R33 GTST front subframe differences?

[Neostead2000]

As I went to paint my engine bay I had to remove the entire subframe and after looking at it for a little bit I then started to compare with pictures from others and their R33s, and mine looks different to theirs! What I mean is, the two faces where the engine mounts bolt up are completely in-line with the entire frame, whereas all other R33 GTST pics I've seen have the locations sticking further outward (towards the front) and are in-line with the forward-most bolt. I am attaching a picture of my subframe (LEFT) and a random R33 GTST subframe (RIGHT). My chassis is an ECR33 factory spec 2 GTS-T RWD. Is this some sort of oddball that left the factory or has the previous owner done a subframe swap? If so, I cannot imagine how an RB20/25 would fit inside the bay with the mounts situated close to 10 centimeters back towards the bulkhead.

Interestingly there is not a single thread or video talking about such differences so I am coming here for your advice.

 

[robbo_rb180]

Looks like an s chassis sr20 subframe

[GTSBoy]

Must haves some altered mounts to be able to sit an RB on it.

[Neostead2000]

Gosh darn it, it's already been hell finding the missing parts for this car, now a subframe?! Will have to modify the mounts or the subframe then but I've got no idea how I would get the motor to sit like OEM. What a mess. 😢

[Neostead2000]

If I was to find a proper 33 gtst subframe would my RB20 be able to sit on it with these brackets?

 

[Neostead2000]

So just a little update for anyone wondering, this has been 100% confirmed S15 SR20 front subframe. The entire rest ofthe front suspension is bolt on, control arms, R33 steering rack, hubs.

While I'm still looking for a GTST subframe I decided to make my own adapter brackets for the engine mounts, similar to the kit ISR sells but just the two mounts. I got the angles and distances right (the bolt hole centers on the adapter brackets need to sit 125mm FORWARD of the S15 mounting holes!) and the driver side bracket needs to be angled slightly more than the other.

However even with these, I cannot mount the custom turbo oil return line I have made for the HX35. The tube bends too far out and clashes with the S15 stock mount point. For this to work, a significant portion of that point will need to be cut out just so the pipe can go through it. Definitely not something I want to do.

 

[iruvyouskyrine]

I have one in AUS that i could ship i guess, no idea how to ship something internationally or how much it would cost as i have never done it before.

[Neostead2000]

Thanks for the offer, but I have already found a 25det r33 front subframe from the UK and it's already on its way to me. Even still, I am slightly worried the engine mount and bracket combination might be wrong. Why did Nissan make so many different  variations of parts on these damn cars?!

[GTSBoy]

On 11/2/2022 at 4:05 PM, Neostead2000 said:

Why did Nissan make so many different  variations of parts on these damn cars?!

They didn't, really.

There's cars based on the R chassis (ie, Skylines Stags) and there's cars based on the S chassis (Silvias and Ceffies). And there's 4 cylinder engines that were mostly in the S chassis cars but sometimes turned up in the nasty budget versions of the R chassis based cars. And there's the RB engines that were pretty much exclusively in the R chassis cars.

There are engine mounts for each type of 4 cylinder engine in the S chassis cars (CAs and SRs). There are engine mounts for the 4cly engines in the R chassis based cars (probably the same as for the S cars). And the RB engines have a couple of different types of mounts - essentially the RB26 and all the others. You can pull an RB25 out of an R34 and drop it and its mounts into an R32.

[Neostead2000]

This just keeps getting worse and worse. I'm at my wits end with this shitbox already regretting getting a Skyline. So I finally got the R33 25det subframe shipped to me from the UK and when I test fitted it what do you know IT ALSO DOESN'T FIT!!!

I'm throwing a tantrum here but rightfully so. Can someone tell me what in the world is the problem? Is the problem the fact that its a 20 block? I assumed their mounting locations and bolt holes are identical across 20/25/26? The rubber mounts themselves are not the issue as these are  BMW mounts 100% identical to the Nissan square ones that came (they were torn and unusable). Regardless, the problem is the surfaces are not remotely parallel to each other so it's not the rubbers.

I'm suspecting it's the metal brackets. The person I got them from said they were from an RB20DET and he assured me they would fit a 25 block also, which in turn would logically mean they would fit an R33 chassis?

Unfortunately I am out of funds for this kind of crap so tomorrow I will be trying to cut these where I have marked with yellow lines and welding a new gusset. My understanding is that the oil pan's bottom naturally is parallel to the ground and to the subframe so I'm using that as a guide. I don't know how wide the gap needs to be between the oil pan and the subframe either. What a headache 😖

 

[Duncan]

OK, so firstly, RBs do not sit parallel to the ground in their engine bay. I don't have an rb25 in an r33 handy to check what angle that combo sits at. A possibility is that you have the brackets on the wrong side?

Secondly, I'm not sure it matters but the the mount brackets look like rb20 not rb25. rb25 look like https://www.jdmgarage.com.au/shop/engine/engine-accessories/engine-crossmembers-and-mounts/rb25-engine-brackets-pair/. Also note the mounts you are using don't have 2 studs at the subframe end but I guess that is your choice

 

[Neostead2000]

I know the engine sits tilted towards the passenger side but the oil sump itself is tilted also and it looks to be parallel to the subframe and ground.  I also thought I had the brackets wrong way round so I switched them and the bolt holes did not line up at all, so that wasn't it.

After further research it appears I do in fact have RB20 mounts which are paired with the rectangular Nismo rubbers (40mm high), and the RB25 mounts come in two kinds, cast aluminium or stamped steel that are paired with the big circular rubbers like in your link.

None of this was really documented anywhere so hopefully this thread will shed some light for people in the future.

[robbo_rb180]

Need to use the matching bracket to subframe.

r32 cross member to rb20 brackets
r33 cross member to rb25 brackets

r33/rb25 from memory have 2 types of bracket a steel and cast aluminium.

Project cars are fun aren't they.........

[Neostead2000]

Last update to this, I'm probably the only person who's ever going to be in this pickle since I know you guys in NZ/Aus have an abundance of the right parts, but still I had to improvise because shit is just too hard to get and overpriced. Ended up modifying the RB20 brackets and they ended up really nice, close to OEM and the motor sits good in the engine bay. It may look cocked to one side but that's because I was supporting it with my jack at the rear of the sump. I am confident once I get the transmission on and its bracket, it will line up true. I even slapped the head on it and tested my rear head breather, it has plenty of clearance from the heater hoses and bulkhead!

Edited November 13, 2022 by Neostead2000