Hi guys. Just bought my first VW diesel and I have lots of questions. Forgive me for being ignorant, but I figure I gotta start somewhere....So here's what I've got. 1985 Quantum GL 1.6TD with the 5 spd. 260K+ on the chassis, 3100 on a new rebuilt engine, 50K on rebuilt tranny/turbo/injector pump. The car is immaculate for it's age. Really enjoying driving it.
So here's my first question. The previous owner replaced the speedometer when it quit working. Replacement speedo reads about 5mph slow at 70...fairly accurate at low speeds (25). The odometer is about 10 miles short every 100 miles. The OEM 13" wheels have been replaced with 14" with 195/60 R14 tires. I figure this must be the cause of my speedo problem. My question is...Is there any way to make the speedometer accurate without going back to 13" wheels? Can I replace the speedometer cable gear with one that has fewer teeth? This can't an original issue. Any thoughts? Thanks for your help!
You are right on with the Speed o gear. (don't mess with it)
I think your tire size is the culprit. The rim size does not matter to the speedo.
Only the aspect ration of the tire. a 195/60 is a fairly tall tire.
When they wear out hit a tire calculator and find a 195/55 185/XX 175/XX ect. until you find a overall diameter that is the same as what is supposed to be there. the folks at larger tire sales place will assist for free.
I change the ratio of my rally car with different tire combinations.
Welcome to the forum. I haven't done this mod on a VW, but I've had to do it when I changed the tires on my old pickup (Chevy). I would start by removing the speedo cable from the transmission and count the teeth on the gear, then call a VW dealer and see if they can get a gear that has about 10% less teeth on it, since your speedo seems about 10% slow. It may not be available or may not work in the configuration, but it's worth a phone call. Or, you can try different combinations of tires with the smaller profile to them as redsqwrl mentioned as another choice.
Everybody else lists their cars here - but not me.
IIRC there are only 3 020 speedo cable gears and they probably aren't specific enough to dial it in. Here is this http://www.miata.net/garage/tirecalc
that will tell you what is actually going on and what size you can run to get real close. 195/55 r14 should be real close to the actual speedo but may rub the fenders. 185/60 r14 is a stock 14 size that will work fine. It is either 60 or 65 I can't remember .
farmgirl wrote:Hi guys. Just bought my first VW diesel and I have lots of questions. Forgive me for being ignorant, but I figure I gotta start somewhere....So here's what I've got. 1985 Quantum GL 1.6TD with the 5 spd. 260K+ on the chassis, 3100 on a new rebuilt engine, 50K on rebuilt tranny/turbo/injector pump. The car is immaculate for it's age. Really enjoying driving it.
So here's my first question. The previous owner replaced the speedometer when it quit working. Replacement speedo reads about 5mph slow at 70...fairly accurate at low speeds (25). The odometer is about 10 miles short every 100 miles. The OEM 13" wheels have been replaced with 14" with 195/60 R14 tires. I figure this must be the cause of my speedo problem. My question is...Is there any way to make the speedometer accurate without going back to 13" wheels? Can I replace the speedometer cable gear with one that has fewer teeth? This can't an original issue. Any thoughts? Thanks for your help!
It would appear that the compensation is up at the speedo end with an inline insert. I had thought that there were some pairs of cogs to replace.Maybe inside the instrument cluster.
I have to say that my favourite tyres are '175's Better fuel economy, better steering. I use mk3 rims
I don't think that wide tyres even grip better, other than in snow, or mud.
"I'm not here to help... I'm here to Pro-Volke"
Be like meeee...Drive a Quantum TD
...The best work-horse after the cart...
Quantae grow on you...but Rabbits are like roses...
... girls like em ;o)
Only one Darwin, Einstein, Poe and Verne.
That is why if you listen, you will learn:
From the one and only Quantum-man,
Who sees the worms from outside of the can.
7 Quantae in 20 years; 4 dead and 3 TD's still alive [2 wagons & 1 fastback] oh and a GTD )
Thanks for the good info. I went to the miata tire calculator (cool site by the way thanks!) and according to them the tires I have ARE the equivilent of the stock 13" tires. The difference is less than .1%. So...now what??? If the tires aren't the problem, why is my speedo off? Is it possible that the previous owner replaced the speedo with one out of another model? It looks right. Would it make a difference if it was out of a car with an automatic?
A speedo change I would think wouldn't cause the issue, but a transmission change would. Transmissions have different final drive ratio's, which I believe effects the speedo cable speed.
Everybody else lists their cars here - but not me.
quantum man makes a good point. I have sen some mileage counters that trigger a idiot light on some early MK2 VW product. they also provide a point to splice Speedo cables.
follow your speedo cable and make sure the Speed changer person did not install a different cable with one of those idiot light switcher on-er things.
The speedo cable attaches to an adaptor, that is unique to each of the transmision types, ie 4 cylinder, 5 cylinder, auto, manual. So 4 different ones.
However, as the take off on the final drive is directly connected to the output flange, high and low gear ranges make no difference.
The only difference is by tyre size.
Just checked the parts for the syncro and the GL5. One has 14", and the other 13" wheels as standard. Same parts.
So the difference is in the optional adaptor up by the speedo, or in the speedo. The speedo clusters do have different codes on the scales don't they?
Having said that; I'm using the undersized 175 tyres and my cluster is out of a Yankee Jetta, because I wanted a revcounter. Rev counter is accurate and speedo possibly a tad high, but only just. Tyre pressures make a difference.
