looking at a car on the forum.running a ford 2 ltr,c3 auto box,3.75 diff,owner says top speed around 70mph! but on high revs..on 16 inch wheels. I could live with the low speed,but would this tow a small 570kg caravan ok?owner did not know.. any ideas or would a change of diff or gearbox be needed..Thanks.
a mk2 cortina 1600e had 3.77 diff and only 13" wheels yet would do 100 mph easy. you'll be fine with that light a caravan.
The problem is that you are usually a gear or half a gear away from the optimum, that's why we have gearboxes! I've driven a car with very similar gearing and it worked OK but again had a low top end because essentially it was in overdrive rather than top, by changing down manually you are back into 'top' even though it's actually 2nd.
It's the rpm per 1000 revs that tells the full tale . Standard Mk 3/4/5 2000cc is 3.7 with 13s but geared to about 18/ 19mph /1000 , the taller rolling radius pushes that up to more like 23/24 which is overdrive territory . Yes, I'd guess it will still tow a 750kg caravan as a Sierra in overdrive top will still tow a caravan.
Putting in a 4.1 axle ( you can't swap the diffs easily on Cortina axles as there is an A and B type axle will drop the gearing back to standard Cortina ...been there done that :):tup:
If it's the motor I'm thinking of then I would say it's well worh buying and doingif needed, had considered purchasing it myself.