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2004-2005 bonneville gxp

SgtMarshal

SgtMarshal

Active member
instead of doing a 4t80 swap into a vehicle, wouldn't it be easier to start with a vehicle that already has that transmission? just pull the 4.6 N* out and swap a 3800 into it. has this already been discussed?
 


I saw that thread and also saw it didn't have a lot of answers, except that swapping a 3800 into a 4T80 would be an electrical/tuning mess.

seemed like the 4t80 swap into a w body car would be more work, but easier to tune for.
 


I don't recall as much problem with that 4.6, they were a much bigger problem when they were put in the last 90's early 2000's caddy devilles, DTS, STS etc's.
 
Fivefingerdeathpunch said:
I don't recall as much problem with that 4.6, they were a much bigger problem when they were put in the last 90's early 2000's caddy devilles, DTS, STS etc's.
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I heard they never fixed the issue of the bolts backing out of the block, in newer years they made the threads coarser to help them hold better, but it only prolongs the inevitable. The only real fix are aftermarket kits that involve removing the engine and studding the block.
 
This is true^
They take a lot work to properly fix the issue with the head bolts backing out. There's a YouTube video time lapsing it.
After that and new gaskets they're pretty tough.
 
It's as if the "clamping force" is reduced over time and thus the leak happen. Seem most guys see it around 100-130k miles.

Dropping the whole motor/trans out the bottom is the key, but for the avg joe thats is a ton of work to do. In end you're going to be in it for atleast $1,000 if you did it yourself. The stud kit is like $550 or so, then any other gasket like cam seals/valve covers, plugs etc etc. I always say this for tons of cars but someday if I could, I would own one just for fact that they are still nice cars. Hard to maintaine for some but overall a pretty solid car.
 


are you guys talking about head studs? 550 seems like a lot for head studs. they are nice cars, the bonneville is the lightest one of all the North star V8 cars with the 4T80 transmission, but the difference is only about 400 lbs between the lightest and the heaviest.
 
Not literally though lol. Compression ratio is way too high, it wants premium as a N/A motor. Northstars are nearly unmodifiable.
 


SgtMarshal said:
are you guys talking about head studs? 550 seems like a lot for head studs. they are nice cars, the bonneville is the lightest one of all the North star V8 cars with the 4T80 transmission, but the difference is only about 400 lbs between the lightest and the heaviest.
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It's my understanding that the studs themselves aren't expensive, it's the other items in the kit that keep everything in alignment while you work on installing the studs.
 
I put a set of arp head studs on my grand prix, and I think I picked them up for 50 bucks. cant really remember how much I paid, but they were pretty inexpensive.

the set previously listed are a lot more than just a set of head studs and some nuts so I can understand a higher cost.
 
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