apologize, don't know the right name for this bit. It has 2 18mm bolts on each end, one end attached to the tail end of the zf6 speed the other end attached to the diff housing.

I was feeling a little movement (up down) slight in the shift lever on a high rev shift like the tran was moving up/down maybe 1/8 inch so I thought I'd go look around.

I can turn one of the 18 mm bolts with an open end wrench pretty easy, I figure from the size it ought to be torqued 150 ft lbs or so.

Gotta drop the exhaust (of course) to get to it.

Questions are:

1) What's the torque spec

2) Should I add some medium loctite (remember this one gets raced a bit)

3)Is there a nut on the other side?


How to hold the top side while you torque the bottom, do you need two people? Any tricks of the trade?

Many thanks

--------------------
1996 LT4 Coupe


--------------------
1996 LT4 Coupe
Black/gray 50k miles

 

1) unfortunately I don't have my service manual with me, but the torque spec is actually a bit less than that. It's also different for the trans and diff bolts. Be particularly careful NOT to overtighten the trans bolts. If you do, it will distort the tailshaft seal and you'll get a leak.
Hopefully someone will chime in who has the manual handy!

2,3) there are nuts on the top (which makes it kind of a pain) and the're nylock nuts (locknuts with nylon inserts), so you shouldn't need any locktite.

 

Thanks Mark,

Should I get some new nuts (for the Vette). I push her pretty hard (autox)

Don't want to do this every year

 

You should get some beam plates from ZF-doc.

http://www.zfdoc.com/c4beamplate.htm

 

The torque spec's for the driveline support beam on my 92 auto are 40 ftlb's at the transmission (18mm bolts) and 60 ftlb's at the differential (21mm bolts). I know this because I just reinstalled my beam last night. As for the thread locker, I did not use any as the nuts are self locking. http://forums.corvetteforum.com/phot...C_beam-med.JPG
Good Luck

 

I have to laugh every time I see these 3" tiny plates, that are suppose to support a 4 ft beam?

I see how they could be helpful in holding the nuts while torqueing down the bolts, but support?

I have had many engineering courses, one of which dealt with beams, and supports, and from an engineering standpoint, these thing have ZERO effect on how stiff the c-beam is.

How people fall for this is beyond me. I think a truer sense of the useage would be to say they make the installation easier, as most of the work can then be done from down under the c-beam, once the bolts are started into the "holder (not support) pieces".

I have done my c-beam about 8 times now for various reasons. I always use a 3/4 air wrench on mine. Hold the nut with a long wrench and hit the bolt with a few quick bursts till tight. Removal is the exact opposite process. Takes about 3 minutes in either installation or removal. The key is to have the tranny on an adjustable jack, to get the bolts to feed up through with no resistance and get both the front and back started on the nuts, before tightening. This technique, has never comes loose during operation.

 

I'm with ya man.
People with an Air Wrench don't need no stinkin torque wrench.

 

Its all in the ear

 

Don't you mean "air"?

 

Something like that...as long as its tight - what is the difference how tight

Once your outside the block - torque specs are optional.

 

Where did I say that?

He didn't say he had a weak c-beam, he said he had a loose bolt. You appear to agree that these will help with correcting that.

Well I guarantee you I've had far more engineering courses than you, several of which dealt with beams and supports, and from an engineering standpoint, I still didn't say anything about these having an effect on the stiffness of the c-beam.

Your high and mighty attitude is appreciated as always.

So, since I was answering his question about how to get the nuts started, you agree with me that this will help.


I've seen you state this opinion before, and you're always putting up this straw man about beam strengthening. They are not there to stiffen the beam. What they do is strengthen the mounting of the beam. And they also make installation easier.

 

By the way, for anybody who hasn't had an engineering course that tells them that this absolutely doesn't help, just do a search for "beam plate" on the CF. Even with the sad state of the search engine, you will find a whole lot of praise.

 

I made mine for the ease of installation , not having a hoist or air gun, the beam install ain't no fun lying on your back balancing a spanner on the top of the beam while trying to turn the bolt.
While I agree on the plates doing little to enhance the stiffness , I believe the benefits come from the bolts clamping over a much bigger area thus preventing movement between the beam and it's mounting that you get when relying only on the area of the washer under the bolt.All I can say is that they made a notable difference to my handling.

 

Quoting ZF doc; "We have found that most C4 Corvettes inherently experience a slight amount of twisting at the fastening points of the support beam to the transmission and differential housing connection surfaces. Although fastened with high grade bolts, self-locking nuts and adhered with factory sealant, the driveline components of the C4 Corvette still experience some level of counterforce load-induced lateral deflection between the members while under heavy loading. This allowance of flex in the driveline beam fastening joints creates a condition where the chassis structure must additionally contend with."

IMHO, They have not indicated the plates increase the C-Beams stiffness. My interpretation is the plates increase the surface area of the mounting points thereby decreasing the amount of flex at the mounting points. I do not subscribe to the theroy that the plates are the "wonder-cure" to torque steer. However, ease of bolt tightening and some addition strength in a high stress area can't hurt.....

-JRC-

 

Thanks guys for all the feedback. If I properly support the tran & diff is it a BIG DEAL to keep the clearance measurements accurate?

On ZF Doc's web site it gives some pretty precise mm measurements.

Should I worry that if I A) Just tighten the existing ones or B) use the beam plates that these fussy measurements are going to make this job into a nightmare or cause me alignment problems.

Again TIA

 

I would just go with option "A", just keep an eye on them and IF they come lose again then maybe do some thing different.

 

So basically through all that - we can sum it up with you 100% agree with my thoughts, except from a more educated point of view.

PS: If you go back and read what I wrote - none of it was directed at you personally - contrary to your post back at me. If you would like to get personal about "Engineering and its application to vehicles" I would be happy to school you publicly or privately - just let me know

 

I'm not an Engineer, but my solution will be a custom c-beam with a trans and rearend crossmember all out of chrome moly! I'll post pics soon! I heard good praises on the beam plates so I brought a set, but may wind up selling'em! Be nice to each other guys!

 

It's very hard to hear any of your thoughts because of the attitude that comes along with them. Do I agree with your thought that people claim that the plates strengthen the beam in bending? no. Do I agree with your thought that people who approve of the beam plates are "falling for" something? no.

Your statements are highly derogatory towards anyone who thinks the beam plates are worthwhile, and that includes me. And at the point you made those comments, I was the only person in this thread that they were being derogatory towards. Furthermore you were responding to my post and quoted me.

Your self importance is noted, as usual.

 

Those measurements are actually quoted straight from the shop manual.

Yeah, I think they're important.