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Building a TH350 for Street or Strip use 
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Joined: Fri Jun 29, 2012 4:23 pm
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When building a TH350 for street racing or drag racing, use the late pump that came with the roller bearing. It offers a better direct drum bushing contact area, and the white plastic ring that sits next to the roller bearing keeps the direct drum centered to help prevent the 2nd gear roller clutch from breaking. Use the wide bushing in the direct drum.

The Blue Plate Specials are good but expensive, factory Borg Warner, Alto Reds are fine for direct, and depending on the direct apply piston you have, machine the piston to except 5 clutches, and use the Kolene turbulator direct steels Alto PN 32705HK, if you can locate them, as they have less drag in 1st & 2nd gear, and set the clutch clearance at .060"-.075", when using the intermediate band.

As for the intermediate band, use the welded Red lined or Carbon lined band. For the intermediate clutches, the Borg Warner's are fine, and the Alto Reds are ok too. For a "quick" WOT 1-2 manual shift, take a used low/reverse clutch and remove all of the lining by scraping, take a hacksaw and cut it open, file down any high spots, and install this under the intermediate apply piston. This will eliminate the 1-2 manual shift delay at WOT. "DO NOT" remove the waved steel in the intermediate clutch pack as it will prevent the intermediate sprag race from breaking. Intermediate clutch clearance .030" - .040".

For the low/reverse steels, use the turbulator steels from a 1996 and later 4L60E transmission. Again less drag. Borg Warner clutches are best here. Use the low/reverse support from a 1987 & up 700R4 or 4L60E, as it is .150" wider. Just match the pressure plate area for thickness if possible, and keep it the same otherwise the clutch clearance will change and you will have to change the steel thickness to get the correct clutch clearance. If this is going to be a drag racing only vehicle, you can remove three of the five low/reverse clutches here, and replace them with the L/R steels. Low/reverse clutch clearance .030" - .060". Install the extra steels toward the rear, otherwise the extra steels will try to move toward the rear from acceleration, and create excess drag. Back up easily though, no hard throttle.

In the forward pack, "always" use the waved steel (from late TH350's) that has the 3 tangs on it against the forward piston. Forward clutch clearance .020" - .040".

The output shaft has a bushing in it sometimes, remove and use the plastic insert (late TH350's) to get lube to the rear section of the unit. Get a Vega or equivilant sunshell that is completely hollowed out. I have these for sale at $45.00. It is very light in weight, and is excellent for drag racing, especially on the 60ft times. I have never seen one break from high horsepower. Use the bronze case bushing, & teflon extension housing bushing, with the three lip Vamac seal. Make sure that the driveshaft yoke is in perfect condition and made smooth as possible (polished), where the bushing & seal rides. Always use solid U-joints, none with Zerx fittings.

Use the plastic washers instead of the bronze washers where possible. With the bronze or metal thrust washers, you will need to flat sand them in most cases, because they are not flat. If you have the planets and hubs with bearings, better yet. End clearance .015" - .020". Add a pan magnet or two. For filter, use the Sealed Power Dacron from the TH350C, this is an excellent filter. As for the valve body modifications, use the TransGo Performance Shift kit, they offer it in automatic & full manual.

Replace any plastic accumulator pistons with aluminum, use cast iron sealing rings on the accumulator pistons, and teflon scarf cut sealing ring rings on the stator shaft. These modifications were what we started doing many years ago in 10 & 9 second vehicles, and were worth some in terms of a drop in ET, and they held up very well. Use Lubrication Engineers Monolec 7500 for the best in terms of longevity, Amsoil is very good for a synthetic fluid, or use a Dexron type fluid only, no B&M Trick Shift or Ford type "F" fluid.


Fri Jul 27, 2012 7:57 am
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