Q for those doing engine conversions

[khughes]

Hi Guys,

I know there are a few people now who have done or are doing RB or SR conversions.

I got my car back from my mechanic friend, with the engine and gearbox mounted, but i am a little concerned about how low the gearbox is on it.

He mounted the engine very low in the car (to help with centre of gravity), the sump is roughly 5mm from the cross member (we are going to have to put in spacers, this is too tight i think).

With the gearbox, he got the original gearbox x-member, cut out a section of the middle and then welded it up sitting around 1.5 inches lower (all box sectioned with steel) and around 2 inches further back. He didn't modify the transmission tunnel as apparently bashing it out doesn't actually get you very far (apart from clearing the odd bump or sensor, and if i wanted to get the box any higher i would need to get the tunnel cut out and presumably a new one made up ($$$$$$$)

I have lost my original gearbox mount support rubbers, and at the moment there is a set of shock rubbers on there, so the mount has no real support, and twists, making the gearbox sit much much lower. I really need to get a set of new rubbers and see how much of a difference it makes.

My Question is, how have the rest of you done your gearbox mounts? anybody got any pictures? having never done a build up like this before, i am not sure about what my friend has done, it seems a little bodgy to me.. but he says it will sit right with proper rubber mounts.

The second question is, how can i get a set of gearbox mount rubbers made up in harder rubber or nolethene (would this be better/stronger?). Should i really be relying on 2 bits of rubber to stop the gearbox mount twisting? i can't imagine how bad this would be for the tailshaft...

The other option i guess would be to do some other type of mount on the car in the correct mounting position for the new gearbox so it wouldn't twist, even if the rubbers wear.. would this be feasible?

[khughes]

I forgot to mention..

as it sits, the lowest point of the car is the gearbox and gearbox cross member, it is a good 2 inches lower than the engine crossmember

[khughes]

I just realised that the RB20 and SR gearbox are a lot smaller than the RB25.. hence why nobody else has had an issue...

I think i might try and get somebody elses advise on getting the gearbox mounted more securely..

anybody know the answer to who can make up custom rubber/nolethane mounts?

[sakijo]

I'd go with urethane bushings. They make them - I got them on my car. You can see the pics in my gallery.

[khughes]

is this the pic? http://www.classiczcars.com/photopost/showphoto.php?photo=17339&cat=500&ppuser=7932

They look like they are turned from aluminimum, any clues on who makes them? or where they are available? anywhere outside of japan? or is it a custom job?

[akwikz]

All of my experience comes from my KGC10 and my friends S30 Z. I would assume the KGC110 would at least be similiar. I could not tell exactly from the post which tranny you are using. The RB20 and N/A RB25 are substantially smaller than the turbo RB25. I am using the turbo RB25 tranny. I also have mounted the motor as far down in the bay as possible. My oil pan sits about .25 inch above the crossmember and the head is .5 inch off the firewall. I spent a great deal of time trying to get the motor perfectly level. I was able to get very close but never exactly level front to back. I then did a lot of research and found that the RB26 does not sit level in it's stock configuration either. The front of the motor is pointed slightly up. I eventually realized that I had the motor exactly where it needed to be. Now, as for the tranny, I did not modify my tunnel in any way except to put one small dent in it to clear the speedo sensor. My shifter comes out in the stock location and sits about .5 inch off of the tunnel walls. I made my tranny mount from regular old square steel bar. My stock mount connected to the car via studs coming straight down from the car. I used T/C rod bushings between the body and the new mount. I may have some pics around, if you send me your direct e-mail I will send you what I have. Let me know.

Brian

[khughes]

Thanks Brian,

that sounds exactly what i am trying to do!

I am using the RB25DET engine and RB25DET gearbox. The engine is mounted very low, but is also still a bit forward so that you can easily get to the top gearbox bolts, probably 2.5" between the firewall and head. My oil pan sits in front of the crossmember (with very little gap at the moment), so it sits very low

I would love to get any photos you have, it will help explain to my friend what needs to be done.

are the studs on the C10 the stock mounting location? they are this way on the C110 too.

khughes@ihug.com.au

[sakijo]

That's the one. Here's a better picture. Must be the lighting because one looks silver and the other is gold. They are urethane, though. They may be custom made to his specifications, but he must have stock on hand. It only took him two days to change out the transmission and replace the clutch and you can't get custom made anything in two days.

is this the pic? http://www.classiczcars.com/photopost/showphoto.php?photo=17339&cat=500&ppuser=7932

They look like they are turned from aluminimum, any clues on who makes them? or where they are available? anywhere outside of japan? or is it a custom job?