3Katz

Hi Guys, been a while! The old BA RTV has been going brilliantly - 740hp these days and in the process of a 4L80e conversion. As it it putting out some power and I've started running radials (and a transbraked 4L80) I'm a little concerned I may damage my factory locker M86 diff. I bought what was supposed to be a BA XR6 Turbo ute diff from a wrecker down South with the view of rebuilding it with a Trutrac and straight swap the diffs out so I can keep my factory locker diff unmolested. This is where the lid started to pop off the can of worms... Upon receiving the diff I pulled the back cover off and noticed it has 2.73 gears not the 3.45's I expected, so I assume it's a BFII diff with the ZF gearing? Secondly, although the measurement from flange to flange is the same (1505mm) the diff casing itself is 30mm to the right of where my RTV diff is, effectively the pinion is 30mm further to the right! I measured the center of the pinion in the ute to the chassis rails and the RTV pinion is exactly in the center of the car. If I were to install this replacement diff the center of the pinion would be 30mm to the right. Weird right? I have 2 questions - how is this so? And would it be a problem?

Yeah mate for sure, sounds like it could be the same issue as mine. My engine builder sized the bore as per CP instructions but I've heard quite a few stories now of the CPs being particularly noisy. We've measured the pistons and bore again to be sure and they're as per spec. Meh it's a sh*tty noise and sounds like a bucket of bolts but is certainly hanging together lol be interested to hear what you find 👍

Hi mate, Nope I never got to the bottom of it, we ended up putting it down to noisy pistons for lack of any other possible issues as everything has been checked. I've run Castrol Edge 10/60 and Edge 5/40 no noticeable difference between the 2. Yeah it's super hard to pin point let me know how you go with the cover removed... For what it's worth we built another one on the side as we were sure the issue would come to light on the dyno or track but it has never given any grief aside from the noise. And we're at 500kw with more to come next tuning session with some more gate spring. I'm just living with the noise, I've found once it's proper warmed up with some decent pulls the noise goes away - gotta be pistons right? Who fkn knows lol

A question for you guys who run or have run before they exploded BTRs at the track. My ute has recently been tuned to 450kw at the hubs and is only 1 second quicker than when I had 260kw. A quick run down: Built engine Plazzy cooler Garrett GTX3582 gen2 Built BTR (stock stall speed convertor) 345 gears ET Streets PCMTEC tune with antilag I can not beat 12.90, runs 12.90's all night. No matter my technique variation (handbrake/antilag activated/etc) I can't better that time. It seems to leave the line pretty hard then immediately bogs down until boost is back up then it's off and pulls hard once she's away and even the change into 3rd feels strong. No wheelspin, traction is not an issue. I'm doing 2.5 sec 60ft's and 112mph. I figure I need a higher stall convertor but I'm sure people run much faster than that with stock convertor. It's loads of fun and I'm looking forward to more practice and would really appreciate some tips, and thoughts as to what might be causing my 60ft times.

For those that tune their own cars they probably make their own kits. I certainly can't tune my own car so am after a kit that is easy to fit and will be easy for a PCMTEC tuner (whoever it may be) to work with. From what I have read PCMTEC will only offer support to the tuner if it's a Pirotta Performance flex fuel kit, is this still correct? I have a BA so will be utilising the boost sensor input. Incorporating an alcohol percentage gauge would be a nice feature to have.

General consensus seems to be the Ross and ATI balancers are possibly more effective than the Powerbond. I had one ready for the other engine anyway so worth a try.

Great thanks mate, I'm not sure why they've come loose this time I suspect I wasn't as liberal with the loctite last time it was out, never had a problem before. I've also removed the Powerbond balancer and installed a Ross which should hopefully help as well.

Well if that's what you would do I'll give it a go too. Save me muckn about with machining stuff and worst case pull the box again, 30min job these days. I'll have a chat with Mackielec when they're back from break and see what the scoop is. They look more like flywheel bolts they've recommended...

"which means I could space the t/c back of the bolt heads" Should read: "space the t/c back OFF the bolt heads"

I have the BTR out again, I should install it with wingnuts this time... I have a Yella Terra flex plate and an unknown built 'heavy duty' Territory converter. The box has been in and out a few times for various reasons- this time because the crank bolts came loose on the dyno. When I pulled it out the first time (not for loose bolts) I noticed marks on the converter where it has been touching the crank bolts. When assembled there is 1mm clearance between the crank bolt heads and the tc. I am supposing that the converter swells under load sometimes enough to slightly touch the bolt heads. The problem I have is because the bolts have come loose I have decided to try a Mackielec retaining plate. This kit requires the use of a different ARP bolt (203-2802) which has a much taller head than the ARP bolt currently in use. A difference of 4mm - room I don't have. As there would probably be thousands of these kits on Yellaterra flexplates I'm guessing the difference I have is the t/c itself is slightly different. I've measured my t/c spacing or air gap at 3.5mm which is at the lower end of spec (3.2-4.8mm) so I can't space the converter back. I can't machine the crank side of the flexplate as that will affect ring gear to starter engagement. I could machine the area opposite where the bolt heads are but 4mm is a decent slice of a 8mm plate. I could maybe take some off the bolt side of the flexplate and some off the bolt heads themselves... Or I could look at a new converter which would be a shame as this one seems fine (I don't have a stock one to measure against for comparison). Or (just popped into my head) I could use a couple extra engine to trans sandwich plates which would push the trans back in relation to the t/c increasing the air gap which means I could space the t/c back of the bolt heads.... Crikey. I'll include some pics, interested to hear your thoughts guys.

Great vid, thanks mate 👍

I have a Yella Terra flex plate and BTR transmission. The converter I got with the transmission is an aftermarket one and I want to check it sits at the correct depth once assembled. Does anyone know the correct spacing for a BTR trans/tc?

No updates other than I haven't been able to find anything definitive. One bloke I was talking to that had the same thing happening on his built engine removed his pistons and had them coated to take up a bit of clearance and that seems to have fixed his noise issue. Mine goes in for a tune on the 12th noise and all so we'll see what happens...

Haha! I'll try to resist the temptation. Awesome, no worries. Thanks all, appreciate your help 👌

Excellent I'll play around with the setup and get it lined up better. I see.... this explains why we had trouble controlling boost. I had way too much preload on the arm, I won't say how much on a public forum lol. When you say 1/4 Aaron do you mean 1/4 of the hole on the rod end or 1/4 turn on the rod adjustment?