The 100 Forum

Alwyn, we have modified the bump stop box so it fits over our reinforcement, while still keeping the rubber itself in the same position height wise about the axle as originally. We will have photos next week - They are still modifying it so as to retain the strength.
And given that the box will be mounted directly to the reinforcing bar, we feel that it will be even stronger than the original which was just mounted to those panels.
To be honest. I cannot see the issue. The original bump stop was in the correct position to limited the upwards movement of the original axle. So we have changed to a later axle, but the amount of movement of that axle, and the angle / type of movement, won't change - It is still just an axle mounted in the same position and manner as the original. The axle won't have any more or less movement than the original one, unless it is restricted by the stronger 8 leaf springs, but that is a separate issue. So why do I need to change the bump stop ???? Maybe the later conical bump stop is "better", but that doesn't mean our current one won't work, especiall since it has been strengthened.
Giles

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https://austin-healeypekingtoparis2019.blogspot.com.au/
https://www.facebook.com/austin.healey.73113?

Not wanting to prolong this subject but you may want to make some measurements to check that the top of the spring doesn't contact the body work above it at full bump ...
The factory had problems with that and had to modify both the rear floor sections and the spring boxes in the boot to solve it.

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Michael Salter
Technical Chairman (Big Healeys)
Austin Healey Concours Committee

??? The axle is above the spring. Surely the axle would hit bodywork long before the spring did ? And the damper arm would not allow the axle to travel up that far, would it ?
Or do you mean at the ends of the spring where it is bolted / shackled to the chassis ?
Giles

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https://austin-healeypekingtoparis2019.blogspot.com.au/
https://www.facebook.com/austin.healey.73113?

Giles,
The reason the rebound buffers are there is to stop the axle movement before the shock absorber reaches the limit of its movement. If you were to rely on the shocker arm to limit the axle movement, your shockers would not last five minutes!

Apparently not ... the factory raised the top of the spring clearance boxes and modified the floor behind the rear outriggers ro prevent those areas being damaged ... just sayin'

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Michael Salter
Technical Chairman (Big Healeys)
Austin Healey Concours Committee

Thanks to Curt for posting the pictures of the box that I should have. It has me begging a question though; why don't I use the box I have with the rubber that I should use? They seem to be similar in dimensions and the only thing I can tell is that the original is slightly recessed on the vertical plane. I'm not sure I care about that. If you looked at my blog you'd realise that I am just a school teacher with a single garage (in the UK these are small), a hammer and a chisel or two who is doing anything but rebuilding a concours car. So, other than originality is there any other reason why I should buy a new set of early BN1 boxes?

I just got some information and photos from Craig Rice. More to follow soon. Here is his email to me...

<My BN1 was restored in 2000. My Bump Boxes came from AH Spares & fit without modification (see attached photos). Bump Boxes should have holes in bottom corners to drain water & dispose of road debris. I looked at Bump Boxes from Moss, AH Spares & AHead4Healeys. All will require grinding off the lower corners to function properly.

Also is attached is the info sheet for the BN1 Axle Bumpers that I supply. The SS base is 4 3/4" x 1 15/16" with 5/16" holes centered at 4 1/8". I used all SS hardware for mounting.>

Cheers,

Curt

As an FYI, drawings of the Spiral Bevel and Hypoid Bevel axles.

Steve,

You wrote... "So, other than originality is there any other reason why I should buy a new set of early BN1 boxes?"

To help answer your question, first ask this question... "If the early Spiral Bevel bump box and rubber would have worked when the factory changed to the Hypoid bevel axle, then why did they go to the expense of changing the pump stop box and rubber?" Could it be that the old style bump box and rubber would not work properly with the new rear axle, and vice versa?

In fact, this is a question that Giles should be thinking about.

Secondly, If you try and put the later Hypoid bevel bump box on the car, you will at least have to drill new holes in the chassis if not do more modifications. Then there is the issue of... Will the conical bump box designed for the Hypoid Bevel axle even fit on a Spiral Bevel Axle setup? If not, and that is my guess, then just buy the correct parts.

As an aside, I don't understand your reluctance to even contact Ahead4Healeys to see if they would take your parts back! Let them make that decision. If you don't even ask them, then you've made the decision yourself. Several folks have contacted me off "List" to say that they thought that good customer service might dictate that Ahead4Healeys would entertain an exchange, even if the part was painted. Heck if the part came in bare metal, put some paint stripper on and remove what you've painted. All they can do is say no, but you don't know that they will.

We're not talking Concours here, just doing good restoration/mechanical work! Heck, if you took your daily driver car to a mechanic, and found out that they put the wrong parts on your car, cobbling them together to make them "almost" work because they ordered the wrong part, and then did not want to return that part and order the correct ones, I think you'd be a bit cross with them. I know I'd be pissed off.

