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LH 308 manual gearbox options


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#1 _MiddaSamid_

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Posted 19 June 2018 - 11:43 AM

OK, thread number 2..

 

In an effort to make the LH the car of my dreams, I need to select a gearbox that will enable functional road use and occasional track use while remaining reliable. The 4spd manual that was often bolted to the back of the 308 from factory is an obvious option but I understand they aren't the toughest box around. I assume, (but really have no clue) that the m21 bolts to the trimatic pattern 308? please confirm.. can they be strengthened enough to cope with 300hp and the associated driveline abuse that might come from a day at the track without requiring a Bathurst race team wallet..?

 

T5 is another option that seems to get bandied around.. I hear that there are plenty of different T5's around. Which is the best option T5 and how do I identify it? Are there bellhousings around to adapt the T5 to either the turbo or tri 308 patterns? Will the T5 require significant tunnel massaging? I see some T5 installs with new tunnels and I'm not keen on such a mod.

 

What other 4spd options are there? and what bellhousing patterns do they use? or is mating a manual box to a 308 as simple as buying the correct bellhousing.?

 

 

 



#2 Redslur

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Posted 19 June 2018 - 12:14 PM

There are plenty of options.  I guess the first thing I would assess is your budget. The Supra 5spd box is a good strong option and a fitting kit is readily available. The R154 from memory.



#3 _MiddaSamid_

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Posted 19 June 2018 - 01:42 PM

i've read mixed reports on the supra box.. frightens me a bit..

 

I like the idea of a 5 spd tho.. Hopefully I can find some more info on the t5 install.. i'll keep digging in the forum.

 

Cheers



#4 lakeside

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Posted 19 June 2018 - 01:49 PM

There are plenty of options.  I guess the first thing I would assess is your budget. The Supra 5spd box is a good strong option and a fitting kit is readily available. The R154 from memory.



If you can find a R154 as they are are rare but handle 500hp. The Tremec 500 or 600 will hand same power as R154 Supra box but twice the money

#5 _MiddaSamid_

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Posted 19 June 2018 - 01:50 PM

ok, I'm reading about the R154 and it looks ok.. another top tip..

 

How does it go in the LH tunnel? Shifter placement and length?

 

I feel like such a newbie.. sorry



#6 Bigfella237

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Posted 19 June 2018 - 03:08 PM

Start with the basic questions... What type of driving do you do, just around town or long highway miles?

 

What size rear tyres and what diff ratio? Are you looking for acceleration or top speed ... performance or fuel economy?

 

I'd think the difference in price of getting all the bits together between an Aussie 4 speed and a T5 would be more than offset by having an overdrive (and a gearbox that doesn't self-destruct when you breath on the gas pedal). There are quite a few threads here detailing the layout so I won't go through it all again here, just have a read...

 

http://www.gmh-toran...om-a-holden-t5/

http://www.gmh-toran...topic/22957-t5/

http://www.gmh-toran...l-transmission/

http://www.gmh-toran...5-confirmation/

http://www.gmh-toran...d-t5-installed/

http://www.gmh-toran...-t5s-different/

http://www.gmh-toran...5-in-308-hatch/

http://www.gmh-toran...t5-box-into-lx/

http://www.gmh-toran...-gearbox-in-lx/



#7 Bigfella237

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Posted 19 June 2018 - 03:11 PM

Dammit, no bloody edit time...

 

Another big factor I should have mentioned is engineering approval, although if you're running a 9" diff it's not much extra to get a T5 approved at the same time?



#8 _MiddaSamid_

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Posted 19 June 2018 - 09:10 PM

Hey thanks.. I'm slowly getting through the forum T5 posts.. My plan is a 9in.. gearing isn't decided and neither is wheel and tyre.. If I can squeeze 280-300 real world hp out of it and it still be relatively roadable with the occasional track day I'll be happy.

 

It seems bellhousings are available for both Turbo and Tri pattern so this makes choosing an engine block less critical..

 

FYI, not interested in fuel economy..



#9 _Lazarus_

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Posted 20 June 2018 - 06:23 AM

If you're not interested in economy a Top Loader might be a good option.



#10 ozyozyozy

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Posted 20 June 2018 - 08:06 PM

If you want the best of both worlds have to be a 5 speed at min.
What sort of track? Drags or circuit?
Drags are quite hard on a box, launching on a sticking preped track.

#11 _MiddaSamid_

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Posted 20 June 2018 - 10:52 PM

Yeah, I'm after the best of both worlds.. I figure if I'm building a non original car I might as well build it the way I want it..

 

I have a slight conflict with a 5 spd (which I'm sure I'll overcome).. I'm looking for a 308 Torana experience.. I should really be using a 4spd.. What bellhousings are available for a top loader?

 

Track work will be circuits.. not interested in drags., 

 

In reality, all this discussion is to help me buy an engine block and get the powerplant underway.. At this stage I'm thinking a QT trimatic pattern and once purchased it might dictate possible paths to gearboxes.. I think I just have to bite the bullet and commit to a block.



#12 Ice

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Posted 20 June 2018 - 11:03 PM

Have you thought about LS 1,2 or 3 with a 6 speed way more power and fun and prob cheaper in the long run

#13 Lima31

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Posted 20 June 2018 - 11:11 PM

What's the budget?

