A2 Sport TDI 90 Engine Refresh (SMF)

audifan

A2OC Donor
We all know the 1.4 was the 1.9 less a cylinder. Unless the three cranks are 120 degrees apart they will vibrate. That is why the special flywheels and balancer shafts were fitted by Audi To further smooth out the 90 the DMF was introduced. Now I for one can not say for sure that the 90 will operate smoothly or how long on a SMF. Later 4 pot diesels from Audi also have DMF so they must have proved it the way to go. PERHAPS a SMF fitted to a 90 that is then fully balanced by machining the flywheel may be the ultimate answer. But until then you are really in uncharted or long term unproven territory when it comes to fitting a SMF to a 90. But if people never tried to find a solution to A2 issues those issues could end the A2s in question.
 

Weetank2

Member
The old flywheel removed is probably from an AMF so preferable to that supplied now
Part numbers would confirm origin

Friction plates also appear to have differing springs ratings
 
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audifan

A2OC Donor
Agree if I was going to go the SMF route then AMF (BHC) parts are the way I would go. With perhaps an uprated friction plate, although the remapped cars still appear to be running fine on standard AMF clutches. In the end it is a gamble that hopefully turns into a win.
 

depronman

A2OC Donor
It depends which engine the smf that you removed was intended for
If it was made for the 1.4 3 pot then it would not vibrate but if made for the 4 pot 1.9/2.0 then I would fully expect it to vibrate
The long term affect of the vibration are obviously bad for the engine gearbox and the rest of the A2

The reason the 90 as a dmf and for that matter the rest of the higher powered diesels in the vag range and other manufactures ranges is to protect the gearbox
The modern tdi’s have the ability to generate massive amounts of torque at very low revs unlike petrols which develop the torque at high revs
This presents a great challenge for the gearbox as massive loads are but on shafts in the gearbox if there is any slack in the gear chain
Think about a car at rest, when you engage a hear and let the clutch out there is likely to be gaps between the gears, so the input shaft starts to turn and gets all the torque dumped into it, this is then transmitted to the first gear which then bashes Into its mating gear causing a shock wave. Once the gap is taken up the process repeats onto the next gear then repeats to the diff and then the drive shafts. Each time the shock wave increases.
So if you get a boy races revs the engine to 3000 rpm and drops the clutch very quickly the gearbox/diff/ drive shaft take one hell of a bounding If you keep doing this something will eventually shear

The dmf was developed to provide a cushion between the engine and gearbox to dampen the torque application. One the slack is taken up in the drive train the gearbox is much better able to handle the torque being applied to it because once all gears are in contact with the next gear there is no shock wave as teeth meet teeth

Try driving down the road at 30 mph on level ground then come off throttle and then after about a second hit the throttle hard then come off throttle Repeat this a few times and the car will kangaroo. The dmf is designed to reduce greatly this affect

If you don’t abuse the revs and clutch then a single mass flywheel can be fitted without issues
Some car manufactures have stopped fitting dmf (due to excessive wear) and replaced them with a software mod into the ecu to reduce fuel and hence reduce torque until the clutch is engaged fully and the backlash is taken up in the drive train. A rather elegant solution in my opinion

Paul


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depronman

A2OC Donor
A remapped tdi 75 is normally an increase of around 45 Nm which adds additional strain on to the clutch and no doubt reduces its like some what but it’s a well designed clutch with lots of spare capacity so we get away with it
It may not last 300k miles with a remap but say only last 200k miles So what. It still is better than most cars
If you map the tdi past 250 Nm then you are beyond the rating for the gearbox, it will likely be ok for a time but you will reduce its life especially if you abuse it

Drive the car, even a heavily remapped car, sympathetically and you can drive it hard without issues, but abuse it and you will shorten the life of the gearbox / drivetrain.
A dmf adds some insurance for the gearbox and driveshafts against abuse, but in the end the dmf as a life of around 80k to 120k so can be seen a sacrificial part to protect the gearbox/diff/ drive shafts

Units of measures edit to correct from lb ft to Nm. (Thank Robin)
Cheers.
Paul


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Weetank2

Member
I would be more concerned with oil pump chain stress / failure with the vibration

Looks like you have a known workable flywheel already
A LUK clutch for an AMF is buttons when you cost your time
 

depronman

A2OC Donor
I would be more concerned with oil pump chain stress / failure with the vibration

Looks like you have a known workable flywheel already
A LUK clutch for an AMF is buttons when you cost your time
Could not agree more.
Re use the smf you already have and fit a LUK clutch kit including a new cross arm and pivot bolt and a new top hat on the gearbox.
At least you know it didn’t vibrate before and will not if refitted

Paul


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Joycey

Member
What is wrong with the flywheel that you removed ?


