Are gearbox and rear diff mounts different?

[steve briance]

Hi all,

Currently gathering parts to replace all the rubber bits under my car with new in order to control the gear stick which lurches back and forth under acceleration / braking.

I ordered 431 399 151 D for gearbox mounts.

I ordered 857 599 431 for differential side mounts but the part that turned up had 431 399 151 D written on it...

The allegedly different parts do look the same in all the pictures I could find and on various websites there seems to be some cross over where one part number does both applications. My question is simply - despite having different part numbers, are they actually interchangeable?

many thanks!

[_ShurikeN]

They are interchangeable.
And rear subframe bushes can be replaced by front ones also.

[Error404]

ABY/RS2 gearbox mounts are different to the diff mounts. 3B are interchangeable, although I have a feeling the OEM ones are probably different rubber compounds, even though they look visually the same.

New mounts & rubber will help with this shunt issue but don't expect that to cure it. A great deal of the driveline shunt is caused by the centre diff

[steve briance]

That is interesting - I have just had a reply from the seller who mentioned rubber hardness is the same so they were interchangeable. I got my box and diff mounts from different suppliers and they are different brands and my thumbs say they are different flex/hardness...

I like the idea of firming up all the slop and have already got a tube of tiger seal so as long as they physically fit, I will (hopefully) be changing the hardness anyway!

cheers

[Nj]

Just digging through your threads Steve as I have a CQ20v to tinker with over a period of time. I have a fair bit of shunt and I'm not sure if it's clutch related or just loose bits down the drive chain. How did your new mounts and bushes work out after you had done them? Did you need to keep going with other bits?
cheers
nj

[steve briance]

hi Nj,

I was quite happy with the mounts, they needed doing anyway as one or two were de-laminating and it is not too tricky to do. Although they made some difference, by FAR the biggest single improvement in the quest to keep my waggling gear stick under control was to modify the front snub mount.

There are ready made anodised alloy CNC machined options out there if you want to pay for them but i didn't and read on here somewhere that the Mk1 golf front engine mount just happened to be a good thing to have as an audi coupe snub mount. Here is one on ebay, (nothing to do with me)

http://www.ebay.co.uk/itm/VW-GOLF-JE...MAAOSw9NdXtMWs

Its close but was not a direct fit so I thought, if i'm modifying it anyway, i may as well modify what i have and with the golf mount being NLA and not on the 'bay when i wanted one, that limited my options anyway. I ended up getting a piece of round steel tube and welding it into the standard snub mount bracket. the closest i could get was 3 inch tube x3mm wall with an internal diametre of 70mm. I think the snub mount was something like 67mm so i modified (cut and shut) to make the tube smaller.

End result is brilliant and improvements very apparent straight away. I found i didn't have to feed the clutch in carefully to avoid the gear lever lurching, it was actually under control for the first time in my ownership! Standard rubber snub bush and engine mounts etc means i don't have any crashing and banging going on but i guess PU mounts would probably yield some improvement again if you went down that route. I dont see how a PU snub mount would make any difference in the original bracket as there is such a big gap all the way round, the engine is pretty much free to do what it wants before the PU hits metal.

I'd post a picture but i can't find one right now. I'll try my best to get one with it in the car...

[Error404]

Looks like that MK1 golf snub is the same as the sport quattro one

[steve briance]

it is!

[Nj]

Steve, you're an absolute gentleman. Thanks for taking the time to reply in such detail. It's exactly that feeding out of the clutch that's driving me nuts now. I'm getting a lurch as I let it out (not just in the gearstick but a noticeable clunk) and I know that when Kit changed my rear diff bushes he said it made a big difference (this is before I even laid eyes on the car and Kit did a load of work for me to make sure it was fit to drive back to Finland).
I will need to do the front gearbox bushes/mounts at some point and I'm totally convinced that I need to sort the snub mount too. Thanks for the link by the way. I went ahead and bought that rather than faff about and wish later that I had
I need to take a look inside today to see how much work modding it will be. We just had our first snow here yesterday so it's getting cold and I now have a pile of parts (including timing belt, water pump and radiator) sitting in my garage waiting for me to make a start.

[Nj]

What do you think? Powerflex or OEM?
https://www.powerflex.co.uk/road-ser...unt/12364.html

[mcandmar]

Don't bother, the stock rubber mount is fine, just fit the golf/sportq snub mount. If you want to go a step further somebody on the forum made a very sexy kit with machined aluminum mounting brackets and a harder snub rubber, cant remember who made the kit but it works great.

[Error404]

Rusty did a very nice K24R billet snub kit

I made my own, pretty straight forward if you can weld

[steve briance]

The decision is unanimous - golf mount is the future! I think you will find the modding you need to do is regards to the hole centres not aligning exactly with the cross member captive nuts. Nothing a file can't fix or knock up another plate �� it sounds like you get proper cold weather where you are so perfect time to have a pile of parts to play with!

[Error404]

The MK1 / sq mount sits too far off the snub too, so it needs a spacer at the back of it to bring it closer to the block by around 15mm from memory. Best thing is actually cut the cup off & fab a more suitable back-plate for it.

[Nj]

damn. I really wish I could weld!
Very tidy job Alex.

Maybe this is a good reason for me to buy a welder and have a go? I've wanted to learn for years.

Alex, are you sure the mount sits too far off the sub in the CQ20v? Could it be different than the 3B/ABY? Or are you speaking from direct experience?

Steve, yeah it gets down to -40 on a bad day in January/February so I need something to do! Having said that, my garage is insulated but not heated so if I want to do any work in there I need to close the vents, get the car in and leave the heater on for a while before I start work. Otherwise it takes the fun right out of things. Before I had this house I had to do a few jobs on my A4 lying on the ground in -20ish and that was... not fun.