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Old 09-07-2019, 05:46 PM
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TransAm 474 TransAm 474 is offline
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Default Anyone use this TH-400 TransGo Shift Kit?

Hi everyone, I was just wondering if anyone has used this TransGo shift kit in their TH-400? I believe it is just a basic kit that comes with some springs, new seperator plate, and gaskets. It is part #K34908, which I believe is the same as the "SK400" kit. We already bought it along with our rebuild kit to install in the TH-400 that will be used behind the mildly upgraded RA III engine we are currently building. We will be using a Hughes GM25-BPO converter. Link below

https://www.google.com/aclk?sa=l&ai=...SABEgI71_D_BwE

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1978 Trans Am
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Old 09-07-2019, 06:17 PM
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Cliff R Cliff R is offline
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Yes, nice kit for a TH400 if you aren't removing the trans from the vehicle. Decades ago we used them in a lot of Chevy TH400's for 4 x 4, heavy duty truck, and towing applications. If the trans is getting a complete overhaul I'd upgrade to the better 400 1 & 2 kit as it has more options and additional parts which include an improve snap ring for the case for the intermediate backing plate, direct drum springs, etc......Cliff

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73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),
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Old 09-07-2019, 06:17 PM
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That kit is okay for a stockish kind of build. The TransGo 400-1&2 is a much better kit.

Edit: Treed by Cliff...lol

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Old 09-07-2019, 08:19 PM
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Thanks guys, does the kit I have Dual Feed the Directs?

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Old 09-07-2019, 08:41 PM
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Quote:
Originally Posted by TransAm 474 View Post
Thanks guys, does the kit I have Dual Feed the Directs?
Unless the kit is new and improved it does not dual feed the direct clutches.

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Old 09-08-2019, 01:45 AM
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I've always only bought the 400-PRO

https://www.summitracing.com/parts/t...-pro/overview/

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Old 09-15-2019, 01:59 AM
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Just an update on this.... Since the transmission is out of the car and going through a complete overhaul, we decided to go ahead and order the Trango 1&2 kit and install it instead of the SK400. I feel the final result will be much better, since this is a performance street application. Now we will have to decide what size to drill the 2nd and 3rd feed holes in the plate and which PR spring to use. Below is the whole combination, if Cliff or anyone else is interested in throwing out some recommendations on what would work good with this

1970 YZ block .030 over
4.150" bore
Zero Decked
Stock N crank 010/010
Eagle H-Beam 6.625 press fit rods
Icon IC891-030 pistons 14cc dish
Butler Total Seal classic rings 4.150" drop-in
Felpro 1016 .039" head gaskets
Stock 12 heads, cc'd at 70c chamber, hardened exhaust seats, Ferrea F5143/F5144 Stainless valves, Crower 68404 springs
9.8-1 compression
Summit 2802 Camshft
Stock 1.5 rockers
Hylift-Johnson 951 lifters from Paul K
ARP rocker studs and poly locks
Stock cast iron intake
R.A. III Qjet setup with Cliffs parts and recipe
Stock points distributor recurved
TH400 transmission
Transgo 1&2 reprogramming kit
Hughes GM25-BOP converter
3.55 rear gears
1970 Trans Am
Pump Gas 91 Octane

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Old 09-15-2019, 02:17 AM
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Used the TransGo kits in my 4L80E for my big block Suburban and the TH350 in my 455HO TA. Top quality kits. For the TH350 I also ordered all the high performance clutches, steels, sprags and direct piston from Pro-Built Automatics since I know how much help a TH350 needs to live behind a 455. Both transmissions have been a joy to drive since I rebuilt them with crisp fast shifts.

Sam

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  #9  
Old 09-15-2019, 10:18 AM
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During my research, I think I have concluded that .125" for the 2nd feed and .140" for the 3rd feed would be about right, am I correct? Still not sure which PR spring to use or what accumulator spring to use, but I think most use the Orange in the accumulator?

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Old 09-15-2019, 10:42 AM
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You are making me search my memory banks from nearly 4 decades ago since I used one of those kits.

Are they supplying different PR springs, red, orange, etc?

They may advise removing the factory "horseshoe" shims if you do one of those directions.

With "shift kits" that supply their own separator plate they may already have modifications done to control accumulator feed. Transgo was the leader in that industry as they tended to be more "conservative" with shift "feel" in the normal driving range vs other companies who had you toss out most of the check-balls and HUGE plate holes sizes for window-shattering/tire chirping shifts even when you weren't in it very hard.

When I do my own shift kits with TH400's I stay pretty small with feed hole sizes using stock plates. I have some pics in the files someplace, but usually start out around .110" vs going to big and having the trans "slam" into gear when I'm just cruising around without being on it hard.

The torque converter is also a BIG player with shift "feel" especially at lower rpms' and light load. You can get away with a lot more if using a smaller diameter converter that isn't as well coupled down there, so factor that into your decision making matrix when it comes to drilling the separator plate. I would always er on the conservative even if I had to go back and make changes vs going too big and having to make things smaller again.

Another "player" is if any waved plates were used in the basic assembly of the clutch packs as they will slow/soften things up just a tad, which is actually a good thing in many cases especially if shift kits are being added to the mix.

I'd add here that Transgo uses different gaskets with most of their shift kits, so do NOT inadvertently mix them with any from a rebuild kit or you can and will end up with very poor results.......Cliff

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73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),
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Old 09-15-2019, 11:54 AM
sdbob sdbob is offline
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When my 74 SD was new, full power it hit 3rd firm.2nd was good. Then I installed their kit best thing i ever did really nice shifting. Before that in my earlier cars i tried Winters,B&M.

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