Over here in the UK theonly MK2 cars with a diesel rev counter were 'some' GTD's
"I'm not here to help... I'm here to Pro-Volke"
Be like meeee...Drive a Quantum TD
...The best work-horse after the cart...
Quantae grow on you...but Rabbits are like roses...
... girls like em ;o)
Only one Darwin, Einstein, Poe and Verne.
That is why if you listen, you will learn:
From the one and only Quantum-man,
Who sees the worms from outside of the can.
7 Quantae in 20 years; 4 dead and 3 TD's still alive [2 wagons & 1 fastback] oh and a GTD )
So I called Tacoma Speedometer and told them my sad story. They told me I needed to find out what the revs per mile are on a stock speedometer for that car. (how do I do that?) They said that printed on the face of most speedometers, usually quite small at the bottom, is a number indicating the revs per mile. He told me most modern cars are set for 1000 or something close. So I looked at the speedo in my car and way at the bottom just below where it says MPH it says "1707". Does anybody have a 5spd Quantum who can tell me what their speedo says??? I finally got hold of the guy I bought the car from and asked him if he kept the old broken speedometer (he changed it out in 98!) and lo and behold he found it in his garage and is mailing it to me. Maybe by comparing it to what I've got it will tell me something. PS The speedo needle doesn't bounce and as far as I know the car has it's original, although rebuilt tranny.
I have an '83 Quantum TD, 5 spd. Looking in my Bentley manual which covers from '82 to '86, there is listed 3 tranny codes for the front wheel drive models. They are: QF, 2W and also 3Z. The 5th gear and final drive ratios are the same in the QF and 2W trannies. The final drive ratio is shown as 4.45:1 and the 5th ratio is shown as 0.54:1 for the foregoing 2 trannies, the QF and 2W. The 3Z tranny has a more aggressive 5th ratio and also the final drive ratio is shown as 4.90:1 and a 5th ratio of 0.64:1.
You might want to find out which code your tranny is. There is quite a bit of difference between the 2 ratio sets.
There was apparently a SYNCRO model which had still different ratios. I've not even seen one, but apparently they exist.
Point being maybe the PO swapped trannys.
Quantum-man probably knows more about these than I, for sure.
I have an '83 Quantum TD, 5 spd. Looking in my Bentley manual which covers from '82 to '86, there is listed 3 tranny codes for the front wheel drive models. They are: QF, 2W and also 3Z. The 5th gear and final drive ratios are the same in the QF and 2W trannies. The final drive ratio is shown as 4.45:1 and the 5th ratio is shown as 0.54:1 for the foregoing 2 trannies, the QF and 2W. The 3Z tranny has a more aggressive 5th ratio and also the final drive ratio is shown as 4.90:1 and a 5th ratio of 0.64:1.
You might want to find out which code your tranny is. There is quite a bit of difference between the 2 ratio sets.
There was apparently a SYNCRO model which had still different ratios. I've not even seen one, but apparently they exist.
Point being maybe the PO swapped trannys.
Quantum-man probably knows more about these than I, for sure.
Nice trannies, but alas those 3 codes are type 093. This means they only fit 5 cylinder engines.
The 1.6TD is 4 cylinder and so requires type 013. The codes in the US will be
2M, 5M. 1.37:1 5TH GEAR and Probably the E series on 1.8 gassers.
2N. 1.46:1 5TH GEAR, I think found on 1.7 gassers
3M, 9Q 1.67:1 5TH GEAR This was gearbox on most 4 cylinder Quantums inc 1.6TD
All final transmissions are equal.
Unlike a gasser, the diesel engine can freely alter mixture for complete combustion, so although the standard g/b looks like the worst of the selection [remember the 1.67 is the gearbox reduction ratio, and not multiplier ] it can simply reduce the amount of fuel burnt per rev for the same workload.. hmm is that clear?
Eg take a cyclist going up a hill, within reason same energy required to go up in 1st or 5th gear.
However I'm sure that the 2M would give the best fuel economy, with a little less care than the standard 3M/9Q
I believe that there are one or two even better ones lurking in the early 4 cylinder Audi stuff.
Or with modification if possible the Audi TDI range
All Quantum Syncros are type 016 which is a modified 093 and so 5 cylinder fitting. The gearig is not like the GL5's and is worse than the TD Germany did do a 4 cylinder Syncro but not exported AFAIK
"I'm not here to help... I'm here to Pro-Volke"
Be like meeee...Drive a Quantum TD
...The best work-horse after the cart...
Quantae grow on you...but Rabbits are like roses...
... girls like em ;o)
Only one Darwin, Einstein, Poe and Verne.
That is why if you listen, you will learn:
From the one and only Quantum-man,
Who sees the worms from outside of the can.
7 Quantae in 20 years; 4 dead and 3 TD's still alive [2 wagons & 1 fastback] oh and a GTD )
I received the old speedo in the mail today. On the face it is marked "1575" as opposed to "1707" on the replacement one in the car. This difference in revs per mile is what's causing the problem. So the guys at the speedo shop are saying I'm better off fixing the original speedo rather than trying to modify the replacement,providing it is repairable. Can anybody recommend a good speedometer shop that you have done business with?
)
] it can simply reduce the amount of fuel burnt per rev for the same workload.. hmm is that clear?