T5 box (split topic)

[aps]

  Turbo6man said:

  aps said:

This gearbox I feel is perfectly suited to the xr6t and in my opinion there's no need to change final drive ratio as we spend 95% of time at speeds between 40 to 120KPH. For those who want to change the final drive ratio that's fine and the 3.23 to1 is freely available.

You may well be right - most people would probably accept that proposition. However I'm a greedy bugger who likes to have his cake and eat it too.

I am referring to performance AND economy and the balance between the two.

My contention is that the gearing should suit three basic parameters - the purpose of use, the weight of the vehicle, and the torque characteristics of the engine.

If you take the first and final drive ratios of the Supra box this is the analysis. (For brevity I will ignore the intermediate ratios, for as long as they are not too stupidly spread, they will bear little consequence to my argument).

With the standard final drive of 3.45 first gear yields 9.2 km/1000 rpm. This gives a first gear maximum speed of 55 kph @ 6000 rpm. I'd suggest this is way too low for normal everyday driving. It may be OK for constant dragging or for constant heavy load towing.

Also, using standard final drive top gear yields 41.7 kph/1000 rpm. At 110 kph the engine is turning over at 2650 rpm.

Compare these results to the standard T5. It yields 69 kph @ 6000 rpm in first and 2350 rpm at 110 kph cruise speed.

My opinion is that the car doesn't need such a low first gear as the Supra box provides - the first gear acceleration with the T5 seems quite adequate. I haven't heard anyone complain about it in any way. There is no talk of it bogging down off the line such as was the common complaint with, say, 70s models 351 Clevelands running single rails and top loaders with tall diff ratios. Also the extra 300 rpm on the motor in fifth gear, if you were travelling from say Sydney to Melbourne, would cause an increase in fuel consumption in the order of 10% to 15%. This is relevant to me as I do mostly long distance driving. It may not be so important to someone who drives mostly in the urban areas at limits less than 90 kph.

Well if you want to have your cake and eat it too, then the supra 6 speed box combined with 3.23 to 1 final drive ratio would provide the best of both worlds, that is a bullet proof trans with magnificent gear shift quality and a good spread of ratios for around town and country driving. :o

This trans simply offers an additional option for owners who are planning on serious levels of torqe and want to use the vehicle in a spirited manner on the race or drag track, and would be an excellent trans under all road conditions.

Peter

APS :o :o

[Turbo6man]

aps> who supplies the 3.23 diff gears please? I'm pretty sure the diff is the same Dana/Spicer in the T6 as is in my T3. And I would like to change my diff ratio, even to somewhere around 3.00:1 would be ideal for the box I'd like to fit in place of the TR3650. Also do you have a ball-park figure on cost?

[aps]

  Turbo6man said:

aps> who supplies the 3.23 diff gears please? I'm pretty sure the diff is the same Dana/Spicer in the T6 as is in my T3. And I would like to change my diff ratio, even to somewhere around 3.00:1 would be ideal for the box I'd like to fit in place of the TR3650. Also do you have a ball-park figure on cost?

These ratios can be purchased through ford spare parts, not sure on the price.

Peter

APS

[aps]

  Turbo6man said:

  aps said:

This gearbox is mighty tough and the shift quality is superb and I know plenty of guys in the states who drag race and run MEGA torque (900+ Nm ) through this trans frequently and the trans is incredibly reliable and cops plenty of punishment without complaint. These TT supra's run low 10's/ high 9's week in week out without problem and they are a very heavy car.

The TT supra gearbox is simply world class (and maybe out of reach of some ford owners in terms of cost) and would be an ideal gearbox  to transmit high torque and to cope with the porky weight of the BA ford. Do you know how heavy the TT Supra is?

I dont understand your comment regarding the windsor's torque and how this is relevant to this discussion, that is coping with high torque levels from the xr6t engine.

I don't doubt that this box has the runs on the board as you attest.

