JK: Hemi Build

[damage_man98]

Originally Posted by DIY

go hard or go home, I like your style. Its good to see some one that is more action than talk. I want to see this in person

I'm Sure you will get a chance. I've still got a long way to go yet though.

[damage_man98]

Just an update on the engineering. I have know spoken to 2 different approved engineers in Perth and they have both advised that in principle there should not be any problems with the 6.4 hemi being approved. There is a recommended limit on the maximum size of the engine for the weight of the vehicle and the calculation is original tare weight x 5cc's meaning that with a tare weight of circa 1900 the maximum engine size is 9.5ltr. The engineers have also confirmed the 2 stage approach of getting the engine approved and then doing the axles and brakes etc is the best way forward. There are no disadvantages to this approach and as the braking system is already approved there should not be a requirement to do any tests on the brakes as all the tests that are conducted on the braking system do not have any load applied by the engine so its pointless to retest the brakes after the engine upgrade as there is no difference to with the exception of the minimal extra weight added by the bigger engine.

The way forward is to complete a new permit to modify for the engine and transmission only. This application should then get approved in principal and once done the engine conversion will then be completed and then inspected by the engineer who has advised he doesn't see there being any problems. Part of the inspection will be a noise test on the exhaust and possibly but not confirmed an emissions test. The axles will need to be approved to handle the extra power but as its unlikely that any data can be easily obtained on the existing axles then a risk assessment should suffice and as the consequences of a broken axle shaft are not dangerous then the engineer will accept them as suitable.

As there now seems to be no show stopping engineering issues its now full steam ahead.

So now for the decisions. After speaking to Jeep Australia I will now be purchasing all the items from Burnsville Offroad as Jeep Australia cant reduce there pricing enough to get it even remotely close to make it worth while to get them locally. To give you all an idea the transmission is $2700USD compared to $6000AUD.

I am now speaking to Jeep Konection seriously regarding the axles and have a few options to choose from. I had previously spoken to a few other Australian venders but with the exception of Solid Axles no one had come up with a complete package that they could offer. If there are any other venders out there that can offer a complete axle package then please PM me or if anyone has any suggestions then please advise. I want to use as many Aus suppliers as possible as I strongly believe in supporting the Aus Jeep community.

[kitrino_tj]

good luck with the build, this will be one of the better JK's in the country

[STEEDS]

Good luck with the build - This is something I have seriously considered myself so it will be good to see how things go!

+1 would love to see this in the flesh when its all done.

[CRDSTU]

Hi there Glen,

Your build sounds awesome, the stuff JK dreams are made of! I just wanted to inform you of a few ongoing issues my best mates 7lt JK has had since he started the build.

1. Broke New Atlas 4 Speed in 2 - it cannot handle the torque of the 7lt and wouldnt really cope with a 6.1lt given the big tyres, ratios and huge extra vehicle weight.
2. 2 Broken (throw away) NEW 545RFE Trannys. They cant handle the torque of the 6.1's or 7lts again with all the extra diff work, extra ratio's and vehicle weight.

This seems to be the achilies heel of the conversion process. The 5.7's dont have an issue and dont seem to cook transmissions unless your "Duning" on sand for prolonged periods of time and a heavy right foot.

From what I can gather and hypothesise on is the W5A580 Merc Tranny found behind the WH CRD's and WH SRT8's is what needs to be included in the equasion. They are designed as an Merc High Performance AMG box - rated my Mercedes to 788Nm of Torque. I've never seen or heard of anyone doing it but that doesnt mean it cant be done.

I'm really interested in seeing how you go. The transmission issue is the big one.

Good luck!

[damage_man98]

CRDSTU, Thanks for the info. I really appreciate it

What did your mate end up changing to. I assume a Atlas 2 for the transfer case but what about the transmission?

I've spoken to Dan McKeag from Burnsville offroad about this and he offered a Heavy Duty 545RFE transmission. To be honest I don't know exactly whats been upgraded in this transmission but its sounded good when he talked about it and at half the price of the transmission from Jeep Australia its worth a shot. The other part of the need to use this transmission is for it to work with the MDS in the 6.4 hemi allowing it to drop down to 4 cylinders when I'm being nice to it.

I know quite some time ago AEV were talking about doing the W5A580 transmission for there 6.1 conversions and last I read it was due to be released in January this year which hasn't happened. I believe its not a simple install and requires a new housing to be built for the transmission or part of it. If you search through all the posts on AEV's forum you may find it.


Glenn

[CRDSTU]

Originally Posted by damage_man98

CRDSTU, Thanks for the info. I really appreciate it

What did your mate end up changing to. I assume a Atlas 2 for the transfer case but what about the transmission?

I've spoken to Dan McKeag from Burnsville offroad about this and he offered a Heavy Duty 545RFE transmission. To be honest I don't know exactly whats been upgraded in this transmission but its sounded good when he talked about it and at half the price of the transmission from Jeep Australia its worth a shot. The other part of the need to use this transmission is for it to work with the MDS in the 6.4 hemi allowing it to drop down to 4 cylinders when I'm being nice to it.

I know quite some time ago AEV were talking about doing the W5A580 transmission for there 6.1 conversions and last I read it was due to be released in January this year which hasn't happened. I believe its not a simple install and requires a new housing to be built for the transmission or part of it. If you search through all the posts on AEV's forum you may find it.


Glenn

Hi Glen, no probs. I'm not sure how much info I should lead on here but my mate is also speaking with Dan and his off sider at the moment trying to come up with a solution. The simple fact is the 545RFE isnt strong enough to handle the constant torque being put through it with that kind of weight to push. 2 Auto Tranny specialists have looked at the cooked boxes and said they never would have handled the power or weight in the 1st place and shouldnt have been used.....why do you thing BOR / AEV are looking at the W5A580 box now? Because action needs to be taken to clear their name!!

Same with the Atlas people, they put their hands up and said - sorry, cant help you there with that weight and power, the 2 speed is the only box for the job........so he was given a replacement 2 speed.

Just going back on that box issue, my mate was also told that the replacment (2nd ) box coming out to him was a you beaut super duper drag spec box. I drove the car numerous times with box boxes. The 1st one was a brand spanker stock 545RFE, lasted 2000klm of moderate driving (engine was still being run in). Cooked. 2nd "Built" box lasted 1800klms although it drove way better. Stronger more pronounced shifts and didnt feel 'slushy' like the stock one (1st one). Pity it fried itself too.
I was riding shotgun in the car when both boxes let go. Both on the freeway just cruising at 95-100ish, went to kick down to overtake and she just free revved like someone had knocked the gearstick into Neutral by acciedent. Bad smell of burnt ceramics occured at the same time. ATF smells like burnt electrical circuitry when overcooked.

I reckon a Manual box would be the only hassle free fix.