Th350 feels like it's slipping

[Mike harris]

Hi guys, just rebuilt my 350 sbc into a cheeky little torque monster and done about 700 mile so far, engine is running like a trooper. Buuuut it now started slipping in second and third in the box. If I'm in 3rd and it kicks down the revs pick up and then slow down and it starts to pull a lot harder when the gearbox actually settles down. It's had a new filter and fresh Dextron 2 oil in and the level is perfect. Could this be worn plates or bad adjustment on the kick down cable etc. I'm unsure on the correct setting for the kick down cable on our trucks could anyone spread some light on how to adjust it properly?

[old Chevy guy]

Sounds like worn clutches. Cable adjustment won't cure slipping.

[Gromit]

The company Lokar has good instructions with photos.

It is for their kickdown cable of course, and not the OEM one or a universal aftermarket one; but it is the same principle so this should be a start anyway.

Here is the link and I'll try to attach the pdf as well

http://www.lokar.com/downloads/pdf-i...structions.pdf

[Hoosier Rick]

A th350 will shift fine without the cable being hooked up, it will just not have passing gear. Check your vacuum line and modulator.

[Gromit]

Wouldn't hurt to get the digital version of Cliff Ruggles TH 350 book ; less than $15; very complete and after a week or two (or three if you're bad as me) to soak it all in well enough to build yourself a nice transmission. Or at least know what it is worth to you to pay someone or buy a rebuilt one.

All you need is a good TH350 core and a rebuild kit (and I'd suggest adding the two sprags/roller clutches (1.) low/reverse and 2.) intermediate) to the full kit that includes all bushings (don't skip any) as well as a set of replacement Torrington bearings and you will be set for life in the transmission department.

A Lisle cam bearing puller/installer kit and a set of aluminum bearing drivers of as many sizes as possible (to install the bushings) and a little Gear Wrench 2398D clutch spring compressor are all the (special) tools you need to DIY a TH350.

It sounds like your intermediate clutch is slipping and it is not good if it slips while you are getting on it and all of a sudden slams into place under lots of torque.. take a look at photos of an intermediate sprag or roller clutch assembly (and look at all those parts in the element) and you will see.

Here is a link to the book - I bought the digital version and I have to go on Amazon or Google to look at it but for $15 it was worth the trouble.

https://www.amazon.com/GM-Turbo-350-.../dp/1613251890

On a separate topic - noticed you are a British brother - best of luck on the Brexit decision tomorrow - not even sure where I stand - I heard a very eloquent and rational Jeremy Corbyn on our USA radio show "Democracy Now" (which is available for streaming) yesterday or the day before and although I'm not generally a leftie it was apparent in that interview why he was elected as a leader... But I do believe Britain is better than most of Europe and definitely should have nothing to fear in going their own way. We'll all know tomorrow anyway!

[1quik70]

Sounds to me like the trans is on the way out. While the kick down does not control pressure in the TH 350 like it does in the 700, I would still make sure its adjusted right. I noticed a small difference in shift points once I got mine straightened out.

You can adjust it by popping the square plug right behind the mounting bracket on top of the cable. Lift the plug, make sure the cable is a short as possible by pushing the end toward the mount. Have someone step on the throttle (don't do it by hand), and push the clip/plug back down while its held at WOT. This should take care of the adjustment. Make sure the cable is mounted to a bracket at the BACK of the intake, not off the carb stud.

As far as the rebuild, Ive never attempted one. I always let a trans guy take care of that. I had extra clutches added to the last one to hold up to the 500hp Im throwing at it, so far so good!

[Mike harris]

Thanks for all the sound advise guys, I managed to track a spare 350 out of an el camino, genuine box but it's hot little bits of steel in the pan and some of the most wrong smelling burned up fluid I've ever seen, so it gonna need a full rebuild which now we have voted out the EU (who knows why) the exchange rate is ****ed so it's gonna cost me a bit more buuuut if I get to drive my truck then I'm gonna pay it anyways!!

[Gromit]

Maybe the link below is just for price comparison; because with all the pre-1994 Jags and Rolls Royce cars that used Turbo Hydramatics (albeit mostly the 400 version); you may have good parts availability in England - but I had good a experience buying from this online source in Long Beach, CA:

http://ctpowertrain.com/

I have no connection to the business other than as a customer a year ago.