live4theking
Old Man with a Hat
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I'm running Cooper Cobras on my 68 NYer. I've got almost 10k on them with no problems.
Can someone tell the name of those rims?
- Thread starter Matze
- Start date
Thanks for that sum up. It really helps. I will measure and, if possible, go with 225/70R15
thought about whitewall to, but would prefer white letter. Decision is not final, yet
Hi Carsten,
are you also German? Sounded like it because of the terminology. I know about the bureaucracy, but was hoping to save the additional money for the speedometer adjustment and the paperwork.
I guess, I have to find out what's what with the tires and if they actually fit the current speedometer display or if I can just switch without changing anything.
They put 265/65R15 into the papers in the initial full inspection from the first registration (Vollabnahme). I still think, it's just a typo or the car came with wrong tires and they missed the mistake.
fc7_plumcrazy
Old Man with a Hat
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yes, I am german, too.
When you pass the Vollabnahme §21 for the first time you have a relativly easy choice with wheels and tires.
Getting anythingin into the paperwork later on is more difficult.
Your wheels and tires are way off from the factory.
My guess is that nothing was adjusted for the speedo.
As mentioned before I would contact your preferred TÜV guy.
Usually if you come along with a Datenblatt and factory specs you should be able to get those into the paperwork
Previous owner of your car was also a member on the german mopar-forum.de IIRC
Carsten
When you pass the Vollabnahme §21 for the first time you have a relativly easy choice with wheels and tires.
Getting anythingin into the paperwork later on is more difficult.
Your wheels and tires are way off from the factory.
My guess is that nothing was adjusted for the speedo.
As mentioned before I would contact your preferred TÜV guy.
Usually if you come along with a Datenblatt and factory specs you should be able to get those into the paperwork
Previous owner of your car was also a member on the german mopar-forum.de IIRC
Carsten
I have somebody who cam help me with that.
Interesting. I bought it in Dortmund in December. Haven't even driven it after the test drive, except in an out of the garage for some work.
After having driven it some weeks I'll know more, but tires are one issue, I want to address sooner.
Currently, I'm replacing some parts, adding some features, getting rid of leaks, changing liquids and refreshing the interior. Well, basically giving it some general love to make it my own. As with every new old car I buy
Interesting. I bought it in Dortmund in December. Haven't even driven it after the test drive, except in an out of the garage for some work.
After having driven it some weeks I'll know more, but tires are one issue, I want to address sooner.
Currently, I'm replacing some parts, adding some features, getting rid of leaks, changing liquids and refreshing the interior. Well, basically giving it some general love to make it my own. As with every new old car I buy
Hey guys,
I have to dig this one out. Had a flat tire last weekend and now the time has come to get to work :-/
I also want/need to change my rear axle. I might get a good 8,75" from a 67 Fury with 2,93 ratio. Mine was 2,76.
When moving from 2,76 with 215/65/15 to a 2,93 ratio with 225/70/15 I might get away without adjusting the speedometer. it will show approx. 2,5% too much, which would be ok for Germany bureaucracy. Please correct me, if my calculations are wrong.
How did you adjust the speedometer when swapping your tires. that's a massive difference? Seems to be a problem to get hands on the speedometer gears in Germany. Can anybody guide me to a good store that delivers to Germany?
AND ONE GENERAL QUESTION:
I'm missing logic here: How come the diff ratio changes the odometer? Shouldn't this just change the ratio between engine revs and axle revs? I know from a Ford Taunus P7 and Volvo 940 the change of diff ratio doesn't affect the speedometer. Only change of tire size does.
Any help is appreciated. It's kind of urgent. Thanks in advance!!!
Last edited:
Going from a 2.76 to 2.93 is not worth the effort, UNLESS you are very sensitive to speed, by observation. To me, not worth the effort and cost involved. 2.93s were usually on 318 Furys back then. 383s got 2.76s. Either one could have 3.23s.
The P225/70R-15 tire will have about 755revs/mile, which relates to the old G70-15 size (which it replaces). Which is also right at the same revs/mile as a P235/55R-17 tire, if that matters.
