Rhett

For some reason the C4 I've just installed a few weeks ago is starting to shift firmer and firmer (it's too firm). My last C4 did this and after 2 years snapped something inside when I shifted from first to second, hence the need to put in my spare. The shift is very solid and sudden. Now I've also got to change the 4 trailing arms on my XE's diff.

P.S. When I removed the petrol tank, ('cos the XE runs straight gas), I fitted an old aircon radiator out the back (complete with thermo fan) and use it as a trans cooler. The distance is a little more then if the cooler was at the front, but I don't think the extra distance and extra fluid capacity would hurt the stock pump, though I'm no trans mechanic.

Any ideas as to why the shift could be getting firmer and harsher all on it's own?

brenx

Clutches bedding in more than likely. A tall diff like a 2.77 or 2.92 will make it snap harder too. I found this out when I ran 3.00. I changed to 4.11's and it doesn't change as hard anymore.

Brenden

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XB Fairmont (street car) 11.07@123.02mph.

Rhett

I'm running 2.77
thanks Brenden.

STROKEXD

A hard shifting trans is what you want, sounds like a good thing. Agree with Brenden it's the clutches bedding in and doing what they should be doing.

The trans cooler sounds trick, well done. The pressure in the trans pump should be plenty to route out the back. It's probably only 10% longer than a stock fitting cooler.

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ltd351

interesting idea. The a/c radiator is Huge. does the trans even warm up??

could runnin it cold all the time hurt an auto??or is cooler better??

brenx

Depends whether theres a histall there. Guaranteed not to run cold if a histalls there. I run two B&M 12,000lb trans coolers in mine. 1 works well but 2 is better for me. I have a 4500rpm histall.

I wouldn't suggest anymore than 1 cooler without a 3500rpm+ histall.

Brenden

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XB Fairmont (street car) 11.07@123.02mph.

Rhett

I was running a 3000 hi stall till I blew my last C10 changing from 1st to 2nd. I had to drain some fluid because I over-filled the trans a bit, so I disconnected one of the hoses way at the back near the cooler to test the pressure, then turned the car on and let the fluid shoot into an icecream container. The fluid came out quite fast, so the extra distance to the rear of the car doesn't appear to be placing too much pressure on the pump.

After I've been driving the car for a while, when I stop - I can place my hand on the radiator and it can be quite warm, so it appears to be transferring the heat OK.

The only downside is that sometimes when I'm cruising and it's cold outside, my front thermo wont turn on, because the cold air flow is sufficent, but this means that the rear thermo mounted on the aircon radiator (alias trans cooler) doesn't turn on, so the cooler can be a bit warm when I stop, because it doesn't get mush airflow tucked up underneath where the fuel tank used to be. This is the main reason why I dropped my stage 1 solinoid switch down from 60C to 50C.