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p7x

280z R200 Differential Mount Bolts Stuck (Help!)

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Posted (edited)

Hey all,

 

The search function on here crashes on me constantly so pardon if there's a thread on this but didn't find it.

 

I'm replacing the Diff mount with a solid billet unit on my 78 280z but the mount bolts in the Diff will not break. I've used a smallish breaker bar and my 18v Impact and I cant break the torque on the bolts. I've used my larger torque wrench to see how much torque i'm putting on them and its showing im put over 65 lb/ft and the aren't moving. I believe the torque spec for the bolts is 58 lb/ft and ready to get a impact wrench but concerned ill snap the head right off the bolts.

 

Any tips / tricks / advice for a new S30 owner?

Edited by p7x
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Are you talking about the stock front diff mount?  And if so, which bolts...the ones that attach the mount to the car's shell or the ones the bolt the mount to the diff?  Take a picture if you're not sure.

 

Fie searching on HybridZ, Google search works better than our website search function.  Just be sure to include HybridZ in your search string.

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3 minutes ago, jhm said:

Are you talking about the stock front diff mount?  And if so, which bolts...the ones that attach the mount to the car's shell or the ones the bolt the mount to the diff?  Take a picture if you're not sure.

 

Fie searching on HybridZ, Google search works better than our website search function.  Just be sure to include HybridZ in your search string.

 

Stock front diff mount - the long bolts that bolt the mount to the diff with the nuts on top of the diff and the head of the bolts facing down. The mount was toast so I torn it apart to access the heads on the bolts

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You need more leverage.  Use a 2 ft. long pipe as a lever i.e., put the pipe over the wrench handle to extend the length.

 

For example, I couldn't get the nuts on the stub axles to break loose. Tried an air impact wrench. The nuts wouldn't budge. So I got a 4 ft length of pipe and slipped it over the handle of a 1/2 drive ratchet wrench. The nut broke loose instantly.

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1 hour ago, Miles said:

You need more leverage.  Use a 2 ft. long pipe as a lever i.e., put the pipe over the wrench handle to extend the length.

 

For example, I couldn't get the nuts on the stub axles to break loose. Tried an air impact wrench. The nuts wouldn't budge. So I got a 4 ft length of pipe and slipped it over the handle of a 1/2 drive ratchet wrench. The nut broke loose instantly.

 

That might have to be the next step.

 

Because in wrenching on the bolt head vice the nuts I'm worried about applying that much pressure 

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Gents you are bolder than I am. Slowly building my skills and know how with basics tools. 

 

Was hoping the mount swap would fix the clunking in the rear end. Just got the car and This year I just need to keep it in running / driving condition until next year when I can actually start restoring it. 

 

Thanks for the replies. I’ll update the thread on how things go. 

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There could be numerous causes of "clunking" in the rear portion of the drivetrain.  The diff mount is certainly one of them, but there are many other potential causes.  Fortunately, there are several discussions in HybridZ on this very topic over the last several years -- you'll find lots of good info in them.  Go over the entire drivershaft, differential, half-shafts, suspension, etc checking for worn bushings and/or loose hardware (nuts and bolts).

 

A popular upgrade you may want to look at is replacing the stock diff mount with a Ron Tyler-style mount.  It's a much more elegant solution than Datsun's stock lower mount and rubber strap.  You can sometimes find them used, or Technoversions still produces them new:  https://www.technoversions.com/DiffMountHome.html?.

 

Good luck with it, and welcome to the wonderful world of old Z cars.  :-)

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Posted (edited)

Welcome to Hybridz.

 

The most efficient  way to search Hybridz is to do a Google search using the following format:

 

site:  hybridz.org   "topic in quotes"   For example,  site:  hybridZ.org   "R200"

 

 

Useful information

  • Download a Factory Service Manual (FSM).  http://forums.hybridz.org/topic/48825-factory-manuals-some/?page=2&tab=comments#comment-1208329
  • Download electrical schematics for your car.  PDFs are easier to read than those found in books. Some are in color.
  • Buy the book How to Restore Your Datsun Z Car by Wick Humble. It will save you hours of searching for "how to" info.
  • Focus on searching Hybridz as 99% of questions have already been addressed.
  • Start bookmarking Z car parts suppliers - there are many!
  • Remember these are 40 year old cars and will need restoration to be safe and drivable.
  • Join ClassicZCars.com website and search there as well.
  • Become well informed about modifications before asking questions. People will be more inclined to   answer informed questions.
  • Search the Hybridz forums.
  • Read all of the new member guidelines and FAQs

Links:

https://www.datsun-240z-upgrades.net/ Recommend the headlight relay harness

http://zhome.com/

https://www.zcar.com/

https://www.classiczcars.com/

http://www.zcarparts.com/

http://www.arizonazcar.com/

http://www.jagsthatrun.com/index.html

http://www.ztherapy.com/

http://www.xenonzcar.com/reference.html

Edited by Miles

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The site specific search I think actually requires no space before "hybridz.org"

Site:hybridz.org search terms. 

With the space I think it treats hybridz.org as just another search term. 

 

(so it will more often find results on hybridz.org, but not exclusively) 

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4 hours ago, p7x said:

Gents you are bolder than I am. Slowly building my skills and know how with basics tools. 

 

Was hoping the mount swap would fix the clunking in the rear end. Just got the car and This year I just need to keep it in running / driving condition until next year when I can actually start restoring it. 

 

Thanks for the replies. I’ll update the thread on how things go. 

 

 

Check out the "Clunk"  here:  

 

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Posted (edited)
4 hours ago, Miles said:

Just to be certain. These are the bolts you are working on:

 

584692710_R200FRONTMOUNTBOLTS.jpg.ed0943c61363664f558e2924dcc7bd60.jpg

 

Yes they were... were as in I made a 3 foot breaker bar and that did the trick. Loud snap and I thought I broke the head off the bolt but once got about a quarter turn they were loose and hit them with the impact and came off / out no problem. Installed the new Mount easily and strap easily. 

 

Thanks for the replies and info. 

 

 

284309A2-474A-4DA2-9D01-483E755FBBD8.jpeg

B36E28F0-4E9E-4D0C-B364-532482ED3194.jpeg

Edited by p7x
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The strap is no longer required.  The  stock rubber differential mount you replaced would flex and rip apart eventually. Nissan installed the strap to keep the nose of the differential from pitching up under load.

 

For normal daily driving the solid mount works well.  But the racers have reported that under hard driving  the front cross member can crack and/or pull the center bolt through the cross member. I installed solid mounts in both of my Z cars 20 years ago and have not had a problem.

 

Cars present us with lessons.  The lesson is repeated until we get it and then we get another lesson etc etc.

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Posted (edited)
12 hours ago, Miles said:

The strap is no longer required.  The  stock rubber differential mount you replaced would flex and rip apart eventually. Nissan installed the strap to keep the nose of the differential from pitching up under load.

 

For normal daily driving the solid mount works well.  But the racers have reported that under hard driving  the front cross member can crack and/or pull the center bolt through the cross member. I installed solid mounts in both of my Z cars 20 years ago and have not had a problem.

 

Cars present us with lessons.  The lesson is repeated until we get it and then we get another lesson etc etc.

 

Ya I was tracking but replaced it as it was simple to do.

 

UPDATE / Another lesson: The clunk is louder more pronounced than before. Worn diff mount might have contributed but now with the solid mount its exacerbated the clunk. Time to dive into the thread posted above and find the next item that needs tightening / replacing....

 

Thanks again for chiming in.

Edited by p7x

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