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Rear subframe removal - how risky ???


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I am treating various bits of rust at the rear end of my Z, I want to remove the pin stay that I believe is held on by 2 of the rear sub frame nuts, so I'm thinking if I'm removing these 2 nuts why do not do a proper job and take off or just lower the full rear subframe enough to treat the rust around it, have watched a number of videos and read a few posts and it doesn't seem a too scary job, and it helps that my car is not a daily so I can take my time.  One of my worries though is my drive is not totally flat it slopes a bit front to back and left to right, I can jack and support car safely enough but just read somewhere refitting the subframe should be done on a flat with car level to ensure subframe aligns properly ??

Apart from this any reason I shouldn't try this 

Cheers

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I removed my rear subframe last year to treat the rust.  I'd say trying to re-fit it without a level suface would be difficult.  Maybe with a few extra people to help it might be possible depending on how bad the slope was.     

 

I've a video on my YouTube channel if that helps but I used a lift.   

 

 

Taylor Ray used a trolley jack 

 

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I dropped my subframe on my drive about February last year to replace bushings and clean up rust, the drive certainly isn't flat and only had the rear of the car on axle stands anyway so the car itself wasn't level. I had a second pair of hands to help when actually removing the subframe and putting it back in, there wasn't really any issues lowering the subframe but using a trolley jack to lift the subframe up we did need to tilt and reposition a lot to get it back in

 

What I will say is when it comes to rust treatment its always a bigger job than you think, If you gone to length to drop the subframe out you want to do a proper job so I spent a long under the car wire-wheeling. Something I didn't account for and looking to go back and do is removing the fuel tank as it stops you reaching/ treating a lot of the areas (from my understanding you need to remove the subframe to remove the fuel tank)

 

 

 

 

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Thanks both seen both of these videos and Im quite happy with process and it doesn't look too bad, sounds as if working on the slope just makes refitting more difficult to get on rather than possible misalignment of the subframe .. suppose first test will be removing pin stay and seeing how hard it is to remove the subframe nuts they are very rusted up

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Oops just realised I have already removed the from 2 19mm subframe nuts when I took off the kidney braces .. at least they came off with no drama but that was to be expected as kidney braces are as new having been replaced just before I got car, have started clean up of the rear nuts, wire brushed to remove as much rust as I can and the lots of penetrating fluid which will continue to do until weekend when I will try to break loose

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Mine weren't rusty as the previous owner had put a thick underseal on all the nuts and threads, but I did have to go through the pain of wire bushings and release fluid to get it all off. You just want to be careful when breaking them and taking them off as the last thing you want to do is snap the stud, one of mine got stuck near the bottom of the thread and I just ended up cutting the nut off and buying new ones from Torqen (was planning to replace them anyway). Once the pin stay and subframe is out then you have full access to clean the thread up so shouldn't be any issues going back on

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Mix of both from what I remember,  started with a breaker bar and from memory it didn't feel great more like I was bending the whole stud rather than twisting the nut unless I was on my back pushing on the socket and pulling the bar with the other hand. So went on to impact which struggled a bit (had to keep stopping as the nut was getting so hot) but like I said I was working with tacky thick underseal which was clogging up the threads big time :D

 

I took some photos so can dig them out if you want to show how I was setup and working 

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I'd start with a breaker bar and if they don't move use an impact as a last resort.  I've snapped bolts using an impact. The key for me was lots of penetrating fluid the day before.   I use a 50/50 mix of acetone and transmission fluid as a penetrating fluid. I find it better than anything yo can buy.  You just need to gve it a shake before every application as it unmixes.

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Spray it with some maintenance spray then get the gun on them and seal with the consequence’s later, majority of the time it’s the ones that look like they won’t move move easiest 😂 I work on enough rot boxes 😂 impact also shocks the bolt/nut where breaker bars put a lot of strain on it, however it’s easier to stop when it’s about to go aha 

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bolts looking a lot better for cleaning with wire brush and already started putting on pen fluid and will do every day until my impact sockets turn up in about a week hope that should be enough 🤞

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Nuts cracked today and loosened 👍 .. impact did the job, so time to order bushes subframe and diff and then tackle in March before japfest .. yep so leaves time for mirrors 😉

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