TKO500 gearboxes?

[amulheirn]

Just wondered what opinions/experience there is out there of the TKO500 in a Hawk 289?

I had planned to get a T5z from Modern Driveline in the US, but when you add VAT at 20%, import duty at 8% and approximately 500 dollars shipping, it made me think again.

So I rang Repower Roadcraft (http://www.roadcraftuk.co.uk) and spoke to Brian (I think his name was). He seemed to know Gerry's cars and had quite a few customers who have put TKO500 in them. He gave me the following bits of info:

- I'll need a different bellhousing to the one I have (T5)
- TKO500 is a lot stronger - you'd choose this over a T5z if you have the space every time. There's enough space in a Hawk.
- There's an aluminium lug on the TKO500 casing which will foul on a cross-member. It can safely be ground down to fit.
- the overdrive ratio is 0.68

I get the impression they don't modify them to order like MD would, so my questions to the forum are:

1. What considerations should I bear in mind fitting this box?
2. Is 0.68 an OK ratio? (I have a standard MGB tube-type rear axle)

Any thoughts would be most appreciated...

Andrew

[JohnO]

Andrew and I have been discussing gearboxes. Sorry, I've just checked and the import duty on a gearbox is actually 4.5% - my fault telling Andrew it was 8%. Still expensive when you add shipping, VAT and maybe some agents handing charges in UK.

Like Andrew I'm looking for a gearbox, but I'm using a Jag rear axle. We did think of sharing a delivery to get the shipping costs down, but still looking quite expensive. I've even looked at putting one in a suitcase, but BA just won't let me carry more than 32Kg in a single bag - and the gearbox is slightly over 34Kg.

On a slightly related topic, if anyone is interested, I've put together a spreadsheet for gear rations (box and rear axle), wheels/tyres to work out which ratios give which speeds. Feel free to download this and have a play. Also, let me know if I've made any mistakes. https://dl.dropboxusercontent.com/u/288 ... tyres.xlsx

John O.

[StewbieC]

I was under the impression that tko's were too big to fit in the Hawk and I've never known one be fitted. Not saying I'm right for 1 second.
The 0.68 final drive is what I have in my t5 with no problems. I have an MG rear axle with standard diff.

There's a lug that needs to be ground off on the t5 too.

I got my T5, bell housing and clutch bits from real steel and if you take out the gold card you get a discount.

It's up to you guys and it's your dosh.

[amulheirn]

I was under the impression that tko's were too big to fit in the Hawk and I've never known one be fitted. Not saying I'm right for 1 second.
The 0.68 final drive is what I have in my t5 with no problems. I have an MG rear axle with standard diff.

There's a lug that needs to be ground off on the t5 too.

I got my T5, bell housing and clutch bits from real steel and if you take out the gold card you get a discount.

It's up to you guys and it's your dosh.

Thanks Stu - I think Real Steel don't do Tremec gearboxes any more. Will give Gerry a ring and see what he says, but that's good to know about the 0.68 OD.

[andyg]

Hi Guys
I am running the Tremec 3550 TKO II which I think was the predecessor o the 500/600. With the 600 being closer to mine I believe.
I did have to grind off a flange just above the chassis cross member but also needed a spacer of about 1". The space is drilled and tapped to bolt to the chassis mounting point and has clearance holes in it to allow it to be bolted to the box. I think I still have the drawings for it somewhere along with some photos if you want them - and I can remember how to upload them!
My ratios are a cross between the two new boxes as I have the 500 ones for 1st, 2nd, 3rd 4th, (3.27 ,1.97, 1.34, 1.00 respectively) but the ratio of the 600 for 5th (.82).
I am running the Jag back end with a 3.54 final drive - great combination in my opinion.
Andy

[Roger King]

0.68 is a very long overdriven top. I prefer the 0.73 option as it allows a closer gearset, i.e. a nicer rear axle ratio. My Mustang runs the same rolling radius wheels as the Hawk, and I switched that from a 0.68 OD T5z with a 3.50 axle ratio to a 0.73 OD T5z with a 3.25 ratio. This gave me pretty much the same cruising ability on revs, but with the gears much more evenly spaced. With the 3.5 I kept wanting to change up out of 4th, but going into 5th with the 0.68 made the motor fall right off the cam. It's much nicer now. The Mustang's 393 stroker gives over 450lbsft and the T5 has coped fine, currently on 25k miles.
The TKO boxes are much bigger but will take more torque. Having said that, the T5z will take a lot to break - even drag racers use them with little problem.
If you have a MG differential and axle, this will break long before your T5 does.