33 replies to this topic

[Statler]

NOTE: This is NOT the only way to do this. It is merely 1 way.

 

Ok, so you've decided that you want that extra gear. The Borg Warner T-5 is a pretty common option these days. These boxes can be found in almost everything around the world. BMW's, Mercs, Mustangs & even the local Commodore & Falcons.

 

While the gearbox is basically the same for all applications, the input shaft length, bell housing,(both determine how far the box sits from the engine)  gear sets & rear extension housings (determines where the gear shifter sits & speedo drive output)  are different to suit the application.

 

So which gearbox should i buy?

 

Here is where it gets tricky. First you will need a bell housing to fit your engine. The most common option is the Commodore gear box. Besides being plentyfull, they also have the 'turbo' bolt up pattern. Using this box saves mixing/matching clutches & if you already have a V8 with the Turbo bolt pattern it will fit with simple tunnel mods. I will get to that bit.

 

A lot of people are using the local Ford T-5's with aftermarket bellhousings (approx $8-900) which will put the gearshift in the correct position. I believe Dellow & Mal Wood have these 'kits' in stock. Personally i don't understand why anyone would drop $900 on a bell housing instead of $100 on a rear extension but hey ..... it's your money.

 

So here's what i done on a shoe string budget.

 

I picked up this nasty old Commodore T-5. It was hanging off the back of a 304, both of which had been under water. I initially only wanted the fly wheel & b/h bolts but for $60 i wasn't complaining.

 

 

Quick trip to my gearbox guru for a complete rebuild & this is what returned.

 

 

We had to change the input shaft due to wear on the hard facing. Another stock Commodore input shaft was installed. I also sourced a rear extension housing from a XF Ford & had it fitted. It's a straight bolt on. This brought the gearshift about 40mm from the stock position & the speedo drive output is on the drivers side. 

 

The main concern when fitting the T-5 is where the rear of the box ends up. It comes close to hitting on the floor x-member (under the front seat bolts) which is a structural member. Yes you can box this section in with steel plate but it is up to your engineer to pass the mod. By using the XF rear extension there is NO cutting of this x-member, which keeps even the most fussy engineer happy.

 

Here you can see where the rear extension sits. I had to fold down the lip slightly to get the threaded part through. Stupid short throw shifters!

 

 

 

Gearbox up & in. 

 

 

I should also mention that before i could fit the box, i Had to bolt the bell housing & clutch assembly in first. 

 

 

With the box in & bolted up it was time to move on to the the x-member.

A trip to the steel merchants & about $28 later i returned with some 40 x 40 x 4 angle & a meter of 50 x 25 RHS. Little bit of cutting, measuring, cutting, measuring, welding ....... did i say measuring? & a squirt with some black paint & ta da!

 

 

 

Using 40 x 4 angle i put the cross bar as high as i could. The 'drop' in the center worked out to 27mm. Because i am using the XF rear gearbox mount all that was required is a simple mount plate with 1 hole. 

 

Now to fill the hole in the tunnel for the shifter.

Because i knew what seal i was using, i just made up a cover plate from 1.2mm zinc & welded it in. . It took maybe 3hrs from start to finish. I made certain that the console would still fit before welding anything. 

 

 

 

Next was the speedo.

 

The Commodore used an electronic speedo sensor at the gearbox end. I simply unscrewed the electronic bit but kept the mechanical drive parts.

 

Around $80 later & a brand new speedo cable arrived from Autocables. Screwed on 1 end & pushed on the other, the speedo works. You may need to play with the speedo gear to get your speedo reading accurately. 

 

The only other 'modification' i made was a gearshift shaft which is 1" forward. I don't think this is necessary & i will swap it out for a straight shaft next time the console is out.

 

So there it is. Interior back in. 5 forward gears to play with & it didn't break the bank.

 

Happy motoring.

 

[Uncle Chop Chop]

So what engineering is required for your custom x-member? Just common sense?

[Statler]

nice work, have been thinking of doing this,,.

is there no mods to be done to the tunnel for clearance???

No. 

 

 

So what engineering is required for your custom x-member? Just common sense?

I think you are confusing the gearbox x-member with the substructure x-member. 

[Uncle Chop Chop]

So a custom gearbox x-member doesn't need engineering then? I've never needed to find out, which is why I'm asking.

[Statler]

So a custom gearbox x-member doesn't need engineering then? I've never needed to find out, which is why I'm asking.

