speedo

  • Thread starter Thread starter John Robertson
  • Start date Start date
J

John Robertson

my 740turbo 1990 has 205- 55-16 tyres on it which are very expensive .Is it
possible to put 215-60-16 which messes the speedo up ,on the car and alter
the gearing going into the differential to compensate or is it an electrical
sender .The difference is about $45 .00au dollars per tyre OR $180.00 a set
of 4 which seems a lot .As it is it would be 3.1 klms perhour too slow on a
straight swap over and with our stupid laws thats enough to get a fine of
$125.00 I think .1.8 Mph = 3 klms per hour an hour and your done cold .What
is the best cheapest way to compensate the speedo difference please .












4
 
Try using the correct combination of wheel/tyre for the car. 15" wheels shod
with 185/65/15 tyres if saloon (sedan) or 195/65/15 tyres if estate (wagon).
If you use a set of alloys from a 740 GLE you will end up with a superb
combination which will enhance the comfort, hold the road like s**t to a
blanket and look like a Bentley/RR into the bargain.

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).
 
Peter K L Milnes said:
Try using the correct combination of wheel/tyre for the car. 15" wheels shod
with 185/65/15 tyres if saloon (sedan) or 195/65/15 tyres if estate (wagon).
If you use a set of alloys from a 740 GLE you will end up with a superb
combination which will enhance the comfort, hold the road like s**t to a
blanket and look like a Bentley/RR into the bargain.
Click to expand...


But that's no help for him since he has a '90 turbo which came with the 16"
Hydra rims. Nice wheels they are too, and getting harder to find in good
shape.
 
Hi its got alloys 16 inch as standard nice too but the cost of tires tyres
is an issue .16 inch are very expensive as for 17 go rob a bank first .
 
Yes they are in good condition but an odd size .LOOKS like I must pay the
man or get the speedo adjusted .Question is can I change a cog \gear teeth
on the drive somewhere to compensate my tire tyre size ?
 
Oh yes it is of help because the brake disc and callipers were made to fit
into a 15" rim. All he has to do is swap with someone for a set of 15s and
"Robert is your father's brother" ( old UK phrase "Bob's yer uncle" meaning
job sorted.).

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).
 
John said:
Yes they are in good condition but an odd size .LOOKS like I must pay the
man or get the speedo adjusted .Question is can I change a cog \gear teeth
on the drive somewhere to compensate my tire tyre size ?
Click to expand...

The speedo has an electronic pick in the diff cover that "counts" the
teeth on a gear on the diff carrier. There's nothing to exchange
easily. However, customization is very common with hot rodders and
there's quite an industry to support this sort of thing. A quick search
of the 'net turned this up at the top of the list.

http://www.abbott-tach.com/era.htm

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)
 
At last an easy way to do it. Thanks for the link Mike.

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).
 
Peter K L Milnes said:
Oh yes it is of help because the brake disc and callipers were made to fit
into a 15" rim. All he has to do is swap with someone for a set of 15s and
"Robert is your father's brother" ( old UK phrase "Bob's yer uncle" meaning
job sorted.).

All the best, Peter.
Click to expand...


Well if he wanted to lose the nice 16" rims. If they're in good shape I'd
trade him my 15" alloys with a decent set of tires on them for the 16"s,
best looking rims Volvo ever made IMO, and they improve the handling of the
car over the 15s too. Tires cost a bit more but so what? Not like they have
to be replaced weekly.
 
Hi its got alloys 16 inch as standard nice too but the cost of tires tyres
is an issue .16 inch are very expensive as for 17 go rob a bank first .
news:[email protected]...
Click to expand...


Speedometers are designed so that 1000 revolutons of the driven wheel
equals one mile or one kilometer. This can be seen on the speedo face by
the designation r=XXX or KXXXX. If the circumference of your wheel and
tire combination can be matched with any other wheel combination
available for the chassis then there is speedometer gearing avaialble
for your car. Provided of course that the rear axle ratio in your car
was also available in other versions.

There are five differential ratios for the US market:
3.31; 3.54; 3.91; 3.73; 4.10, and five different speedo ratios. The
available combinations in your market should be similar.

Bob
 
Speedometers are designed so that 1000 revolutons of the driven wheel
equals one mile or one kilometer. This can be seen on the speedo face by
the designation r=XXX or KXXXX. If the circumference of your wheel and
tire combination can be matched with any other wheel combination
available for the chassis then there is speedometer gearing avaialble
for your car. Provided of course that the rear axle ratio in your car
was also available in other versions.
Click to expand...


That doesn't really apply to these cars though as they don't have a speedo
gear, it's electronic and replacing the pickup wheel involves dissasembling
the rear axel assembly.
 
That doesn't really apply to these cars though as they don't have a speedo
gear, it's electronic and replacing the pickup wheel involves dissasembling
the rear axel assembly.
Click to expand...
That's why the speedometer gearing is matched to the differential ratio.
The shutter wheel on the diff is the same for all models with an
electronic speedo.

Bob
 
User said:
That's why the speedometer gearing is matched to the differential ratio.
Click to expand...

Is it? I thought that it was attached to the hemisphere, not the pinion?!?

If it's on the hemisphere (or ring gear, or an axle) it'll depend only on
the tyre diameter.
The shutter wheel on the diff is the same for all models with an
electronic speedo.
Click to expand...

Almost. According to someone on brickboards, there is a 12-tooth for non-ABS
and a different one (48 or 96) for ABS.
Click to expand...
 
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