kinda felt like i might've been hijacking the '4.9l vs sbc' thread, so i started a new post.
from the looks of things on that thread, the 4.9l is the eventual swap for me. so my question now is transmissions. I have a 4spd manual right now thats had extensive work done on it and has a kevlar clutch. can i bolt that right up to the caddy 4.9, either as is or with some kind of adapter? will my tranny stand up to the bigger engine or am i gonna blow it? if it won't, what manual transmission can i use? also, i've never drag raced before, and even with a V8 i don't plan to do much of it, just put a few modded hondas to shame. if im nice to it 95% of the time, will my 4spd be ok with it?
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12:48 AM
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crzyone Member
Posts: 3571 From: Alberta, Canada Registered: Dec 2000
Your 4 speed muncie will hold up fine. You will need a neutrally balanced flywheel from a early 90s Cav Z-24 or baretta. You can also use the cavaliers stock clutch, no need to buy an expensive one. The engine will bolt up to the trani, but the trani will have to be notched to allow you to use the Cadillac starter.
------------------ 86SE 5 speed 85GT 4.9 isuzu 5 speed https://www.fiero.nl/forum/Forum1/HTML/027839.html Will trade both for a fastback GT
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01:33 AM
DRA Member
Posts: 4543 From: Martinez, Ga, USA Registered: Oct 1999
Your 4 speed muncie will hold up fine. You will need a neutrally balanced flywheel from a early 90s Cav Z-24 or baretta. You can also use the cavaliers stock clutch, no need to buy an expensive one. The engine will bolt up to the trani, but the trani will have to be notched to allow you to use the Cadillac starter.
Very well said!
I'd be more worried about my CV joints and axles than the transmission itself. As long as the car is not already on the edge and is driven civilly most of the time I wouldn't worry about the transaxle that much. My opinion is based on research and not personal experience. When you start getting over 300 in the hp/tq dept I would start being a little more skeptical of reliability issues, especially if you are aggressive. The 4.9L seems to be a good performance upgrade for the chassis without going overkill!
Heres the real question could I use the 4.9 mated to my TH125C?
Sure you can bolt up the 4.L to the TH-125H but since you are devoting much work to upgrading the engine why not use the matching 4T60E 4 speed automatic. It's much more pleasant cruising the highway with a 4 speed overdrive tranny than with the stock 3 speed. If you use the 3.06 FDR version of the TH-125 it would probably work OK but you'll get much better mileage with the 4T60E. Plus the 4T60E is a stronger transmission.
Sure you can bolt up the 4.L to the TH-125H but since you are devoting much work to upgrading the engine why not use the matching 4T60E 4 speed automatic. It's much more pleasant cruising the highway with a 4 speed overdrive tranny than with the stock 3 speed. If you use the 3.06 FDR version of the TH-125 it would probably work OK but you'll get much better mileage with the 4T60E. Plus the 4T60E is a stronger transmission.
Bare bones cheap ass swap. Stupid hole in the ground (Well) is eating up my funding.
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04:18 PM
collinwestphal Member
Posts: 698 From: Waukesha, WI, USA Registered: Jun 2003
Yes, you can use the 88 flywheel, and a fiero clutch.
My flywheel cost $45
plugged, drilled, bushed and resurfaced cost me $200 Pretty much a new flywheel after that.
Make sure you use the throwout bearing from the specific manual transmission you use. It will bolt up like a manual flywheel was meant to go on this engine.
Good Luck!
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01:24 PM
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Oct 15th, 2003
collinwestphal Member
Posts: 698 From: Waukesha, WI, USA Registered: Jun 2003
go to a junkyard and get a flywheel for any early 90's fwd car with either a 2.2L, 2.8L or a 3.1L engine. berettas, corsicas, S-10's, cavaliers, cutlass siera, etc.
When they show you the clutch, measure the diameter of the disk it was used with. You want one that is 9 1/8" not 8 1/2". Check the teeth, and make sure they are good. Last thing you want to do is spend $200 on a crappy flywheel. It should cost between $20-$50 for a used one. I got a 96' s-10 flywheel for $25. Also check to see if it is really worn where the disk goes. if there is a definate ridge, ask for another one.
I went to 4 machine shops before finding one that would do the work, and had done them before. I gave him my caddy auto spacer, and caddy auto driveplate. This was all he needed. He made a bushing, drilled the holes, but did not resurface the flywheel. The flywheel was in very good condition and there was no ridge. It fit on with perfect precision. $227 for machining and tax.
then you can use the fiero v6 clutch disk, pressure plate, and throwout bearing. If you have a getrag get a getrag bearing, if you have a 4 spd muncie get a 4 spd bearing, if you have a izuzu get an izuzu bearing.
thats about it. Good luck.
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03:28 PM
Oct 16th, 2003
FierOmar Member
Posts: 1639 From: Glendale, California, USA Registered: Dec 2001
I recently had an aluminum flywheel made to fit the 4.9. The bolt pattern and center bore were matched to the 4.9 flexplate and the balance is matched to the 88 Fiero flywheel. Steel insert for the clutch surface. The shop retained the specs and can duplicate this flywheel out of aluminum or steel. BTW the aluminum flywheel weighs about 1/2 of the original steel.