Curt

There are other issues here.

I have painted the inner bodywork and during the welding work I had to modify the position of one of the captive nuts on the inner wheel arch on one side of the car to get the box to fit. I was vaguely intrigued that I only had to do one side and wondered if the inner panels were correct for the car at the time but as they came with the car I had no way of knowing or investigating. I am very reluctant to go anywhere near changing the positions of the captive nuts at this stage.

I did put some extra holes in the bottom of the boxes for drainage as it looks like a complete rust trap to me so in addition to the liberal coating of POR15 they are modified. I wouldn't be pleased to receive them from the supplier so I am unprepared to expect them to sell them to somebody else. I do regularly send parts back to A-head 4 Healeys but only parts that I would be happy to receive as new myself.

Thank you for the photos.

Or, just maybe, could it be that AH found out through experience that the new conical bump stop just worked "a bit better" than the old style box, so decided to upgrade ? In other words, the old one works fine, but we have found one that works better so will improve our car accoridingly.

If they both work, then it is only an issue of originality. The fact that one works "better" than the other is a different discussion.

Believe me, I am thinking about it Curt. But as with all these issues there are so many conflicting opinions, and as Steve mentions, some of us are restricted by financial considerations rather than originality ones, and as we have already purchased our replacement bump boxes (and maybe modified them to where they can no longer be returned), we are not in a position to just go out and buy another different one unless there is a very good reason. I need proof that ours won't work before I go spending (even) more money !! We will have to do a lot of work on checking axle movements etc as soon as we have everything back in the car so we know where the ride heights will be.

Giles

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https://austin-healeypekingtoparis2019.blogspot.com.au/
https://www.facebook.com/austin.healey.73113?

Giles,

You wrote..."If they both work, then it is only an issue of originality."

The operative word is IF. If the early bump stop setup worked on the later Hypoid bevel axle, then why did the factory change the bump stop design? My point is that BMC would not have gone to the trouble, time and expense if the old bump stop system worked on the newer axle.

-Curt

Perhaps the bump stops changed with the introduction of the hypoid axle because the new stops were used when the axle was fitted to other cars in the BMC range. It would be interesting to see the bump stop arrangement on a Devon or Hampshire, Austins that used the spiral bevel axle.

OK, so I am 3/4 of the way through converting from the 4-bolt Spiral-Bevel axle to the Hypoid version (My late BN1 was supposed to have come with the Hypoid axle anyway) You actually have a very good picture of the early bump-stop above, you just have to look at the far side of the top picture. That is it. Do not attempt to use both the conical Hypoid type bump stops as they are not compatible. If you are using the conical bumpers on the axel you need to replace the Spiral bevel bump-stop with the one for the Hypoid axel. They have identical bolt patters so they will bolt right in. The difference is that the Hypoid version is not quite as thick and has a flat steel surface for the conical bumper to hit under full rebound, the rubber part of the spiral bevel bump-stop will interfere with the correct function (you will have no suspension travel) if you try t use them together. I know you can get the Hypoid Bump-Stop boxes from Moss (https://mossmotors.com/bump-stop-box-hypoid-axle?assoc=4552) and I am sure from any of the other usual suspects (AHSpares, Victoria British, etc.) Note, they used the same ones from late BN1 to early BJ8.

This is the picture I was talking about:


Oh, and one side note, there are no "Captivated" nuts holding these bump-stops in, they use four bolts with nuts and lock washers (two from the side on the top and two from underneath front and rear)

Good Luck!
Dan M.



Edited 1 time(s). Last edit at 2018-01-29 04:03 PM by DTDuck.

Giles

You wrote...

"Can't believe how compliated some of these seemingly minor issues become !!"

No, it's not complicated at all...

- Spiral bevel rear axle... square rubber bump rubber attached to the bump box,

- Hypoid Bevel rear axle, conical rubber bump rubber attached to the axle and bump box attached to the body.

All clearly spelled out in exploded diagrams, and by separate part numbers, and then clearly delineated by chassis number in any of the following free catalogs, Moss, SC Parts, AHead4 Healeys, AH Spares. Rather simple!!

Now, if you don't want to do that, then careful measurement and testing of the of mixed and matched components must be done to ensure that all parts work as intended. Especially on a car that will be subjected to extreme and potentially hazardous road conditions, in a remote Country, far from home with limited resupply options. But you already know this.

Just look at the careful engineering that fellow poster Michael Salter did with AHX-12, a highly modified but successful early BN1.

http://www.acmefluid.com.au/larry/ahx12.html

http://www.netbug.net/blogmichael/2006/12/29/revised-rear-suspension-for-ahx12/

Your job should be easier since the rules spell out what modifications you can and cannot perform. "The Devils in the details"

This is my last post on this subject.

-Curt