Fox Busted Clutches (Automatic)


Jun 7, 2018
Dublin, OH
Hi there, I have a 1991 LX V8 with a 347 stroker swap with roughly 420 bhp, and it seems my clutches have decided they no longer want to engage. I have a rebuilt AOD with a shift kit, and it has serious issues with slippage and shifting now. I noticed some slipping on the top end (downshifting from 4th to 3rd at 70 mph) and some at the low end (giving 1/3 throttle from a standstill), and now it is way worse. After flooring it from a stop I smoked the tires but the transmission wanted in on some of the action. I was able to get where I needed to go by taking it slow, I could use first gear fine, but once it finally shifted into second, it would slip pretty bad unless I barely gave it throttle, and would only shift into third around 30 mph, when the shifter was in the 'D' position. The valve body is stock, but I am waiting on my manual transbrake valve body to ship. With plans to get to ~750bhp next summer, I am wondering if it would be better to get this transmission rebuilt yet again to handle that much, or to just buy the AOD-700 from SilverFox Performance transmissions. I am located in central Ohio, and am wondering if you guys know of anyone in the area that could do high performance work on an AOD, or if I should just spring for the new transmission. Any input helps (the car will still be a daily so putting in a three speed is not viable).
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Wayne Waldrep

Before I post a pic, do you have one of yours?
15 Year Member
Apr 14, 2003
Cuba, AL
Totally opinion here based on nothing....but that's too much power for an AOD. Yes it's been done etc etc. I'd find out how to swap in one of the new automatics from the mustang. They are solid. Do it once and totally forget about it.
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Reactions: General karthief

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
polk county florida
With 420 on tap and a daily driver along with planning 'mopower to boot I would talk to a performance trans shop, the shop I hang out at uses a local guy for stock stuff and Jasper for more performance oriented stuff. There are several high performance trans shops.
you did know this trans problem was come'n right?


CT Material here
Mod Dude
Jul 7, 2005
Don't get it rebuilt as it most likely will still not be able to handle the power you are planning on throwing at it. You should definitely go with the Stage 3 Silverfox Performance AOD. That guy really knows his stuff and will build it right including his custom stuff he does.


Crap, didn’t realize my crotch was in that picture
5 Year Member
Oct 6, 2011
If you aren't buying new, then go for a 4r70. Should be able to handle what you're throwing at it.


SN Certified Technician
Aug 8, 2003
What is your plan to get from 420hp to 750hp? Is this a dart build? Turbo's? Supercharger?
420 to 750hp is a serious jump in power, crossing the 500rwhp threshold gets crazy expensive.
It's also a little simpler to speak in terms of rwhp since it is a measurable parameter.

No consideration to a t56 magnum?