 

I have a 308 trimatic pattern and a muncie M21, a 4 speed more than capable for what you want.  Rockcrusher M22 and uprated 'M23' gearsets are pretty much bulletproof, would outlast everything else on the car.

 

Check out the reviews on them and the internals, they shift great. You can get them in various ratios too.  Pair one with a gearvendors overdrive in the tail housing and you can auto 1-2 shift to 100 km/hr faster than an auto.


Edited by Lima31, 20 June 2018 - 11:18 PM.


#14 lakeside

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Posted 20 June 2018 - 11:19 PM

Have you thought about LS 1,2 or 3 with a 6 speed way more power and fun and prob cheaper in the long run



I’m dead set sick of looking at those ugly LS engines in everything.

#15 _MiddaSamid_

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Posted 21 June 2018 - 10:45 AM

No LS.. I'm after a period, performance carby set up..

 

Lee, I've thought about buying a previously built engine but I'd rather build my own. Apart from the enjoyment of it, I'd be confident in the build and know exactly what I've got.. Nothing worse than doubting your equipment. No defined budget at this stage but under $4k would be more acceptable than over $4k.. I'll build it myself after the machining and balancing is done.. The unknown for me is head work and cost.. I've typically only built 4 cyl engines from scratch so I expect an engine with 2 heads will cost me twice as much to put a top end on.

 

I'll check out the Muncie M21.. I've heard of them but know nothing..

 

 



#16 _LXT333_

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Posted 21 June 2018 - 09:05 PM

I would LS my Torana in a heartbeat if I had the money to get it done.
Just easy cheap power, drivability and economy.

#17 ozyozyozy

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Posted 21 June 2018 - 09:51 PM

If 308, turbo/chev bolt pattern, far more bellhousing options.
For circuit, dont bother with top loader, shifting action is average at best, super t10 have a much better shift action but do have a max torque capability.

Most 4 speeds will limit how much hp/torque you can make, unless you go to a nascar dog box 4 speed.

Tremec TKO have good strength but dont like shifting above about 6500rpm, it hurts syncros, myself and many others i know have been through this.

Your going to have to deal with the fact, if you want decent power, a gearbox to suit will require tunnel mods.

If your fun/club racing on a circuit in a class, check the regs of that class, alot dont allow more than 5 forward gears i a classic car.

#18 _MiddaSamid_

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Posted 21 June 2018 - 10:38 PM

I'm going to collect my tired worn out trimatic QT tomorrow.. Next step is strip it and see how much money I've wasted..

 

If anyone has a set of A9L rods laying about that they want to part with let me know..

 

Need a flywheel too.. Any recommendations?

 

Head prep and porting can get underway pretty soon after tearing them off.. I'm bayside Melb.. any recommendations for experienced 308 head porting company? I don't want to go crazy on them but know nothing about what is best for the 308.

 

Orger in Bayswater will get the block prep and balancing job unless someone can convince me there is someone better..



#19 myss427

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Posted 22 June 2018 - 10:03 AM

Don't bother with A9L rods, by the time you have them re-sized balanced and rod bolts, you could have bough Scat or eagle rods which are way stronger and lighter.



#20 Rainman

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Posted 23 June 2018 - 12:00 AM

What is the max torque for m21 and the t10 ? Rainman



#21 Ice

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Posted 23 June 2018 - 01:37 AM

Before you start spending money on recon early heads wont be cheap compare a price for some alloy heads probs same price better performance
just sayin

#22 kodulh

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Posted 24 June 2018 - 02:20 PM

I'm going to collect my tired worn out trimatic QT tomorrow.. Next step is strip it and see how much money I've wasted..

 

If anyone has a set of A9L rods laying about that they want to part with let me know..

 

Need a flywheel too.. Any recommendations?

 

Head prep and porting can get underway pretty soon after tearing them off.. I'm bayside Melb.. any recommendations for experienced 308 head porting company? I don't want to go crazy on them but know nothing about what is best for the 308.

 

Orger in Bayswater will get the block prep and balancing job unless someone can convince me there is someone better..

hi Mate,

I can help with A9L rods . pm me..



#23 ozyozyozy

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Posted 24 June 2018 - 02:54 PM

Super t10 is only rated to about 450 flywheel hp, most of those original fit 4 speed boxes are about there.
can handle more depend on driving style.
Its not just the gear strength itself, most of those boxes dont use a bearing between the gears and mainshaft, so under big power they squeeze the oil out and seize.
Most later gearboxes address this issue.

#24 Dr Terry

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Posted 24 June 2018 - 06:25 PM

Gearbox ratings are based on the torque not horsepower.

 

AFAIK there were several varieties of Super T-10s.

 

Some had nickel gears & cast iron separator plates.

 

I seem to remember Dick Johnson & other Ford drivers changed from Top Loaders to Super T-10s in late XC/XD/XE Fords in touring car racing, because they were tougher.

 

Dr Terry



#25 Rainman

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Posted 24 June 2018 - 09:17 PM

Thank you Dr Terry, I do recall hearing the early ones were all aluminium and would twist or break teeth, something like that :). Didn't know they were rated by torque. Will do a bit of reading soon and find out why some people want torque and some horsepower. From what I know torque is required more for pulling. Does changing the diff alter your torque and h/p figures. Thanks ozyozyozy for replying

 

 

 

Rainman






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