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-   -   *Jackanory* Had my car for 4 years (http://shoevomit.com/showthread.php?t=38793)

Enoch Powell 26-04-2018 21:16

Had my car for 4 years
 
Only realised today it has a torque limiter in 1st because otherwise the gearbox is prone to breaking. The oldest Pumas have a quicker 0-60 than mine but were fragile so from Aug 1998 they limited torque below 2500rpm in 1st, which explains why it feels a bit lethargic until you rev it. Apparently Ford were too cheap to find a proper solution like improving the transmission so just took the simple option of working around it in the ECU.

Absolutely FASCINATING I'm sure you'll all agree :yes:

Chuckles 26-04-2018 21:26

Still getting through the MOTs ok?

Enoch Powell 26-04-2018 21:35

It did last year, just needed an indicator bulb. It's due again soon, though I've only done about 1k miles so fingers crossed.

I gather the Fiesta ST has the same torque limits, in fact it's in 2nd gear as well. Tut tut Ford.

Visage 26-04-2018 23:22

So I tied an onion to my belt, which was the style at the time....

Malcolm Tucker 26-04-2018 23:28

:lmao:

Chuckles 27-04-2018 00:07

Has to google :google:

Groot 27-04-2018 09:11

Quote:

Originally Posted by Enoch Powell (Post 1002273)
Only realised today it has a torque limiter in 1st because otherwise the gearbox is prone to breaking. The oldest Pumas have a quicker 0-60 than mine but were fragile so from Aug 1998 they limited torque below 2500rpm in 1st, which explains why it feels a bit lethargic until you rev it. Apparently Ford were too cheap to find a proper solution like improving the transmission so just took the simple option of working around it in the ECU.

Absolutely FASCINATING I'm sure you'll all agree :yes:

Yup, which is why when you transplant the 1.7 into a MK4/5 Fiesta you use a TAPE ECU which gets rid of the torque limiter.

The 'feeling lethargic' until revved isn't the torque limiter - the limiter' only comes into effect at higher RPM where the torque is. It's just a characteristic of the engine; you can feel it come on cam at around 4.5-5krpm. Really enjoyed the Sigma engines cars I've driven - keep them over 5,000 and on top of gear changes and they hustle along quite well.

Enoch Powell 27-04-2018 10:36

Quote:

I recently put a puma engine in my mk4 fiesta with the 1.25 mk4 gear box on it, found it to be really sluggish in first and the beginning of second gear.

did some reading and found that it was due to a torque limiter they have to "protect" the gear box and presumably drive shafts. I located the sensor people were talking about and gave it a test run with it off and then again with it back in, the difference in first is VERY noticeable!
https://passionford.com/forum/ford-p...e-limiter.html

Torque is hobbled with the limiter on. I've read lots of reports like the above - it makes a major difference to how the car drives. Obviously, I am not going to get it removed (or superchipped) because I'd like the gearbox to keep working.

Apparently in the Ford Racing Puma they shotpeened some of the components to make it able to take the extra torque reliably. But the volume model Pumas were just hobbled as it was cheaper.

Groot 27-04-2018 11:46

Stock boxes will take 180lb/ft all day long and have been used in almost every fwd ford since the mid eighties so replacements, upgrades, LSDs, different ratios etc are cheap and plentiful.

Dunno why you're whining about torque being limited in first - it is only limited at the upper reaches of the rev range. The car isn't 'hobbled' - you only use first when pulling away. When pressing on, you just keep it at high revs and keep shifting in the other four gears.

Remember that engine torque gets multiplied as it goes through the 'box.

The ratios on the 1.25 'box are very short as well - it will sit at 30mph in fifth.

Enoch Powell 27-04-2018 12:01

Quote:

Originally Posted by Groot (Post 1002289)
Stock boxes will take 180lb/ft all day long

And yet in the car's development, Ford found gearboxes were breaking, so they took the drastic step of limiting torque below 1500rpm. And in 1998 when too many failures were still occuring, they increased it to 2500rpm. Later they increased it further to 2800rpm.

Quote:

In answer to various questions on the Pumapeople list, a Pumapeople member back in like 1999 offered the following write up:

1) Torque truncation works by taking the crank speed sensor reading and the road speed reading and by doing a comparison in the ECU it calculates when it is in first gear. This does not require all gear ratios to be programmed in. It is simply a comparison table. You may not like the sound of it, but that's how it works :-)

2)As a history, the IB5 started off as the B-4 in 1978 for the 1.0/1.1/1.3 litre Fiestas (max 60HP). The IB-5 program started in 1996, with closed bearings, bearing D with innering, 1st/2nd and 3rd gear double synchronisation, retuning of 4th/5th gear synchronisation, neutral selection springs in the transmission and hydraulic clutch actuation.

3) Failures. When the 1.7 Sigma SE161 project began (Puma to non-Fordies), durability testing discovered three main flaws with the gearbox.

a ) Final drive gear tooth failure
b ) Reverse gear tooth failure
c ) Bearing D failure (I have no idea what this is)

Other failures experienced were 4th gear crashing, and 1st gear jumping out.

At this time there were two final drive ratios under test - 4.27 and 3.82. At 4.27 the teeth broke off the pinion gear. This was then shotpeened to improve the failure rate. This improved it by 20%, but it still failed. Torque truncation was introduced to limit the torque from 157Nm to 135Nm, and 110Nm in reverse gear (as reverse is lower and hence has a higher loading). Someone made a bloody stupid comment on this list about "how does torque limiting protect the car in 2/3/4/5/ gears". Well, if you have ever ridden a bike with more than one gear, you will know that the torque multiplication goes down as the gear ratio goes up, and hence torque truncation only needs to be on 1st/reverse gears.

The production final gear ratio was chosen as 3.82. This could not be shotpeened for manufacturing reasons (gear size). Without torque truncation on the super accelerated life test, there was a 62% failure rate. With torque truncation this became 100% pass rate.
http://www.pumapeople.com/forum/inde...owtopic=101226

Quote:

Dunno why you're whining about torque being limited in first - it is only limited at the upper reaches of the rev range.
Wrong. It's limited at the lower end.

Quote:

Torque limiter

Pumas built before Aug 98, had the Torque Limiter set at 1500 rpm. After that it was changed to 2500 rpm, then 2800rpm from March 2000. (This is one reason the earlier cars have a faster 0-60mph time)
https://www.projectpuma.com/viewtopic.php?t=11165

Quote:

The car isn't 'hobbled' - you only use first when pulling away.
I said torque was hobbled. Without the limiter 0-60 is a second quicker, all in 1st gear. Someone got 0-60 of 8.3 with no limiter. The early factory Pumas do 8.8, the later ones 9.2. You can split hairs whether that's hobbled or not.

Quote:

The ratios on the 1.25 'box are very short as well - it will sit at 30mph in fifth.
The only thing in your post which is correct.

I wonder if you'll acknowledge that you were mistaken. I am thinking... no.

Am I whining? No. The car is still a delight regardless, and nippy, but I didn't realise it could be quite a bit quicker if not for this limitation. I realise the limit is for the car's own good, so I won't be foolish enough to remove it.


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