Need for more speed

[Bigheadbdman]

Hello I'm looking for some help with my 109 I've had a remap everything is fine except for the constant gear changing is there a way to get more top end and any ideas what will fit ie gearbox or diff to get what i need cheers

 

[BTB 500]

Hi & welcome.

The 109 had the lowest diff ratio of any W639, presumably to make it up hills with only 90 bhp and a full load. You could look at fitting a diff from one of the other models ... the ratios were:

3.727 (109)​

3.455 (low ratio option for 111 and 115 ... rare)​

3.273 (standard for 111 and 115 ... this will be easiest to find)​

2.923 (120)​

I guess you'd need to get the speedo corrected though ... it would potentially under-read quite significantly with a 111/115 diff fitted.

 

[BIG UN]

Agree with BTB500 the diff would be the next swap, as you will get better cruising (motorway) speeds..