The rear axle ratio relates to speed of the engine vs wheel speed. The tire size comes into play as "the lever" which the rear axle turns. Longer lever, more road speed per engine rpm, and vice versa. Now, changing the tire size will NOT affect the readings (speed and distance) you see ont he speedometer, but will show a difference via GPS speed readings, where actual road speed is measured.
There are several tire size comparison "charts" on the Internet. The first one I found was at the Miata Club website. Later, I found the same thing in other places. You put in your starting tire size and then the second tire size. It will show a graphic of how much taller/wider one tire is than the other, plus speedometer error in percents.
The Chrysler TorqueFlite was used by a few foreign car manufacturers. Jensen was on (Jensen Interceptor) and Monteverdi was another one. You can look at tire sizes and speedometer gears (drive and driven) in the Chrysler Factory Service Manual, with tire sizes . . . it's the combination of rear axle ratio and tire size that matters.
Just some thoughts,
CBODY67
The P225/70R-15 tire will have about 755revs/mile, which relates to the old G70-15 size (which it replaces). Which is also right at the same revs/mile as a P235/55R-17 tire, if that matters.
The rear axle ratio relates to speed of the engine vs wheel speed. The tire size comes into play as "the lever" which the rear axle turns. Longer lever, more road speed per engine rpm, and vice versa. Now, changing the tire size will NOT affect the readings (speed and distance) you see ont he speedometer, but will show a difference via GPS speed readings, where actual road speed is measured.
There are several tire size comparison "charts" on the Internet. The first one I found was at the Miata Club website. Later, I found the same thing in other places. You put in your starting tire size and then the second tire size. It will show a graphic of how much taller/wider one tire is than the other, plus speedometer error in percents.
The Chrysler TorqueFlite was used by a few foreign car manufacturers. Jensen was on (Jensen Interceptor) and Monteverdi was another one. You can look at tire sizes and speedometer gears (drive and driven) in the Chrysler Factory Service Manual, with tire sizes . . . it's the combination of rear axle ratio and tire size that matters.
Just some thoughts,
CBODY67
I know, the rear end in question is from a 67 Fury with a 318. I absolutely don't care about speed. It's just a cruiser but at some point before export to Germany some idiot put a Chevy axle in there. Must have been around 2002. I didn't notice when I purchased it last year. The certificate even says it's matching numbers. So the whole thing was a fraud.
The diff sounds like a washing machine and needs revision anyway so now is the time to go back to an original 8,75". Since it's an urgent matter (car is also used commercially) and rear ends in Germany are rare, thats my only option right now. Or an 2,76 from a b-body which is a little shorter. Would that fit as well?
I checked a lot of charts before writing here but unfortunately none of them helped me regarding German laws.
Thanks a lot. I will check the other manufacturers as well.
Ripinator
Old Man with a Hat
I think you will be pretty happy with the 8.75 / 2.93 axle. I just installed a Sure Grip 2.94 in my '66 300 convertible which formerly had a one-legger 3.23. It was a good all around ratio, but the car always seemed like it needed to shift into a next higher gear. I'm hoping the engine will be a little less busy when cruising down the road with the 2.94.
Thanks for the additional information. In the world of rear axles, it's not only the "tread width", it's the width between the spring mounting pads which determine interchangeability. In the rear leaf springs, there is a center bolt which holds everything together at that point. From that point, the front of the leaf springs usually angle a degree or so inward or outward (don't remember which it is on Chryslers) to the front eye mounting point on the body. That "pad dimension" is not usually listed in any factory literature we normally have access to, unfortunately, but with the large number of C-body Chryslers in Germany, perhaps someone might measure theirs for your information?
Once you get the rear axle installed, then you can determine the equivalent OEM tire size and can seek the correct speedometer gears for your trans. Perhaps even using a GM-style (who used these things more frequently than other OEMs seemed to) get a speedomater shop to build you a "ratio adapter" (a small box which mounts at the trans to, between where the cable would normally screw on and the cable itself, to get the end revs/mile of the speedometer cable correct) for your particular vehicle.
