OBX LSD in a A413! Tips and tricks I found.

[turbovanman²]

Did it last night, just thought I would cover what I found. Got the spacer place from DBBMini-Awesome piece, thanks man.

Had to grind the inside of the trans pretty good, just kept installing the LSD and moving it out around, it would leave a nice mark in the aluminium. Go an inch to the right so you have room for the bolt heads too.

You should buy a bunch of preload shims so you can set the preload properly. I ended up using a .050" shim, I ground down a .058" shim down to .044", was a bit off so used the seal deflector I modified-perfect.

Axles fit with no grinding, even the intermediate shaft.

I angled ground the bolts-adapter to LSD. This gave the necessary clearance for the trans case.

The cover fit with minor dimpling, I didn't have to cut it like others have???????? I guess the angle grinding of the bolts gave me all the clearance I needed.

So far, it works fine. No more torque steer on badly road crowned roads, even with rubber stock busings in my Cast control arms. The steering is a bit heavier but nothing extreme.

[Kulgii]

So how are the burnouts?

[turbovanman²]

Burnouts are awesome, with slicks, leaves 2 big blackies. Just have to get used to launching this beast with some boost, last run I launched at 15 psi.

I can honestly say, if your going to drag race, this should be your first priority.

[DBB mini]

Thanks S for the positive feedback. BTW I still have a few of the ring gear spacers left. I have to reorder bolts though. So you clearanced out the case without having to weld it up? You also clearanced the diff cover without much trouble? You tha man.

Coy

[looneytuner]

"WE" got a little careless with the grinder there didn't "WE" I don't recall my obx having grind marks on the edge. Shadow's cover is going to be 3/8 aluminum which should be stronger for the bobble strut mount.
At least that transmission is really clean now.

[turbovanman²]

Thanks S for the positive feedback. BTW I still have a few of the ring gear spacers left. I have to reorder bolts though. So you clearanced out the case without having to weld it up? You also clearanced the diff cover without much trouble? You tha man.

Coy

Yeah, as you can see, I just angle ground the diff bolts, aprox half way back. Seemed to work, maybe thats why I did't have to modify the cover?

Thanks again for the spacer,

"WE" got a little careless with the grinder there didn't "WE" I don't recall my obx having grind marks on the edge. Shadow's cover is going to be 3/8 aluminum which should be stronger for the bobble strut mount.
At least that transmission is really clean now.

Nah, I didn't think about the bolts and was getting tired of grinding the case. I guess it worked out in the end,

[Dave]

Simon, in the last pic where you see the diff. case, what's that bracket for?

Why are you using half shafts instead of unequal length axles? Is there any benefit to that?

[turbovanman²]

Simon, in the last pic where you see the diff. case, what's that bracket for?

Why are you using half shafts instead of unequal length axles? Is there any benefit to that?

Its the dog bone bracket from an Omni, I modified it to fit my trans, then welded a PB bobble strut bracket to the K-member and run the stock rubber bushed dog bone. Tightens up the powertrain nicely and not to much vibration transfer,

I find it has slightly less torque steer, the engine is easier to work on, and I only need to take one spare axle with me when I go drag racing.

[TurboJerry]

I have a suggestion, why not make the threads into the spacer something like 7/16-20 so a regular button head allen could fit with no grinding. The threads could be whatever you wanted to be able to find common size bolts.

[looneytuner]

Simon Did your half shaft u joint come with the grease fittings??

[turbovanman²]

Simon Did your half shaft u joint come with the grease fittings??

Yep, I bought the heavy duty one and they put the grease nipple in the cap. BM has the part numbers listed for regular and heavy duty u-joints.

[DBB mini]

I have a suggestion, why not make the threads into the spacer something like 7/16-20 so a regular button head allen could fit with no grinding. The threads could be whatever you wanted to be able to find common size bolts.

Spacers are already made, drilled & tapped. Think you can find a m10x1 in a button head? That would help.

