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MG MGB Technical - Installing Seats.

I can't find a definitive guide in the archives, and John Twist doesn't say: is it better to install the seats fully assembled, or is it just as easy to install the base and then add the backrest later? I'm thinking of strain on worn-out back!
All advice gratefully received ... regards, John.
J P Hall

I'm sure I've only ever seen them installed as complete units.

If you think it's possible to assemble them in-situ, give it a go.
Dave O'Neill 2

Like Dave I've only ever fitted them assembled, can't see a reason not to. The hinge set screws, particularly the tunnel side, I feel would be difficult. If yours have the hinge covers, even more so!
Allan Reeling

It's a bit of a job, but it can be done.

1 - run two bolts up from the underside of the car floor so they act as
guide pins.

2- lightly but snugly attach the notched sliders to the runners with zip
ties.
Be sure the notched sliders are mated to the spring loaded catch on
the seat assy. Clean well, and lube the sliders so they move easily.

3- With the attached notched sliders zip tied to the seat assy, move
the sliders to the full forward position.

4 - Place the entire seat assy into the car and be sure to get the holes
of sliders through the bolts you screwed up from under the car. The
seat should now be in the correct position to bolt into the the floor
from the top.

5 - Move the seat to gain access to the two available bolt holes then
bolt from the top.

6- Remove the two bolts from the underside of the car floor and bolt
them from the top.

7- Cut and remove zip ties before tightening all four bolts firmly to the
floor board.


Cheers

Gary
79 MGB

P.S. Ask me how I know this (LOL)
gary hansen

As a variation on Gary's method, you can use studs in lieu of bolts and install these from the top. Or cut the heads of four bolts and use those as studs.

Regards
Roger
R Taylor

I've only ever done them fully assembled, and just plonking them on the floor then fitting bolts from above. Sticking a screwdriver down through the holes in the runners and the metal spacers soon locates the holes in the floor - if needed. With both my cars I can push the seats forward far enough - even with all four bolts in - to fully expose the rear bolts and tighten them with a socket on an extension, some have said theirs are still concealed. With those in (but not fully tightened yet) the front holes are concealed from above but should be directly in line with the floor holes, bar a little side to side wiggling. The position of the frame and adjuster mean that a 7/16" ratchet ring spanner makes fitting these much easier than an ordinary ring or open-ended.
paulh4

I use a tapered punch to align the seat rails, otherwise I use Paul's method. Just did the job this past week after replacing a clutch in our MGB. Cheers - Dave
DW DuBois

Dave and Allan: spot on gentlemen - the inner hinge bolt would be unnecessarily difficult to access; it's much easier to assemble the seat and squab outside the car.
Driver's seat successfully installed this morning using the method recommended by Paul, Dave du Bois et al - but NOTE: the original 1 1/4" bolts won't reach through carpet as well - you can imagine how I know this.
One other thing - I also learned how important it is to make sure the backrest angle adjusting lever (the chrome one) operates the mechanism freely before you install the seat. Otherwise you think there's something drastically wrong because your seat won't lean back at the appropriate angle.
Otherwise, seat installation successful, and thanks again to all who took the trouble to respond to my query. Regards, John.
J P Hall

"the original 1 1/4" bolts won't reach through carpet as well"

They aren't supposed to. Whilst the wood slats sit on top of the carpet, the large alloy spacers should have holes cut for them, and they sit directly between runner and floor pan. This may be to prevent the carpet compressing over time and loosening the bolts.
paulh4

My car still has rubber mats. I can't remember if the mats have holes for the spacers - I'll have to check.

If they do, I would assume that the spacer would be a different thickness than would be required for carpets.

Thinking about it, even if they don't, the spacer would only need to be the same thickness as the wooden slat.
Dave O'Neill 2


When I pulled the seats out about a year ago, after getting caught in a deluge, I discovered the slats are still in very good condition. Happily nothing electrical got wet.

I think the webbing in the seat cushion has finally failed. But, that is a whole new topic

Cheers

Gary
79 MGB
gary hansen

Noting John's and Paul's comments on the bolts and carpet thickness, in my car the slats are fitted beneath the carpet and the spacers sit in matched diameter drillings in the slats. This sounds like the situation John has. I wonder, might this be a local Australian assembly difference to home market cars?

My spacers are also the same thickness as the slats as Dave has commented.

I have always assumed this setup was to allow a small degree of movement at the mounting points to accommodate body flex/twist transfer in the floor pan.

