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Discussion Starter #1
Anyone install an aluminum MonteCarlo engine cradle in their Grand Prix to reduce weight? Is it worth reducing weight right over your front tires where you need it most?

My engine cradle is out, (transmission failure) and I was cleaning it up and realized how heavy it was. Just wondering if anyone has done this swap.

Richard
 

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It's been done by someone on ClubGP. You need the bushings to swap it over.
 

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Discussion Starter #3
You mean the body mount bushings?
Do my lower control arms work, or do I need to use the MonteCarlo ones?


Thanks
Richard
 

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That I understand, you need the sub frame(engine cradle) bushings. I can get you the part numbers if desired.
 

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I could be wrong, but I thought the subframe bushings between the aluminum subframe and GP/GS subframe weren't interchangeable. A friend of mine ordered bushings for the aluminum subframe for his stock GS subframe on accident and they wouldn't work. He then ordered stock GP bushings and they worked fine in his GS subframe. I plan on swapping my GS bushings with GP bushings this or next week.
 

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Does anyone know how much a MC subframe weighs versus a stock GP one? I'm curious how much weight this would save...
 

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I believe it's a 22lb savings, but don't quote me on that. Here's the p/n's...

#10288271 - sub frame
#10402880 - front upper mounts (x2)
#10402882 - front lower mounts (x2)
#10402881 - rear upper mounts (x2)
#10402883 - rear lower mounts (x2)
#10403403 - front bolts (x2)
#10410940 - rear bolts (x2)
 

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FACE said:
I could be wrong, but I thought the subframe bushings between the aluminum subframe and GP/GS subframe weren't interchangeable. A friend of mine ordered bushings for the aluminum subframe for his stock GS subframe on accident and they wouldn't work. He then ordered stock GP bushings and they worked fine in his GS subframe. I plan on swapping my GS bushings with GP bushings this or next week.
Exactly, that's why you need to change the bushings if you change to the aluminum sub frame. The bushings for the steel sub frame won't work in the aluminum one and visa versa.
 

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I see where you're comming from. I assumed the person was getting it from a junkyard. Too bad none around here have one. :mad:
1Hot97 said:
Exactly, that's why you need to change the bushings if you change to the aluminum sub frame. The bushings for the steel sub frame won't work in the aluminum one and visa versa.
 

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Discussion Starter #10
What about the lower control arms? With the Grand Prix control arms bolt right in? I did some research and found that the Monte Carlo does have different part numbers for control arms then the Grand Prix. The salvage yard is telling me that I have to have the Monte Carlo control arms. I don't want to buy them if I don't need them.

Thanks
Richard
 

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I know of one person that changed the subframe and re-used his original bushings. He did get some movement and banging until he put the correct ones in. IIRC, two of them were a little longer? Sorry, it's been a while.

You do not need the MC control arms. The stockers fit just fine. A buddy of mine got the specs on both the stock steel AND the MC aluminum subframe that body shops use for frame straightening. We compared the center to center spacing on every hole and dimension and everything was identical except two holes. IIRC, those are used to attach the control arms. This is probably where the misconception comes from that you have to swap control arms. You really don't have to because the holes in question on the MC subframe are slotted to accomodate both MC and GP control arms.

I do want to add one more caveat though. My car is a '98 GTP. I'm assuming that the control arms for other GPs are the same, but they could have changed over the years.

John
 

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We put an aluminum cradle in Bronzo23's car about 3 weeks before it got smashed. He put new lower controls arms(grand prix), motor and trans mounts, at the same time. We did it on the ground in my garage, and reused everything. It took a lil work to get it all lined up, but it did all fit. Total project time = 3 hours.

After getting it all out and everything, total weight savings was a whopping 23 pounds w/ the alum cradle.


IIRC the stock one weighed in at around 50 and the alum one weighed in at like 28 or so.


Not really worth it unless you already have done all the other weight saving mods.
 

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Discussion Starter #13
Thanks so much for the information ZR2_S10. That is exactly the information I was looking for. The work would have not been a problem being that my subframe is already out (transmission replacement). But I can not find one cheap enough around here. The best price I found used was $250. :eek: That is pretty expensive just to save 23 lbs. :( I was actually thinking of taking my scale with me and weighing the subframe at the salvage yard. Now I don't have to. Thanks a bunch. :)

I think I will use the money for some new race tires. :D


Richard
 

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There is a U Pull R Parts in Ham Lake, MN; $32 for the K member. There's a ton of them in the yard, and hoists, you just have to pull them.

Also, so some really nice aluminum lower control arms on a Bonneville; will they fit the Grand Prix? Anyone know?

We put an aluminum cradle in Bronzo23's car about 3 weeks before it got smashed. He put new lower controls arms(grand prix), motor and trans mounts, at the same time. We did it on the ground in my garage, and reused everything. It took a lil work to get it all lined up, but it did all fit. Total project time = 3 hours.

After getting it all out and everything, total weight savings was a whopping 23 pounds w/ the alum cradle.


IIRC the stock one weighed in at around 50 and the alum one weighed in at like 28 or so.


Not really worth it unless you already have done all the other weight saving mods.
 

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Wow, zombie post resurrection from 15yrs ago. No biggie, this is an easy one. Bonneville's run both bolts horizontal, while the W-body's are one each, horizontal and vertical. Also, no idea if the geometry is even close, where the ball joint mounts. Overall, not worth it.

I actually got my GTP's cradle during an engine swap while living in the Twin Cities, from a yard in Blaine, I think. Use car-part.com to look up local yards who have them pulled and inventoried already. Had to do the U-pull work for the Regal's, but wasn't bad (pic from 2009 below, was 2001 Impala's).

 

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Wow, zombie post resurrection from 15yrs ago. No biggie, this is an easy one. Bonneville's run both bolts horizontal, while the W-body's are one each, horizontal and vertical. Also, no idea if the geometry is even close, where the ball joint mounts. Overall, not worth it.

I actually got my GTP's cradle during an engine swap while living in the Twin Cities, from a yard in Blaine, I think. Use car-part.com to look up local yards who have them pulled and inventoried already. Had to do the U-pull work for the Regal's, but wasn't bad (pic from 2009 below, was 2001 Impala's).

Quick question; there is a noticable hump in the steel crossmember, by the rack, that is not in the aluminum one. I am running Speed Daddy Headers....this isn't going to be a clearance issue, will it?
 

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Not sure why that's there, but doesn't interfere with anything.

I've run those headers on my GTP (and installed on many others) with both cradles just fine. You'll want to flip the sway bar for some clearance, typically. Also, the O2 sensor usually butts against the firewall, and should get a little hammer "massage" to ensure it has clearance. (Don't know if that was copied from the original SLP placement, or just where these got them put.)
 

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I've already moved the O2 sensor down past the flex pipe, in the 3" section that looks like a trap (like under your sink). I have larger sway bars; they won't fit without flipping them around? That kinda sucks...
 

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You might get by, all headers tend to be fighting for space in that busy area.
 
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