Jump to content
SAU Community

Please Help Me With A Diff Problem

SRE30

By SRE30,
in Queensland

 Share

Recommended Posts

SRE30 Rookie

SRE30

Posted
Posted

Ok, I have a E30 BMW with a Nissan SR20DET. I recently replaced the weak open wheel BMW diff with a second hand R32 Skyline LSD diff. To put it in I had to get a new 3" single piece tailshaft made up, two new Mazda half shafts, new Magna outer CV's, and the original R32 inner CV's.

Now between 3-4000 RPM (~110kmh) there is a horrid shudder that shakes the whole car and you can feel it most through the seat of you pants.

Now, since it's all new and most of it custom it's proving difficult to track down what's causing it. The place that made the driveshaft had a look at it and ran a dial guage over everything and couldn't see what could be causing it, so suggested the diff could be the problem.

I have replaced the rear wheels and tyres, same problem...

Removed left hand half shaft, same problem...

Remover right hand half shaft, same problem...

All that's left is tailshaft and diff so I have two questions:

1. Has aonyone had this sort of problem with their diff?

2. Does anyone in Brisbane have a known good R32 LSD diff with 4.1 ratio that they would like to sell on the basis that it is the diff at fault (ie, I pay you after I fit your diff and problem goes away, or I give it back if it doesn't :)

Any opinions?

Cheers

Link to comment
https://www.sau.com.au/forums/topic/98650-please-help-me-with-a-diff-problem/
Share on other sites
SteveL Mentor

SteveL

Posted
Posted (edited)

It's unlikely to be the diff, BUT if the input pinion bearings are shagged it could cause the tailshaft to float around sufficiently to cause this sort of problem. I've never seen an R200 that was that bad and usually they get quite noisy well beforehand. A badly worn slipjoint at the gearbox can give a similar problem, although in that case oil leaks preceed other signs.

To me it sounds like tailshaft whip, which can occur when there is too much 'offset' between the connection of the tailshaft to the gearbox and its connection to the diff. IOW the imaginary line drawn between the centre of the gearbox to the centre of the diff should be as straight as possible. Shimming the gearbox mount can help but it depends on which way you need to go.

I had a similar problem with an Oz spec R31 Skyline sedan when I replace the tailshaft with a single piece unit that was quite long. Had bad shudders at similar speeds to yours and ended up modifying the gearbox mount. The problem is still there but nowhere near as great.

Generally the longer the tailshaft the more sensitive it will be.

Edited by SteveL
Oz Grand Master

Oz

Posted
Posted

the R31s are well knowen for the sort problem it sound like you might have, the tail shafts throw the balance weights off & @ around 80 too 100 k it shudders might be worth taking the shaft out & have it balanced....

SRE30 Rookie

SRE30

Posted
  • Author
Posted

I can't detect any movement/play at either the gearbox or pinion end. I first thought whip, but the gearbox and pinion are pretty well lined up. The rotational speed of the driveshaft is only about 4000rpm and they guaranteed no problems up to 9000rpm. I also can't detect any significant vibration from the gear leaver (I expect I would if it was the tailshaft whipping).

If I can't get a diff to try I guess I can take it to a diff lapping place and get them to inspect the internals of the diff, if it's all OK, I will take the tailshaft to some where else to have it inspected/rebalanced.

Ahh, the cost of doing something different...

SRE30 Rookie

SRE30

Posted
  • Author
Posted
the R31s are well knowen for the sort problem it sound like you might have, the tail shafts throw the balance weights off & @ around 80 too 100 k it shudders might be worth taking the shaft out & have it balanced....

I took it out last night, it's still got the weight on it, and it's brand new so it should be balanced...

dangerous_daveo Grand Master

dangerous_daveo

Posted
Posted

Uni joints. I had the same prob with mine when I got the rb25 box put in. We went to a 1 piece tailshaft. The place said the angle was too much, so we jacked the box up didnt help. Did a few other things. Then put it on a dyno. Shaft shacked to the s-house. Went back and said fix it. Low and behold they used cheap uni's. Had them replaced within about 3hours.

Thats my bet anyway.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Murray_Calavera
      Should I use rust converter on this?

      By Murray_Calavera · Posted

      The easiest option might be to just spray a bunch of fish oil in there.  At least that way you can feel like you've done something while you continue to ignore it
    • GTSBoy
      WTB noltec r32 front upper (camber) arms

      By GTSBoy · Posted

      I'm firmly on the "zero compliance is good compliance" for FUCAs. I'd be looking to solid metal joints even if the primary reason for having them is because they facilitate the twist in the arm. I have never been more happy with the way the front suspension behaves than I have since I got rid of the FUCA bushes. Even the thin little (short lived) poly bushes in the Whiteline adjustables have too much compliance for my liking. It probably won't be long before I have sphericals nearly everywhere, probably including both top and bottom arms in the rear, and I'll start complaining about the increased costs for dental work. But I will be enjoying the driving more, I'm sure.
    • GTSBoy
      Brake pad Compound suggestion

      By GTSBoy · Posted

      Plus, you'll get great experience in bedding in pads!
    • Matvei27
      WTB noltec r32 front upper (camber) arms

      By Matvei27 · Posted

      I have offset Nismo brackets so the fact the gktechs can pivot is less important to me. I have 170mm JIC arms with bushings - but they provide no adjustment and I'm not sure whiteline eccentric bushings will fit them (I don't want to ruin the bushings currently in them to find out). Ideally I want something with bushings + adjustment; hence why I'd like to find a pair of these. Unfortunately they aren't easy to find.
    • Murray_Calavera
      Brake pad Compound suggestion

      By Murray_Calavera · Posted

      @Vee37 How much do you really care about finding these pads again? If your pads are quiet, work well and produce minimal dust, really isn't that enough? If you are set on finding the exact pads again, I suppose I'd do something like this -  Visit your local Jax, find out what brand of pads they carry. If the Jax workshop you previously went to had the pads on the shelf, then you can almost guarantee it will be of said brand.   I'm guessing you don't have the receipt for the previous work and pads. Can you visit a Jax workshop and see if they can look up your previous job to see what pads were fitted?  Still no luck? Put your stalker hat on, find the staff that used to work at the Jax store and ask them. Talk to local workshops, try to find out where the mechanics went to. Talk to Jax workshops, maybe they relocated to another workshop. When it comes to mechanics, its a small world. You'd be surprised how easy it is to track someone down. If these ideas don't work, shit will start getting crazy very quickly.... You could find out every brand and model of pad that fits that car... and try them individually ticking each off the list if it wasn't the one you were looking for.... If you go down this path your going to want to learn how to swap pads yourself, it is very easy, takes minimal tools and space. If you have room to park the car you have room to swap the pads. Plus you have the advantage of making sure all the brake hardware goes back in so they won't squeal! 
×
×
  • Create New...