Low profile tyres but not on the automatic

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Eccles60
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Low profile tyres but not on the automatic

Post by Eccles60 »

Does anyone know why for the 1988 range of BX models low profile (70 profile) tyres are fitted to most variants but for the automatic version of the 16TRS they are plain 155R14? The manual version of the same model has 165/70R14. I'm confused.

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Re: Low profile tyres but not on the automatic

Post by panky »

I'm no expert but were the manual box ratios changed (final drive) but the auto left as it was? Or maybe just tyre availability and cost/weight saving.
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Re: Low profile tyres but not on the automatic

Post by Kitch »

70-profile aren't exactly 'low profile'! It was probably help gearing, not that it'd make a huge difference, but a 16 auto needs all the help it can get!
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Eccles60
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Re: Low profile tyres but not on the automatic

Post by Eccles60 »

Many thanks, seems reasonable. I hope 16 autos aren't too bad, I've just bought one (it's currently being fettled by a respected specialist in Hertfordshire). Yikes!

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jamescarruthers
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Re: Low profile tyres but not on the automatic

Post by jamescarruthers »

Eccles60 wrote:
Thu Apr 07, 2022 7:19 pm
Many thanks, seems reasonable. I hope 16 autos aren't too bad, I've just bought one (it's currently being fettled by a respected specialist in Hertfordshire). Yikes!
I’ve never driven an automatic BX but did have the same gearbox in another car. It went okay I’d say, not amazing, but in time I learnt to take control of 3rd a gear a bit more and would make it hold on to that gear a bit longer when needed or drop it down myself early before attempting an overtake on the motorway rather than rely on the kickdown.

Also, at 30mph it would sometimes be in too low a gear (just the noise was a problem) so I used to end up passing 30 a little, waiting for it to change gear and then slow down to 30 so it would have a higher gear. You can comfort yourself that the speedo is likely under reading and you’re not being too naughty!

If it is in a garage for work, I’d recommend having the gearbox oil changed three times in quick succession to get something approaching a decent fluid change— about 1/3 is stuck in the torque converter sadly each time.
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Previous BX's:
A966 XRL -- BX 16 TRS
H767 BEG -- BX 14 TGE
B316 AMP -- BX 14 E

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Re: Low profile tyres but not on the automatic

Post by bowei001 »

We have had our 1986 16TRS Auto from new and it came from the factory with 165/70/14 tyres (on steel wheels) so there is no problem using this size.
The performance is never going to set the World alight but it keeps up with modern traffic and the changes are OK but not as seamless as with modern autos. It doesn't always understand hills, changing down and then changing up again almost immediately. Kickdown or holding in a gear usually solves the problem. I heartily agree with "triple-changing" the oil initially and then I do a single 2.5l change each year. The auto filters and sump gaskets are readily available and not too expensive but don't need to be changed very often if oil changes are regular. The auto sump undoes easily to get to the filter but actually taking it down is a pain because the sump flange will not clear some hydraulic parts (things may have been modified by 1988 but I doubt it) - be prepared to do a bit of unbolting and fiddling.
I hope you enjoy the car as we enjoy ours.

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Re: Low profile tyres but not on the automatic

Post by bowei001 »

I forgot to say, only use Dexron 2 transmission fluid (not Dexron 3). There have been comments on various forums saying that Dexron 3 is not good for the boxes. How true it is I don't know but Dexron 2 is cheap and autobox parts are not.

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Re: Low profile tyres but not on the automatic

Post by Tim Leech »

Some earlier 16 petrol autos had the 155/80 tyres..which I feel are rather too skinny!
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jamescarruthers
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Re: Low profile tyres but not on the automatic

Post by jamescarruthers »

True and “Little Red Friend” the 1985 14E had skinny little tyres too.
The size is 145r14, which translates into 145/80r14
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2006 Citroen C6 Exclusive 3.0 petrol/LPG

Previous BX's:
A966 XRL -- BX 16 TRS
H767 BEG -- BX 14 TGE
B316 AMP -- BX 14 E

Eccles60
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Re: Low profile tyres but not on the automatic

Post by Eccles60 »

jamescarruthers wrote:
Fri Apr 08, 2022 11:21 am
Eccles60 wrote:
Thu Apr 07, 2022 7:19 pm
Many thanks, seems reasonable. I hope 16 autos aren't too bad, I've just bought one (it's currently being fettled by a respected specialist in Hertfordshire). Yikes!
I’ve never driven an automatic BX but did have the same gearbox in another car. It went okay I’d say, not amazing, but in time I learnt to take control of 3rd a gear a bit more and would make it hold on to that gear a bit longer when needed or drop it down myself early before attempting an overtake on the motorway rather than rely on the kickdown.

Also, at 30mph it would sometimes be in too low a gear (just the noise was a problem) so I used to end up passing 30 a little, waiting for it to change gear and then slow down to 30 so it would have a higher gear. You can comfort yourself that the speedo is likely under reading and you’re not being too naughty!

If it is in a garage for work, I’d recommend having the gearbox oil changed three times in quick succession to get something approaching a decent fluid change— about 1/3 is stuck in the torque converter sadly each time.
Very interesting, much obliged.

Eccles60
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2005 Jaguar S-Type Sovereign 4.2 V8
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x 1

Re: Low profile tyres but not on the automatic

Post by Eccles60 »

bowei001 wrote:
Fri Apr 08, 2022 4:31 pm
We have had our 1986 16TRS Auto from new and it came from the factory with 165/70/14 tyres (on steel wheels) so there is no problem using this size.
The performance is never going to set the World alight but it keeps up with modern traffic and the changes are OK but not as seamless as with modern autos. It doesn't always understand hills, changing down and then changing up again almost immediately. Kickdown or holding in a gear usually solves the problem. I heartily agree with "triple-changing" the oil initially and then I do a single 2.5l change each year. The auto filters and sump gaskets are readily available and not too expensive but don't need to be changed very often if oil changes are regular. The auto sump undoes easily to get to the filter but actually taking it down is a pain because the sump flange will not clear some hydraulic parts (things may have been modified by 1988 but I doubt it) - be prepared to do a bit of unbolting and fiddling.
I hope you enjoy the car as we enjoy ours.
Many thanks for the encouraging words - much appreciated.