Hi ozconnection
I was wondering who fitted the..L4N71B four speed overdrive automatic. for you.. I have a 280C (430)and want a four speed put in it. if you can point me in the right direction . would be much appreciated.
Hey 80cedric,
I had the conversion done at Stewart Wilkins. We used a late model R30 L24E transmission.
There are several things to look out for:
The engine flexplate (auto trans flywheel) is different on the 4 speed unit.
The output shaft on the 4 speed is bigger than the L3N71B or FS571B output shafts.
The 4 speed trans is longer and slightly wider than the 3 speed so some tunnel massaging may be needed on the 430 Cedric (the 330 needed it!). The tailshaft needed to be shortened with the new yoke. The second part of the shaft was unmodified.
The crossmember needed to be custom fabricated. I grabbed an R31 crossmember and had that modified as it was quite close to what was needed to work.
The shifter linkage needed some 'lateral thinking' to select 1st gear on the shifter. I got the car home and sorted this one out myself by drilling a new hole in the Tee bar linkage. (think of a see saw and you'll have an idea of what I'm saying, I just sat closer to the centre and not on the end of the see saw for the shifter to work the way it was supposed to and get 1st gear.)
So, get the R30 box, the flexplate and the 1st part of the tailshaft from the R30 and a crossmember from an R31 automatic with the L4N71B, the later ones ran a different box. The VL's ran 4N's, look for the hydraulic shifted ones, and avoid the added work to instal the electronically controlled E4N71B trannies.
Final drive is different on the R30's, so you may want to change out the speedo drive to one that suits a 4.11 diff in the Cedric. I used a converter box supplied by a company called "Mark's 4WD adapters". Told them what I had and they sent me a box that goes between the speedo drive and cable to sort the speedo out. Works great.
The 1st two gears are slightly lower on the 4 speed (2.8 1st, 1.5 2nd) so accel is a bit better off the line. That 0.686 O/D is what we're after, and its awesome on the open road.
There is a heap of aftermarket upgrades for these boxes, high stall converters, adjustable modulator valves and 'shift kits'. Or keep it stock.
Transforms the car and cuts the buzz at 100km/h with better accel and improved fuel economy. I love it.