Alternative

Rexpelagi

Binding on what? I think it actually may be an excessive lash issue.

Rexpelagi

Thanks for the pictures - I didn't even touch the side of the PPF.

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Look at the top of the PPF I'm willing to bet it's hitting the rear subframe above the front mount in the Getrag.

Rexpelagi

Gotcha - with the front mount I added the diff can't really move, but I'll check. I pulled the diff and brought it to a shop just to check it out, and I'm going to do some more work on the PPF.

Did you replace the bushing at the front of the diff? I want to put something stiffer in there while I'm at it.

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I am using a shackle spring mount from a ford ranger if I recall. Found a part number for it on a Cadillac site that recommended that over the $80 bushings being sold. I can try to find the part number again.


The amount of TQ applied to the rear will easily flex the brace you have it attached to, alternatively it will shear the 2 6mm bolts rather easily.

Rexpelagi

Gotcha - my bushing is pretty perished so maybe that was the issue? I couldn't even move the diff by hand though.

If you have a part number for what you are using let me know. Google led me to this - https://creative-steel.com/shop/05-0...ntial-bushing/

It looks legit at least, and mentions that it cures clunking.

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Differential Bushing $16 DIY option

Rexpelagi

Cheap and you don't have to remove the race? I'm sold, thanks! :-)

My torch has been lonely anyway.

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Fu@k I think the bearings are shot in my diff.... I was relating the clunks and rattles to something hitting and it appears to be slop in the diff.

Any updates for you?

Rexpelagi

I picked the diff back up from the shop - they said everything looks good. I have the bushing you linked too, so I should be good to go. Just need time to put in the diff, maybe this weekend, but if not next for sure.

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It looks like V8R discontinued the PPF mount as an option.

I have 2 autocross events on mine and with the 949 twin I have zero cushion in my driveline so it's pretty fighting sounding, I figured it would either break or it wouldn't and just went with it.

Id like to hear how you make out after reinstillation, maybe we can compare how much play we have in our setups

Rexpelagi

Diff is back in, and I did my first autocross today in the car post-swap.

https://youtu.be/uXmG9FHhYiw

It was fun having the taller gearing, but I must say, changing from the completely perished stock bushing (it was way worse than I thought, I pushed it out of the race by hand) with the poly bushing did absolutely nothing. The clunks are exactly the same. To be fair, the little brace I made didn't fit at midnight last night because the diff was in a slightly different position now that I re-clearanced everything and have the poly mount, so I'm not running that now. But, it seems like the mount was not the issue.

Honestly, right now I'm tempted to just get a 3.63 in the stock housing, even though that's not what I really want, just so I can go back to enjoying the car. :(

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I plan to call V8R today and see if they have gotten anywhere with the transmission mount they have been working on that deletes the PPF, it appears as if they have discontinued the PPF mount all together on the website and do not have an option listed for using a stock trans and PPF.

I get a horrexdious reverberation transmitted through the PPF when loading the car under 3k and quite a bit of banging when loading and unloading the driveline from a stop. I have silicone coupler jammed in any areas that could be making contact and it has not stopped the banging so I am relatively convinced it's not hitting anything. If I need to buy framerails and rig something up I think deleting the PPF is going to help the situation a lot.

Rexpelagi

So, if we agree it's not the diff itself banging around (which, I don't think mine is either as far as I can tell), do you think the diff just isn't at the correct angle with respect to the trans, and is causing bind in the driveline somewhere? I think you alluded to that earlier...?

I agree on the PPF issue, I think it's just not a good design from Mazda to begin with and we aren't doing it any favors here.

Rexpelagi

To add additional datapoints, I have a friend who has this setup in his LS2 car, and obviously doesn't have the PPF. He measured his pinion angle and set it to 1.5° and welded that tab on accordingly. He has no reported clunks, so there may be something to the driveline alignment.

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I think the PPF can and does work well IF it is used as intended, same with the Getrag rear end.

I have not experemented with pinion angle yet and that is a hat is a great point to check.

The V8R kit removes almost all compliance from the system and I believe that is why we are experiencing the issues we are.

If you get a chance can you check your driveline freeplay?

email me DShultz25 at Gmail and maybe we can come up with some methods to compare.

acedeuce802

iTrader: (1)

Pinion angle was my first thought when I read your experience. I believe KMiata is working on a transmission mount to delete the PPF as well.

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FWIW K-Miata = V8R

acedeuce802

iTrader: (1)

In what way?