Regards
Roger
R Taylor

Roger, mine is '73 BGT so as I understand it, has to be UK built/assembled. That said, I can confirm :

(1) The old bluish carpet had the slats underneath, but with slits in the carpet so that the lower section of the seat runners poked through the carpet and sat direct on the slats - with the metal inserts bearing the bulk of the weight.
(2) I'm unsure as to whether the carpets were slit at original assembly, or by a later PO - probably Paul H would know.
(3) My reference to " bolts not going through the carpet" should really have referred to new underlay and the Dynamat which I have fitted under the new carpet. I have slit both the carpet and the underlay, poked the runners through, sat the slats on the Dynamat and reused the original bolts.

Hope this helps! Regards, John.
J P Hall

John,

Yes, UK production then and, of course, POs do change things over time. Your solution sounds a good one so a job well done.

The underlay would make a difference. Mine looks like the faint remains of the original style matting material that I struggle to throw out for its original connection with the car. I have had new underlay (pressed foam-like material that compresses very little) for a number of years but put off using for the reason of the issue you found.

This thread has given me some options for installing that though.

Regards
Roger
R Taylor

My spacers are thicker than the wood slats and the slats only rest comparatively lightly on the carpet. If they were the same thickness the runner would bow as the bolts were tightened ... unless the carpet had slits so the runners and slats lay underneath

Neither of mine had original carpet when I got them, I can only think I looked at the relative thicknesses of spacer and slat and decided the spacer needed a hole in the carpet, or the slat would be doing nothing at all. Presmably the slat is there to support the middle of the runner and prevent it bowing. Prestige show quite large holes in their carpets.

The spacers do sit in holes in the slats, although when I replaced the slats even though each had one hole at one end and two at the other they did not line up with the holes in my runners or floor, and I had to cut additional ones.
paulh4

At first sight the spacer looks to be nearly twice as thick as the slat, but in fact spacer thickness is 0.34", slat thickness 0.21". This is why I decided to cut holes for the spacers and sit the slats on the carpet, which is of a relatively thin and cheap type and all I was aware of 26 years ago. Still very little signs of wear though.

Five minutes to remove seat, 10 minutes to refit, as it happens.

paulh4

Interesting, Paul - the thicker spacer would as you say enable the spacer to protrude through a hole in the carpet, and still occupy the hole in the slat ABOVE the carpet - thus the runner can sit on the load-spreading slat, albeit with most of the weight borne by the spacers. A cunning way of not having to put a slit in the carpet.
That still leaves the rest of us, who have spacers the same thickness as the slats. I'll settle for the slit-in-the-carpet for now!
By the way, my slats have 2 holes at each end, but the inner holes match the bolt locations. Regards, John.
J P Hall

Yes, there really are some variations here. My slats have Paul's one hole/two hole ends but, like John's, the holes align with the bolt/runner hole locations - though I don't recall whether the inner or outer on the double end.

I think you have both found good solutions. I need to get cracking!

Regards
Roger
R Taylor

"but the inner holes match the bolt locations"

Ditto, after cutting an additional inner hole.
paulh4

As my car does not have the original interior, I have the wooden slats that sit on top of the carpet and the thicker alloy spacers. I was not aware of any variation in the "design" of the seat mountings.

Cheers

Gary
79 MGB
gary hansen

Just to add to the confusion, I've found a photo of when I removed my seats.

My slats have two holes at each end and my runners have three holes, so you have a choice of three positions to mount the seat.

I recall that I repositioned the driver's seat some twenty years ago, to give myself more leg room.

As you can see, the passenger seat was fitted fully forward. To move back one position, the slat can be moved backwards and the spacers fitted to the other holes.

To move the seat back two positions, the slat needs to be turned around.

Dave O'Neill 2

Driver's seat runners in 'long-leg' position.

Dave O'Neill 2

Oh, and the mats do appear to have holes large enough for the spacers.

Dave O'Neill 2

And the drivers carpet seems to have the holes much further back than the passengers!
paulh4

Yes, they do appear to. How odd.
Dave O'Neill 2

We never stop learning, Dave - thanks for that update.
Roger in the ACT, no excuses now - you just have to decide which configuration you prefer. If it were me, starting from scratch, I reckon I'd make the thicker spacers and have the slats sit on top of the carpet. Only need 4 holes in the carpet, and easier to remove everything if needed.Regards, John.
J P Hall

John,

Yes, I will need to decide, but now have some options.
Regards
Roger
R Taylor

Ninety minutes, several F bombs, and the drivers seat is back where it belongs.
Dan Hiltz

This thread was discussed between 11/09/2016 and 30/09/2017

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