Frozen suspension bolt

The bolt (red) attaching the inner silent block bush (blue) to the right rear upper chassis attachment point (green) was completely frozen with corrosion.

Ferrari 308 Frozen Rear Bush

I needed to remove the wishbone to repaint it and fit new bushes so somehow that bolt needed to be removed. The lower wishbones are attached to the chassis via detatchable forks which can be removed so the bush can be separated on the bench but the upper ones are bolted through the chassis. With the nut undone there seemed no way to extract the bolt. I could not get any leverage due to the proximity of some body work. There is no room to swing a hammer in there and there is no room to get a puller on the bolt head. Rotating the bolt with the nut off simply tore up the rubber inside the bush so I knew it was really stuck. There’s a metal sleeve that runs through the bush. Moisture must have crept in between the sleeve and the bolt and effectively make them a single piece of metal.

Ferrari 308 corroded bush bolt

Well and truly stuck

Given such corrosion, heat can be used to crack the frozen components apart by expanding the bolt and then letting it contract as it cools to free it but I chose not to use heat this time. Been there, done that. These silent block bushes fill the shop with black acrid smoke when the surrounding metal is heated with a torch. Instead, based on prior experience, I know these bolts can be readily cut with a reciprocating saw; even when the bolts are rated at 10.9 hardness. The narrow blade of the reciprocating saw is perfect for making two cuts between the suspension wishbone and the chassis.

Cutting Ferrari 308 suspension bolt

With cuts carefully made, the wishbone is loose and can be removed.

Cutting Ferrari 308 suspension bolt

When I checked the cut bush, I could see literally no separation between the bolt and the sleeve, only a faint discoloured arc. That bolt was always going to be difficult to extract in place. Cutting it was definitely the most expedient route. Especially, as I already have spare suspension bolts.

Cut Ferrari 308 suspension bolt

With the wishbone gone, the remainder of the bolt need to be removed as well… Now with significant easier access, a few blows with a cold chisel pop them off of the chassis tabs.

Remains of Ferrari 308 suspension bolt

The chassis tabs show signs of corrosion as well. I’m not sure why the right side seems to have more corrosion than the left. I wonder if it is to do with the proximity of the exhaust that runs a couple of inches away above these tabs.

Ferrari 308 suspension chassis tabs

Even after the silent block bush was pushed out of the wishbone I still could not get the bolt out of the center of the bush…

Remains of Ferrari 308 silent block bush

Please leave a comment below if you’d like and/or signup with your email address to never miss a future post. Share this post on social media:

2 Responses

  1. Andrew Hinitt says:

    Hi, Did you use an air reciprocating saw to get in there? and what blade did you use, I can’t find one thin enough to go down the side of the bush, or long enough to cut the whole bush.

Leave a Reply