However, the absolute figures you quote are far and away in excess of the manufacturers ratings. I'm just wondering if there is anything "hidden" behind these figures. For example, torque delivered through a gearbox to a heavy vehicle places much more strain on it. So what is the weight rating of the gearbox at it's 490NM? Maybe the 900NM car is only 900kg in weight? Don't get me wrong, I am not questioning YOUR experience or claims, just stating the things I would have to consider in order to make a value judgement when choosing a box to suit my needs.

No I don't know the weight of a Supra, what is it? I'll stick my neck out and say that I'd be very surprised if it went over 1600kg. (My T3 is 1940kg before I even get on board.)

My comment on the Windsor's torque was obviously misunderstood. I was referring to the torque characteriscs of the engine, not the amount of torque produced in absolute terms. My motor produces 80% of its maximum torque through the entire rev range ie. from idle to 6000 rpm. It has 400NM at idle. This means that a close ratio gearbox is unnecessary - I can call up plenty of oomph at any time in any gear. Within reason of course. I'm not saying it will pull a final drive ratio of 1:1.

The T6 engine has a similar broad band of torque. Therefore my contention is that they would require a similar gearset.

This is my point, the TT supra is a very heavy car from memory they weigh in at just over 1750KG.

When you see the times these cars run in the US (frequently in the low 10's) you will be amazed at the strength of the entire drivetrain given the power and torqe generated and the vehicle weight.

The TT supra is one of the very few cars out of Japan that continues to impress me, and the 6 speed trans is a work of engineering art, if you get a chance have a peep inside life wont be the same after that.

Peter

APS

[Turbo6man]

Peter, OK so I'm very surprised :lol: I sure wouldn't have picked a Supra to go 1750kg.

[aps]

  Turbo6man said:

Peter, OK so I'm very surprised :lol: I sure wouldn't have picked a Supra to go 1750kg.

They are very heavy, I am O/S this week I will get out the corner weights and get an exact street and race weight for you.

Peter

APS

[sixfan]

OK.

This all sounds good. What sort of $$ are you talking about?

will the Prop shaft need to be modified?

where is the speed sensor on the xr6T

and how will a new box affect the Speed limiter?

[aps]

  sixfan said:

OK.

This all sounds good. What sort of $$ are you talking about?

will the Prop shaft need to be modified?

where is the speed sensor on the xr6T

and how will a new box affect the Speed limiter?

Sixfan, I dont have the answers to all of your questions as we have planned to build a one off test vehicle for evaluation and to suit my new big grunter engine.

1) price, currently dont know though one is going in my xr6t regardless of the cost.

2) Most likely as we need to cope with over 1000Nm of torque.

3) speed sensors, at the wheels.

40 Not sore yet though I am about to find out.

Sorry I dont have all of the answers now as its impossible to know before the work is completed.

Peter

APS

[Cypher]

Supra weight is 1490 - 1590kg depending on year and specs.

Specs on the V160/161 at:

http://www.mkiv.com/techarticles/getrag/sp...pecs/index.html

I have also attached a spreadsheet that you can play with (found at www.mkiv.com). Allows you to play with tyre and diff size and calcs the expected engine rpm in each gear at certain mph.

The lightest I have ever seen a supra is around the 1,300kg mark.

Has anyone considered the toyota R154 or W58 box??

getrag_233_ratio_info.zip

Edited 07/02/04 09:59 AM by Cypher

[sixfan]

  aps said:

  sixfan said:

OK.

This all sounds good. What sort of $$ are you talking about?

will the Prop shaft need to be modified?

where is the speed sensor on the xr6T

and how will a new box affect the Speed limiter?

Sixfan, I dont have the answers to all of your questions as we have planned to build a one off test vehicle for evaluation and to suit my new big grunter engine.

1) price, currently dont know though one is going in my xr6t regardless of the cost.

2) Most likely as we need to cope with over 1000Nm of torque.

3) speed sensors, at the wheels.

40 Not sore yet though I am about to find out.

Sorry I dont have all of the answers now as its impossible to know before the work is completed.

Peter

APS

Hey,

thanks for your prompt reply, I'm interested.

I'll leave the technical arguments up to those who know more than me, but I'm watching with keen interest. NT would be a good place to test such a box...Need a car up here??