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I don't know the age of this flywheel and it has a little bit of surface roughness. I'll swap the complete assembly over and be done with it. If I get any unwanted vibrations I'll swap back to a normal flywheel.
 

dj_efk

A2OC Donor
I have to say that I have enjoyed reading this thread, found myself nodding in agreement in a few places. But, at the end I thought.... I haven't got a fecking clue what anyone just talked about 😊
I agree, I’m waiting hopefully for someone to put together a sticky “how to” post with all the bits needed once it’s proven to work, which I think it has if I read correctly.
 

Robin_Cox

Member
If you map the tdi past 250lb ft ..
[/QUOTE]

It is necessary to be careful about the units - the gearbox family name contains number ratings of the two gearbox families used in typical transverse VAG Tdi applications - in Nm, not lb ft.

MQ250 - manual, 250Nm rating. Ie O2J (1.4Tdi box) and derivatives
MQ350 - manual, 350Nm rating (1.9/2.0Tdi box and more potent petrol engines)

Obviously there will be some capacity in that to go beyond those figures, but with a 36% difference between the two units numerically, 250lbft is around 340Nm which might be pushing the 250Nm-rated box a bit.
 

depronman

A2OC Donor
If you map the tdi past 250lb ft ..
It is necessary to be careful about the units - the gearbox family name contains number ratings of the two gearbox families used in typical transverse VAG Tdi applications - in Nm, not lb ft.

MQ250 - manual, 250Nm rating. Ie O2J (1.4Tdi box) and derivatives
MQ350 - manual, 350Nm rating (1.9/2.0Tdi box and more potent petrol engines)

Obviously there will be some capacity in that to go beyond those figures, but with a 36% difference between the two units numerically, 250lbft is around 340Nm which might be pushing the 250Nm-rated box a bit.[/QUOTE]

Good point Robin. I need to double check as it’s some years since I last looked at this and I remember the numbers for the remapped engine getting close to the gearbox limits so I think the numbers are correct and I had stated lb ft instead of Nm. It makes sense as my would a metric car use imperial unit of measure

Paul


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depronman

A2OC Donor
It is necessary to be careful about the units - the gearbox family name contains number ratings of the two gearbox families used in typical transverse VAG Tdi applications - in Nm, not lb ft.

MQ250 - manual, 250Nm rating. Ie O2J (1.4Tdi box) and derivatives
MQ350 - manual, 350Nm rating (1.9/2.0Tdi box and more potent petrol engines)

Obviously there will be some capacity in that to go beyond those figures, but with a 36% difference between the two units numerically, 250lbft is around 340Nm which might be pushing the 250Nm-rated box a bit.
Good point Robin. I need to double check as it’s some years since I last looked at this and I remember the numbers for the remapped engine getting close to the gearbox limits so I think the numbers are correct and I had stated lb ft instead of Nm. It makes sense as my would a metric car use imperial unit of measure

Paul


Sent from my iPhone using Tapatalk[/QUOTE]

I was indeed correct with the numbers was wrong with the U of M. The figures are Nm
A remapped 75 bhp or 55kw tdi commonly known as the tdi 75 is 195Nm std and a remap takes this to around 240Nm. The gearbox is rated to 250Nm

Figures for the tdi 90 will be higher pre and post remap

Cheers. Paul


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Joycey

Member
So today went well. I followed up on some people’s points and advise. First thing I looked at was the old flywheel, I can confirm it’s from an AMF engine the part number on the back confirmed this.
C7205EA6-0395-4DA3-8799-AFCA42667FC5.jpeg

it’s also worth nothing there was an additional spacer between the gearbox and engine so this was removed.
94AEA61D-7929-44CD-86A5-E73E5B2759DD.jpeg

0EBE557C-9827-4781-8137-37F27E11E4EB.jpeg

I took some photos showing the flywheel fitment.
5432B09D-4B20-4683-951D-5A14D03CED39.jpeg

705EB09C-EFEB-4DBB-A22D-8CB619054590.jpeg

then the assembly all together.
F6F64D38-D6B2-493D-A386-D00BD0F8AE96.jpeg

I can safely say this is the most awkward gearbox I’ve ever fitted. The back of the gearbox clashes on the subframe along with the near side output flange catching on a gearbox dowel. It was all about the funny angles to get things in.

This is the old clutch n flywheel, looks huge in comparison. This SMF has defiantly been on my A2 for a long time, I could spin all the springs in the clutch disc by hand.
362A5675-3442-41F5-BFEA-31224E2BD986.jpeg

I got to first start today and all seems well, no excessive vibrations or shaking. I did a little video for you guys.


