Transmission failure?

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Apr 12, 2005
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Long Island, NY
I have a 98 mustang gt with 95,000 miles. Just had a blackstone oil analysis done and it came out great. My vehicle is equipped with the 4r70w 4-speed auto transmission. At wide open throttle the shifts are sloppy and slip. I had the transmission flushed by ford with mercon-v and added lubeguard ATF protectant a few months ago. The fluid doesn't smell burnt and is pink. Before i had it flushed the fluid wasn't burnt or discolored but it smelled like varnish. I have my car tuned with a diablosport predator tuner and adjusted the shift firmness hoping this would fix the problem. It does not. Is there any alternative than a full rebuild or should I bite the bullet?
 
I'd try an Auto-RX in the transmission before I spent any more money. It could just need to be cleaned up a bit more. Was the ATF changed for the first time at 95K?
 
If you need a rebuild, there's a lot of good info at www.tccoa.com. Look under the Tech section, transmissions.

For what it's worth, I think that the "J-mod" is recommended over the Transgo kit for the 4R70W, as it originated from one of the original designers of the 4R70W.

If it's something like clutches or part of the internals that's dying, then a shift kit won't help. But if it's a sloppy shift, the j-mod may be the ticket for you. Basically it's modifying the separator plate by enlarging certain holes that feed the 1-2, 2-3 accumulators, etc. I think that the plate in your car may actually have some of the larger holes, but there are other components that may need to be replaced while you're at it.

I have never been convinced that a flush will really do a thorough cleaning of the valve body internals.

I've almost finished getting the parts together to do the j-mod mod to my 95 CV, equipped with same transmission. Besides the mod, I decided to replace the accumulator pistons, OD servo, and the pressure relief boost valve, all generally considered to be higher wear items, at least on a 95. Also going with Mercon V as well.

Anyway, do some reading on Jerry's mod and tech at the site I mentioned - might be of help to you.
 
just had the Trans-go Shift Kit installed. WOW! The car feels like it is brand new and shifts firm. The sloppiness is gone and the slipping is gone. My mechanic looked at the transmission and said it was super clean and perfect!
 
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