How to repair a scored input shaft? - PeachParts Mercedes-Benz Forum

GGR · #1 02-02-2010, 07:01 PM

Hi all,

I am in the middle of transforming a 6 cyl 5 speed manual transmission into a V8 one by using a 3.5 four speed input shaft, constant gear and front cover. I will also be putting reinforced bearings and a second shaft key for the 5th gear pinion on the countershaft.

Unfortunately the input shaft I want to use is scored by 4 thousands of an inch (on the total diameter) where the pilot bearing goes. I was unable to trace a good one and it is discontinued new.

I was told by a professional and also read on the net that I could have the shaft welded then machined back to spec. But two different machine shops have discouraged me to go that way as welding on the shaft would weaken it or could even break it.

I have considered putting a sleeve on it but the cost of machining the shaft then the sleeve is high and the strength of the sleeve would not be the same as the original shaft ending up in scoring again quickly.

I found this Belzona product on the net: http://www.belzonamolecular.com/ProductFlyers/MPT.pdf
Apparently one can fill the scored area with their product and then have it machined back to spec. But I was not able to find any info on how hard this will be and if it will be OK for an input shaft.

Any idea on what I should do would be very helpful.

Thanks in advance!