5 speed conversions
Posted: Wed Jun 30, 2010 9:09 am
Hi all- enjoy the weather
Just a bit of a footnote really-I've had a T9 in my sprint since around 1999. With a 3.54 diff ration and std 80 aspect 13 inch tyres it gives roughly gearing of 22.7mph/1000 revs. Having heard of a clever mod (to further raise 5th gearing) that's possible only on boxes sourced from ".8 engined Capris etc the opportunity to try it out presented itself when I had to have 3rd gear attended to.
Basically you swap the complete 5th gear cluster from a 1.6/2.0 sourced box. This ups 5th from 0.82 to 0.75. In my case 5th is now approx 24.5/1000 revs. To see 50 mph at around 2000 revs is to say the least "interesting". Any concerns I had about "bogging down" were unfounded- 5th is still perfectly usable in give and take driving. No difference in noise levels though- and probably no significant difference in fuel use either. Worth doing though if anybody else has a similar T9 in their car.
On a related note- any ideas on a problem. I lifted the box to cure an annoying noise that occurred only on overrun- it's developed over the last 2 years or so. Something like a light rattle. Definitely not a whine or grinding. Gear operation seems entirely unaffected on both up and down shifts. Only 3rd is affected.
I demonstrated the fault to somebody who has worked on these boxes (and probably most other types of box as well) over the last 30 odd years. He didn't know what it was likely to be. Gave me some pointers to look for once I had it apart.
I couldn't see anything obvious so I handed the problem to him. What did he find- absolutely sod all. No odd wear patterns, no stress cracks on the teeth, no teeth chipped. All bearings etc were as new. Selector forks are as new. As I had a brand new 3rd gear he swapped it over as a last resort. I'm 100% certain it isn't related to the conversion simply because for years I've had no problems with it. The box is fairly low mileage from new
You can guess the outcome- problem still there. No worse but no better. I've done the usual checks- prop joints, gearbox mounting, checked for contact between the box and other components, engine mounts etc.
Any ideas?
Regards
John
Just a bit of a footnote really-I've had a T9 in my sprint since around 1999. With a 3.54 diff ration and std 80 aspect 13 inch tyres it gives roughly gearing of 22.7mph/1000 revs. Having heard of a clever mod (to further raise 5th gearing) that's possible only on boxes sourced from ".8 engined Capris etc the opportunity to try it out presented itself when I had to have 3rd gear attended to.
Basically you swap the complete 5th gear cluster from a 1.6/2.0 sourced box. This ups 5th from 0.82 to 0.75. In my case 5th is now approx 24.5/1000 revs. To see 50 mph at around 2000 revs is to say the least "interesting". Any concerns I had about "bogging down" were unfounded- 5th is still perfectly usable in give and take driving. No difference in noise levels though- and probably no significant difference in fuel use either. Worth doing though if anybody else has a similar T9 in their car.
On a related note- any ideas on a problem. I lifted the box to cure an annoying noise that occurred only on overrun- it's developed over the last 2 years or so. Something like a light rattle. Definitely not a whine or grinding. Gear operation seems entirely unaffected on both up and down shifts. Only 3rd is affected.
I demonstrated the fault to somebody who has worked on these boxes (and probably most other types of box as well) over the last 30 odd years. He didn't know what it was likely to be. Gave me some pointers to look for once I had it apart.
I couldn't see anything obvious so I handed the problem to him. What did he find- absolutely sod all. No odd wear patterns, no stress cracks on the teeth, no teeth chipped. All bearings etc were as new. Selector forks are as new. As I had a brand new 3rd gear he swapped it over as a last resort. I'm 100% certain it isn't related to the conversion simply because for years I've had no problems with it. The box is fairly low mileage from new
You can guess the outcome- problem still there. No worse but no better. I've done the usual checks- prop joints, gearbox mounting, checked for contact between the box and other components, engine mounts etc.
Any ideas?
Regards
John