I guess that depends on the D.O.T in your state but i can't see why. It would probably be inspected at the same time as the rest of the conversion just to make sure that you haven't made it out of old bed frames. 

 

 

What would be the clutch set up, cable?
Does the hydraulic conversion fit with these?

The Commodore bell housing accepts a cable clutch. I used a UC cable (around $80 new & still available) with a modified pedal. The pedal feel is very good compared to the old hydraulic systems or rat traps. 

The pedal hook can be used from the Commodore manual clutch pedal. It is a lot longer than the Torana hook (which is also getting hard to find & expensive) but it's a simple matter of cut & weld the hook on. 

 

There are plenty of guys using the hydraulic throwout bearings in their T5's. 

 

 

Also whas the difference in ford holden and v8 and v6 gearboxes?

Gear sets, input shafts, bell housings & rear extensions. 

[Statler]

That would be preferable because you would have the V8 bell housing & input shaft. 

[purrlx]

This was a budget build of how to do it, not buy heap of new parts from the states, dellow etc.

[Peter UC]

Did you even read the thread? It states that by using the Commodore T5 and then putting the shorter Falcon rear extension on it there is no cutting required and no special parts need to be bought. Of course this only works when you have a turbo pattern engine already.

[Statler]

Yes

 

 

While the gearbox is basically the same for all applications, the input shaft length, bell housing,(both determine how far the box sits from the engine)  gear sets & rear extension housings (determines where the gear shifter sits & speedo drive output)  are different to suit the application.

While the gearbox is basically the same for all applications, the input shaft length, bell housing,(both determine how far the box sits from the engine)  gear sets & rear extension housings (determines where the gear shifter sits & speedo drive output)  are different to suit the application.

[Statler]

If you aren't getting enough pull on the cable, then the pedal hook needs to be higher.

[Antman]

Great Info thanks. Will a VN-VT T5 fit behind a 253?  Does it have to be a VN-VT V8 T5 gearbox?

[yel327]

If you use a later (HJ onwards) 4.2 and get the engine redrilled to TH pattern yes. Costs less than $300 in Sydney region. Or buy an aftermarket bellhousing.

[Antman]

Thanks Yel327,

So just to be clear. 

 

A V8 VN-VT T5 will fit up to a late model 253 by either redrilling to TH or buying the correct bellhousing to suit?  and the V6 T5 gearboxes aren't suitable?

[yel327]

I can’t comment on the V6 one, but the only difference (at the rear of the block) between a 253, 304, 308 or 350 Holden engine after the start of HJ engine production Is how it was drilled and tapped. Either they were drilled (initially) for TH400 or drilled for Aussie 3/4spd and Trimatic. Drilled and tapped for the 6 bolts and drilled for the two different dowels used, all in different locations between the TH pattern and the other pattern. So if a T5 from a VN to VS (not VT as I think these were Getrags) fits an injected TH pattern block it will fit a 4.2 if you redrill it (or find a Bedford 4.2 as these were TH pattern). This may or may not work depending upon what sort of clutch operation you plan to use.

The other option is to find a VK or VL T5 bellhousing, or an aftermarket one from Dellow or CRS. Just sort out your clutch mech first.

Edited by yel327, 18 February 2020 - 06:48 PM.

[76lxhatch]

Regarding the V6 box it has different ratios (wider spread/lower first gear) which isn't a big deal, but also a longer input shaft which needs to be modified/shortened to suit the standard length V8 bell housing.

 

Also watch out for the two different main case bolt patterns if you're mixing and matching bell housings - one is standard Chevy (as in the photos above) which would probably be the easier option with an aftermarket bell housing.

[yel327]

If the input shaft is the same length as a Saginaw you could get away with a HT-HG 253/308 4spd bellhousing if you wanted to run an LH-LX half cable and rat-trap. GMH used the same bellhousing if a T10 was fitted to an A9X.

[Statler]

When i posted this thread it was intended to make this conversion as simple & cheap as possible .

 

Pulling a V6 gearbox apart to swap the input shafts  isn't cheap with both parts & labour . Buying an aftermarket bellhousing would have added almost another grand to the job which also didn't make economical sense to me. 

 

Same with the Mustang box. If the clutch goes bad i can simply buy a new Holden clutch kit instead of a ppppppiece from here & a ppppiece from there. 

 

It has been doing duty for over 3 years now without issue .