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Technical: Cylinder Head Bolts: Design Changes On Head & Washer

This technical report discusses cylinder head bolt designs and the inclusion of washers. It notes that washers are included to increase the supporting surface area against the cylinder head and avoid damaging aluminum casting surfaces. The report details the manufacturer's policy of including washers that cannot be pulled through the threaded bolt zone and excluding washers that can be reused. It also explains that some bolt designs now include a flange in the head instead of a separate washer to achieve the same effect, and lists specific part numbers where the bolt length has decreased with this change.

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Robson Matos de Souza
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159 views3 pages

Technical: Cylinder Head Bolts: Design Changes On Head & Washer

This technical report discusses cylinder head bolt designs and the inclusion of washers. It notes that washers are included to increase the supporting surface area against the cylinder head and avoid damaging aluminum casting surfaces. The report details the manufacturer's policy of including washers that cannot be pulled through the threaded bolt zone and excluding washers that can be reused. It also explains that some bolt designs now include a flange in the head instead of a separate washer to achieve the same effect, and lists specific part numbers where the bolt length has decreased with this change.

Uploaded by

Robson Matos de Souza
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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55

TECHNICAL
REPORT
Cylinder head bolts: design
changes on head & washer
TECHNICAL REPORT

PURPOSE
To inform our customers about Ajusa’s washers
inclusion in cylinder head bolts policy and the
design changes about head carried out in some
bolts sets.

INTRODUCTION
Frequently, we find a washer under the head of the cylinder head bolt. The main function of this
washer is to increase the supporting surface against the cylinder head. This way, the closing forces are
better distributed and there is no need to use bigger heads.

Moreover, having an increased contact area against the cylinder head, we avoid damaging its
surface, which is usually made of aluminium casting and therefore has a lower hardness than the
steel of the bolts. We achieve it by lowering the pressure per square centimeter.

The washer inclusion policy in AJUSA bolts is the following:

It will include the washer, in those cases


in which it cannot be pulled out of the bolt
through the threaded zone.

It will not include the washer, in those cases


in which it can be pulled out of the bolt,
understanding that in these cases it can be
reused. It is necessary to check the washer
condition before reusing it. Bolt with Bolt with flange
washer under in its head
On the other hand, some bolts, instead of the head
the washer, include a “flange” together with
the head that has the same function

2
TECHNICAL REPORT

In some part numbers, the original manufacturer In these cases, Ajusa also adapts its bolts to the
changes the original design of the bolt, which new design, being the part numbers involved
turns from having a loose washer to include the following:
it in the head as a flange. When the flange is
included, the length of the bolt stem decreases
(measured form under the head to the threaded
end), because the thickness of the washer is
included.

BOLTS SET HEAD CHANGE L (MM) PREVIOUS L (MM) CURRENT

81002000 178,5 173

81007100 103 99

81007100 85 83,5

81010100 95 91

81010100 60 56

81016100 119 119 121

81017400 146 142

81022300 106 103

81024700 131,5 131 126

81029300 144 140

81033400 & 225 219


81037800

81044800 & 204 200


81045000

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