Spacing Down The Subframe To Fit An Rb30dett In An R32 Gtr

[dorifticon]

Hey all

Some time ago I posted up looking to see if there were retail options to buy a subframe spacer to insert between the k-frame and the chassis rail in the r32 GTR to drop the motor height relative to anything else. Well there weren't, so I had to improvise.

Now, as everybody knows, the deck height on the rb30 is some 38mm higher than the rb26, so in order to minimise the efforts getting the bonnet to shut, I decided to insert a spacer in between the k-frame and where it bolts to the rails.

Now, dissassembling all the suspension pickup points sounds like a lot of work, but if you have the engine out already chances are you're undone the front hubs to remove the driveshafts, and also the tie rod ends. So really if you can get the ball joint off, then loosen the steering knuckle, that's all that;s really required to drop the k-frame (of course, ensure the car is supported somewhere else than the k-frame - this isn't too difficult with the engine out).

The k-frame is held in by four bolts on each side (total of 8x17mm nuts). You will however need a 17mm deep socket set and extension to remove the nuts. The front set of bolts is actually a removable bracket that slots in through the rail and is visible in the engine bay.

[dorifticon]

Once you have the k-frame loose, you can have a look at what is required and the constraints.

Ideally, I would have made a spacer that dropped the motor down an inch or even more, to take up most of the difference in the deck height, but the problem is that the two bolts holding in the rear k-frame nuts on each side don't have heaps of spare meat on the threads. Obviously you don't want the k-frame held in with nuts that only have a couple turns on them!

My recommendation is for a spacer 10mm thick. It makes enough of a difference to be worthwhile but still lets the nuts wind on fully to the threads.

In terms of the dimensions of the spacers themselves, the attached pic gives an indication. I made the distance between the holes roughly 50mm and 75mm, but measure it carefully for yourselves. The holes themselves need to be 12mm thick.

I made mine out of 10mm steel plate, which is of course very strong but pretty hard to work with. My mate used an oxy torch to cut it out and then grinded off the edges to make it neat. I used a 12mm high-speed steel drill bit and a centrepunch to make the holes, and they fitted up really neatly with not much lateral movement at all.

Given that the issue is probably crush strength I see no reason why alloy could not be used - it would certainly be much easier to work with. But I figured steel plate is probably more engineer friendly. And in any case once it's painted matt black you really can't see it in the engine bay at all.

[dorifticon]

Please note that spacing the k-frame down 10mm will not solve all your problems. You will still need to hack, slash, and generally get creative to make that bonnet shut, especially if you are retaining the twin turbo setup.

Also some people on here seem to be lowering their motor by modding the engine mounts - I was not keen to do this because by the time you put a 10mm sump adapter in there, there is very little clearance between the sump and the k-frame and all the power steering stuff, so I didn't want to reduce this clearance even more.

Anyway, that's how I did mine, hope the pics help any fellow DIY'ers visualise what's required.

[N1GTR]

Great write up!

For future people searching, it may be worth mentioning how much the plates cost to be made up normally

[dorifticon]

Great write up!

For future people searching, it may be worth mentioning how much the plates cost to be made up normally

Don't get what you mean, N1GTR - "normally"? I couldn't buy them on the internet, and didn't ask any workshops because we used steel plate that was lying around in the shed from another project...

Don't imagine it would be much though?

[dorifticon]

So we spaced the subframe down, and test fitted the long motor with the timing covers attached. The main problem is the front, top timing belt cover hitting on the bonnet. Now, this was with my old, crappy, saggy engine mounts being used, so I was pretty sure that with brand new, stiff nismo rubbers it would be higher if anything.

I should point out that because the r32 GTR bonnet is alloy, and very thin, it's not really possible to cut and weld it. Even professional panel shops were saying they weren't prepared to do it for fear of blowing through or warping the metal. If anyone knows any different I'd be very interested to know.

Once you have the motor test fitted, you will see that it is obvious there is a rib running down the centre of the bonnet that it hits on. Now, I'm not suggesting that chopping a rib out of the bonnet is legal, however I will point out that this area is completely covered by the underbonnet felt, so it will work as a temporary solution until you can get something better sorted out.

I am currently thinking of getting a GTST bonnet (which, I think, is metal) and modifying that in an engineer-friendly way. But this will work as a short-term proposition.

The ribs arnen't attached to the bonnet in any serious way, so I found it helpful to insert thin wedges of wood between the rib and the bonnet to sit it up slightly, then carefully cut through with an angle grinder. Then I got a file and smoothed off any edges so it wouldn't rub and cut through the felt.

Edited August 22, 2010 by dorifticon

[dorifticon]

The other issue is that if you are anything like me, doing a rb30 conversion in your shed will represent a big enough investment of time and money such that you won't want to go changing your turbo setup at the same time. If you are sticking with the OEM-style twin turbo arrangement, the big y-collector on top will be an additional pain in the ass. I got around it by grinding off the alloy boss where the twin turbo sticker sits, and putting washers in the bonnet. Again, quick and dirty but gets the car on the road (and adds that "Drift" look).

If I don't go a big single in the near future, I may see if I can get the flange off the front turbo milled down by 5mm or so to lower the position of the y-pipe.

http://www.skylinesaustralia.com/forums/in...t&p=5375352

Edited August 22, 2010 by dorifticon

[30ed32]

Is it possible to redrill engine mount brackets or use shorter engine mounts at all or will the diff hit the subframe

[Adriano]

No, not really, there os about 3mm between the crossmember and the sump

[jeffworld2]

could you do shorter mounts AND space out the k frame?

[Marko R1]

If I don't go a big single in the near future, I may see if I can get the flange off the front turbo milled down by 5mm or so to lower the position of the y-pipe.

http://www.skylinesaustralia.com/forums/in...t&p=5375352

how about milling the flange off the twin turbo pipe itself? i might try that myself as i have a replacement twin turbo pipe & would liek to retain the badge/boss if possible

[Scooby]

don't forget about the option of spacing the turbos down with spacers between the exhaust manifold and the turbos. drops the whole assembly down and you can use the original hard piping etc. but it does mean taking the turbos off.

[Marko R1]

don't forget about the option of spacing the turbos down with spacers between the exhaust manifold and the turbos. drops the whole assembly down and you can use the original hard piping etc. but it does mean taking the turbos off.

i was close to doing this with my setup at the time

[T04GTR]

sounds like a pain in the ass. id be abit woried for a track car having alterd the roll center down with the subframe.

[Marko R1]

sounds like a pain in the ass. id be abit woried for a track car having alterd the roll center down with the subframe.

i totally agree with you, this is why i chose to trim my bonnet bracing