Once you know the "revs/mile" of your tire size, then you can work backward from there to determine the same "revs/mile" of the driveshaft. Then compare THAT figure to the closest OEM application of rear axle ratio and tire size. Seeking to match the revs/mile of the OEM application, you can then get as close as you can with your new combination, which is where the ratio adapter box might be needed.
As for what the speedometer indicates, work toward a correct MILEAGE figure. Get THAT correct first. The reason is that the odometer is driven by the speedometer cable itself. The speed reading happens when the "speed cup" (turned by the cable) is turned, which has a bar magnet internal to it, which then spins the outer speed cup, to which the speedometer needle is attached. So, no direct contact between the two. The intensity of the bar magnet is what gets that outer speed cup to spin. Magnetic intensity can vary and is adjustable (by an electric device), which is a "cut and try" operation to get it closest to what it needs to be.f But get the revs/mile of the speedometer cable correct FIRST. With that correct, then the speed readiing should be "in spec" for original production items. For the final check, check the odometer and speed via GPS of known-accurate mile markers on the highways (I like to do 10 miles at 60mph to check speed and distance. 60 seconds = 1 mile @ 60mph, in the USA. 5 miles can work, too).
Hope this might help,
CBODY67
Hope this might help a bit,
CBODY67
Once you get the rear axle installed, then you can determine the equivalent OEM tire size and can seek the correct speedometer gears for your trans. Perhaps even using a GM-style (who used these things more frequently than other OEMs seemed to) get a speedomater shop to build you a "ratio adapter" (a small box which mounts at the trans to, between where the cable would normally screw on and the cable itself, to get the end revs/mile of the speedometer cable correct) for your particular vehicle.
Once you know the "revs/mile" of your tire size, then you can work backward from there to determine the same "revs/mile" of the driveshaft. Then compare THAT figure to the closest OEM application of rear axle ratio and tire size. Seeking to match the revs/mile of the OEM application, you can then get as close as you can with your new combination, which is where the ratio adapter box might be needed.
As for what the speedometer indicates, work toward a correct MILEAGE figure. Get THAT correct first. The reason is that the odometer is driven by the speedometer cable itself. The speed reading happens when the "speed cup" (turned by the cable) is turned, which has a bar magnet internal to it, which then spins the outer speed cup, to which the speedometer needle is attached. So, no direct contact between the two. The intensity of the bar magnet is what gets that outer speed cup to spin. Magnetic intensity can vary and is adjustable (by an electric device), which is a "cut and try" operation to get it closest to what it needs to be.f But get the revs/mile of the speedometer cable correct FIRST. With that correct, then the speed readiing should be "in spec" for original production items. For the final check, check the odometer and speed via GPS of known-accurate mile markers on the highways (I like to do 10 miles at 60mph to check speed and distance. 60 seconds = 1 mile @ 60mph, in the USA. 5 miles can work, too).
Hope this might help,
CBODY67
Hope this might help a bit,
CBODY67
Thanks, this helps a lot.
Unfortunately, I have to start with the new tires. I used a tire calculator that says: 225/70/15 is 5% larger than 215/65/15, So speedometer shows 5% less. The 2,93 results in 7,5% more revs than the now installed Chevy axle which has a 2,71 ratio, I guess (have to recheck the badge). So at the end, the speedometer displays 2,5% more speed that actually driven. This would be fine. Then the odometer should also work correct. Well, it'll be gaining 2,5% more miles, but who cares? When it comes to German MOT it's all about a correct speedometer
This would mean, I don't have to change any of the speedo gears or add an adapter-box.
I thought of that because:
Original tire size would fit 215/70/15 with 2,76 ratio.
Now I drive 215/65/15 with 2,71 ratio. That results in correct speedo display.
I guess they put on smaller tires to compensate the diff ratio change without changing the speedo gear. That's what I want to do when swapping mine to a 2,93. I just go with 225/70/15... Without changing anything regarding odo/speedo.
More expensive tires save adjustment costs and time and I just have to put in in the paperworks at the MOT and DMV.