[TurboJerry]

I see. That thread size is so wierd. I know of a local military bolt warehouse. I'll see if They have something like that. I just meant use a regular size so the diff to spacer bolts could be easy to deal with. Maybe something to consider on the next batch. The spacers are awesome though!

[DBB mini]

I see. That thread size is so wierd. I know of a local military bolt warehouse. I'll see if They have something like that. I just meant use a regular size so the diff to spacer bolts could be easy to deal with. Maybe something to consider on the next batch. The spacers are awesome though!

Thanks. Actually I fibbed. I found like 4 more of the lathed out spacers ready for millwork. I have a interested party on TD forum wanting 7/16-20 instead of m10x1. I think he has spoken for at least 2 of them. I have one of the old style metric tapped spacer left. May be a while before I can make a second run, so act now if you want one. On the second run I may make deposited reservations as I had to pay my boss (weekly out of my check) for the damages, then sell them. Not too bad though, they are selling. Kinda hard for me to keep up with everyone as busy as the mini is keeping me.

[TurboJerry]

I am courious if you agree with using a common bolt size DBB mini? The wherehouse does not have any of the m10X1 right now, but they say that there is a gov. contract that uses them, and they get them from time to time. It's surplus, so I can only wait and see........ Let me know before you start the 2nd run, I have some ideals I need to figure out so I need to buy myself some time. I'm actually thinking of making the cover with the ring gear flange moved over, so it requires no spacer. But this may not be worth it due to all the internal machining required for the fitment of the pinions and the registers. And of course the Quaiffe is different then the OBX, so it's not a "1 cover fits all" deal. I just need to make up my mind......

[looneytuner]

I am courious if you agree with using a common bolt size DBB mini? The wherehouse does not have any of the m10X1 right now, but they say that there is a gov. contract that uses them, and they get them from time to time. It's surplus, so I can only wait and see........ Let me know before you start the 2nd run, I have some ideals I need to figure out so I need to buy myself some time. I'm actually thinking of making the cover with the ring gear flange moved over, so it requires no spacer. But this may not be worth it due to all the internal machining required for the fitment of the pinions and the registers. And of course the Quaiffe is different then the OBX, so it's not a "1 cover fits all" deal. I just need to make up my mind......

He has a source for the bolts and is buying 100 at a time. 12.9 grade at 1.56 each so the cap heads work fine.

[turbovanman²]

When setting diff preload, you need to get more shims, Sonnax sells a shim pack kit. You will need at least .026" more shims to correctly set the preload.

When I redid my tranny and had to use a new case, I didn't angle grind the diff bolts and they cleared my stock cover.


Another option is to have a cast aluminium cover made, I was planning on it but as usual, never enough time.

From Chad on shim setup-

Hey Simon, I had the same problem installing an OBX today. I had a .062" shim, and I had to add another .055" to get my correct preload.
Here's an easy way to decipher the charts (actually I mean to throw the charts in the garbage). The language of the charts just tells you that you need .008" (or .20mm) preload on the bearings. So in your example where you had .026" end play on the diff, just add .008" to that (.026"+.008"=.034") and throw in an extra .034" to the shim pack. Your turning torque should fall into spec by doing this.

[Vigo]

now, seeing as how i am no where near one, dont have bolt measurements down to eyeballed yet, and am completely shooting in the dark... this is probly useless.

but how about the bolts that hold bellhousing to case on newer 4l60s? thy've got really low profile heads and are metric.. i can get more info this week but i think they are bigger than the sizes mentioned..

good thread, thanks for the info!

[Dave]

Simon, is there a disadvantage to angle grinding the heads off the bolts? My dad has his OBX installed like that. I remember you stating it didn't hold enough pressure to the ring gear and it came apart.

[turbovanman²]

Simon, is there a disadvantage to angle grinding the heads off the bolts? My dad has his OBX installed like that. I remember you stating it didn't hold enough pressure to the ring gear and it came apart.

Never had the ring gear come off. Those are ground donwn after there installed.

Reason is to clear the diff cover and also less grinding at the back of the trans.