Can anyone tell me what diameter the central shaft is on the 2 litre Sierra push in driveshaft? I have a drivers side (835mm) 26/28 spline shaft which has a diameter of 23.8mm which looks small to me as I thought these shafts had a bigger diameter than this and I don't have another to compare it with.

I googled it!
7th heaven came up trumps again.

The driveshafts themselves come in different lengths and diameters with different numbers of splines. They are available with 23, 25, 26, 27, 28 and 25/27. The drive shafts are different lenghts on both sides of the car. The early 23 splines shafts are the narrowest at 26.95mm and later higher performance models are the thickest at 28.5mm.

Thanks Snapper, I've got a lot of this info including those shaft diameters but the one that I bought has a diameter of 23.8mm and don't know which variant Sierra it came from. From memory it certainly doesn't look like the ones I used to have that came from a 2 litre.

Bug me over the next few days. I've got the lightweight 6.5" diff (in a 7" case as fitted to the 1.3 Sierra) which has thin drive shafts. I've also got a normal 7" diff.

(6.5" caused me no end of problems with the drive shafts (and bearings) being smaller than normal)

Do your thin shafts have 23 or 26 splines at the diff end? It looks like my reconditioned shaft might be for a 1.3 or been rebuilt using a mix of parts

Just measured my halfshafts from a '90 1.6 with a 7" diff and they're 23.8mm

No idea what the splines are though

With all that said, there is a big difference in the weight and grip of a 7 compared to the donor, it’s just going to wheel spin. Unless you jam both wheels on rock with your foot on the floor

Thanks for the replies and the measurement. The 23.8mm shaft just looks a bit thin to take the load even though our cars are lighter! My engine produced 140bhp on the Rolling Road (can't remember what that would be at the wheels) and was a bit worried about this shaft taking that. I'm currently running J & R shafts and they have developed backlash after only 2000 miles and the company doesn't want to know as they are well out of warranty time. I was thinking of changing back to genuine Ford items even though they are getting old now.

Anyone got a 2 litre shaft they could measure the diameter for me to see the difference?