Fitting an alloy undertray

Having bought an unused alloy under tray from Pablo (thanks Pablo) I fitted it last night. It was very straight forward to fit so here is some info if you are thinking of doing the same.

The 156 GTA alloy tray is the same as the one for the GT 3.2 (and I presume for the 147 GTA).

Tools required: 10mm socket for 4 No. bolts onto subframe and wheel enclosure, T30 Torx (or star) bit for 5 No. bolts along u/s of bumper. Copper grease to apply to bolt threads when refitting (stops threads rusting and seizing). 2mm pilot drill bit and approx 8mm drill bit for repositioning holes.

I raised the car by driving the front wheels onto car ramps, but needed to use some flag stones under the front wheels to raise the car high enough for the front bumper to clear the ramps. The front edges of the ramps were also placed onto the flags so the car didn't drop before going up the ramps. Then try to ignore the smell of burning clutch when working under the car!!

The original tray is easily removed after undoing the 9 bolts. Then the alloy tray can be slid into place. I found that when aligning the rear holes onto the subframe, 3 of the holes to the front bumper (centre & n/s) lined up fine, but the 2 o/s holes needed fresh holes drill into the tray. You will be left with the 2 bolts that fixed the OEM tray to the wheel enclosures, these are not needed for the alloy tray.

OEM tray lowest point: 93mm (centre, between wheels)

New alloy tray lowest point: 110mm (centre, between wheels)

Although the new tray only gives 17mm additional clearance towards the back of the tray, the front section is 40mm higher meaning improved clearance going up rams and low curbs (see PDF sketch below)

I also weighed the OEM and alloy trays to see if there was a difference (thanks to the wifes electronic kitchen scales...):

OEM tray (plus the left over bolts!!!): 4.37 kg

Alloy tray: 4.34 kg

So an extra 17mm of ground clearance and a weight saving of 0.03 kg…result!

I also checked if there is enough clearance to fit a front subframe brace and it seemed fine, a few spacers or washers maybe required to drop the tray slightly.

Good job

Fed up of smashing my undertray - gonna get one of these AND look at getting the suspension under control!

I never had an OEM undertray, obviously broke off for the previous owner. What bolt size are required for fitting the aluminium undertray? Bought it expecting (wrongly) the nuts and bolts to come supplied...

Originally Posted by Irish_156

I never had an OEM undertray, obviously broke off for the previous owner. What bolt size are required for fitting the aluminium undertray? Bought it expecting (wrongly) the nuts and bolts to come supplied...

The bolts used for the tray under the bumper are the same as the bolts used on the top ebge of the bumper (under the grill trims). They are special large head bolts and may be easier to get straight from Alfa.
The rear two bolts are just std M8 bolts, about 40mm long I think, with large dia washers.

Why cant you get an alloy undertray for the GTV?

I think it is only 156/147/GT

Originally Posted by Alfie GTV

Why cant you get an alloy undertray for the GTV?

Watch this space
i need a good photo of a GTV undertray tho. im going to make a prototype out very thin steel first. but my gtv doesnt have a tray.so it's abit of guess work.


regards john

the undertray on my 147 was held on by cable ties caught it before it fell off

silly rustable bolts!

looks good that alloy one tho, nice one

The bolts used for the tray under the bumper are the same as the bolts used on the top ebge of the bumper (under the grill trims). They are special large head bolts and may be easier to get straight from Alfa.

Well damn it, dont have time to be calling to dealers at the moment with work. Any1 any idea .. and save me a lot of time fiddling with different bolts under my car if I can fit any standard type of bolt to secure the undertray???

Originally Posted by johnboy

Watch this space
i need a good photo of a GTV undertray tho. im going to make a prototype out very thin steel first. but my gtv doesnt have a tray.so it's abit of guess work.


regards john

Count me in for one of these, Don't have one!!

Originally Posted by Irish_156

Well damn it, dont have time to be calling to dealers at the moment with work. Any1 any idea .. and save me a lot of time fiddling with different bolts under my car if I can fit any standard type of bolt to secure the undertray???

[Edit] Ignore this post - changed my mind

Originally Posted by kernowmcrae

Count me in for one of these, Don't have one!!

Hi chap

hopefully in acouple of weeks i should get round to make a prototype.
will put up a post in the GTV lounge

regards john

cool, I'll keep my eyes peeled!

Originally Posted by johnboy

Watch this space
i need a good photo of a GTV undertray tho. im going to make a prototype out very thin steel first. but my gtv doesnt have a tray.so it's abit of guess work.


regards john

Hi Johnboy, if you need some pic's i'll see if i can get mine off and taks some photo's I can write the measurements on there aswell if it'll help

Originally Posted by Alfie GTV

Hi Johnboy, if you need some pic's i'll see if i can get mine off and taks some photo's I can write the measurements on there aswell if it'll help

Hi Aflie

That would be great chap.
will make my job abit easyer

regards john

Originally Posted by johnboy

Hi Aflie

That would be great chap.
will make my job abit easyer

regards john

I'll try and get it done this weekend

Originally Posted by Alfie GTV

I'll try and get it done this weekend

Hi Chap

that's great man,but dont bust a gut ok


regards john

Aren't there issues with gearbox cooling cut outs and mild fouling of rubber / aircon hoses with the GT alloy undertray

Pass
this will be for a GTV not GT
but i could put some vents in it.

Thanks for the pics and the diagram - am planning to get one of these myself at the earliest opportunity as the local speed bumps (of which there are many) are driving me up the wall - my OEM tray is being held on with cable ties and drags along the floor unless I take the bumps at about 2mph. I've called Autodelta in London a couple of times about the trays but they seem to rarely have them in stock - could somebody recommend an alternative by any chance? I'm in London, near Autodelta hence trying them first.

AND look at getting the suspension under control!

With regard to this - is there anything easily doable to a 156 2.0 JTS to change the damping? I have standard springs and shocks and whilst it's fine going over the upside of the bumps, it seems to really plunge coming down the down slope - the same also applies to driving over rough roads at high speed.

If I could get the two sorted, I'd be a happy badger...

Originally Posted by Seabadger

With regard to this - is there anything easily doable to a 156 2.0 JTS to change the damping? I have standard springs and shocks and whilst it's fine going over the upside of the bumps, it seems to really plunge coming down the down slope - the same also applies to driving over rough roads at high speed.

Only way really is shocks and springs - apparently the Autodelta ones are good if pricey!