Frame rails with integrated transmission mounts

[Boy from Oz]

I was never really happy with the LSx/t56 JCI tranmission mounts, either 240 or 280 type, and as I needed new rails I decided to integrate mounting points into the rails. The rails are deeper at 30mm (about 1 1/4")but I figure the exhaust will probably be lower so it would not be an issue.

 

Unfortunately I treated inside the rails before taking the photos and it is a bit difficult to see but I trust you will get the idea. I have TIGed the rails at intervals along the floor but have yet to MIG the new spot welds.

Edited June 29, 2010 by Boy from Oz

[Kenji]

That looks really good, I'd like to see some of the installed pictures and cross member pics as well.

[Boy from Oz]

That looks really good, I'd like to see some of the installed pictures and cross member pics as well.

That's probably some time off as the shell is still on the rotisserie. I have nothing unique in mind and just plan to mimic the JCI 280Z cross-member. I didn't have any issues with the cross-members but rather how they were attached to the shell.

[260DET]

Nice work sport, Zincanneal material? Put some braces across that trans tunnel while you are at it, those S30 bodies need all the help they can get

[Boy from Oz]

... Put some braces across that trans tunnel while you are at it, those S30 bodies need all the help they can get

You have given me something to think about there. I'm halfway through attaching new seat support plates and there is a possibility of combining them with an extra cross-member. While the t56 transmission mount will also act as a cross-member I had planned on doing away with the standard diff front bracket as I'm fitting the GM diff with an RT style bracket, an extra cross-member in that area would be good. I'll probably wait until the tail-shaft and exhaust are fitted and see what clearance issues arise but I think it should be okay. Thanks.

[Boy from Oz]

It has taken some time to get the shell off the rotisserie, the engine installed and the exhaust fitted (longtubes). So this week I made up the transmission crossmember. Fairly straightforward but the exhaust are tucked up so close to the transmission tunnel that I had to run the cross-member underneath them, but it is still higher than the bellhousing.

Edited April 4, 2011 by Boy from Oz

[rjstcroix]

Hey Boy from Oz,

 

Nice work, been contemplating a similar mount for our build. We used Bad Dog Subframe connectors for our chassis. The rails project about 1.25" from the bottom of the floors so doing a tube through the rail for structure is a little more involved with some extra plating etc. Haven't fully engineered this do-up yet though.

 

Looks fairly straight forward, wouldn't have a dimensioned drawing available from your setup would you?

 

Thanks.

 

Regards,

 

RSC

[Boy from Oz]

Sorry there are no drawings as it was a one-off and I simply made up the components and then tack-welded them in-situ. Having had a little time to reflect on this I now have a few misgivings.

 

As stated earlier I was more interested in the mountings rather than the cross-member design and I had it in mind to replicate the JCI 280Z mount. Somewhat unfortunately my exhaust was made such a close fit to the floor pan that I have to have the cross-member run under the exhaust. Although it is high I am now a little concerned that any accidental contact with a speed hump will create a severe impact on the blunt leading edge rather than just scrapping along it. I'm now going to fit a skid-guard with a raised front edge.

 

I still think the spacers in the rail is a good idea (very easy it install and remove the cross-member) but I think you will have to wait until YOUR exhaust is fitted to design your own cross-member.

 

Regards