Now it get interesting, not sure if somethings up with my linkage system. I followed a setup procedure locking the gearstick and the gearbox end with the L shape pin but only one of my lines has a spring retainer, makes 2nd gear not achievable. I’ll need to do some digging unless any of you guys spot anything obvious, next photo is a close up with the selector nut already removed.

4D56D05D-77B5-4996-90D0-5B084E9CAEA6.jpeg

I also fitted a new starter as my old one was starting to stick.
F7A19FAC-B11E-4C9C-99EC-1377DD69D34F.jpeg
EGR bypass in and looking stock, Paul you got the head 180* out so I removed the vacuum line and blanked it instead
9C0441C4-E793-4EC5-905D-ED0434038D45.jpeg

Productive afternoon in all. Only have a few bits left to fit, various bits of trim and both shafts. I tested operation of the clutch and it feels fine both flanges spun up, couldn’t go too mad or the ABS system would have a melt down.
 
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nod

Member
So today went well. I followed up on some people’s points and advise. First thing I looked at was the old flywheel, I can confirm it’s from an AMF engine the part number on the back confirmed this.
View attachment 74924
it’s also worth nothing there was an additional spacer between the gearbox and engine so this was removed.
View attachment 74925
View attachment 74926
I took some photos showing the flywheel fitment.
View attachment 74927
View attachment 74928
then the assembly all together.
View attachment 74929
I can safely say this is the most awkward gearbox I’ve ever fitted. The back of the gearbox clashes on the subframe along with the near side output flange catching on a gearbox dowel. It was all about the funny angles to get things in.

This is the old clutch n flywheel, looks huge in comparison. This SMF has defiantly been on my A2 for a long time, I could spin all the springs in the clutch disc by hand.
View attachment 74930
I got to first start today and all seems well, no excessive vibrations or shaking. I did a little video for you guys.


Now it get interesting, not sure if somethings up with my linkage system. I followed a setup procedure locking the gearstick and the gearbox end with the L shape pin but only one of my lines has a spring retainer, makes 2nd gear not achievable. I’ll need to do some digging unless any of you guys spot anything obvious, next photo is a close up with the selector nut already removed.

View attachment 74931
I also fitted a new starter as my old one was starting to stick.
View attachment 74932EGR bypass in and looking stock, Paul you got the head 180* out so I removed the vacuum line and blanked it instead
View attachment 74933
Productive afternoon in all. Only have a few bits left to fit, various bits of trim and both shafts. I tested operation of the clutch and it feels fine both flanges spun up, couldn’t go too mad or the ABS system would have a melt down.

I’ll go get a cuppa I’m expecting a few questions this evening.
All the A2 gearboxes I've adjusted have 2 spring connectors, one for each cable. has someone welded the end of one of your cables to a connector?
 

Joycey

Member
All the A2 gearboxes I've adjusted have 2 spring connectors, one for each cable. has someone welded the end of one of your cables to a connector?
Very possible. It looks like it’s been played with. This might cause me a headache I think.
 
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Joycey

Member
Today was test drive day. Got the rest of the covers and various drainage trays back in.

First things I noticed on first start was how much quieter the engine was, no more clattering at idle. Also the clutch pedal feels so much lighter. Being sat in the car at idle you can feel a little bit more vibration in your bum, nothing that causes anything to rattle but just enough to notice, I’m on original engine mounts they are very soft so this could be sorted.

Bite point is nice and crisp with no snagging or chattering, I took the A2 for a little drive to warm up and did a couple of runs with no excessive vibrations at all, you could hear a different frequency from the engine at high speeds, I’m assuming this is the lighter flywheel or possibly the mapped out EGR bypass I’ve now got.

The gear alignment was a right pain because someone in the pass bonded the fitting on the end.
048DA87B-8DDB-4564-9BD2-539858F8A5BA.jpeg


I’ll give it a few months and report back if anything goes amiss. Happy to be the guinea pig :)

Single Mass fly on a 90 now in test.
 
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spike

Well-Known Member
The cut-out on the rim on the back of a standard AMF flywheel probably equates to half a kilo of metal. Just imagine the effect of that weight related to balance weights on a car wheel.
I'm pleased but really surprised the expected engine vibration did not shake the car to bits and you had to revert back to an AMF flywheel.
All I can think is it's changed the torsional characteristics of the crankshaft assembly and this could influence gear chatter in the gearbox and possibly the balancer shaft drive rather than any 'out of balance' vibrations being transmitted to the cabin.

Still have visions of a guinea pig living in a cage on a shaker rig - but I've been proved wrong many times - just ask the wife

Cheers Spike
 
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