Unfortunately, I have to start with the new tires. I used a tire calculator that says: 225/70/15 is 5% larger than 215/65/15, So speedometer shows 5% less. The 2,93 results in 7,5% more revs than the now installed Chevy axle which has a 2,71 ratio, I guess (have to recheck the badge). So at the end, the speedometer displays 2,5% more speed that actually driven. This would be fine. Then the odometer should also work correct. Well, it'll be gaining 2,5% more miles, but who cares? When it comes to German MOT it's all about a correct speedometer
This would mean, I don't have to change any of the speedo gears or add an adapter-box.
I thought of that because:
Original tire size would fit 215/70/15 with 2,76 ratio.
Now I drive 215/65/15 with 2,71 ratio. That results in correct speedo display.
I guess they put on smaller tires to compensate the diff ratio change without changing the speedo gear. That's what I want to do when swapping mine to a 2,93. I just go with 225/70/15... Without changing anything regarding odo/speedo.
More expensive tires save adjustment costs and time and I just have to put in in the paperworks at the MOT and DMV.
Sorry for bothering again.
So I'm about to close the deal on my new rear end and tire size. Could somebody please confirm my math regarding the ratios of tire size and diff ratio?
Tire calculator says: 225/70/15 is 5% larger than 215/65/15 -> speedo shows 5% less (95 when driving 100)
2,93 is 5,81% shorter than 2,76, hence the difference should be compensated by the new diff ratio. Correct?
Thanks again!!!
So I'm about to close the deal on my new rear end and tire size. Could somebody please confirm my math regarding the ratios of tire size and diff ratio?
Tire calculator says: 225/70/15 is 5% larger than 215/65/15 -> speedo shows 5% less (95 when driving 100)
2,93 is 5,81% shorter than 2,76, hence the difference should be compensated by the new diff ratio. Correct?
Thanks again!!!
Paul Stubbs
New Member
That sounds accurate. Hopefully the brake drums and associated equipment are in good repair on the 8.75 axle.
Next time I visit Deutschland I will have to buy you a Bitburger.
Next time I visit Deutschland I will have to buy you a Bitburger.
Thanks for the confirmation.
Next time you are in Germany, you should try Erzquell Pils. It's a small local brewery in my hometown near Cologne. Krombacher is also right around the corner but Erzquell is the hidden champion ;-)
Paul Stubbs
New Member
Thank you for the suggestion!
Are all large American cars popular in Germany/ Europe now, or mainly Chrysler vehicles?
Are all large American cars popular in Germany/ Europe now, or mainly Chrysler vehicles?
I don't really know. Basically I'm a big MCM fan in general (music, furniture, houses). But my weakness for old cars comes from being a film buff since I was a kid. I also love European and Asian cars mainly from 60s to 80s. We have a VW Golf I Convertible (You know it as VW Rabit), a Volvo 940 Turbo wagon and I always wanted to drive a V8 from the muscle era. I was very close to buying a B-body (had offers for a 69 Satellite and a 67 Coronet) but the budget forced me to move to a C-body. Unfortunately the seller was a rotten egg.
Chevys, Fords and Pontiacs were also on my list but deep down I wanted a Mopar for some reason. Maybe because I see Chevys and especially Fords quite often in Germany.
pomonamissel
Senior Member
225/70-15 front 245/60-15 rear on 8.5 vintage torq thrusts , both 27 plus tall
![DSC03389[1].JPG](https://forcbodiesonly.com/mopar-forum/attachments/dsc03389-1-jpg.539670/ "DSC03389[1].JPG")
Knebel
Senior Member
Hey, I am German too!
The problem is that any wheels or tire size change he will need to have papers for that show that they are tested for his car and then have an inspection done and have the cars papers changed (if you have a good inspector that knows his stuff but thats rare). On top of it if he wants to retain his classic registration the car needs to be original as far as i know.
Germany is not a good country to customize your car, steeringwheel change without inspection and papercorrections means the car lost its license to be operated on public roads.
The problem is that any wheels or tire size change he will need to have papers for that show that they are tested for his car and then have an inspection done and have the cars papers changed (if you have a good inspector that knows his stuff but thats rare). On top of it if he wants to retain his classic registration the car needs to be original as far as i know.
Germany is not a good country to customize your car, steeringwheel change without inspection and papercorrections means the car lost its license to be operated on public roads.
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