dreaded rear end clunk

[grantf]

I know there are many a post regarding this topic but I am still a bit confused. My car sufers from it and I would like to know a bit more before I star buying parts and dismanteling the car. here is a picture of where I think the problem is but I am not sure.....

[spitz17]

I maybe wrong, but I've read that it may be the differential mount insulator... or the diff strap (esprist sells these).

[grantf]

??? is the pic I provided the dif mount? sort of confused with my set up compared to other poasted pics I have seen here. I have a 78 280z.

[Travel'n Man]

If you do a search on R/T Mount it will give you some great reading information -

[Zs-ondabrain]

Your diff mount has failed. Nissan didn't build it with a "Failsafe" so when the rubber seperates from the metal on either side of the front diff mount, the diff lifts up and "Clunks" thediff strap or body, then also clunks on the way back down.

There are a few options.

1) buy a new diff mount (I think they're still readily available)

2) Buy an R/T mount from Roostmonkey on Hybridz.org (About $65 I think, last I checked)

3) Bolt in a 1/4" thick L-bracket to the back side of the mount, so the other half of the "L" is face up with the bottom of the cross-member, place a rubber pad on it to keep it from Thumping the cross-member upon raising.

I've attached a drawing (my own take on it) to help you visualize #3. I've been informed that it works very well and is obviously inexpensive. You just need to drill the stock diff mount and tap it for the decent size bolts you'll use.

Use your imagination on that one, might even be a market for it if customers want to drill and tap their stock diff mounts.

Dave

[Arne]

I was going to try number 3, until a batch of RT mounts became available. Went that way instead.

But on the other hand, there are other parts of the drivetrain that can cause clunks that sound and feel very much the same as the diff mount. I would start with that, but don't be too surprised if that doesn't totally eliminate it.

Edited May 4, 2010 by Arne

[grantf]

already replaced all of the u-joints over a year ago, I just wanted to know if the picture posted showed any glaring signs of a mount failure.

[mgood]

I had the same problem, I completely redid my rear suspension and found the the nut attaching the cross member to the diff mount was bad. See the picture attached. The stud is pressed into the mount, not a good design for access or strength.

[Arne]

already replaced all of the u-joints over a year ago, I just wanted to know if the picture posted showed any glaring signs of a mount failure.

A failed mount generally shows no outward signs while sitting parked and relaxed.

[nomnomnom]

could this clunking be caused by too much power being applied and if so is there a solution ie stronger bracing or just strait welding plate steel to hold it in place? i have about 400HP being routed to mine. Maybe an after market kit to reinforce the diff?

[jmortensen]

could this clunking be caused by too much power being applied and if so is there a solution ie stronger bracing or just strait welding plate steel to hold it in place? i have about 400HP being routed to mine. Maybe an after market kit to reinforce the diff?

The RT mount will handle 400 hp no problem. The stock mount... not so much.

[Arne]

The RT mount will handle 400 hp no problem. The stock mount... not so much.

Ummm, the stock mount has trouble with the stock 150 hp...

Even on my stock-motored 240Z, I'm loving my RT mount.