickier about who's doing the build. I still agree that even a very basic stock rebuild with stock converter is the right choice for this build.