Mera7

Asked about the clutch because in many hi hp swaps with a manual Fiero trans the trans is
somewhat protected from damage by a clutch that slips under hi torque, shock loads.
In my case, I had a stock 4 spd mated to my LS1 using a Quartermaster 7 1/4" dual
disk clutch, a clutch that won't slip at all when engaged. At about 20mph, with the
clutch fully engaged, I floored it and stripped all the teeth from 2nd gear. I now use a
beefed-up 4T65E HD.

Orville

quote Originally posted by mera7: hey calikid, engine dynoed at 638hp 520ft lbs of torque. slightly modified ls2 i will keep you up to date on the clutch components build up. mike in oklahoma

At that power you're really going to put a cryo'd Getrag to the test!!! Even it that holds, you're going to be breaking the splined axles or CV's very early in the game. The guy that fabricated my halfshafts suggested fabricating a new design halfshaft that would have old style universals (like the corvette used), only problem is that he'd charge a lot of money to do it, and probably wouldn't guarantee them, so it's a big chance.

I agree with Orville, based on your engine, you should go with the automatic. It will make the ass end a little heavier, but should minimize breaking parts. From my experience the shock loading does start micro tears in the axles (haven't had problems with cryo'd trans yet). 4 different high performance clutches with sprung hubs were tried in my car to reduce shock load, all of the got their center's tore out in under a 1,000 miles each (and you've got more power than I do).

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[This message has been edited by mera7 (edited 11-13-2010).]

mera7 how about the 6 speed i know i have looked at it. i dont like the things i am hearing and dont realy want to go with an auto trans and i plan to beat the living dog snot out of my car

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I do not like autos and I don't have the skills to do a longitudinal swap so I have been using a G6 6-speed behind my 383 with great success. The initial cost of the 6-speed swap was high, but once you have it, parts are cheap. I'm only making 440 ft lbs. at the crank, but I constantly abuse it with no breakage. I am using a Spec 3+ clutch with no slippage yet. The axles are stronger. I am slowly building a much more powerful V8 and hope to continue using the 6-speed. I am trying to find the failure point of the 6-speed before the next engine gets finished, but I don't believe it will with out more torque. It has been mated to the 383 for over a year now and does not complain one bit. And it definately shifts like a dream compared to most Fiero clunk-boxes.

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87 GT Tilt Clip-Widebody-RamAir-Fastback-GlassHatch Powered by SBC 383 6-speed w/ NOS
Build Thread

"Roads?...Where we're going, we don't need roads." - Emmett "Doc" Brown

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[This message has been edited by mera7 (edited 11-13-2010).]

I don't have all the details, but here's the axles used on the Pontiac Fiero Race Cars:



Hope it readable, I haven't looked into going this route yet, as it requires some other modification. Keep in mind that those race cars had a lot less HP / Torque than you're planning on.

[This message has been edited by California Kid (edited 10-31-2009).]

Is the getrag 284 stronger than the 282 i have read it is

While the 284 might be a little stronger, it isn't by much, and the major problem is finding one from what I've read on the forum.

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[This message has been edited by mera7 (edited 11-13-2010).]

Sprint car 360 or 410 ASCS heads pleas tell i got out of sprint cars about 3 years now and cry everey race season . it was a small dog just the 360 ASCS heads

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I miss read what you said mera7 thats how much i miss my race car

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[This message has been edited by mera7 (edited 11-13-2010).]

quote Originally posted by engine man: Is the getrag 284 stronger than the 282 i have read it is

I have a 284. It is a substantially more robust box (legend has it at about 400 ft-lbs). It's a world-class transmission with a wonderful shift feel, but it is a completely different animal from a 282. Different master/slave cylinders, hydraulic lines, clutch, clutch fork, throwout bearing, axles, linkage, mounts, speedometer output, and cables. It uses one of the only pull-type clutches in existence and has a jackshaft configuration that would be beneficial from an axle standpoint (they're equal-length on both sides, rather than the short-side/long-side) but a pain to adapt to a V8 because there probably isn't even a boss on the engine block to attach it. I doubt it would be much easier than an F40.

[This message has been edited by crazyd (edited 10-31-2009).]

Just wondering. Has anyone tried to build an engine tailored to the available low torque transaxles for the Fieros. For instance a small cube high RPM engine to keep the torque low and the HP high, (like Ferrari). You could build a 600 HP engine that only makes 350 ft lbs. at 8500 RPM. Maybe a 283 or 302 sbc with massive heads or a progressive Nitrous system.

What's worse for the tranny, high rpms or high torque shock?

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How is the 4 speed i think i am geting one with the cars i am buying

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[This message has been edited by mera7 (edited 11-13-2010).]

quote Originally posted by ClayTonto: Just wondering. Has anyone tried to build an engine tailored to the available low torque transaxles for the Fieros. For instance a small cube high RPM engine to keep the torque low and the HP high, (like Ferrari). You could build a 600 HP engine that only makes 350 ft lbs. at 8500 RPM. Maybe a 283 or 302 sbc with massive heads or a progressive Nitrous system. What's worse for the tranny, high rpms or high torque shock?

Not quite that extreme, but I'm building a Gen II/III turbo 3.1 for that reason. It should make around 350whp and only a bit less torque, but on boost. The shock loading will be much less because the turbo takes some time to spool/respool to full boost. Eventually I plan on building a high-boost capable 3.1 that I'd like to put out around 500whp on race gas, and I think the Getrag would handle that. Pure speculation at this point, though.

As far as I know, heavy shock loading will grenade the tranny (duh) but high RPM's will only prevent it from shifting quickly (or at all at 8500rpm?), and the synchros would wear out faster. I think there are some 3.4 TDC guys shifting at 7k with Getrags, though.

Mera7, talk to user "Doc John", he has a 328 rebody with an LS2 and an F40 and he loves it. I'm sure he could give you the combos ins and outs.
Edit: Here's his "18+ Year Build Thread"...
https://www.fiero.nl/forum/Forum3/HTML/000006.html

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[This message has been edited by mera7 (edited 11-13-2010).]

What are you doing about the starter on the LS4?

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[This message has been edited by mera7 (edited 11-13-2010).]

http://www.manual-transmission.com/?q=node/2 A place in Tallahassee that does transmission rebuilds.. I'm thinking of having a getrag that I have on a shelf go there for a rebuild, sometime..They have getrags in there inventory, just call.

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[This message has been edited by mera7 (edited 11-13-2010).]

hello all... i have recently aquired a 84 se duke 5spd car for a later ls4 chop top build. i might even think about a 4t65e, dunno yet. mike