RMC Kit - Gearbox Dilemma!

[shelley]

First, I need to disclose I am not the most experienced mechanically... what I know I have picked up after owning a RMC for the last 8 years. I bought a pre-built car in 2006.

Over the years, I have occasionally tracked the car at Eastern Creek but never at the Nationals!

After my last trip to the Easter Creek I have lost 3rd gear as my second gearbox has given up the ghost. I am starting to think that I have a fundamental design flaw with the car.

A few details:

1) Windsor 302
2) Celica 5 Speed Aluminium gearbox connected to
3) Jag transmission

A couple of people have said that the gearbox is not able to cope with the power from the Windsor.

So I have a few questions...

1) Anyone out there with a RMC kit which gearboxes are you using? What do you recommend?
2) I believe if I change gearbox I need to change the configuration i.e. the gearstick position and the way it is mounted?

Any recommendations or experienced would be invaluable...

[elvis]

I had a toploader in my 351 r.mc no problems,I replaced it for a t5 which was ok.I still have my toploader $1200 if anyone is interested

[David Hodgson]

Hi Shelley, welcome aboard. You will find endless info here.
There were some celica/supra boxes that would handle a low horse 302 if treated right, but IMHO you are best to take this opportunity to upgrade.
Just about any box will fit in an RMC. If you have a stock 302 and don't punish it a T5 would work but they are getting a bit long in the tooth second hand.

Tremec do 5 or 6 speed box's with variable shifter mounting positions. You can pick the 6 speeds up second hand out of production cars or any of these from Mal Wood Automotive in QLD. Jump on their web site and have a look.

Most guys are building with the T56 6 speed. I'm not sure why, 5 gears is enough for me.

[dhs.buckley]

The aluminium box wont even put up with a 253 holden, you need to change to a toyota supra steel case box, which will fit in the celica place, but i would swap to a 4 speed toploader if you are going to take it to tracks, or somthing better than the old T5s

[dave295]

A Ford Toploader is a great gearbox, being a bit stronger than a single rail.
A Single rail was used in the XC Falcon Cobra. That's a big heavy car with a 351C.
A single rail was also used in the Ford Cortina with a 250ci engine. This gearbox has a shorter extension housing on it as the car is smaller than a Falcon.
The gear shifter is screwed into the top of the rear of the ext. housing. This may give you a better stick position in your car in relation to your seat.
Plus you can always bend the gearstick with an oxy to suit you and your car.
The Toploader has external linkages which may cause clearance issues with your transmission tunnel during usage and servicing.
A single rail could be sourced from an old XD 250ci etc. fairly cheaply (you'll need another bellhousing to suit the V8).
As a side point I picked up a single rail (sans bellhousing) a week or so ago from the Darwin dump shop for $10.00 a week ago.

A lot of the Cobra's built in the sixties had a V8, a four speed and a Jag rear end.

[DaveW]

HI Shelley,
I have a lot of experience with Toyota 5 speeds.
As dhs.buckley has said, the alloy case Celica box (T50) will not last long with any abuse, very small lay shaft and gears.
With the Steel cases, there are 2, W50 and P50, of these the P50 can handle mammoth torque, it has huge shafts, Gearset and syncros, but the bearings are fairly low rated, fortunately, they are all standard spec bearing sizes and can easily be swapped for much higher rated options in the same size, I regularly swapped out for TSK, SKF products then fitted to modified 302's 308's 351's etc with reasonable HP.
The P50 box was also used in the Dyna trucks, hence the upgraded load ratings.
It is also the exact same box as the Dyna P40, but with 5th gear.

However, if you are going to swap boxes to get to this reliability, you might as well swap to a box designed from the outset for motor power you have.
Although along with this you will also have to consider clutch slave cylinder or cable pull brackets etc as these will probably have come from Hadfields, Dellow or some other to suit your current mix and match.

cheers
Dave

[stiffy]

Shelley,

As mentioned you need the steel Supra box or visit Mal Wood

For a Tremec.

I have a T3350 in my Cobra and I love it, I also had the Supra 5

Speed in a V8 MGB which was the Tremec equivalent in its day, I suggest

Speaking to Mal so you won't have any gearbox issues in the future.

Stiffy

[750hp]

Welcome to the forum! If you're used to having an overdriven 5th gear, it might be a step backwards to choose a single rail or toploader 4 speed. On the other hand, I f you're happy with how the car feels on the highway in 4th gear, a toploader might be an option.

Your budget might determine your choice. A steel case Toyota box will be a less expensive 5 speed option than a new TKO 500 or TKO 600, but won't be as strong.

[stephen low]

I'd second the suggestion to talk and deal with Mal wood for a complete change over to say a TKO 500 or 600 with an appropriate bellhousing and clutch set up.

Keep it all in one shop and you'll have less hassles when it comes to any issues such as clutch pedal pressure and hydraulic ratios and so forth.

Slo

[shelley]

Just wanted to say a BIG thank you to everyone, fantastic response. I am already talking to Mal and have asked him for his recommendation.

I am keen to keep the gearstick position and minimise the changes required..

Will let you know where I land..

Thanks again.

[Gav]

I agree with the Supra option, they are a stronger box that will handle a 302 no worries.

[boxhead]

As others have said, the alloy case box is the weak one.
You want the steal cased P50 if you have many upgrades on engine.
If a fairly stock 302 then the W50 should also suffice.
From memory a steel case and alloy case are both physically same dimensions outside, so a swap in your case should be faily simple.

I have a steal case I am using on another project, If need be I can put a tape measure over it to see if dimensions are the same.

[shelley]

Originally Posted by shelley

Just wanted to say a BIG thank you to everyone, fantastic response. I am already talking to Mal and have asked him for his recommendation.

I am keen to keep the gearstick position and minimise the changes required..

Will let you know where I land..

Thanks again.

So after discussion with Mal, I am dropping the old gearbox out and sending it up to Mal. He is going to configure a new Tremec 50 which hopefully will fit the same configuration and that will be the last time I blow a gearbox...

Thanks again to everyone for the their help.

I will let you know how the new gearbox goes...

Simon.

[David Hodgson]

Just in time for the nationals!

[Donunder]

Ahhh Simon, Simon --- and so it begins.

Now that you've gone for a good strong gearbox, it won't be long before the little voice starts whispering in your ear that this new box won't even raise a sweat dealing with the stocker 302. Bit of a waste really isn't it having that good box and only that mild 302 driving through it? the voice will say. Then that same little voice will start talking about stout 351s that will suit the Tremec and deserve to be in an old champ like the RMC. And then eight stack systems. And then working side pipes ..... Sorry mate but once you start down this road there ain't no turnin' back.

We're all addicted --- but we love it !!!

[spookypt]

......and then you'll be right back to where you started with the gear box and we'll all be talking Jerico.......

What a disease we all have. Wonderful isn't it!

[shelley]

I know it has been a few months but I thought I would give a final update..

I know have a very nice TKO Tremec (5 speed) in my cobra. It is working well..

Mal Wood did a sensational job and there was no need to change the configuration of the car as the gearbox slotted straight in.

I would like to thank everyone for their advice.. it was a major purchase decision and it really helped..

Now Don has a point that I am now starting to look at other parts of the car :-)

Simon